WO2023190751A1 - Thermally conductive sheet and method for producing thermally conductive sheet - Google Patents

Thermally conductive sheet and method for producing thermally conductive sheet Download PDF

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Publication number
WO2023190751A1
WO2023190751A1 PCT/JP2023/012964 JP2023012964W WO2023190751A1 WO 2023190751 A1 WO2023190751 A1 WO 2023190751A1 JP 2023012964 W JP2023012964 W JP 2023012964W WO 2023190751 A1 WO2023190751 A1 WO 2023190751A1
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Prior art keywords
thermally conductive
conductive sheet
sheet
less
molded body
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PCT/JP2023/012964
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French (fr)
Japanese (ja)
Inventor
栄治 太田
圭佑 武笠
佑介 久保
育巳 佐藤
雅彦 伊東
セルゲイ ボロトフ
直哉 大野
大地 森
真理奈 戸端
義知 宮崎
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デクセリアルズ株式会社
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Priority claimed from JP2023053547A external-priority patent/JP2023152951A/en
Publication of WO2023190751A1 publication Critical patent/WO2023190751A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K7/00—Constructional details common to different types of electric apparatus
    • H05K7/20—Modifications to facilitate cooling, ventilating, or heating

Definitions

  • the present technology relates to a thermally conductive sheet and a method for manufacturing a thermally conductive sheet.
  • This application is based on Japanese Patent Application No. 2022-058407 filed in Japan on March 31, 2022 and Japanese Patent Application No. 2023-053547 filed in Japan on March 29, 2023. These applications are incorporated by reference into this application.
  • thermally conductive sheets that meet such requirements include thermally conductive sheets using anisotropic thermally conductive materials (see, for example, Patent Documents 1 to 6).
  • Carbon fiber which is an example of an anisotropic thermally conductive material, is an anisotropic filler having a thermal conductivity of about 600 to 1200 W/(m ⁇ K) in the fiber direction. It is known that thermal conductivity can be dramatically improved by orienting the fiber direction of carbon fibers in the thickness direction of a thermally conductive sheet, which is the direction of heat transfer.
  • thermally conductive sheet with oriented carbon fibers In order to achieve low thermal resistance using a thermally conductive sheet with oriented carbon fibers, it is also important to consider the contact thermal resistance of the thermally conductive sheet. However, even if carbon fibers have high thermal conductivity, when viewed from the entire thermally conductive sheet, the contact between the adherend and the carbon fibers is point contact, and even if the carbon fibers sink into the binder resin due to pressure, There is a problem that air gets mixed in between the thermally conductive sheet and the adherend.
  • thermal resistance is thermal resistance that occurs between a thermally conductive sheet and an adherend.
  • the contact thermal resistance tends to increase as the thickness decreases, and as a result, the total thermal resistance value (thermal conduction The thermal resistance value (the sum of the thermal resistance value of the sheet itself plus the contact thermal resistance value) also tends to increase.
  • the present technology has been proposed in view of such conventional circumstances, and provides a thermally conductive sheet with a reduced total thermal resistance value.
  • the inventors of the present application have determined whether or not to suppress the average height Spk of the protruding peaks in a thermally conductive sheet containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin. , or suppress the value of the average height Spk of the protruding peaks relative to the sum (Spk+Svk) of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys, and also suppress the root mean square gradient of the protruding peaks. It has been found that the above-mentioned problems can be solved by suppressing Sdq.
  • This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin.
  • the average height Spk of the protruding peaks of the thermally conductive sheet is less than 3.5 ⁇ m, as measured using a microscope according to ISO 25178.
  • This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin.
  • the volume Vmp of the protruding peaks of the thermally conductive sheet is 0.16 ml/m 2 or less, as measured using a microscope according to ISO 25178.
  • This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin.
  • the value of the average height Spk of the protruding peaks (Spk/( Spk+Svk)) is 40% or less, and the root mean square gradient Sdq of the thermally conductive sheet is 1.1 or less.
  • the method for manufacturing a thermally conductive sheet involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet.
  • the step of obtaining a thermally conductive sheet the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 1 below.
  • Condition 1 The average height Spk of the protruding peaks is less than 3.5 ⁇ m, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the method for manufacturing a thermally conductive sheet involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet.
  • the step of obtaining a thermally conductive sheet the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 2 below.
  • the volume Vmp of the protruding peak is 0.16 ml/m 2 or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the method for manufacturing a thermally conductive sheet involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet. In the step of obtaining a thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 3 below.
  • the present technology can provide a thermally conductive sheet with a reduced total thermal resistance value.
  • FIG. 1 is a sectional view showing an example of a thermally conductive sheet.
  • FIG. 2 is a cross-sectional view showing an example of the surface of a thermally conductive sheet.
  • FIG. 3 is a perspective view of a brush that is an example of a polishing member.
  • FIG. 4 is a perspective view for explaining an example of a method of polishing the surface of a sheet-like molded body with a brush.
  • FIG. 5 is a perspective view for explaining an example of a method of continuously polishing the surfaces of a plurality of sheet-like molded bodies with a brush.
  • FIG. 6 is a cross-sectional view showing an example of a semiconductor device to which a thermally conductive sheet is applied.
  • FIG. 1 is a sectional view showing an example of a thermally conductive sheet.
  • FIG. 2 is a cross-sectional view showing an example of the surface of a thermally conductive sheet.
  • FIG. 3 is a perspective view of a brush that is an example
  • the average particle diameter (D50) refers to the cumulative value when a cumulative curve of particle diameter values is calculated from the small particle diameter side of the particle diameter distribution, assuming that the entire particle diameter distribution is 100%. This refers to the particle diameter when 50%.
  • the particle size distribution (particle size distribution) in this specification is determined on a volume basis. Examples of methods for measuring particle size distribution include a method using a laser diffraction type particle size distribution analyzer.
  • FIG. 1 is a sectional view showing an example of a thermally conductive sheet 1 according to the present technology.
  • the thermally conductive sheet 1 is made of a cured product of a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4 other than the anisotropic thermally conductive material 3.
  • the thermally conductive sheet 1 has an anisotropic thermally conductive material 3 and an inorganic filler 4 dispersed in a binder resin 2, and the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1. There is.
  • the fact that the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1 means that, for example, out of all the anisotropic thermally conductive materials 3 in the thermally conductive sheet 1, the The proportion of the anisotropic thermally conductive material 3 whose long axis is oriented in the thickness direction B of the conductive sheet 1 is 50% or more, may be 55% or more, or may be 60% or more, It may be 65% or more, 70% or more, 80% or more, 90% or more, 95% or more, 99% or more. It's okay.
  • the long axis of the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1. It may be in the range of 60 to 120 degrees with respect to A, it may be in the range of 70 to 100 degrees, or it may be 90 degrees (substantially perpendicular).
  • a thermally conductive sheet 1 which is a first embodiment of the present technology, is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2.
  • the average height Spk of the protruding peaks is less than 3.5 ⁇ m, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x lens (hereinafter also referred to as satisfying Condition 1).
  • the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
  • a thermally conductive sheet 1 according to a second embodiment of the present technology is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2.
  • the volume Vmp of the protruding peak measured according to ISO 25178 using a scanning white interference microscope with a 20x lens is 0.16 ml/m 2 or less (hereinafter also referred to as satisfying condition 2).
  • satisfying condition 2 the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
  • a thermally conductive sheet 1 according to a third embodiment of the present technology is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2.
  • the ratio of the protruding peaks to the sum of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys (Spk+Svk), which is measured according to ISO 25178 using a scanning white interference microscope with a 20x lens.
  • the value of the average height Spk (Spk/(Spk+Svk)) is 40% or less, and the root mean square gradient Sdq is 1.1 or less (hereinafter also referred to as satisfying condition 3).
  • the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
  • the thermally conductive sheet 1 satisfies at least one of Conditions 1 to 3, may satisfy two of Conditions 1 to 3, and may satisfy all of Conditions 1 to 3. It's okay. Further, it is preferable that the thermally conductive sheet 1 further satisfies the conditions described below in addition to conditions 1 to 3.
  • the thermally conductive sheet 1 may have an average height Spk of the protruding peaks of 3.0 ⁇ m or less as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens; 2. It may be 6 ⁇ m or less, 2.2 ⁇ m or less, 1.5 ⁇ m or less, 1.0 ⁇ m or less, 0.9 ⁇ m or less, 0. It may be 8 ⁇ m or less, 0.7 ⁇ m or less, 0.6 ⁇ m or less, or 0.5 ⁇ m or less.
  • the lower limit of the average height Spk of the protruding peaks of the thermally conductive sheet 1 is not particularly limited, but may be, for example, 0.4 ⁇ m or more.
  • the average height Spk of the protruding peaks of the thermally conductive sheet 1 may be in the range of 0.494 to 2.967 ⁇ m, may be in the range of 0.494 to 2.642 ⁇ m, and may be in the range of 0.494 to 2.642 ⁇ m. ⁇ 2.342 ⁇ m, 0.494 ⁇ 2.189 ⁇ m, 0.494 ⁇ 2.153 ⁇ m, 0.494 ⁇ 0.562 ⁇ m It may be a range. It is preferable that the average height Spk of the protruding peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the average height Spk of the protruding peaks on both surfaces may satisfy the above-mentioned range.
  • the average height Spk of the protruding peaks of the thermally conductive sheet 1 can be measured by the method described in Examples described below. Note that the average height Spk of the protruding peaks and each value measured according to ISO 25178, which will be described later, is affected by the magnification of the objective lens of the scanning white interference microscope.
  • the thermally conductive sheet 1 may have a volume Vmp of the protruding peaks of 0.15 ml/m 2 or less as measured in accordance with ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20 times. .14ml/ m2 or less, 0.11ml/ m2 or less, 0.08ml/ m2 or less, 0.06ml/ m2 or less , 0.04 ml/m 2 or less, or 0.02 ml/m 2 or less.
  • the lower limit of the volume Vmp of the protruding peaks of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0.01 ml/m 2 or more, or 0.02 ml/m 2 or more.
  • the volume Vmp of the protruding peak portion may be in the range of 0.027 to 0.137 ml/ m2 , or may be in the range of 0.027 to 0.134 ml/ m2 . It may be in the range of 0.027 to 0.114 ml/ m2 , it may be in the range of 0.027 to 0.106 ml/ m2 , or it may be in the range of 0.027 to 0.102 ml/m2. It may be in the range of 2 .
  • the volume Vmp of the protruding peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the volume Vmp of the protruding peaks on both surfaces may satisfy the above-mentioned range.
  • the thermally conductive sheet 1 may have (Spk/(Spk+Svk)) of 36% or less, 30% or less, or 29% or less.
  • the lower limit of (Spk/(Spk+Svk)) of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 10% or more, 15% or more, or 20% or more. It may be 25% or more.
  • (Spk/(Spk+Svk)) of the thermally conductive sheet 1 may be in the range of 28.22 to 45.29%, or may be in the range of 28.22 to 39.78%, for example.
  • the thermally conductive sheet 1 may be in the range of 28.22 to 39.69%, may be in the range of 28.22 to 35.27%, or may be in the range of 28.22 to 34.90%. .
  • Spk/(Spk+Svk) on at least one surface satisfies the above-mentioned range, and Spk/(Spk+Svk) on one surface and the other surface may satisfy the above-mentioned range.
  • the average depth Svk of the protruding valleys may be 5.5 ⁇ m or less, or 4.5 ⁇ m or less. It may be 4.0 ⁇ m or less, 3.5 ⁇ m or less, 3.0 ⁇ m or less, 2.5 ⁇ m or less, 2.0 ⁇ m or less, The thickness may be 1.5 ⁇ m or less, or 1.1 ⁇ m or less.
  • the lower limit of the average depth Svk of the protruding valleys of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 1.0 ⁇ m or more.
  • the average depth Svk of the protruding valleys of the thermally conductive sheet 1 may be in the range of 1.165 to 5.156 ⁇ m, may be in the range of 1.165 to 4.490 ⁇ m, and may be in the range of 1.165 to 4.490 ⁇ m. 4.291 ⁇ m, 1.165 to 3.711 ⁇ m, and 1.165 to 3.559 ⁇ m. It is preferable that the average depth Svk of the protruding troughs on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the average depth Svk of the protruding troughs on both surfaces may satisfy the above-mentioned range.
  • the average depth Svk of the protruding valleys of the thermally conductive sheet 1 can be measured by the method described in Examples described below.
  • the root mean square gradient Sdq of the thermally conductive sheet 1 is the local unevenness of the surface of the thermally conductive sheet 1 measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens. Represents the average size of the slope (differential of shape). For example, when the surface of the thermally conductive sheet 1 is completely flat, the root mean square gradient Sdq is zero. Moreover, the steeper the surface of the thermally conductive sheet 1 is, the larger the root mean square gradient Sdq becomes.
  • the thermally conductive sheet 1 may have a root mean square gradient Sdq of 1.0 or less, 0.9 or less, 0.8 or less, or 0.7 or less. It may be 0.6 or less, 0.5 or less, or 0.4 or less.
  • the lower limit of the root mean square gradient Sdq of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0.1 or more, or 0.2 or more.
  • the root mean square gradient Sdq of the thermally conductive sheet 1 may be in the range of 0.278 to 1.074, may be in the range of 0.278 to 0.733, or may be 0.278. 0.730, 0.278 to 0.578, or 0.278 to 0.565. It is preferable that the root mean square gradient Sdq of at least one surface of the thermally conductive sheet 1 satisfies the above range, and the root mean square gradient Sdq of both surfaces may satisfy the above range.
  • the thermally conductive sheet 1 has an arithmetic mean curvature Spc (1/mm) of the mountain peak and a developed area ratio Sdr ( %), and when a graph is created in which the values are plotted with Spc on the horizontal axis and Sdr on the vertical axis, it is preferable that Spc and Sdr satisfy the following formula 1. In this manner, the thermally conductive sheet 1 satisfies Expression 1 in addition to Conditions 1 to 3, thereby making it possible to more effectively reduce the total thermal resistance value.
  • Formula 1: Y 0.0143X-(12.329 ⁇ 10)
  • the developed area ratio Sdr of the interface of the thermally conductive sheet 1 is measured according to ISO 25178, and represents how much the developed area (surface area) of the defined region increases relative to the area of the defined region. . For example, when the surface of the thermally conductive sheet 1 is completely flat, the developed area ratio Sdr of the interface is 0%.
  • the thermally conductive sheet 1 preferably has an interface developed area ratio Sdr of 40% or less, may be 35% or less, may be 30% or less, may be 25% or less, It may be 20% or less, 19% or less, or 18% or less.
  • the lower limit of the developed area ratio Sdr of the interface of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0% or more, 2% or more, or 10% or more. Good too.
  • the developed area ratio Sdr of the interface of the thermally conductive sheet 1 may be in the range of 0 to 45.00%, 0 to 40.00%, or 3.45 to 45.00%, for example.
  • the developed area ratio Sdr of the interface on at least one surface of the thermally conductive sheet 1 satisfies the above range, and the developed area ratio Sdr of the interfaces on both surfaces may satisfy the above range.
  • the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. Represents the average of the principal curvatures of points.
  • the larger the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 the sharper the point of contact with another object on the thermally conductive sheet.
  • the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is preferably 3500 (1/mm) or less, may be 3200 (1/mm) or less, and may be 2800 (1/mm) or less. 2500 (1/mm) or less, 2100 (1/mm) or less, 1700 (1/mm) or less, 1500 (1/mm) or less It may be 1200 (1/mm) or less, or 1000 (1/mm) or less.
  • the lower limit of the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0 (1/mm) or more, or 500 (1/mm) or more. However, it may be 900 (1/mm) or more.
  • the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 may be, for example, in the range of 0 to 3500 (1/mm), or may be in the range of 927 to 3136 (1/mm), It may be in the range of 927 to 2475 (1/mm), it may be in the range of 927 to 2290 (1/mm), it may be in the range of 927 to 2066 (1/mm), or it may be in the range of 927 to 2066 (1/mm). , 927 to 1937 (1/mm).
  • the arithmetic mean curvature Spc of the peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the arithmetic mean curvature Spc of the peaks on both surfaces may satisfy the above-mentioned range.
  • the thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 0.70 kgf/cm 2 measured according to ASTM-D5470.
  • the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.230°C ⁇ cm 2 /W when pressurized with 0.70 kgf/cm 2 , and not more than 0.220°C ⁇ cm 2 / W. It may be 0.200°C ⁇ cm 2 /W or less, it may be 0.190°C ⁇ cm 2 /W or less, or it may be 0.160°C ⁇ cm 2 /W or less. It's okay.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.312° C.cm 2 /W or less when a pressure of 0.7 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.525° C.cm 2 /W or less when 0.7 kgf/cm 2 is applied when the thickness is 2.0 mm.
  • the lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 0.70 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, such as It can be 0.05° C.cm 2 /W or more.
  • the thermally conductive sheet 1 has a total thermal resistance value of 0.143 to 0.212° C.cm 2 /W when a pressure of 0.70 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.143 to 0.200°C ⁇ cm 2 /W, or may be in the range of 0.143 to 0.185°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 1.4 kgf/cm 2 measured according to ASTM-D5470.
  • the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.208°C ⁇ cm 2 /W when pressurized with 1.4 kgf/cm 2 , and not more than 0.200°C ⁇ cm 2 /W. It may be 0.190°C ⁇ cm 2 /W or less, it may be 0.180°C ⁇ cm 2 /W or less, or it may be 0.170°C ⁇ cm 2 /W or less.
  • the temperature may be 0.160° C.cm 2 /W or less.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.289° C.cm 2 /W or less when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.601° C.cm 2 /W or less when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 2.0 mm.
  • the lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 1.4 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, such as It can be 0.05° C.cm 2 /W or more.
  • the thermally conductive sheet 1 has a total thermal resistance value of 0.128 to 0.179° C.cm 2 /W when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.128 to 0.166°C ⁇ cm 2 /W, or may be in the range of 0.128 to 0.165°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 2.1 kgf/cm 2 measured according to ASTM-D5470.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.200°C ⁇ cm 2 /W or less when 2.1 kgf/cm 2 is applied, or 0.190°C ⁇ cm 2 / W or less. It may be 0.180°C ⁇ cm 2 /W or less, it may be 0.170°C ⁇ cm 2 /W or less, or it may be 0.160°C ⁇ cm 2 /W or less.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.303° C.cm 2 /W or less when pressurized with 2.1 kgf/cm 2 when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.682° C.cm 2 /W or less when a pressure of 2.1 kgf/cm 2 is applied when the thickness is 2.0 mm.
  • the lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 2.1 kgf/cm 2 is preferably a lower value, exceeding 0°C.cm 2 /W, for example, 0.05°C. cm 2 /W or more.
  • the thermally conductive sheet 1 has a total thermal resistance value of 0.126 to 0.161° C.cm 2 /W when a pressure of 2.1 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.126 to 0.155°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 2.8 kgf/cm 2 measured according to ASTM-D5470.
  • the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.190°C ⁇ cm 2 /W when pressurized with 2.8 kgf/cm 2 , and not more than 0.180°C ⁇ cm 2 /W. It may be 0.170°C ⁇ cm 2 /W or less, it may be 0.160°C ⁇ cm 2 /W or less, or it may be 0.150°C ⁇ cm 2 /W or less. It may be 0.140°C ⁇ cm 2 /W or less, or it may be 0.130°C ⁇ cm 2 /W or less.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.327° C.cm 2 /W or less when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.732° C.cm 2 /W or less when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 2.0 mm.
  • the lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 2.8 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example It can be 0.05° C.cm 2 /W or more.
  • the thermally conductive sheet 1 has a total thermal resistance value of 0.122 to 0.157° C.cm 2 /W when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.122 to 0.153°C ⁇ cm 2 /W, or may be in the range of 0.122 to 0.150°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 3.5 kgf/cm 2 measured according to ASTM-D5470.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.180°C ⁇ cm 2 /W or less when pressurized with 3.5 kgf/cm 2 , or 0.170°C ⁇ cm 2 / W or less. It may be 0.160°C ⁇ cm 2 /W or less, it may be 0.150°C ⁇ cm 2 /W or less, or it may be 0.140°C ⁇ cm 2 /W or less. It may be 0.130°C ⁇ cm 2 /W or less, or it may be 0.120°C ⁇ cm 2 /W or less.
  • the thermally conductive sheet 1 may have a total thermal resistance value of 0.350° C.cm 2 /W or less when pressurized with 3.5 kgf/cm 2 when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.765° C.cm 2 /W or less when a pressure of 3.5 kgf/cm 2 is applied when the thickness is 2.0 mm.
  • the lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 3.5 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example It can be 0.05° C.cm 2 /W or more.
  • the thermally conductive sheet 1 has a total thermal resistance value of 0.119 to 0.156° C.cm 2 /W when pressurized with 3.5 kgf/cm 2 when the thickness is 0.3 mm. It may be in the range of 0.119 to 0.151°C ⁇ cm 2 /W, or may be in the range of 0.119 to 0.148°C ⁇ cm 2 /W.
  • FIG. 2 is a cross-sectional view showing an example of the surface of the thermally conductive sheet 1.
  • at least one surface of the thermally conductive sheet 1 is a polished surface, and it is preferable that this polished surface has polishing residue 5.
  • at least one surface of the thermally conductive sheet 1 is a polished surface, and it is preferable that the polished surface has a polishing residue 5 made of a constituent material of the thermally conductive composition detached by polishing.
  • the polishing residue 5 is, for example, a lump made of a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4.
  • the polishing residue 5 is present on the surface of the thermally conductive sheet 1 to such an extent that the thermally conductive sheet 1 satisfies conditions 1 to 3, for example, the polishing residue 5 is present on the entire surface.
  • the polishing residue 5 may be present almost uniformly over the entire surface, or the polishing residue 5 may be present partially (in the form of islands) on the surface, for example, as shown in FIG.
  • Whether or not the thermally conductive sheet 1 has polishing residues 5 on the surface can be determined, for example, by pasting an adhesive tape on the surface of the thermally conductive sheet 1 and then peeling off the adhesive tape. You can check whether it is transferred or not.
  • the average particle diameter and maximum particle diameter of the polishing residue 5 are not too large.
  • the average particle diameter of the polishing residue 5 may be 50 ⁇ m or less, 40 ⁇ m or less, 35 ⁇ m or less, 30 ⁇ m or less, or 20 ⁇ m or less.
  • the thickness may be 15 ⁇ m or less, 10 ⁇ m or less, or in the range of 0.5 to 40 ⁇ m.
  • the average particle diameter of the polishing residue 5 in the case of the irregularly shaped polishing residue 5, the length (diameter) of the longest part of the particle is taken into consideration.
  • the maximum particle diameter of the polishing residue 5 may be, for example, 100 ⁇ m or less, 90 ⁇ m or less, 80 ⁇ m or less, 70 ⁇ m or less, or 50 ⁇ m or less. It may be in the range of ⁇ 100 ⁇ m.
  • the thickness of the thermally conductive sheet 1 can be appropriately selected depending on the purpose, and may be, for example, 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more. It may be 0.3 mm or more. Further, the upper limit of the thickness of the thermally conductive sheet 1 can be, for example, 5 mm or less, may be 4 mm or less, may be 3 mm or less, may be 2 mm or less, and may be 1 mm or less. It may be 0.5 mm or less.
  • the thickness of the thermally conductive sheet 1 can be determined by measuring the thickness B of the thermally conductive sheet 1 at five arbitrary locations and calculating the arithmetic mean value thereof.
  • the thermally conductive sheet 1 As the thermal resistance of the sheet itself becomes lower, the contribution of the contact thermal resistance to the total thermal resistance generated between the sheet and the adherend tends to increase. As mentioned above, this tendency becomes more pronounced as the sheet becomes thinner. In other words, in the thermally conductive sheet 1, as the thermal conductivity of the sheet itself increases, the proportion of the contact thermal resistance in the total thermal resistance value increases. In this technology, the contact thermal resistance is reduced by the thermally conductive sheet 1 in which the anisotropic thermally conductive material 3 is oriented in the thickness direction, by satisfying at least one of the conditions 1 to 3 described above. As a result, the total thermal resistance value can be reduced.
  • the binder resin 2, the anisotropic thermally conductive material 3, and the inorganic filler 4, which are examples of the structure of the thermally conductive sheet 1, will be explained.
  • Binder resin 2 is for holding anisotropic thermally conductive material 3 and inorganic filler 4 within thermally conductive sheet 1 .
  • the binder resin 2 is selected depending on the properties required of the thermally conductive sheet 1, such as mechanical strength, heat resistance, and electrical properties.
  • the binder resin 2 can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins.
  • thermoplastic resins include polyethylene, polypropylene, ethylene- ⁇ olefin copolymers such as ethylene-propylene copolymers, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymers, Fluoropolymers such as polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer Polymer (ABS) resin, polyphenylene-ether copolymer (PPE) resin, modified PPE resin, aliphatic polyamide, aromatic polyamide, polyimide, polyamideimide, polymethacrylic
  • Examples include acid esters, polyacrylic acids, polycarbonates, polyphenylene sulfides, polysulfones, polyethersulfones, polyethernitrile, polyetherketones, polyketones, liquid crystal polymers, and ionomers.
  • thermoplastic elastomers examples include styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and vinyl chloride-based thermoplastic elastomers. , polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like.
  • thermosetting resin examples include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, addition reaction type silicone resin, condensation reaction type silicone resin, and the like.
  • crosslinked rubber examples include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Examples include chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, and silicone rubber.
  • silicone resin is preferable, for example, from the viewpoint of adhesion between the heat generating surface of the heat generating element (for example, an electronic component) and the heat sink surface.
  • silicone resin for example, a two-component type silicone resin containing silicone (polyorganosiloxane) having an alkenyl group as the main component, a main resin containing a curing catalyst, and a curing agent having a hydrosilyl group (Si-H group) is used.
  • Addition reaction type silicone resins can be used.
  • silicone having an alkenyl group a polyorganosiloxane having at least two alkenyl groups in one molecule can be used.
  • the curing catalyst is a catalyst for promoting an addition reaction between an alkenyl group in the silicone having an alkenyl group and a hydrosilyl group in the curing agent having a hydrosilyl group.
  • the curing catalyst include catalysts well known as catalysts used in hydrosilylation reactions, such as platinum group curing catalysts, such as simple platinum group metals such as platinum, rhodium, and palladium, platinum chloride, and complexes of platinum and organic compounds. etc. can be used.
  • a polyorganosiloxane having a hydrosilyl group for example, a polyorganosiloxane having a hydrosilyl group (organohydrogenpolysiloxane having at least two hydrogen atoms in one molecule directly bonded to a silicon atom) can be used.
  • the ratio of the main component (silicone main component) to the curing agent component that is, the polyorganosiloxane having a vinyl group and
  • the mixing ratio of the polyorganosiloxane having a hydrosilyl group is not particularly limited, and may be such that the hydrosilyl group is in the range of 0.3 to 0.9 mol per mol of the vinyl group.
  • the mixing ratio may be in the range of 4 to 0.7 mol.
  • the content of the binder resin 2 in the thermally conductive sheet 1 is not particularly limited, and can be appropriately selected depending on the purpose.
  • the content of the binder resin 2 in the thermally conductive sheet 1 may be 20 volume% or more, may be 24 volume% or more, may be 28 volume% or more, or may be 30 volume%.
  • the content may be more than 32% by volume.
  • the upper limit of the content of the binder resin 2 in the thermally conductive sheet 1 can be 60 volume% or less, may be 50 volume% or less, or may be 40 volume% or less, It may be 38 volume% or less, 35 volume% or less, 32 volume% or less, or 30 volume% or less.
  • the content of the binder resin 2 in the thermally conductive sheet 1 can be, for example, in the range of 24 to 32% by volume, and can also be in the range of 24 to 28% by volume.
  • the binder resin 2 may be used alone or in combination of two or more. When using two or more types of binder resins 2, it is preferable that the total amount thereof satisfies the above-mentioned content.
  • the anisotropic thermally conductive material 3 is a thermally conductive material that has anisotropy in shape.
  • an example of the anisotropic thermally conductive material 3 is a thermally conductive filler having a long axis and a short axis, and a specific example is a fibrous filler.
  • the fibrous filler which is an example of the anisotropic thermally conductive material 3, is not particularly limited as long as it is fibrous and has the necessary thermal conductivity, and examples thereof include carbon fibers, aluminum nitride whiskers, and the like. In the following, a case where carbon fiber is used as the anisotropic thermally conductive material 3 will be described in detail as an example.
  • Anisotropic thermally conductive material 3 is a shape that has a long axis and a short axis, the lengths of the long axis and the short axis are different, and the aspect ratio (average major axis length/average short axis length) exceeds 1. including those that are.
  • the anisotropic thermally conductive material 3 may be used alone or in combination of two or more.
  • carbon fiber examples include pitch-based carbon fiber, PAN-based carbon fiber, carbon fiber obtained by graphitizing PBO fiber, arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (catalytic chemical vapor deposition method) Carbon fibers synthesized by a method such as a carbon fiber growth method) can be used. Among these, pitch-based carbon fibers are preferred from the viewpoint of thermal conductivity.
  • the average fiber length (average major axis length) of the anisotropic thermally conductive material 3 can be, for example, 50 to 250 ⁇ m, and may be 75 to 220 ⁇ m. Further, the average fiber diameter (average minor axis length) of the anisotropic thermally conductive material 3 can be appropriately selected depending on the purpose, and can be, for example, 4 to 20 ⁇ m, or 5 to 14 ⁇ m. Good too.
  • the aspect ratio of the anisotropic thermally conductive material 3 can be appropriately selected depending on the purpose. For example, from the viewpoint of thermal conductivity, it can be set to 8 or more, and may be in the range of 9 to 30. .
  • the average major axis length and average minor axis length of the anisotropic thermally conductive material 3 can be measured using, for example, a microscope or a scanning electron microscope (SEM).
  • the content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, 5% by volume or more, and can be 10% by volume or more. It may be 14 volume% or more, 20 volume% or more, 22 volume% or more, 24 volume% or more, 26 volume% or more. It's okay. Further, from the viewpoint of formability of the thermally conductive sheet 1, the content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, 30% by volume or less, and 28% by volume or less. There may be.
  • the content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, in the range of 26 to 29% by volume, and can also be in the range of 26 to 28% by volume.
  • the inorganic filler 4 is a thermally conductive filler other than the anisotropic thermally conductive material 3.
  • the inorganic filler 4 includes, for example, spherical, powdery, granular, and other thermally conductive fillers.
  • the material of the inorganic filler 4 is preferably a ceramic filler, for example, and specific examples include aluminum oxide (alumina, sapphire), aluminum nitride, aluminum, aluminum hydroxide, and nitride. Examples include boron.
  • the inorganic filler 4 may be used alone or in combination of two or more. For example, as the inorganic filler 4, two or more types of thermally conductive fillers having different average particle diameters may be used in combination.
  • the inorganic filler 4 is at least one selected from aluminum oxide, aluminum nitride, and aluminum, taking into consideration the thermal conductivity of the thermally conductive sheet 1 and the specific gravity of the thermally conductive sheet 1. It is preferable that there be.
  • aluminum oxide and aluminum nitride may be used together, or aluminum oxide, aluminum nitride, and aluminum may be used together.
  • the average particle diameter of aluminum nitride may be in the range of 0.1 to 10 ⁇ m, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, may be in the range of 0.5 to 5 ⁇ m, and may be in the range of 0.5 to 5 ⁇ m. The range may be 3 ⁇ m or 0.5 to 2 ⁇ m.
  • the average particle diameter of aluminum oxide can be in the range of 0.1 to 10 ⁇ m, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, and may be in the range of 0.1 to 8 ⁇ m, and may be in the range of 0.1 to 8 ⁇ m. It may be in the range of 7 ⁇ m or may be in the range of 0.1 to 3 ⁇ m.
  • the average particle diameter of aluminum can be less than 15 ⁇ m, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, and may be in the range of 1 to 14 ⁇ m.
  • the content of the inorganic filler 4 in the thermally conductive sheet 1 can be appropriately selected depending on the purpose.
  • the content of the inorganic filler 4 in the thermally conductive sheet 1 can be, for example, 10 volume% or more, may be 15 volume% or more, may be 20 volume% or more, and may be 25 volume%. It may be 30 volume% or more, 35 volume% or more, 39 volume% or more, or 45 volume% or more.
  • the upper limit of the content of the inorganic filler 4 in the thermally conductive sheet 1 may be, for example, 55 volume% or less, may be 50 volume% or less, or may be 49 volume% or less. It may be 45% by volume or less, or 40% by volume or less.
  • the content of the inorganic filler 4 in the thermally conductive sheet 1 can be, for example, in the range of 39 to 49% by volume. When two or more types of inorganic fillers 4 are used together, it is preferable that the total amount thereof satisfies the above-mentioned content.
  • the content of aluminum nitride in the thermally conductive sheet 1 is in the range of 10 to 35% by volume, and the content of aluminum oxide is in the range of 5 to 25% by volume. %, the content of aluminum nitride can be in the range of 20-30% by volume, and the content of aluminum oxide can be in the range of 10-25% by volume.
  • the content of aluminum nitride in the thermally conductive sheet 1 is set in the range of 10 to 30% by volume, and the content of aluminum oxide is set in the range of 10 to 30% by volume.
  • the aluminum content can be in the range of 1 to 20% by volume, and the aluminum content can be in the range of 10 to 30% by volume.
  • the thermally conductive sheet 1 may further contain other components other than those described above, as long as the effects of the present technology are not impaired.
  • other components include coupling agents, dispersants, curing accelerators, retarders, tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants, and solvents.
  • the thermally conductive sheet 1 is made of anisotropic thermally conductive material 3 treated with a coupling agent and/or a coupling agent. A treated inorganic filler 4 may also be used.
  • thermally conductive sheet 1 is preferably, for example, 40 to 95 in terms of Shore OO hardness, from the viewpoint of ease of polishing and conformability to an adherend due to the flexibility of the sheet.
  • the thermally conductive sheet 1 is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2, and satisfies the conditions 1 to 3 described above. Since at least one condition is satisfied, the contact area between the thermally conductive sheet 1 and the adherend increases, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, so the contact heat The resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
  • the method for manufacturing the thermally conductive sheet 1 includes the following steps A, B, and C.
  • step A a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4 is molded into a predetermined shape and cured to form a molded body of the thermally conductive composition (thermal A conductive molded body) is obtained.
  • the anisotropic thermally conductive material 3 and the inorganic filler 4 are dispersed in the binder resin 2, thereby containing the binder resin 2, the anisotropic thermally conductive material 3, and the inorganic filler 4.
  • a thermally conductive composition is produced.
  • the thermally conductive composition is prepared by uniformly mixing the binder resin 2, the anisotropic thermally conductive material 3, the inorganic filler 4, and other components mentioned above as necessary using a known method. can.
  • the thermally conductive composition is extruded and then cured to obtain a columnar cured product (thermally conductive molded body).
  • the extrusion molding method is not particularly limited, and can be appropriately adopted from various known extrusion molding methods depending on the viscosity of the thermally conductive composition, the characteristics required of the thermally conductive sheet 1, and the like.
  • the extrusion molding method when extruding a thermally conductive composition from a die, the binder resin 2 in the thermally conductive composition flows, and the anisotropic thermally conductive material 3 is oriented along the flow direction.
  • the size and shape of the columnar cured product can be determined depending on the required size of the thermally conductive sheet 1. For example, a rectangular parallelepiped with a vertical cross section of 0.5 to 15 cm and a horizontal cross section of 0.5 to 15 cm may be mentioned. The length of the rectangular parallelepiped may be determined as necessary.
  • step B the thermally conductive molded product obtained in step A is cut into sheet shapes to obtain sheet-like molded products.
  • the columnar cured product obtained in step A is cut into a predetermined thickness in the length direction of the column to obtain a sheet-like molded product.
  • the anisotropic thermally conductive material 3 is exposed on the surface (cut surface) of the sheet-like molded body.
  • the method for cutting the thermally conductive molded body is not particularly limited, and can be appropriately selected from known slicing devices depending on the size and mechanical strength of the thermally conductive molded body.
  • the anisotropic thermally conductive material 3 may be oriented in the extrusion direction, so the cutting direction of the thermally conductive molded body must be in the extrusion direction.
  • the angle is preferably 60 to 120 degrees, more preferably 70 to 100 degrees, and even more preferably 90 degrees (substantially perpendicular).
  • the cutting direction of the thermally conductive molded body is not particularly limited other than the above, and can be appropriately selected depending on the intended use of the thermally conductive sheet 1 and the like.
  • the sheet-like molded product obtained in step B has irregularities on its surface.
  • the sheet-like molded product obtained in step B has a plurality of convex portions 1a on the surface and concave portions adjacent to the convex portions 1a. Therefore, the sheet-like molded product obtained in step B usually tends not to satisfy the above-mentioned conditions 1 to 3.
  • air tends to get mixed in between the sheet-like molded product and the adherend, making it difficult to reduce the contact thermal resistance of the sheet-like molded product. There is a tendency.
  • step C by polishing the surface of the sheet-like molded body obtained in step B, the binder resin 2, anisotropic thermally conductive material 3, and By covering the recesses on the surface of the sheet-like molded body with the inorganic filler 4 (in other words, the polishing residue 5 scraped from the projections 1a remains in the recesses), the surface of the thermally conductive sheet 1 meets the above-mentioned condition 1. - At least one of 3 can be satisfied, the contact area between the thermally conductive sheet 1 and the adherend is improved, and air is prevented from entering between the thermally conductive sheet 1 and the adherend. However, the contact thermal resistance of the thermally conductive sheet 1 can be reduced.
  • the contact area between the thermally conductive sheet 1 and the adherend is further improved, and the surface of the thermally conductive sheet 1 and the adherend are further improved. It is considered that the mixture of air with the adherend can be more effectively suppressed, and the contact thermal resistance of the thermally conductive sheet 1 can be further reduced.
  • the sheet-like molded body is polished with a polishing member.
  • the polishing member include those that can be brought into surface contact with the surface of the sheet-like molded body for polishing.
  • abrasive members include sandpaper, wrapping films, and brushes, which are appropriately selected depending on durability, accuracy of abrasive grain size, and throughput.
  • a lapping film is a film in which abrasive grains are fixed to a resin film as a base material using an adhesive.
  • the conductive material 3 and the inorganic filler 4 can more efficiently cover the recesses on the surface of the sheet-like molded body.
  • the wrapping film for example, one using a polyester film as the base material and aluminum oxide with an average particle size of 2 to 40 ⁇ m as the abrasive grains can be used.
  • a lapping film with a nominal value of #400 to #6000 can be used as an indicator of the particle size of the abrasive grains.
  • the size and thickness of the wrapping film can be changed as appropriate depending on the size of the sheet-like molded body to be polished. For example, the thickness of the wrapping film can be 0.01 to 0.5 mm.
  • FIG. 3 is a perspective view of a brush 6, which is an example of a polishing member.
  • the brush 6 has a shape in which bristles 8 are arranged in the length direction of a columnar base material 7, as shown in FIG. 3, for example.
  • the hair material 8 is a bundle of a plurality of hairs, and has a length B, a depth C, and a width A.
  • the material of the brush 6 is not particularly limited, and for example, from the viewpoint of versatility, abrasion resistance, flexibility, bending recovery, etc., nylon, acrylic, vinyl chloride, polypropylene, polyphenylene sulfide, copper, brass, stainless steel, Materials used for brushes include horses, pigs, sheep, etc., and materials that have been treated with abrasives to improve polishing efficiency, electrostatic treatment to prevent contamination of polishing powder brushes, conductive treatment, etc. are also used. Is possible.
  • the thickness of the hair is 0.05 mm to 2.2 mm, and the length of the hair is 1 to 100 mm.
  • processing speed, etc. can be appropriately selected and used in combination within a range that does not impair the present invention.
  • FIG. 4 is a perspective view for explaining an example of a method of polishing the surface of the molded sheet 9 with the brush 6.
  • a fixing means such as a suction pad or tape (not shown) to polish the back side of the surface of the molded sheet 9 to be polished or It is preferable to temporarily fasten the end on the side where processing is to be started.
  • temporary fixing using tape when polishing with the brush 6 in the direction of D1 in FIG. to move the brush 6.
  • the means for moving the brush 6 may be manual or automatic.
  • polishing the molded sheet 9 move the brush 6 so that the tips of the bristles 8 touch the surface of the molded sheet 9 in the entire direction A, and stroke with the tips of the bristles 8. It is preferable to let
  • the polishing method is not limited to moving the polishing member in one direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9.
  • polishing the surface of the molded sheet 9 from one end 9A to the other end 9B with a polishing member and polishing the surface of the molded sheet 9 from the other end 9B to one end 9A with a polishing member.
  • the polishing member may be reciprocated to polish the surface of the molded sheet 9 from one end side 9A to the other end side 9B.
  • the brush 6 when used, it may be polished by reciprocating in the D1 direction and the D2 direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9 in FIG. FIG.
  • FIG. 5 is a perspective view for explaining an example of a method of continuously polishing the surfaces of a plurality of molded body sheets with a brush.
  • the polishing member when polishing a plurality of thermally conductive sheets 1 in succession, for example, the polishing member is fixed, a plurality of formed sheets 9 are placed on a conveyor 10, and the conveyor 10 is By moving, a plurality of molded sheets 9 may be polished continuously.
  • the direction of movement of the conveyor 10 may be one direction, D3 direction or D4 direction in FIG. 5, or may be reciprocated in the D3 direction and D4 direction. It is also possible to install and use a plurality of brushes. Furthermore, a rolled brush may be rotated and used.
  • only one side of the molded sheet 9 may be polished, or after one side of the molded sheet 9 is polished, the other side may also be polished.
  • the polishing method is the same as the polishing method for the brush 6 described above, as long as the wrapping film is brought into contact with the surface of the molded sheet 9 and at least one of the molded sheet 9 and the wrapping film is moved.
  • various modifications can be made in the movement method, movement direction, arrangement, and shape.
  • the number of times of polishing can be changed as appropriate depending on the polishing method, the type of polishing member, the particle size of the polishing member, etc.
  • the greater the number of times of polishing the more easily the concave portions on the surface of the sheet-like molded body 9 are covered with the binder resin 2, anisotropic heat conductive material 3, and inorganic filler 4 carved out from the convex portions 1a on the surface of the sheet-like molded body 9. Therefore, it is preferable to set the number of times to a certain number or more.
  • the number of times of polishing can be, for example, 1 or more times, 10 times or more, 20 times or more, 30 or more times, 40 times or more, 50 times or more, It may be more than 60 times, it may be more than 70 times, it may be more than 80 times, it may be more than 90 times, it may be more than 100 times, it may be more than 200 times, it may be more than 300 times, it may be more than 400 times.
  • the number of times may be more than 1,000 times, or may be in the range of 100 to 1,000 times, or may be in the range of 100 to 400 times.
  • the number of times of polishing refers to one time of polishing in one direction from one end side 9A to the other end side 9B of the surface of the sheet-like molded body 9 in FIG. 4, for example.
  • the size of the polishing residue 5 that the thermally conductive sheet 1 has on the surface can be changed as appropriate depending on the material and particle size of the polishing member used.
  • the maximum size of the polishing residue 5 can be 100 ⁇ m or less, and can also be in the range of 0.5 to 100 ⁇ m.
  • the polishing member may have the same roughness in the polishing step (step C).
  • Polishing members having the same roughness in the polishing process mean, for example, polishing members with the same abrasive grain size in step C, rather than using two or more types of polishing members with different abrasive grain sizes together. It means to use.
  • conditions 1 to 3 described above can be satisfied, and the thermal conductivity is improved.
  • the total thermal resistance value of the adhesive sheet 1 can be reduced.
  • the thermally conductive sheet 1 in the method for manufacturing the thermally conductive sheet 1, the thermally conductive sheet 1 can be polished under the conditions 1 to 1 without using two or more types of polishing members having different abrasive grain sizes in combination in step C. 3 can be satisfied, the process can be simplified.
  • step C of the method for manufacturing the thermally conductive sheet 1 two or more types of polishing members having different abrasive grain sizes may be used together.
  • the thermally conductive sheet 1 described above can be obtained.
  • the method for manufacturing the thermally conductive sheet 1 is not limited to the above-mentioned example, and may further include a pressing step D.
  • Process D may be between process B and process C, or may be after process C.
  • an example of the method for manufacturing the thermally conductive sheet 1 includes, in addition to the above-mentioned steps A to C, a step D of pressing the surface of the sheet-like molded body 9 obtained in step B;
  • the thermally conductive sheet 1 may be obtained by polishing the surface of the sheet-like molded body 9 pressed in step D.
  • a pair of press devices consisting of a flat plate and a press head with a flat surface can be used. Alternatively, it may be pressed using pinch rolls.
  • the pressure during pressing can be, for example, 0.1 to 100 MPa.
  • the pressing is preferably performed at a temperature equal to or higher than the glass transition temperature (Tg) of the binder resin 2.
  • Tg glass transition temperature
  • the pressing temperature can be from 0 to 180°C, may be within the temperature range of room temperature (eg, 25°C) to 100°C, or may be from 30 to 100°C.
  • the thermally conductive sheet 1 is, for example, placed between a heat generating element and a heat radiating element, so that the heat generated by the heating element is dissipated to the heat radiating element. ).
  • the electronic device includes at least a heating element, a heat radiating element, and a thermally conductive sheet 1, and may further include other members as necessary. In this way, electronic devices to which the thermally conductive sheet 1 is applied can achieve high thermal conductivity due to the thermally conductive sheet 1 because the thermally conductive sheet 1 is sandwiched between the heating element and the heat radiating element. , the thermally conductive sheet 1 has excellent adhesion to the heating element, and excessive bleeding of the binder resin 2 from the thermally conductive sheet 1 can be suppressed.
  • the electronic device to which the thermally conductive sheet 1 is applied is such that the thermally conductive sheet 1 and the adherend meet at least one of the conditions 1 to 3 described above.
  • the contact area with the heating element and the heat radiating element is further increased, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, contributing to a reduction in the contact thermal resistance of the thermally conductive sheet 1. , As a result, the total thermal resistance value can be reduced.
  • the heating element is not particularly limited, and examples include electronic components that generate heat in electric circuits, such as CPUs, GPUs (Graphics Processing Units), DRAMs (Dynamic Random Access Memory), integrated circuit elements such as flash memories, transistors, and resistors. etc.
  • the heating element also includes components that receive optical signals, such as optical transceivers in communication equipment.
  • the heat sink is not particularly limited, and includes, for example, heat sinks, heat spreaders, and other heat sinks that are used in combination with integrated circuit elements, transistors, optical transceiver casings, and the like.
  • Examples of the material for the heat sink and heat spreader include copper and aluminum.
  • the heat dissipation body may be anything that conducts heat generated from a heat source and dissipates it to the outside, such as a heat dissipator, cooler, die pad, printed circuit board, cooling fan, Peltier element, etc.
  • Examples include heat pipes, vapor chambers, metal covers, and casings.
  • a heat pipe is, for example, a cylindrical, substantially cylindrical, or flat cylindrical hollow structure.
  • FIG. 6 is a cross-sectional view showing an example of a semiconductor device to which a thermally conductive sheet is applied.
  • the thermally conductive sheet 1 is mounted on a semiconductor device 50 built into various electronic devices, and is sandwiched between a heat generating body and a heat radiating body.
  • a semiconductor device 50 shown in FIG. 6 includes an electronic component 51, a heat spreader 52, and a thermally conductive sheet 1, and the thermally conductive sheet 1 is sandwiched between the heat spreader 52 and the electronic component 51.
  • the thermally conductive sheet 1 is sandwiched between the heat spreader 52 and the heat sink 53, thereby forming a heat radiating member that radiates heat from the electronic component 51 together with the heat spreader 52.
  • the mounting location of the thermally conductive sheet 1 is not limited to between the heat spreader 52 and the electronic component 51 or between the heat spreader 52 and the heat sink 53, and can be appropriately selected depending on the configuration of the electronic device or semiconductor device.
  • the heat spreader 52 is formed into a rectangular plate shape, for example, and has a main surface 52a facing the electronic component 51, and a side wall 52b erected along the outer periphery of the main surface 52a.
  • a thermally conductive sheet 1 is provided on a main surface 52a surrounded by side walls 52b, and a heat sink 53 is provided on the other surface 52c opposite to the main surface 52a via the thermally conductive sheet 1.
  • Example 1 32% by volume of silicone resin, 14% by volume of aluminum oxide (average particle diameter: approximately 2 ⁇ m), 25% by volume of aluminum nitride (average particle diameter: approximately 1 ⁇ m), and 28% by volume of carbon fiber (average fiber length: approximately 150 ⁇ m).
  • a thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed.
  • Example 1 As shown in Fig. 3, the hair thickness is 0.2 mm, the hair length (B in Fig. 3) is 25 mm, the hair bundle (depth: C in Fig. 3) is 4 mm, and the width (B in Fig. 3) is 4 mm.
  • a 70 mm nylon brush 6 manufactured by Kakuda Brush Co., Ltd. was used. Then, as shown in FIG. 4, while bending the bristles of the brush 6 so that the bristles of the brush 6 (the tips of the bristles 8) contact the sheet-like molded body 9 in the entire direction A, The brush 6 was moved in one direction 100 times from one end to the other end of the surface of the sheet-like molded body 9 in a caressing motion.
  • thermally conductive sheet By polishing the surface of the sheet-like molded body 9 in this manner, a thermally conductive sheet was obtained. Polishing was performed on both sides of the sheet-like molded body.
  • the thermally conductive sheet obtained in Example 1 had a polished surface, and had the constituent material of the thermally conductive composition detached from the surface by polishing.
  • Example 2 a thermally conductive sheet was obtained in the same manner as in Example 1, except that the number of times of polishing was changed to 1000 times.
  • the thermally conductive sheet obtained in Example 2 had a polished surface, and contained the constituent material of the thermally conductive composition detached by polishing on the surface.
  • Example 3 In Example 3, the sheet-like molded body was sandwiched between two veneers and pressed under the conditions of 70° C., 0.5 MPa, and 30 seconds, and the sheet-like molded body 9 after pressing was polished. A thermally conductive sheet was obtained in the same manner as in Example 1. The thermally conductive sheet obtained in Example 3 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
  • Example 4 In Example 4, 24% by volume of silicone resin, 10% by volume of aluminum oxide (average particle size: about 2 ⁇ m), 20% by volume of aluminum nitride (average particle size: about 1 ⁇ m), and aluminum (average particle size: about 6 ⁇ m) ), 26 volume % of carbon fibers (average fiber length: approximately 150 ⁇ m), and 1 volume % of a coupling agent, and a nylon brush. Instead, using a #4000 wrapping film (manufactured by 3M) with a thickness of about 100 ⁇ m, the surface of the sheet-like molded body 9 was polished 100 times in one direction from one end to the other end ( A thermally conductive sheet was obtained in the same manner as in Example 1, except that the sheet was rubbed. The thermally conductive sheet obtained in Example 4 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
  • silicone resin 10% by volume of aluminum oxide (average particle size: about 2 ⁇ m), 20% by volume of aluminum nitride (average particle
  • Example 5 a #2000 wrapping film (manufactured by 3M) with a thickness of about 100 ⁇ m was used instead of the nylon brush to cover the surface of the sheet-like molded body 9 from one end to the other end.
  • a thermally conductive sheet was obtained in the same manner as in Example 1, except that it was polished 100 times in one direction over the entire area.
  • the thermally conductive sheet obtained in Example 5 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
  • Example 6 > 28% by volume of silicone resin, 22% by volume of aluminum oxide (average particle diameter: approximately 2 ⁇ m), 23% by volume of aluminum nitride (average particle diameter: approximately 1 ⁇ m), and 26% by volume of carbon fiber (average fiber length: approximately 150 ⁇ m).
  • a thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed.
  • Example 7 a thermally conductive sheet was obtained in the same manner as in Example 6 except that the thickness of the sheet-like molded body was 2 mm. Thus, the thermally conductive sheet obtained in Example 7 had a polished surface and had polishing residue on the surface.
  • Comparative Example 1 the sheet-like molded product obtained in Example 1 was used as it was. That is, in Comparative Example 1, the same procedure as in Example 1 was carried out except that the surface of the sheet-like molded body was not polished. The sheet-like molded article obtained in Comparative Example 1 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached from the surface by polishing.
  • Comparative Example 2 the pressed sheet-shaped molded product obtained in Example 3 was used as it was. That is, in Comparative Example 2, the same procedure as in Example 3 was carried out except that the surface of the sheet-shaped molded body after pressing was not polished. The sheet-like molded article obtained in Comparative Example 2 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached from the surface by polishing.
  • Comparative Example 3 a composition in which a silicone resin, carbon fibers, and other inorganic fillers were mixed was injected into a mold, and a magnetic field was applied in the thickness direction to orient the carbon fibers in the thickness direction. After that, it was cured to form a columnar cured product. By cutting (slicing) the obtained columnar cured product into a sheet with a thickness of 0.3 mm using a slicer in a direction substantially perpendicular to the length direction of the column, the carbon fibers are cut into sheets with a thickness of 0.3 mm. A sheet-like molded body oriented in the direction was obtained.
  • Comparative Example 3 after slicing the columnar cured product into 0.3 mm thick pieces, the surface of the sheet-like molded product was not polished.
  • the sheet-like molded article obtained in Comparative Example 3 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached by polishing on the surface.
  • a thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed.
  • Comparative Example 5 a sheet-like molded product was obtained in the same manner as Comparative Example 4, except that the thickness of the sheet-like molded product was 2 mm.
  • ⁇ Surface property parameters of thermally conductive sheet> The surface quality parameters of the thermally conductive sheet obtained in each Example and the sheet-like molded article obtained in each Comparative Example were measured. Specifically, the average height Spk ( ⁇ m) of the protruding peaks of the thermally conductive sheet, the average depth Svk ( ⁇ m) of the protruding valleys, the volume Vmp (ml/m 2 ) of the protruding peaks, and the root mean square of the heat conductive sheet.
  • the thermally conductive sheets obtained in Examples 1 to 7 are made of cured products of thermally conductive compositions containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin, and meet the conditions 1 to 3 described above. It has been found that the total thermal resistance value can be reduced by satisfying at least one of the conditions.
  • the thermally conductive sheets obtained in Examples 1 to 5 can reduce the total thermal resistance value at low loads, and specifically, the total thermal resistance value at a load of 0.70 kgf/ cm2 is 0.230. It was found that the temperature was less than °Ccm 2 /W.
  • thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.179°C cm 2 /W or less at a load of 1.4 kgf/cm 2 .
  • thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.161°C cm 2 /W or less under a load of 2.1 kgf/cm 2 .
  • thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.157°C cm 2 /W or less at a load of 2.8 kgf/cm 2 .
  • thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.156°C cm 2 /W or less at a load of 3.5 kgf/cm 2 .
  • the thermally conductive sheets obtained in Examples 1 to 7 had a polished surface, and had constituent materials (polishing residue) of the thermally conductive composition released by polishing on the polished surface.
  • This polishing residue was confirmed to be a lump containing silicone resin, carbon fiber, and other inorganic fillers (aluminum oxide, aluminum nitride, aluminum, etc.) produced by polishing.
  • the thermally conductive sheets obtained in Examples 1 to 7 have a developed area ratio Sdr of the interface of the thermally conductive sheet, which is measured according to ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20. 45% or less, and the arithmetic mean curvature Spc of the peak of the thermally conductive sheet was found to be 3500 (1/mm) or less.
  • FIG. 7 shows the results of Examples and Comparative Examples with the horizontal axis representing the arithmetic mean curvature Spc (1/mm) of the peak of the thermally conductive sheet and the vertical axis representing the developed area ratio Sdr (%) of the interface of the thermally conductive sheet. This is a plotted graph.
  • the thermally conductive sheets obtained in Examples 1 to 7 have an arithmetic mean curvature of the peak Spc measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the sheet-like molded bodies obtained in Comparative Examples 1, 3 to 5 do not satisfy the requirements that the developed area ratio Sdr of the interface is 45% or less and the arithmetic mean curvature Spc of the peak is 3500 (1/mm) or less. That's what I found out.
  • the thermally conductive sheets obtained in Examples 6 and 7 and the molded sheets obtained in Comparative Examples 4 and 5 are thicker than Examples 1 to 5 and Comparative Examples 1 to 3, respectively.
  • the arithmetic mean curvature Spc of the peak, the developed area ratio Sdr of the interface of the thermally conductive sheet, the volume Vmp of the protruding peak of the thermally conductive sheet, etc. were improved, and the total thermal resistance was reduced. It became clear.
  • thermoly conductive sheet 1 thermally conductive sheet, 1a convex portion, 2 binder resin, 3 anisotropic thermally conductive material, 4 inorganic filler, 5 polishing residue, 6 brush, 7 base material, 8 bristle material, 9 sheet-shaped molded body, 10 conveyor, 50 Semiconductor device, 51 Electronic component, 52 Heat spreader, 52a Main surface, 52b Side wall, 52c Other surface, 53 Heat sink

Abstract

Provided is a thermally conductive sheet with a reduced total thermal resistance value.　This thermally conductive sheet 1 is composed of a cured product of a thermally conductive composition containing an anisotropic thermal conductive material 3, an inorganic filler 4, and a binder resin 2, and has an average height Spk of protruding peak parts of less than 3.5 μm, as measured according to ISO 25178 by using a scanning white light interference microscope with a 20× object lens. The thermally conductive sheet 1 is composed of the cured product of the thermally conductive composition containing the anisotropic thermal conductive material 3, the inorganic filler 4, and the binder resin 2, and has a volume Vmp of the protruding peak parts of at most 0.16 ml/m2, as measured according to ISO 25178 by using a scanning white light interference microscope with a 20× object lens. The thermally conductive sheet 1 is composed of the cured product of the thermally conductive composition containing the anisotropic thermal conductive material 3, the inorganic filler 4, and the binder resin 2, and has a value (Spk/(Spk+Svk)) of the average height Spk of the protruding peak parts to the sum (Spk+Svk) of the average height Spk of the protruding peak parts and an average depth Svk of protruding valley parts of at most 40% and a root mean square gradient Sdq of at most 1.1, as measured according to ISO 25178 by using a scanning white light interference microscope with a 20× object lens.

Description

熱伝導性シート及び熱伝導性シートの製造方法Thermal conductive sheet and method for manufacturing the thermally conductive sheet
　本技術は、熱伝導性シート及び熱伝導性シートの製造方法に関する。本出願は、日本国において２０２２年３月３１日に出願された日本特許出願番号特願２０２２－０５８４０７及び日本国において２０２３年３月２９日に出願された日本特許出願番号特願２０２３－０５３５４７を基礎として優先権を主張するものであり、これらの出願は参照されることにより、本出願に援用される。 The present technology relates to a thermally conductive sheet and a method for manufacturing a thermally conductive sheet. This application is based on Japanese Patent Application No. 2022-058407 filed in Japan on March 31, 2022 and Japanese Patent Application No. 2023-053547 filed in Japan on March 29, 2023. These applications are incorporated by reference into this application.
　電子機器の更なる高性能化により、半導体素子の高密度化、高実装化が進んでいる。それと比例して、ＩＣ（Integrated Circuit）等からの発熱量、発熱密度も増大する傾向にあり、より効率的に熱伝導性シートを介して放熱フィン、放熱板等の放熱部材に熱を伝達することが求められる。また、電子機器は、小型化、薄型化が急速に進んでおり、必要とされる熱伝導性シートの厚みも薄くなる傾向にあり、より低熱抵抗なものが求められている。このような要求を満たす熱伝導性シートとしては、異方性熱伝導材料を用いた熱伝導性シートが挙げられる（例えば、特許文献１～６を参照）。異方性熱伝導材料の一例である炭素繊維は、繊維方向に約６００～１２００Ｗ／（ｍ・Ｋ）の熱伝導率を有する異方性フィラーである。炭素繊維の繊維方向を、熱の伝達方向である熱伝導性シートの厚み方向に配向させることによって、熱伝導性が飛躍的に向上することが知られている。 With the further improvement in the performance of electronic devices, the density and packaging of semiconductor elements are increasing. In proportion to this, the heat generation amount and heat generation density from ICs (Integrated Circuits), etc. tend to increase, and heat is more efficiently transferred to heat dissipation members such as heat dissipation fins and heat dissipation plates through thermally conductive sheets. That is required. In addition, electronic devices are rapidly becoming smaller and thinner, and the thickness of the thermally conductive sheet required is also becoming thinner, leading to a demand for lower thermal resistance. Examples of thermally conductive sheets that meet such requirements include thermally conductive sheets using anisotropic thermally conductive materials (see, for example, Patent Documents 1 to 6). Carbon fiber, which is an example of an anisotropic thermally conductive material, is an anisotropic filler having a thermal conductivity of about 600 to 1200 W/(m·K) in the fiber direction. It is known that thermal conductivity can be dramatically improved by orienting the fiber direction of carbon fibers in the thickness direction of a thermally conductive sheet, which is the direction of heat transfer.
　炭素繊維を配向した熱伝導性シートを用いて低熱抵抗化を実現するには、熱伝導性シートの接触熱抵抗を考慮することも重要である。しかし、高熱伝導の炭素繊維であっても、熱伝導性シート全体から見れば、被着体と炭素繊維との接触は点接触であり、圧力により炭素繊維がバインダ樹脂内に沈み込むとしても、熱伝導性シートと被着体との間にエアーが混入する課題がある。 In order to achieve low thermal resistance using a thermally conductive sheet with oriented carbon fibers, it is also important to consider the contact thermal resistance of the thermally conductive sheet. However, even if carbon fibers have high thermal conductivity, when viewed from the entire thermally conductive sheet, the contact between the adherend and the carbon fibers is point contact, and even if the carbon fibers sink into the binder resin due to pressure, There is a problem that air gets mixed in between the thermally conductive sheet and the adherend.
　また、使用される熱伝導性シートが薄くなるにつれて、熱伝導性シートと、被着体との間に生じる接触熱抵抗の寄与が大きくなる傾向にある。接触熱抵抗とは、熱伝導性シートと被着体の間に生じる熱抵抗である。特に、炭素繊維のような異方性熱伝導材料が厚み方向に配向した熱伝導性シートは、厚みが薄くなるほど、接触熱抵抗が大きくなる傾向があり、結果として、全熱抵抗値（熱伝導性シートそのものが有する熱抵抗値に接触熱抵抗値を加えたもの）も大きくなりやすい。 Additionally, as the thermally conductive sheet used becomes thinner, the contribution of contact thermal resistance generated between the thermally conductive sheet and the adherend tends to increase. Contact thermal resistance is thermal resistance that occurs between a thermally conductive sheet and an adherend. In particular, for a thermally conductive sheet in which an anisotropic thermally conductive material such as carbon fiber is oriented in the thickness direction, the contact thermal resistance tends to increase as the thickness decreases, and as a result, the total thermal resistance value (thermal conduction The thermal resistance value (the sum of the thermal resistance value of the sheet itself plus the contact thermal resistance value) also tends to increase.
特許５７５２２９９号Patent No. 5752299 特許４８１４５５０号Patent No. 4814550 特許６６５０１７５号Patent No. 6650175 国際公開第２０２０／０６７１４１号公報International Publication No. 2020/067141 特開２０２１－００４２８３号公報JP 2021-004283 Publication 特開２０２１－００４２８４号公報JP2021-004284A
　本技術は、このような従来の実情に鑑みて提案されたものであり、全熱抵抗値が低減された熱伝導性シートを提供する。 The present technology has been proposed in view of such conventional circumstances, and provides a thermally conductive sheet with a reduced total thermal resistance value.
　本願発明者らは、鋭意検討の結果、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性シートについて、突出山部の平均高さＳｐｋを抑制するか、突出山部の体積Ｖｍｐを抑制するか、突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値を抑制するとともに二乗平均平方根勾配Ｓｄｑを抑制することにより、上述した課題を解決できることを見出した。 As a result of intensive studies, the inventors of the present application have determined whether or not to suppress the average height Spk of the protruding peaks in a thermally conductive sheet containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin. , or suppress the value of the average height Spk of the protruding peaks relative to the sum (Spk+Svk) of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys, and also suppress the root mean square gradient of the protruding peaks. It has been found that the above-mentioned problems can be solved by suppressing Sdq.
　本技術は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、熱伝導性シートの突出山部の平均高さＳｐｋが３．５μｍ未満である。 This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin. The average height Spk of the protruding peaks of the thermally conductive sheet is less than 3.5 μm, as measured using a microscope according to ISO 25178.
　本技術は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、熱伝導性シートの突出山部の体積Ｖｍｐが０．１６ｍｌ／ｍ２以下である。 This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin. The volume Vmp of the protruding peaks of the thermally conductive sheet is 0.16 ml/m 2 or less, as measured using a microscope according to ISO 25178.
　本技術は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が４０％以下であり、熱伝導性シートの二乗平均平方根勾配Ｓｄｑが１．１以下である。 This technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin. The value of the average height Spk of the protruding peaks (Spk/( Spk+Svk)) is 40% or less, and the root mean square gradient Sdq of the thermally conductive sheet is 1.1 or less.
　本技術に係る熱伝導性シートの製造方法は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、熱伝導性シートを得る工程では、熱伝導性シートの表面が以下の条件１を満たすように、シート状成形体の表面を研磨する。
（条件１）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋが３．５μｍ未満である。 The method for manufacturing a thermally conductive sheet according to the present technology involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet. In the step of obtaining a thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 1 below.
(Condition 1) The average height Spk of the protruding peaks is less than 3.5 μm, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
　本技術に係る熱伝導性シートの製造方法は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、熱伝導性シートを得る工程では、熱伝導性シートの表面が以下の条件２を満たすように、シート状成形体の表面を研磨する。
（条件２）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の体積Ｖｍｐが０．１６ｍｌ／ｍ２以下である。 The method for manufacturing a thermally conductive sheet according to the present technology involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet. In the step of obtaining a thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 2 below.
(Condition 2) The volume Vmp of the protruding peak is 0.16 ml/m 2 or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
　本技術に係る熱伝導性シートの製造方法は、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、熱伝導性シートを得る工程では、熱伝導性シートの表面が以下の条件３を満たすように、シート状成形体の表面を研磨する。
（条件３）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が４０％以下であり、かつ、二乗平均平方根勾配Ｓｄｑが１．１以下である。 The method for manufacturing a thermally conductive sheet according to the present technology involves molding a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive sheet. a step of slicing the thermally conductive molded object into sheet shapes to obtain a sheet-like molded object; and a step of polishing the surface of the sheet-like molded object to obtain a thermally conductive sheet. In the step of obtaining a thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 3 below.
(Condition 3) Regarding the sum of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys (Spk+Svk), measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. , the value of the average height Spk of the protruding peak portion (Spk/(Spk+Svk)) is 40% or less, and the root mean square gradient Sdq is 1.1 or less.
　本技術は、全熱抵抗値が低減された熱伝導性シートを提供できる。 The present technology can provide a thermally conductive sheet with a reduced total thermal resistance value.
図１は、熱伝導性シートの一例を示す断面図である。FIG. 1 is a sectional view showing an example of a thermally conductive sheet. 図２は、熱伝導性シートの表面の一例を示す断面図である。FIG. 2 is a cross-sectional view showing an example of the surface of a thermally conductive sheet. 図３は、研磨部材の一例であるブラシの斜視図である。FIG. 3 is a perspective view of a brush that is an example of a polishing member. 図４は、シート状成形体の表面をブラシで研磨する方法の一例を説明するための斜視図である。FIG. 4 is a perspective view for explaining an example of a method of polishing the surface of a sheet-like molded body with a brush. 図５は、複数のシート状成形体の表面を連続してブラシで研磨する方法の一例を説明するための斜視図である。FIG. 5 is a perspective view for explaining an example of a method of continuously polishing the surfaces of a plurality of sheet-like molded bodies with a brush. 図６は、熱伝導性シートを適用した半導体装置の一例を示す断面図である。FIG. 6 is a cross-sectional view showing an example of a semiconductor device to which a thermally conductive sheet is applied. 図７は、熱伝導性シートの山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）を横軸、熱伝導性シートの界面の展開面積比Ｓｄｒ（％）を縦軸として実施例及び比較例の結果をプロットしたグラフである。FIG. 7 shows the results of Examples and Comparative Examples with the horizontal axis representing the arithmetic mean curvature Spc (1/mm) of the peak of the thermally conductive sheet and the vertical axis representing the developed area ratio Sdr (%) of the interface of the thermally conductive sheet. This is a plotted graph.
　本明細書において、平均粒子径（Ｄ５０）とは、粒子径分布全体を１００％とした場合に、粒子径分布の小粒子径側から粒子径の値の累積カーブを求めたとき、その累積値が５０％となるときの粒子径をいう。なお、本明細書における粒度分布（粒子径分布）は、体積基準によって求められたものである。粒度分布の測定方法としては、例えば、レーザー回折型粒度分布測定機を用いる方法が挙げられる。 In this specification, the average particle diameter (D50) refers to the cumulative value when a cumulative curve of particle diameter values is calculated from the small particle diameter side of the particle diameter distribution, assuming that the entire particle diameter distribution is 100%. This refers to the particle diameter when 50%. Note that the particle size distribution (particle size distribution) in this specification is determined on a volume basis. Examples of methods for measuring particle size distribution include a method using a laser diffraction type particle size distribution analyzer.
　＜熱伝導性シート＞
　図１は、本技術に係る熱伝導性シート１の一例を示す断面図である。熱伝導性シート１は、バインダ樹脂２と、異方性熱伝導材料３と、異方性熱伝導材料３以外の無機フィラー４とを含む熱伝導性組成物の硬化物からなる。熱伝導性シート１は、異方性熱伝導材料３と無機フィラー４とがバインダ樹脂２に分散しており、異方性熱伝導材料３が熱伝導性シート１の厚み方向Ｂに配向している。ここで、熱伝導性シート１の厚み方向Ｂに異方性熱伝導材料３が配向しているとは、例えば、熱伝導性シート１中の全ての異方性熱伝導材料３のうち、熱伝導性シート１の厚み方向Ｂに長軸が配向している異方性熱伝導材料３の割合が５０％以上であり、５５％以上であってもよく、６０％以上であってもよく、６５％以上であってもよく、７０％以上であってもよく、８０％以上であってもよく、９０％以上であってもよく、９５％以上であってもよく、９９％以上であってもよい。異方性熱伝導材料３の長軸が熱伝導性シート１の厚み方向Ｂに配向しているとは、例えば、異方性熱伝導材料３の長軸が、熱伝導性シート１の面方向Ａに対して６０～１２０度の範囲であってもよく、７０～１００度の範囲であってもよく、９０度（略垂直）であってもよい。 <Thermal conductive sheet>
FIG. 1 is a sectional view showing an example of a thermally conductive sheet 1 according to the present technology. The thermally conductive sheet 1 is made of a cured product of a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4 other than the anisotropic thermally conductive material 3. The thermally conductive sheet 1 has an anisotropic thermally conductive material 3 and an inorganic filler 4 dispersed in a binder resin 2, and the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1. There is. Here, the fact that the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1 means that, for example, out of all the anisotropic thermally conductive materials 3 in the thermally conductive sheet 1, the The proportion of the anisotropic thermally conductive material 3 whose long axis is oriented in the thickness direction B of the conductive sheet 1 is 50% or more, may be 55% or more, or may be 60% or more, It may be 65% or more, 70% or more, 80% or more, 90% or more, 95% or more, 99% or more. It's okay. For example, the long axis of the anisotropic thermally conductive material 3 is oriented in the thickness direction B of the thermally conductive sheet 1. It may be in the range of 60 to 120 degrees with respect to A, it may be in the range of 70 to 100 degrees, or it may be 90 degrees (substantially perpendicular).
　本技術の第１の実施の形態である熱伝導性シート１は、異方性熱伝導材料３と、無機フィラー４と、バインダ樹脂２とを含む熱伝導性組成物の硬化物からなり、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋが３．５μｍ未満である（以下、条件１を満たすともいう）。熱伝導性シート１は、条件１を満たすことにより、熱伝導性シート１と被着体との接触面積が増大し、熱伝導性シート１と被着体との間にエアーが混入することが抑制されるため、接触熱抵抗を低減でき、結果として、全熱抵抗値を低減することができる。 A thermally conductive sheet 1, which is a first embodiment of the present technology, is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2. The average height Spk of the protruding peaks is less than 3.5 μm, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x lens (hereinafter also referred to as satisfying Condition 1). By satisfying Condition 1, the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
　本技術の第２の実施の形態である熱伝導性シート１は、異方性熱伝導材料３と、無機フィラー４と、バインダ樹脂２とを含む熱伝導性組成物の硬化物からなり、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される突出山部の体積Ｖｍｐが０．１６ｍｌ／ｍ２以下である（以下、条件２を満たすともいう）。熱伝導性シート１は、条件２を満たすことにより、熱伝導性シート１と被着体との接触面積が増大し、熱伝導性シート１と被着体との間にエアーが混入することが抑制されるため、接触熱抵抗を低減でき、結果として、全熱抵抗値を低減することができる。 A thermally conductive sheet 1 according to a second embodiment of the present technology is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2. The volume Vmp of the protruding peak measured according to ISO 25178 using a scanning white interference microscope with a 20x lens is 0.16 ml/m 2 or less (hereinafter also referred to as satisfying condition 2). By satisfying condition 2, the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
　本技術の第３の実施の形態である熱伝導性シート１は、異方性熱伝導材料３と、無機フィラー４と、バインダ樹脂２とを含む熱伝導性組成物の硬化物からなり、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が４０％以下であり、かつ、二乗平均平方根勾配Ｓｄｑが１．１以下である（以下、条件３を満たすともいう）。熱伝導性シート１は、条件３を満たすことにより、熱伝導性シート１と被着体との接触面積が増大し、熱伝導性シート１と被着体との間にエアーが混入することが抑制されるため、接触熱抵抗を低減でき、結果として、全熱抵抗値を低減することができる。 A thermally conductive sheet 1 according to a third embodiment of the present technology is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2. The ratio of the protruding peaks to the sum of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys (Spk+Svk), which is measured according to ISO 25178 using a scanning white interference microscope with a 20x lens. The value of the average height Spk (Spk/(Spk+Svk)) is 40% or less, and the root mean square gradient Sdq is 1.1 or less (hereinafter also referred to as satisfying condition 3). By satisfying condition 3, the thermally conductive sheet 1 increases the contact area between the thermally conductive sheet 1 and the adherend, and prevents air from entering between the thermally conductive sheet 1 and the adherend. Therefore, the contact thermal resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
　このように、本技術に係る熱伝導性シート１は、条件１～３の少なくとも１つを満たしており、条件１～３のうち２つを満たしてもよく、条件１～３の全てを満たしてもよい。また、熱伝導性シート１は、条件１～３以外に、以下で説明する条件をさらに満たすことが好ましい。 As described above, the thermally conductive sheet 1 according to the present technology satisfies at least one of Conditions 1 to 3, may satisfy two of Conditions 1 to 3, and may satisfy all of Conditions 1 to 3. It's okay. Further, it is preferable that the thermally conductive sheet 1 further satisfies the conditions described below in addition to conditions 1 to 3.
　熱伝導性シート１は、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３．０μｍ以下であってもよく、２．６μｍ以下であってもよく、２．２μｍ以下であってもよく、１．５μｍ以下であってもよく、１．０μｍ以下であってもよく、０．９μｍ以下であってもよく、０．８μｍ以下であってもよく、０．７μｍ以下であってもよく、０．６μｍ以下であってもよく、０．５μｍ以下であってもよい。熱伝導性シート１の突出山部の平均高さＳｐｋの下限値は、特に限定されないが、例えば、０．４μｍ以上であってもよい。熱伝導性シート１は、突出山部の平均高さＳｐｋが、０．４９４～２．９６７μｍの範囲であってもよく、０．４９４～２．６４２μｍの範囲であってもよく、０．４９４～２．３４２μｍの範囲であってもよく、０．４９４～２．１８９μｍの範囲であってもよく、０．４９４～２．１５３μｍの範囲であってもよく、０．４９４～０．５６２μｍの範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の突出山部の平均高さＳｐｋが上述した範囲を満たすことが好ましく、両面の突出山部の平均高さＳｐｋが上述した範囲を満たしてもよい。熱伝導性シート１の突出山部の平均高さＳｐｋは、後述する実施例に記載の方法で測定できる。なお、突出山部の平均高さＳｐｋや、後述する、ＩＳＯ　２５１７８に従って測定される各値は、走査型白色干渉顕微鏡の対物レンズの倍率の影響を受ける。 The thermally conductive sheet 1 may have an average height Spk of the protruding peaks of 3.0 μm or less as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens; 2. It may be 6 μm or less, 2.2 μm or less, 1.5 μm or less, 1.0 μm or less, 0.9 μm or less, 0. It may be 8 μm or less, 0.7 μm or less, 0.6 μm or less, or 0.5 μm or less. The lower limit of the average height Spk of the protruding peaks of the thermally conductive sheet 1 is not particularly limited, but may be, for example, 0.4 μm or more. The average height Spk of the protruding peaks of the thermally conductive sheet 1 may be in the range of 0.494 to 2.967 μm, may be in the range of 0.494 to 2.642 μm, and may be in the range of 0.494 to 2.642 μm. ~2.342μm, 0.494~2.189μm, 0.494~2.153μm, 0.494~0.562μm It may be a range. It is preferable that the average height Spk of the protruding peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the average height Spk of the protruding peaks on both surfaces may satisfy the above-mentioned range. The average height Spk of the protruding peaks of the thermally conductive sheet 1 can be measured by the method described in Examples described below. Note that the average height Spk of the protruding peaks and each value measured according to ISO 25178, which will be described later, is affected by the magnification of the objective lens of the scanning white interference microscope.
　熱伝導性シート１は、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される突出山部の体積Ｖｍｐが０．１５ｍｌ／ｍ２以下であってもよく、０．１４ｍｌ／ｍ２以下であってもよく、０．１１ｍｌ／ｍ２以下であってもよく、０．０８ｍｌ／ｍ２以下であってもよく、０．０６ｍｌ／ｍ２以下であってもよく、０．０４ｍｌ／ｍ２以下であってもよく、０．０２ｍｌ／ｍ２以下であってもよい。熱伝導性シート１の突出山部の体積Ｖｍｐの下限値は、特に限定されず、例えば、０．０１ｍｌ／ｍ２以上であってもよいし、０．０２ｍｌ／ｍ２以上であってもよい。熱伝導性シート１は、突出山部の体積Ｖｍｐが、０．０２７～０．１３７ｍｌ／ｍ２の範囲であってもよいし、０．０２７～０．１３４ｍｌ／ｍ２の範囲であってもよいし、０．０２７～０．１１４ｍｌ／ｍ２の範囲であってもよいし、０．０２７～０．１０６ｍｌ／ｍ２の範囲であってもよいし、０．０２７～０．１０２ｍｌ／ｍ２の範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の突出山部の体積Ｖｍｐが上述した範囲を満たすことが好ましく、両面の突出山部の体積Ｖｍｐが上述した範囲を満たしてもよい。 The thermally conductive sheet 1 may have a volume Vmp of the protruding peaks of 0.15 ml/m 2 or less as measured in accordance with ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20 times. .14ml/ m2 or less, 0.11ml/ m2 or less, 0.08ml/ m2 or less, 0.06ml/ m2 or less , 0.04 ml/m 2 or less, or 0.02 ml/m 2 or less. The lower limit of the volume Vmp of the protruding peaks of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0.01 ml/m 2 or more, or 0.02 ml/m 2 or more. . In the thermally conductive sheet 1, the volume Vmp of the protruding peak portion may be in the range of 0.027 to 0.137 ml/ m2 , or may be in the range of 0.027 to 0.134 ml/ m2 . It may be in the range of 0.027 to 0.114 ml/ m2 , it may be in the range of 0.027 to 0.106 ml/ m2 , or it may be in the range of 0.027 to 0.102 ml/m2. It may be in the range of 2 . It is preferable that the volume Vmp of the protruding peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the volume Vmp of the protruding peaks on both surfaces may satisfy the above-mentioned range.
　熱伝導性シート１は、（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が３６％以下であってもよく、３０％以下であってもよく、２９％以下であってもよい。熱伝導性シート１の（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））の下限値は、特に限定されず、例えば、１０％以上であってもよいし、１５％以上であってもよいし、２０％以上であってもよいし、２５％以上であってもよい。熱伝導性シート１の（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））は、例えば、２８．２２～４５．２９％の範囲であってもよいし、２８．２２～３９．７８％の範囲であってもよいし、２８．２２～３９．６９％の範囲であってもよいし、２８．２２～３５．２７％の範囲であってもよいし、２８．２２～３４．９０％の範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面に関するＳｐｋ／（Ｓｐｋ＋Ｓｖｋ）が上述した範囲を満たすことが好ましく、一方の表面と他方の表面に関するＳｐｋ／（Ｓｐｋ＋Ｓｖｋ）が上述した範囲を満たしてもよい。 The thermally conductive sheet 1 may have (Spk/(Spk+Svk)) of 36% or less, 30% or less, or 29% or less. The lower limit of (Spk/(Spk+Svk)) of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 10% or more, 15% or more, or 20% or more. It may be 25% or more. (Spk/(Spk+Svk)) of the thermally conductive sheet 1 may be in the range of 28.22 to 45.29%, or may be in the range of 28.22 to 39.78%, for example. , may be in the range of 28.22 to 39.69%, may be in the range of 28.22 to 35.27%, or may be in the range of 28.22 to 34.90%. . In the thermally conductive sheet 1, it is preferable that Spk/(Spk+Svk) on at least one surface satisfies the above-mentioned range, and Spk/(Spk+Svk) on one surface and the other surface may satisfy the above-mentioned range.
　熱伝導性シート１は、突出谷部の平均深さＳｖｋが５．５μｍ以下であってもよく、４．５μｍ以下であってもよく。４．０μｍ以下であってもよく、３．５μｍ以下であってもよく、３．０μｍ以下であってもよく、２．５μｍ以下であってもよく、２．０μｍ以下であってもよく、１．５μｍ以下であってもよく、１．１μｍ以下であってもよい。熱伝導性シート１の突出谷部の平均深さＳｖｋの下限値は、特に限定されず、例えば、１．０μｍ以上であってもよい。熱伝導性シート１は、突出谷部の平均深さＳｖｋが、１．１６５～５．１５６μｍの範囲であってもよく、１．１６５～４．４９０μｍの範囲であってもよく、１．１６５～４．２９１μｍの範囲であってもよく、１．１６５～３．７１１μｍの範囲であってもよく、１．１６５～３．５５９μｍの範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の突出谷部の平均深さＳｖｋが上述した範囲を満たすことが好ましく、両面の突出谷部の平均深さＳｖｋが上述した範囲を満たしてもよい。熱伝導性シート１の突出谷部の平均深さＳｖｋは、後述する実施例に記載の方法で測定できる。 In the thermally conductive sheet 1, the average depth Svk of the protruding valleys may be 5.5 μm or less, or 4.5 μm or less. It may be 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, The thickness may be 1.5 μm or less, or 1.1 μm or less. The lower limit of the average depth Svk of the protruding valleys of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 1.0 μm or more. The average depth Svk of the protruding valleys of the thermally conductive sheet 1 may be in the range of 1.165 to 5.156 μm, may be in the range of 1.165 to 4.490 μm, and may be in the range of 1.165 to 4.490 μm. 4.291 μm, 1.165 to 3.711 μm, and 1.165 to 3.559 μm. It is preferable that the average depth Svk of the protruding troughs on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the average depth Svk of the protruding troughs on both surfaces may satisfy the above-mentioned range. The average depth Svk of the protruding valleys of the thermally conductive sheet 1 can be measured by the method described in Examples described below.
　熱伝導性シート１の二乗平均平方根勾配Ｓｄｑとは、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される熱伝導性シート１の表面の凹凸形状の局所的な勾配（形状の微分）の平均的な大きさを表す。例えば、熱伝導性シート１の表面が完全に平坦である場合、二乗平均平方根勾配Ｓｄｑは０となる。また、熱伝導性シート１の表面が急峻になるほど、二乗平均平方根勾配Ｓｄｑが大きくなる。熱伝導性シート１は、二乗平均平方根勾配Ｓｄｑが、１．０以下であってもよく、０．９以下であってもよく、０．８以下であってもよく、０．７以下であってもよく、０．６以下であってもよく、０．５以下であってもよく、０．４以下であってもよい。熱伝導性シート１の二乗平均平方根勾配Ｓｄｑの下限値は、特に限定されず、例えば、０．１以上であってもよいし、０．２以上であってもよい。熱伝導性シート１の二乗平均平方根勾配Ｓｄｑは、例えば、０．２７８～１．０７４の範囲であってもよいし、０．２７８～０.７３３の範囲であってもよいし、０．２７８～０．７３０の範囲であってもよいし、０．２７８～０.５７８の範囲であってもよいし、０．２７８～０.５６５の範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の二乗平均平方根勾配Ｓｄｑが上述した範囲を満たすことが好ましく、両面の二乗平均平方根勾配Ｓｄｑが上述した範囲を満たしてもよい。 The root mean square gradient Sdq of the thermally conductive sheet 1 is the local unevenness of the surface of the thermally conductive sheet 1 measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens. Represents the average size of the slope (differential of shape). For example, when the surface of the thermally conductive sheet 1 is completely flat, the root mean square gradient Sdq is zero. Moreover, the steeper the surface of the thermally conductive sheet 1 is, the larger the root mean square gradient Sdq becomes. The thermally conductive sheet 1 may have a root mean square gradient Sdq of 1.0 or less, 0.9 or less, 0.8 or less, or 0.7 or less. It may be 0.6 or less, 0.5 or less, or 0.4 or less. The lower limit of the root mean square gradient Sdq of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0.1 or more, or 0.2 or more. The root mean square gradient Sdq of the thermally conductive sheet 1 may be in the range of 0.278 to 1.074, may be in the range of 0.278 to 0.733, or may be 0.278. 0.730, 0.278 to 0.578, or 0.278 to 0.565. It is preferable that the root mean square gradient Sdq of at least one surface of the thermally conductive sheet 1 satisfies the above range, and the root mean square gradient Sdq of both surfaces may satisfy the above range.
　熱伝導性シート１は、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）と、界面の展開面積比Ｓｄｒ（％）とを、Ｓｐｃを横軸、Ｓｄｒを縦軸として値をプロットしたグラフを作成した場合、ＳｐｃとＳｄｒが下記式１を満たすことが好ましい。このように、熱伝導性シート１は、条件１～３の他に、式１も満たすことにより、より効果的に全熱抵抗値を低減させることができる。
式１：Ｙ＝０．０１４３Ｘ－（１２．３２９±１０） The thermally conductive sheet 1 has an arithmetic mean curvature Spc (1/mm) of the mountain peak and a developed area ratio Sdr ( %), and when a graph is created in which the values are plotted with Spc on the horizontal axis and Sdr on the vertical axis, it is preferable that Spc and Sdr satisfy the following formula 1. In this manner, the thermally conductive sheet 1 satisfies Expression 1 in addition to Conditions 1 to 3, thereby making it possible to more effectively reduce the total thermal resistance value.
Formula 1: Y=0.0143X-(12.329±10)
　すなわち、熱伝導性シート１は、山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）を横軸（Ｘ軸）、界面の展開面積比Ｓｄｒ（％）を縦軸（Ｙ軸）として値をプロットしたときに、プロットした値が、下記式１Ａと式１Ｂで囲まれる領域内に存在することが好ましい。
式１Ａ：Ｙ＝０．０１４３Ｘ－２２．３２９
式１Ｂ：Ｙ＝０．０１５３Ｘ－２．３２９ That is, when the value of the thermally conductive sheet 1 is plotted with the arithmetic mean curvature Spc (1/mm) of the mountain top as the horizontal axis (X axis) and the developed area ratio Sdr (%) of the interface as the vertical axis (Y axis), It is preferable that the plotted values exist within a region surrounded by the following formulas 1A and 1B.
Formula 1A: Y=0.0143X-22.329
Formula 1B: Y=0.0153X-2.329
　熱伝導性シート１の界面の展開面積比Ｓｄｒとは、ＩＳＯ　２５１７８に従って測定されるものであり、定義領域の展開面積（表面積）が、定義領域の面積に対してどれだけ増大しているかを表す。例えば、熱伝導性シート１の表面が完全に平坦である場合、界面の展開面積比Ｓｄｒは０％となる。 The developed area ratio Sdr of the interface of the thermally conductive sheet 1 is measured according to ISO 25178, and represents how much the developed area (surface area) of the defined region increases relative to the area of the defined region. . For example, when the surface of the thermally conductive sheet 1 is completely flat, the developed area ratio Sdr of the interface is 0%.
　熱伝導性シート１は、界面の展開面積比Ｓｄｒが４０％以下であることが好ましく、３５％以下であってもよく、３０％以下であってもよく、２５％以下であってもよく、２０％以下であってもよく、１９％以下であってもよく、１８％以下であってもよい。熱伝導性シート１の界面の展開面積比Ｓｄｒの下限値は、特に限定されず、例えば、０％以上であってもよいし、２％以上であってもよいし、１０％以上であってもよい。熱伝導性シート１の界面の展開面積比Ｓｄｒは、例えば、０～４５．００％の範囲であってもよいし、０～４０．００％の範囲であってもよいし、３．４５～３４．００％の範囲であってもよいし、３．４５～１８．６８％の範囲であってもよいし、３．４５～１７．３５％の範囲であってもよいし、３．４５～１０．４４％の範囲であってもよいし、３．４５～１０．３２％の範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の界面の展開面積比Ｓｄｒが上述した範囲を満たすことが好ましく、両面の界面の展開面積比Ｓｄｒが上述した範囲を満たしてもよい。 The thermally conductive sheet 1 preferably has an interface developed area ratio Sdr of 40% or less, may be 35% or less, may be 30% or less, may be 25% or less, It may be 20% or less, 19% or less, or 18% or less. The lower limit of the developed area ratio Sdr of the interface of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0% or more, 2% or more, or 10% or more. Good too. The developed area ratio Sdr of the interface of the thermally conductive sheet 1 may be in the range of 0 to 45.00%, 0 to 40.00%, or 3.45 to 45.00%, for example. It may be in the range of 34.00%, it may be in the range of 3.45 to 18.68%, it may be in the range of 3.45 to 17.35%, or it may be in the range of 3.45%. It may be in the range of ~10.44%, or it may be in the range of 3.45 to 10.32%. It is preferable that the developed area ratio Sdr of the interface on at least one surface of the thermally conductive sheet 1 satisfies the above range, and the developed area ratio Sdr of the interfaces on both surfaces may satisfy the above range.
　熱伝導性シート１の山頂の算術平均曲率Ｓｐｃとは、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定されるものであり、熱伝導性シート１の表面の山頂点の主曲率の平均を表す。熱伝導性シート１の山頂の算術平均曲率Ｓｐｃが小さいほど、熱伝導性シート１における他の物体（例えば被着体）と接触する点が丸みを帯びていることを表す。一方、熱伝導性シート１の山頂の算術平均曲率Ｓｐｃが大きいほど、熱伝導性シートにおける他の物体と接触する点が尖っていることを表す。 The arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. Represents the average of the principal curvatures of points. The smaller the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1, the more rounded the point in the thermally conductive sheet 1 that contacts another object (for example, an adherend) is. On the other hand, the larger the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1, the sharper the point of contact with another object on the thermally conductive sheet.
　熱伝導性シート１は、山頂の算術平均曲率Ｓｐｃが３５００（１／ｍｍ）以下であることが好ましく、３２００（１／ｍｍ）以下であってもよく、２８００（１／ｍｍ）以下であってもよく、２５００（１／ｍｍ）以下であってもよく、２１００（１／ｍｍ）以下であってもよく、１７００（１／ｍｍ）以下であってもよく、１５００（１／ｍｍ）以下であってもよく、１２００（１／ｍｍ）以下であってもよく、１０００（１／ｍｍ）以下であってもよい。熱伝導性シート１の山頂の算術平均曲率Ｓｐｃの下限値は、特に限定されず、例えば、０（１／ｍｍ）以上であってもよいし、５００（１／ｍｍ）以上であってもよいし、９００（１／ｍｍ）以上であってもよい。熱伝導性シート１の山頂の算術平均曲率Ｓｐｃは、例えば、０～３５００（１／ｍｍ）の範囲であってもよいし、９２７～３１３６（１／ｍｍ）の範囲であってもよいし、９２７～２４７５（１／ｍｍ）の範囲であってもよいし、９２７～２２９０（１／ｍｍ）の範囲であってもよいし、９２７～２０６６（１／ｍｍ）の範囲であってもよいし、９２７～１９３７（１／ｍｍ）の範囲であってもよい。熱伝導性シート１は、少なくとも一方の表面の山頂の算術平均曲率Ｓｐｃが上述した範囲を満たすことが好ましく、両面の山頂の算術平均曲率Ｓｐｃが上述した範囲を満たしてもよい。 The arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is preferably 3500 (1/mm) or less, may be 3200 (1/mm) or less, and may be 2800 (1/mm) or less. 2500 (1/mm) or less, 2100 (1/mm) or less, 1700 (1/mm) or less, 1500 (1/mm) or less It may be 1200 (1/mm) or less, or 1000 (1/mm) or less. The lower limit of the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is not particularly limited, and may be, for example, 0 (1/mm) or more, or 500 (1/mm) or more. However, it may be 900 (1/mm) or more. The arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 may be, for example, in the range of 0 to 3500 (1/mm), or may be in the range of 927 to 3136 (1/mm), It may be in the range of 927 to 2475 (1/mm), it may be in the range of 927 to 2290 (1/mm), it may be in the range of 927 to 2066 (1/mm), or it may be in the range of 927 to 2066 (1/mm). , 927 to 1937 (1/mm). It is preferable that the arithmetic mean curvature Spc of the peaks on at least one surface of the thermally conductive sheet 1 satisfies the above-mentioned range, and the arithmetic mean curvature Spc of the peaks on both surfaces may satisfy the above-mentioned range.
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される０．７０ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が低いほど好ましい。熱伝導性シート１は、例えば、０．７０ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．２３０℃・ｃｍ２／Ｗ未満であってもよく、０．２２０℃・ｃｍ２／Ｗ以下であってもよく、０．２００℃・ｃｍ２／Ｗ以下であってもよく、０．１９０℃・ｃｍ２／Ｗ以下であってもよく、０．１６０℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１は、厚みを１．０ｍｍとしたときに、０．７ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．３１２℃・ｃｍ２／Ｗ以下であってもよい。また、熱伝導性シート１は、厚みを２．０ｍｍとしたときに、０．７ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．５２５℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の０．７０ｋｇｆ／ｃｍ２加圧時の全熱抵抗値の下限値は、特に限定されず、より低い値であることが好ましく、０℃・ｃｍ２／Ｗを超え、例えば０．０５℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、厚みを０．３ｍｍとしたときに、０．７０ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が、０．１４３～０．２１２℃・ｃｍ２／Ｗの範囲であってもよく、０．１４３～０．２００℃・ｃｍ２／Ｗの範囲であってもよく、０．１４３～０．１８５℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 0.70 kgf/cm 2 measured according to ASTM-D5470. For example, the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.230°C·cm 2 /W when pressurized with 0.70 kgf/cm 2 , and not more than 0.220°C·cm 2 / W. It may be 0.200°C·cm 2 /W or less, it may be 0.190°C·cm 2 /W or less, or it may be 0.160°C·cm 2 /W or less. It's okay. The thermally conductive sheet 1 may have a total thermal resistance value of 0.312° C.cm 2 /W or less when a pressure of 0.7 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.525° C.cm 2 /W or less when 0.7 kgf/cm 2 is applied when the thickness is 2.0 mm. The lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 0.70 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, such as It can be 0.05° C.cm 2 /W or more. The thermally conductive sheet 1 has a total thermal resistance value of 0.143 to 0.212° C.cm 2 /W when a pressure of 0.70 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.143 to 0.200°C·cm 2 /W, or may be in the range of 0.143 to 0.185°C·cm 2 /W.
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が低いほど好ましい。熱伝導性シート１は、例えば、１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．２０８℃・ｃｍ２／Ｗ未満であってもよく、０．２００℃・ｃｍ２／Ｗ以下であってもよく、０．１９０℃・ｃｍ２／Ｗ以下であってもよく、０．１８０℃・ｃｍ２／Ｗ以下であってもよく、０．１７０℃・ｃｍ２／Ｗ以下であってもよく、０．１６０℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１は、厚みを１．０ｍｍとしたときに、１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．２８９℃・ｃｍ２／Ｗ以下であってもよい。また、熱伝導性シート１は、厚みを２．０ｍｍとしたときに、１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．６０１℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値の下限値は、特に限定されず、より低い値であることが好ましく、０℃・ｃｍ２／Ｗを超え、例えば０．０５℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、厚みを０．３ｍｍとしたときに、１．４ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が、０．１２８～０．１７９℃・ｃｍ２／Ｗの範囲であってもよく、０．１２８～０．１６６℃・ｃｍ２／Ｗの範囲であってもよく、０．１２８～０．１６５℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 1.4 kgf/cm 2 measured according to ASTM-D5470. For example, the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.208°C·cm 2 /W when pressurized with 1.4 kgf/cm 2 , and not more than 0.200°C·cm 2 /W. It may be 0.190°C·cm 2 /W or less, it may be 0.180°C·cm 2 /W or less, or it may be 0.170°C·cm 2 /W or less. The temperature may be 0.160° C.cm 2 /W or less. The thermally conductive sheet 1 may have a total thermal resistance value of 0.289° C.cm 2 /W or less when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.601° C.cm 2 /W or less when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 2.0 mm. The lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 1.4 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, such as It can be 0.05° C.cm 2 /W or more. The thermally conductive sheet 1 has a total thermal resistance value of 0.128 to 0.179° C.cm 2 /W when a pressure of 1.4 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.128 to 0.166°C·cm 2 /W, or may be in the range of 0.128 to 0.165°C·cm 2 /W.
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が低いほど好ましい。熱伝導性シート１は、例えば、２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．２００℃・ｃｍ２／Ｗ以下であってもよく、０．１９０℃・ｃｍ２／Ｗ以下であってもよく、０．１８０℃・ｃｍ２／Ｗ以下であってもよく、０．１７０℃・ｃｍ２／Ｗ以下であってもよく、０．１６０℃・ｃｍ２／Ｗ以下であってもよく、０．１５０℃・ｃｍ２／Ｗ以下であってもよく、０．１４０℃・ｃｍ２／Ｗ以下であってもよく、０．１３０℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１は、厚みを１．０ｍｍとしたときに、２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．３０３℃・ｃｍ２／Ｗ以下であってもよい。また、熱伝導性シート１は、厚みを２．０ｍｍとしたときに、２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．６８２℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値の下限値は、より低い値であることが好ましく、０℃・ｃｍ２／Ｗを超え、例えば０．０５℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、厚みを０．３ｍｍとしたときに、２．１ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が、０．１２６～０．１６１℃・ｃｍ２／Ｗの範囲であってもよく、０．１２６～０．１５５℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 2.1 kgf/cm 2 measured according to ASTM-D5470. For example, the thermally conductive sheet 1 may have a total thermal resistance value of 0.200°C·cm 2 /W or less when 2.1 kgf/cm 2 is applied, or 0.190°C·cm 2 / W or less. It may be 0.180°C·cm 2 /W or less, it may be 0.170°C·cm 2 /W or less, or it may be 0.160°C·cm 2 /W or less. It may be 0.150°C·cm 2 /W or less, it may be 0.140°C·cm 2 /W or less, or it may be 0.130°C·cm 2 /W or less. good. The thermally conductive sheet 1 may have a total thermal resistance value of 0.303° C.cm 2 /W or less when pressurized with 2.1 kgf/cm 2 when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.682° C.cm 2 /W or less when a pressure of 2.1 kgf/cm 2 is applied when the thickness is 2.0 mm. The lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 2.1 kgf/cm 2 is preferably a lower value, exceeding 0°C.cm 2 /W, for example, 0.05°C. cm 2 /W or more. The thermally conductive sheet 1 has a total thermal resistance value of 0.126 to 0.161° C.cm 2 /W when a pressure of 2.1 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.126 to 0.155°C·cm 2 /W.
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が低いほど好ましい。熱伝導性シート１は、例えば、２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．１９０℃・ｃｍ２／Ｗ未満であってもよく、０．１８０℃・ｃｍ２／Ｗ以下であってもよく、０．１７０℃・ｃｍ２／Ｗ以下であってもよく、０．１６０℃・ｃｍ２／Ｗ以下であってもよく、０．１５０℃・ｃｍ２／Ｗ以下であってもよく、０．１４０℃・ｃｍ２／Ｗ以下であってもよく、０．１３０℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１は、厚みを１．０ｍｍとしたときに、２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．３２７℃・ｃｍ２／Ｗ以下であってもよい。また、熱伝導性シート１は、厚みを２．０ｍｍとしたときに、２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．７３２℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値の下限値は、特に限定されず、より低い値であることが好ましく、０℃・ｃｍ２／Ｗを超え、例えば０．０５℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、厚みが０．３ｍｍであるときの２．８ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が、０．１２２～０．１５７℃・ｃｍ２／Ｗの範囲であってもよく、０．１２２～０．１５３℃・ｃｍ２／Ｗの範囲であってもよく、０．１２２～０．１５０℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 2.8 kgf/cm 2 measured according to ASTM-D5470. For example, the thermally conductive sheet 1 may have a total thermal resistance value of less than 0.190°C·cm 2 /W when pressurized with 2.8 kgf/cm 2 , and not more than 0.180°C·cm 2 /W. It may be 0.170°C·cm 2 /W or less, it may be 0.160°C·cm 2 /W or less, or it may be 0.150°C·cm 2 /W or less. It may be 0.140°C·cm 2 /W or less, or it may be 0.130°C·cm 2 /W or less. The thermally conductive sheet 1 may have a total thermal resistance value of 0.327° C.cm 2 /W or less when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.732° C.cm 2 /W or less when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 2.0 mm. The lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 2.8 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example It can be 0.05° C.cm 2 /W or more. The thermally conductive sheet 1 has a total thermal resistance value of 0.122 to 0.157° C.cm 2 /W when a pressure of 2.8 kgf/cm 2 is applied when the thickness is 0.3 mm. It may be in the range of 0.122 to 0.153°C·cm 2 /W, or may be in the range of 0.122 to 0.150°C·cm 2 /W.
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が低いほど好ましい。熱伝導性シート１は、例えば、３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．１８０℃・ｃｍ２／Ｗ以下であってもよく、０．１７０℃・ｃｍ２／Ｗ以下であってもよく、０．１６０℃・ｃｍ２／Ｗ以下であってもよく、０．１５０℃・ｃｍ２／Ｗ以下であってもよく、０．１４０℃・ｃｍ２／Ｗ以下であってもよく、０．１３０℃・ｃｍ２／Ｗ以下であってもよく、０．１２０℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１は、厚みを１．０ｍｍとしたときに、３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．３５０℃・ｃｍ２／Ｗ以下であってもよい。また、熱伝導性シート１は、厚みを２．０ｍｍとしたときに、３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が０．７６５℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値の下限値は、特に限定されず、より低い値であることが好ましく、０℃・ｃｍ２／Ｗを超え、例えば０．０５℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、厚みが０．３ｍｍであるときの３．５ｋｇｆ／ｃｍ２加圧時の全熱抵抗値が、０．１１９～０．１５６℃・ｃｍ２／Ｗの範囲であってもよく、０．１１９～０．１５１℃・ｃｍ２／Ｗの範囲であってもよく、０．１１９～０．１４８℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 preferably has a lower total thermal resistance value when pressurized with 3.5 kgf/cm 2 measured according to ASTM-D5470. For example, the thermally conductive sheet 1 may have a total thermal resistance value of 0.180°C·cm 2 /W or less when pressurized with 3.5 kgf/cm 2 , or 0.170°C·cm 2 / W or less. It may be 0.160°C·cm 2 /W or less, it may be 0.150°C·cm 2 /W or less, or it may be 0.140°C·cm 2 /W or less. It may be 0.130°C·cm 2 /W or less, or it may be 0.120°C·cm 2 /W or less. The thermally conductive sheet 1 may have a total thermal resistance value of 0.350° C.cm 2 /W or less when pressurized with 3.5 kgf/cm 2 when the thickness is 1.0 mm. Further, the thermally conductive sheet 1 may have a total thermal resistance value of 0.765° C.cm 2 /W or less when a pressure of 3.5 kgf/cm 2 is applied when the thickness is 2.0 mm. The lower limit of the total thermal resistance value of the thermally conductive sheet 1 when pressurized with 3.5 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example It can be 0.05° C.cm 2 /W or more. The thermally conductive sheet 1 has a total thermal resistance value of 0.119 to 0.156° C.cm 2 /W when pressurized with 3.5 kgf/cm 2 when the thickness is 0.3 mm. It may be in the range of 0.119 to 0.151°C·cm 2 /W, or may be in the range of 0.119 to 0.148°C·cm 2 /W.
　図２は、熱伝導性シート１の表面の一例を示す断面図である。熱伝導性シート１は、例えば図２に示すように、少なくとも一方の表面が研磨面であり、この研磨面に研磨残渣５を有することが好ましい。換言すると、熱伝導性シート１は、少なくとも一方の表面が研磨面であり、この研磨面に、研磨により脱離した熱伝導性組成物の構成材料からなる研磨残渣５を有することが好ましい。研磨残渣５は、例えば、バインダ樹脂２、異方性熱伝導材料３及び無機フィラー４を含有する熱伝導性組成物からなる塊状物である。熱伝導性シート１が表面に研磨残渣５を有することにより、熱伝導性シート１の表面をより平滑にすることができ、上述のように熱伝導性シート１が条件１～３を満たしやすい傾向にある。 FIG. 2 is a cross-sectional view showing an example of the surface of the thermally conductive sheet 1. As shown in FIG. 2, for example, at least one surface of the thermally conductive sheet 1 is a polished surface, and it is preferable that this polished surface has polishing residue 5. In other words, at least one surface of the thermally conductive sheet 1 is a polished surface, and it is preferable that the polished surface has a polishing residue 5 made of a constituent material of the thermally conductive composition detached by polishing. The polishing residue 5 is, for example, a lump made of a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4. By having the polishing residue 5 on the surface of the thermally conductive sheet 1, the surface of the thermally conductive sheet 1 can be made smoother, and the thermally conductive sheet 1 tends to satisfy conditions 1 to 3 as described above. It is in.
　熱伝導性シート１が研磨残渣５を有するとは、熱伝導性シート１が条件１～３を満たす程度に熱伝導性シート１の表面に研磨残渣５が存在することが好ましく、例えば、表面全体にわたってほぼ均一に研磨残渣５を有していてもよいし、例えば図２に示すように表面に部分的に（島状に）研磨残渣５を有していてもよい。熱伝導性シート１が表面に研磨残渣５を有するかどうかは、例えば、熱伝導性シート１の表面に粘着テープを貼り付けた後、この粘着テープを剥離することで、粘着テープに研磨残渣５が転着されるかどうかで確認できる。 When the thermally conductive sheet 1 has the polishing residue 5, it is preferable that the polishing residue 5 is present on the surface of the thermally conductive sheet 1 to such an extent that the thermally conductive sheet 1 satisfies conditions 1 to 3, for example, the polishing residue 5 is present on the entire surface. The polishing residue 5 may be present almost uniformly over the entire surface, or the polishing residue 5 may be present partially (in the form of islands) on the surface, for example, as shown in FIG. Whether or not the thermally conductive sheet 1 has polishing residues 5 on the surface can be determined, for example, by pasting an adhesive tape on the surface of the thermally conductive sheet 1 and then peeling off the adhesive tape. You can check whether it is transferred or not.
　研磨残渣５の大きさについて、上述のように熱伝導性シート１が条件１～３を満たしやすくするためには、研磨残渣５の平均粒子径や最大粒子径が大きすぎないことが好ましい。例えば、研磨残渣５の平均粒子径は、５０μｍ以下であってもよいし、４０μｍ以下であってもよいし、３５μｍ以下であってもよいし、３０μｍ以下であってもよいし、２０μｍ以下であってもよいし、１５μｍ以下であってもよいし、１０μｍ以下であってもよいし、０．５～４０μｍの範囲であってもよい。研磨残渣５の平均粒子径について、異形の研磨残渣５の場合は、粒子の最も長い部分の長さ（径）を考慮する。また、研磨残渣５の最大粒子径は、例えば、１００μｍ以下であってもよいし、９０μｍ以下であってもよいし、８０μｍ以下であってもよいし、７０μｍ以下であってもよいし、５０～１００μｍの範囲であってもよい。 Regarding the size of the polishing residue 5, in order for the thermally conductive sheet 1 to easily satisfy Conditions 1 to 3 as described above, it is preferable that the average particle diameter and maximum particle diameter of the polishing residue 5 are not too large. For example, the average particle diameter of the polishing residue 5 may be 50 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, or 20 μm or less. The thickness may be 15 μm or less, 10 μm or less, or in the range of 0.5 to 40 μm. Regarding the average particle diameter of the polishing residue 5, in the case of the irregularly shaped polishing residue 5, the length (diameter) of the longest part of the particle is taken into consideration. Further, the maximum particle diameter of the polishing residue 5 may be, for example, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 50 μm or less. It may be in the range of ~100 μm.
　熱伝導性シート１の厚みは、目的に応じて適宜選択することができ、例えば、０．０５ｍｍ以上とすることができ、０．１ｍｍ以上であってもよく、０．２ｍｍ以上であってもよく、０．３ｍｍ以上であってもよい。また、熱伝導性シート１の厚みの上限値は、例えば、５ｍｍ以下とすることができ、４ｍｍ以下であってもよく、３ｍｍ以下であってもよく、２ｍｍ以下であってもよく、１ｍｍ以下であってもよく、０．５ｍｍ以下であってもよい。例えば、熱伝導性シート１の厚みは、例えば、熱伝導性シート１の厚みＢを任意の５箇所で測定し、その算術平均値から求めることができる。 The thickness of the thermally conductive sheet 1 can be appropriately selected depending on the purpose, and may be, for example, 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more. It may be 0.3 mm or more. Further, the upper limit of the thickness of the thermally conductive sheet 1 can be, for example, 5 mm or less, may be 4 mm or less, may be 3 mm or less, may be 2 mm or less, and may be 1 mm or less. It may be 0.5 mm or less. For example, the thickness of the thermally conductive sheet 1 can be determined by measuring the thickness B of the thermally conductive sheet 1 at five arbitrary locations and calculating the arithmetic mean value thereof.
　熱伝導性シート１は、シート自体の熱抵抗が低くなるにつれて被着体との間に生じる全熱抵抗中の接触熱抵抗の寄与が大きくなる傾向にある。上述のように、シートが薄くなるとその傾向は顕著となる。換言すると、熱伝導性シート１は、シート自体の熱伝導率が上がるほど全熱抵抗値中の接触熱抵抗の占有率が大きくなる。本技術では、異方性熱伝導材料３が厚み方向に配向した熱伝導性シート１について、熱伝導性シート１が上述した条件１～３の少なくとも１つを満たすことにより、接触熱抵抗を低減することができ、結果として、全熱抵抗値を低減することができる。 In the thermally conductive sheet 1, as the thermal resistance of the sheet itself becomes lower, the contribution of the contact thermal resistance to the total thermal resistance generated between the sheet and the adherend tends to increase. As mentioned above, this tendency becomes more pronounced as the sheet becomes thinner. In other words, in the thermally conductive sheet 1, as the thermal conductivity of the sheet itself increases, the proportion of the contact thermal resistance in the total thermal resistance value increases. In this technology, the contact thermal resistance is reduced by the thermally conductive sheet 1 in which the anisotropic thermally conductive material 3 is oriented in the thickness direction, by satisfying at least one of the conditions 1 to 3 described above. As a result, the total thermal resistance value can be reduced.
　次に、熱伝導性シート１の構成例である、バインダ樹脂２と、異方性熱伝導材料３と、無機フィラー４について説明する。 Next, the binder resin 2, the anisotropic thermally conductive material 3, and the inorganic filler 4, which are examples of the structure of the thermally conductive sheet 1, will be explained.
　＜バインダ樹脂＞
　バインダ樹脂２は、異方性熱伝導材料３と無機フィラー４とを熱伝導性シート１内に保持するためのものである。バインダ樹脂２は、熱伝導性シート１に要求される機械的強度、耐熱性、電気的性質等の特性に応じて選択される。バインダ樹脂２としては、熱可塑性樹脂、熱可塑性エラストマー、熱硬化性樹脂の中から選択することができる。 <Binder resin>
Binder resin 2 is for holding anisotropic thermally conductive material 3 and inorganic filler 4 within thermally conductive sheet 1 . The binder resin 2 is selected depending on the properties required of the thermally conductive sheet 1, such as mechanical strength, heat resistance, and electrical properties. The binder resin 2 can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins.
　熱可塑性樹脂としては、ポリエチレン、ポリプロピレン、エチレン－プロピレン共重合体等のエチレン－αオレフィン共重合体、ポリメチルペンテン、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリ酢酸ビニル、エチレン－酢酸ビニル共重合体、ポリビニルアルコール、ポリビニルアセタール、ポリフッ化ビニリデン及びポリテトラフルオロエチレン等のフッ素系重合体、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート、ポリスチレン、ポリアクリロニトリル、スチレン－アクリロニトリル共重合体、アクリロニトリル－ブタジエン－スチレン共重合体（ＡＢＳ）樹脂、ポリフェニレン－エーテル共重合体（ＰＰＥ）樹脂、変性ＰＰＥ樹脂、脂肪族ポリアミド類、芳香族ポリアミド類、ポリイミド、ポリアミドイミド、ポリメタクリル酸、ポリメタクリル酸メチルエステル等のポリメタクリル酸エステル類、ポリアクリル酸類、ポリカーボネート、ポリフェニレンスルフィド、ポリサルホン、ポリエーテルサルホン、ポリエーテルニトリル、ポリエーテルケトン、ポリケトン、液晶ポリマー、アイオノマー等が挙げられる。 Examples of thermoplastic resins include polyethylene, polypropylene, ethylene-α olefin copolymers such as ethylene-propylene copolymers, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymers, Fluoropolymers such as polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer Polymer (ABS) resin, polyphenylene-ether copolymer (PPE) resin, modified PPE resin, aliphatic polyamide, aromatic polyamide, polyimide, polyamideimide, polymethacrylic acid, polymethacrylic acid methyl ester, etc. Examples include acid esters, polyacrylic acids, polycarbonates, polyphenylene sulfides, polysulfones, polyethersulfones, polyethernitrile, polyetherketones, polyketones, liquid crystal polymers, and ionomers.
　熱可塑性エラストマーとしては、スチレン－ブタジエンブロック共重合体又はその水添化物、スチレン－イソプレンブロック共重合体又はその水添化物、スチレン系熱可塑性エラストマー、オレフィン系熱可塑性エラストマー、塩化ビニル系熱可塑性エラストマー、ポリエステル系熱可塑性エラストマー、ポリウレタン系熱可塑性エラストマー、ポリアミド系熱可塑性エラストマー等が挙げられる。 Examples of thermoplastic elastomers include styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and vinyl chloride-based thermoplastic elastomers. , polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like.
　熱硬化性樹脂としては、架橋ゴム、エポキシ樹脂、フェノール樹脂、ポリイミド樹脂、不飽和ポリエステル樹脂、ジアリルフタレート樹脂、付加反応型シリコーン樹脂や縮合反応型シリコーン樹脂等が挙げられる。架橋ゴムの具体例としては、天然ゴム、アクリルゴム、ブタジエンゴム、イソプレンゴム、スチレン－ブタジエン共重合ゴム、ニトリルゴム、水添ニトリルゴム、クロロプレンゴム、エチレン－プロピレン共重合ゴム、塩素化ポリエチレンゴム、クロロスルホン化ポリエチレンゴム、ブチルゴム、ハロゲン化ブチルゴム、フッ素ゴム、ウレタンゴム、及びシリコーンゴムが挙げられる。 Examples of the thermosetting resin include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, addition reaction type silicone resin, condensation reaction type silicone resin, and the like. Specific examples of crosslinked rubber include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Examples include chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, and silicone rubber.
　バインダ樹脂２としては、例えば、発熱体（例えば電子部品）の発熱面とヒートシンク面との密着性の観点では、シリコーン樹脂が好ましい。シリコーン樹脂としては、例えば、アルケニル基を有するシリコーン（ポリオルガノシロキサン）を主成分とし、硬化触媒を含有する主剤と、ヒドロシリル基（Ｓｉ－Ｈ基）を有する硬化剤とからなる、２液型の付加反応型シリコーン樹脂を用いることができる。アルケニル基を有するシリコーンとしては、１分子中に少なくとも２個のアルケニル基を有するポリオルガノシロキサンを用いることができる。一例として、ビニル基を有するポリオルガノシロキサンを用いることができる。硬化触媒は、アルケニル基を有するシリコーン中のアルケニル基と、ヒドロシリル基を有する硬化剤中のヒドロシリル基との付加反応を促進するための触媒である。硬化触媒としては、ヒドロシリル化反応に用いられる触媒として周知の触媒が挙げられ、例えば、白金族系硬化触媒、例えば白金、ロジウム、パラジウムなどの白金族金属単体や塩化白金、白金と有機化合物の錯体などを用いることができる。ヒドロシリル基を有する硬化剤としては、例えば、ヒドロシリル基を有するポリオルガノシロキサン（ケイ素原子に直接結合した水素原子を１分子中に少なくとも２個有するオルガノハイドロジェンポリシロキサン）を用いることができる。 As the binder resin 2, silicone resin is preferable, for example, from the viewpoint of adhesion between the heat generating surface of the heat generating element (for example, an electronic component) and the heat sink surface. As the silicone resin, for example, a two-component type silicone resin containing silicone (polyorganosiloxane) having an alkenyl group as the main component, a main resin containing a curing catalyst, and a curing agent having a hydrosilyl group (Si-H group) is used. Addition reaction type silicone resins can be used. As the silicone having an alkenyl group, a polyorganosiloxane having at least two alkenyl groups in one molecule can be used. As an example, polyorganosiloxanes having vinyl groups can be used. The curing catalyst is a catalyst for promoting an addition reaction between an alkenyl group in the silicone having an alkenyl group and a hydrosilyl group in the curing agent having a hydrosilyl group. Examples of the curing catalyst include catalysts well known as catalysts used in hydrosilylation reactions, such as platinum group curing catalysts, such as simple platinum group metals such as platinum, rhodium, and palladium, platinum chloride, and complexes of platinum and organic compounds. etc. can be used. As the curing agent having a hydrosilyl group, for example, a polyorganosiloxane having a hydrosilyl group (organohydrogenpolysiloxane having at least two hydrogen atoms in one molecule directly bonded to a silicon atom) can be used.
　バインダ樹脂２として、例えば、上述した２液型の付加反応型シリコーン樹脂を用いる場合、主剤となる成分（シリコーン主剤）と硬化剤となる成分との割合、すなわち、ビニル基を有するポリオルガノシロキサンと、ヒドロシリル基を有するポリオルガノシロキサンの混合比率は、特に限定されず、ビニル基１ｍｏｌに対してヒドロシリル基が０．３～０．９ｍｏｌの範囲となるような混合比率であってもよく、０．４～０．７ｍｏｌの範囲となるような混合比率でもあってもよい。 For example, when using the above-mentioned two-component addition reaction type silicone resin as the binder resin 2, the ratio of the main component (silicone main component) to the curing agent component, that is, the polyorganosiloxane having a vinyl group and The mixing ratio of the polyorganosiloxane having a hydrosilyl group is not particularly limited, and may be such that the hydrosilyl group is in the range of 0.3 to 0.9 mol per mol of the vinyl group. The mixing ratio may be in the range of 4 to 0.7 mol.
　熱伝導性シート１中のバインダ樹脂２の含有量は、特に限定されず、目的に応じて適宜選択することができる。例えば、熱伝導性シート１中のバインダ樹脂２の含有量は、２０体積％以上とすることができ、２４体積％以上であってもよく、２８体積％以上であってもよく、３０体積％以上であってもよく、３２体積％以上であってもよい。また、熱伝導性シート１中のバインダ樹脂２の含有量の上限値は、６０体積％以下とすることができ、５０体積％以下であってもよく、４０体積％以下であってもよく、３８体積％以下であってもよく、３５体積％以下であってもよく、３２体積％以下であってもよく、３０体積％以下であってもよい。熱伝導性シート１中のバインダ樹脂２の含有量は、例えば、２４～３２体積％の範囲とすることができ、２４～２８体積％の範囲とすることもできる。バインダ樹脂２は、１種単独で用いてもよいし、２種以上を併用してもよい。２種以上のバインダ樹脂２を併用する場合、その合計量が上述した含有量を満たすことが好ましい。 The content of the binder resin 2 in the thermally conductive sheet 1 is not particularly limited, and can be appropriately selected depending on the purpose. For example, the content of the binder resin 2 in the thermally conductive sheet 1 may be 20 volume% or more, may be 24 volume% or more, may be 28 volume% or more, or may be 30 volume%. The content may be more than 32% by volume. Further, the upper limit of the content of the binder resin 2 in the thermally conductive sheet 1 can be 60 volume% or less, may be 50 volume% or less, or may be 40 volume% or less, It may be 38 volume% or less, 35 volume% or less, 32 volume% or less, or 30 volume% or less. The content of the binder resin 2 in the thermally conductive sheet 1 can be, for example, in the range of 24 to 32% by volume, and can also be in the range of 24 to 28% by volume. The binder resin 2 may be used alone or in combination of two or more. When using two or more types of binder resins 2, it is preferable that the total amount thereof satisfies the above-mentioned content.
　＜異方性熱伝導材料＞
　異方性熱伝導材料３は、形状に異方性を有する熱伝導性材料である。例えば、異方性熱伝導材料３の一例として、長軸と短軸とを有する熱伝導性フィラーが挙げられ、具体例として繊維状フィラーが挙げられる。異方性熱伝導材料３の一例である繊維状フィラーは、繊維状であって必要な熱伝導性を有するものであれば特に限定されず、例えば、炭素繊維、窒化アルミニウムウィスカーなどが挙げられる。以下では、異方性熱伝導材料３として、炭素繊維を用いた場合を例に挙げて詳述する。異方性熱伝導材料３とは、長軸と短軸とを有し、長軸と短軸の長さが異なりアスペクト比（平均長軸長さ／平均短軸長さ）が１を超える形状であるものを含む。異方性熱伝導材料３は、１種単独で用いてもよいし、２種以上を併用してもよい。 <Anisotropic heat conductive material>
The anisotropic thermally conductive material 3 is a thermally conductive material that has anisotropy in shape. For example, an example of the anisotropic thermally conductive material 3 is a thermally conductive filler having a long axis and a short axis, and a specific example is a fibrous filler. The fibrous filler, which is an example of the anisotropic thermally conductive material 3, is not particularly limited as long as it is fibrous and has the necessary thermal conductivity, and examples thereof include carbon fibers, aluminum nitride whiskers, and the like. In the following, a case where carbon fiber is used as the anisotropic thermally conductive material 3 will be described in detail as an example. Anisotropic thermally conductive material 3 is a shape that has a long axis and a short axis, the lengths of the long axis and the short axis are different, and the aspect ratio (average major axis length/average short axis length) exceeds 1. including those that are. The anisotropic thermally conductive material 3 may be used alone or in combination of two or more.
　炭素繊維は、例えば、ピッチ系炭素繊維、ＰＡＮ系炭素繊維、ＰＢＯ繊維を黒鉛化した炭素繊維、アーク放電法、レーザー蒸発法、ＣＶＤ法（化学気相成長法）、ＣＣＶＤ法（触媒化学気相成長法）等で合成された炭素繊維を用いることができる。これらの中でも、熱伝導性の観点では、ピッチ系炭素繊維が好ましい。 Examples of carbon fiber include pitch-based carbon fiber, PAN-based carbon fiber, carbon fiber obtained by graphitizing PBO fiber, arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (catalytic chemical vapor deposition method) Carbon fibers synthesized by a method such as a carbon fiber growth method) can be used. Among these, pitch-based carbon fibers are preferred from the viewpoint of thermal conductivity.
　異方性熱伝導材料３の平均繊維長（平均長軸長さ）は、例えば、５０～２５０μｍとすることができ、７５～２２０μｍであってもよい。また、異方性熱伝導材料３の平均繊維径（平均短軸長さ）は、目的に応じて適宜選択することができ、例えば、４～２０μｍとすることができ、５～１４μｍであってもよい。異方性熱伝導材料３のアスペクト比は、目的に応じて適宜選択することができ、例えば、熱伝導性の観点では、８以上とすることができ、９～３０の範囲であってもよい。異方性熱伝導材料３の平均長軸長さ及び平均短軸長さは、例えば、マイクロスコープや走査型電子顕微鏡（ＳＥＭ）で測定できる。 The average fiber length (average major axis length) of the anisotropic thermally conductive material 3 can be, for example, 50 to 250 μm, and may be 75 to 220 μm. Further, the average fiber diameter (average minor axis length) of the anisotropic thermally conductive material 3 can be appropriately selected depending on the purpose, and can be, for example, 4 to 20 μm, or 5 to 14 μm. Good too. The aspect ratio of the anisotropic thermally conductive material 3 can be appropriately selected depending on the purpose. For example, from the viewpoint of thermal conductivity, it can be set to 8 or more, and may be in the range of 9 to 30. . The average major axis length and average minor axis length of the anisotropic thermally conductive material 3 can be measured using, for example, a microscope or a scanning electron microscope (SEM).
　熱伝導性シート１中の異方性熱伝導材料３の含有量は、熱伝導性シート１の熱伝導性の観点では、例えば、５体積％以上とすることができ、１０体積％以上であってもよく、１４積％以上であってもよく、２０体積％以上であってもよく、２２体積％以上であってもよく、２４体積％以上であってもよく、２６体積％以上であってもよい。また、熱伝導性シート１中の異方性熱伝導材料３の含有量は、熱伝導性シート１の成形性の観点では、例えば、３０体積％以下とすることができ、２８体積％以下であってもよい。熱伝導性シート１中の異方性熱伝導材料３の含有量は、例えば、２６～２９体積％の範囲とすることができ、２６～２８体積％の範囲とすることもできる。２種以上の異方性熱伝導材料３を併用する場合、その合計量が上述した含有量を満たすことが好ましい。 From the viewpoint of thermal conductivity of the thermally conductive sheet 1, the content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, 5% by volume or more, and can be 10% by volume or more. It may be 14 volume% or more, 20 volume% or more, 22 volume% or more, 24 volume% or more, 26 volume% or more. It's okay. Further, from the viewpoint of formability of the thermally conductive sheet 1, the content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, 30% by volume or less, and 28% by volume or less. There may be. The content of the anisotropic thermally conductive material 3 in the thermally conductive sheet 1 can be, for example, in the range of 26 to 29% by volume, and can also be in the range of 26 to 28% by volume. When using two or more types of anisotropic thermally conductive materials 3 in combination, it is preferable that the total amount thereof satisfies the above-mentioned content.
　＜無機フィラー＞
　無機フィラー４は、異方性熱伝導材料３以外の熱伝導性フィラーである。無機フィラー４には、例えば、球状、粉末状、顆粒状などの熱伝導性フィラーが含まれる。無機フィラー４の材質は、熱伝導性シート１の熱伝導性の観点では、例えば、セラミックフィラーが好ましく、具体例としては、酸化アルミニウム（アルミナ、サファイア）、窒化アルミニウム、アルミニウム、水酸化アルミニウム、窒化ホウ素などが挙げられる。無機フィラー４は、１種単独で用いてもよいし、２種以上を併用してもよい。例えば、無機フィラー４として、平均粒子径が異なる２種以上の熱伝導性フィラーを併用してもよい。 <Inorganic filler>
The inorganic filler 4 is a thermally conductive filler other than the anisotropic thermally conductive material 3. The inorganic filler 4 includes, for example, spherical, powdery, granular, and other thermally conductive fillers. From the viewpoint of thermal conductivity of the thermally conductive sheet 1, the material of the inorganic filler 4 is preferably a ceramic filler, for example, and specific examples include aluminum oxide (alumina, sapphire), aluminum nitride, aluminum, aluminum hydroxide, and nitride. Examples include boron. The inorganic filler 4 may be used alone or in combination of two or more. For example, as the inorganic filler 4, two or more types of thermally conductive fillers having different average particle diameters may be used in combination.
　特に、無機フィラー４としては、熱伝導性シート１の熱伝導率や、熱伝導性シート１の比重の観点などを考慮して、酸化アルミニウム、窒化アルミニウム及びアルミニウムから選択される少なくとも１種以上であることが好ましい。例えば、無機フィラー４としては、酸化アルミニウムと窒化アルミニウムとを併用してもよく、酸化アルミニウムと窒化アルミニウムとアルミニウムとを併用してもよい。 In particular, the inorganic filler 4 is at least one selected from aluminum oxide, aluminum nitride, and aluminum, taking into consideration the thermal conductivity of the thermally conductive sheet 1 and the specific gravity of the thermally conductive sheet 1. It is preferable that there be. For example, as the inorganic filler 4, aluminum oxide and aluminum nitride may be used together, or aluminum oxide, aluminum nitride, and aluminum may be used together.
　窒化アルミニウムの平均粒子径は、例えば熱伝導性シート１の比重の観点では、０．１～１０μｍの範囲であってもよく、０．５～５μｍの範囲であってもよく、０．５～３μｍの範囲であってもよく、０．５～２μｍの範囲であってもよい。酸化アルミニウムの平均粒子径は、例えば熱伝導性シート１の比重の観点では、０．１～１０μｍの範囲とすることができ、０．１～８μｍの範囲であってもよく、０．１～７μｍの範囲であってもよく、０．１～３μｍの範囲であってもよい。アルミニウムの平均粒子径は、例えば熱伝導性シート１の比重の観点では、１５μｍ未満とすることができ、１～１４μｍの範囲であってもよい。 The average particle diameter of aluminum nitride may be in the range of 0.1 to 10 μm, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, may be in the range of 0.5 to 5 μm, and may be in the range of 0.5 to 5 μm. The range may be 3 μm or 0.5 to 2 μm. The average particle diameter of aluminum oxide can be in the range of 0.1 to 10 μm, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, and may be in the range of 0.1 to 8 μm, and may be in the range of 0.1 to 8 μm. It may be in the range of 7 μm or may be in the range of 0.1 to 3 μm. The average particle diameter of aluminum can be less than 15 μm, for example from the viewpoint of the specific gravity of the thermally conductive sheet 1, and may be in the range of 1 to 14 μm.
　熱伝導性シート１中の無機フィラー４の含有量は、目的に応じて適宜選択することができる。熱伝導性シート１中における無機フィラー４の含有量は、例えば、１０体積％以上とすることができ、１５体積％以上であってもよく、２０体積％以上であってもよく、２５体積％以上であってもよく、３０体積％以上であってもよく、３５体積％以上であってもよく、３９体積％以上であってもよく、４５体積％以上であってもよい。また、熱伝導性シート１中の無機フィラー４の含有量の上限値は、例えば、５５体積％以下とすることができ、５０体積％以下であってもよく、４９体積％以下であってもよく、４５体積％以下であってもよく、４０体積％以下であってもよい。熱伝導性シート１中における無機フィラー４の含有量は、例えば、３９～４９体積％の範囲とすることができる。２種以上の無機フィラー４を併用する場合、その合計量が上述した含有量を満たすことが好ましい。 The content of the inorganic filler 4 in the thermally conductive sheet 1 can be appropriately selected depending on the purpose. The content of the inorganic filler 4 in the thermally conductive sheet 1 can be, for example, 10 volume% or more, may be 15 volume% or more, may be 20 volume% or more, and may be 25 volume%. It may be 30 volume% or more, 35 volume% or more, 39 volume% or more, or 45 volume% or more. Further, the upper limit of the content of the inorganic filler 4 in the thermally conductive sheet 1 may be, for example, 55 volume% or less, may be 50 volume% or less, or may be 49 volume% or less. It may be 45% by volume or less, or 40% by volume or less. The content of the inorganic filler 4 in the thermally conductive sheet 1 can be, for example, in the range of 39 to 49% by volume. When two or more types of inorganic fillers 4 are used together, it is preferable that the total amount thereof satisfies the above-mentioned content.
　無機フィラー４として、例えば、酸化アルミニウムと窒化アルミニウムとを併用する場合、熱伝導性シート１中、窒化アルミニウムの含有量を１０～３５体積％の範囲とし、酸化アルミニウムの含有量を５～２５体積％の範囲とすることができ、窒化アルミニウムの含有量を２０～３０体積％の範囲とし、酸化アルミニウムの含有量を１０～２５体積％の範囲とすることもできる。また、無機フィラー４として、例えば、酸化アルミニウムと窒化アルミニウムとアルミニウムとを併用する場合、熱伝導性シート１中、窒化アルミニウムの含有量を１０～３０体積％の範囲とし、酸化アルミニウムの含有量を１～２０体積％の範囲とし、アルミニウムの含有量を１０～３０体積％の範囲することができる。 For example, when aluminum oxide and aluminum nitride are used together as the inorganic filler 4, the content of aluminum nitride in the thermally conductive sheet 1 is in the range of 10 to 35% by volume, and the content of aluminum oxide is in the range of 5 to 25% by volume. %, the content of aluminum nitride can be in the range of 20-30% by volume, and the content of aluminum oxide can be in the range of 10-25% by volume. Further, when using aluminum oxide, aluminum nitride, and aluminum together as the inorganic filler 4, for example, the content of aluminum nitride in the thermally conductive sheet 1 is set in the range of 10 to 30% by volume, and the content of aluminum oxide is set in the range of 10 to 30% by volume. The aluminum content can be in the range of 1 to 20% by volume, and the aluminum content can be in the range of 10 to 30% by volume.
　＜他の成分＞
　熱伝導性シート１は、本技術の効果を損なわない範囲で、上述した成分以外の他の成分をさらに含有してもよい。他の成分としては、例えば、カップリング剤、分散剤、硬化促進剤、遅延剤、粘着付与剤、可塑剤、難燃剤、酸化防止剤、安定剤、着色剤、溶剤などが挙げられる。例えば、熱伝導性シート１は、異方性熱伝導材料３及び無機フィラー４の分散性をより向上させるために、カップリング剤で処理した異方性熱伝導材料３及び／又はカップリング剤で処理した無機フィラー４を用いてもよい。 <Other ingredients>
The thermally conductive sheet 1 may further contain other components other than those described above, as long as the effects of the present technology are not impaired. Examples of other components include coupling agents, dispersants, curing accelerators, retarders, tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants, and solvents. For example, in order to further improve the dispersibility of the anisotropic thermally conductive material 3 and the inorganic filler 4, the thermally conductive sheet 1 is made of anisotropic thermally conductive material 3 treated with a coupling agent and/or a coupling agent. A treated inorganic filler 4 may also be used.
　このような熱伝導性シート１の硬度は、研磨のしやすさと、シートの柔軟性による被着体への追従性の観点から、例えばショアＯＯ硬度として４０～９５であることが好ましい。 The hardness of such a thermally conductive sheet 1 is preferably, for example, 40 to 95 in terms of Shore OO hardness, from the viewpoint of ease of polishing and conformability to an adherend due to the flexibility of the sheet.
　以上のように、熱伝導性シート１は、異方性熱伝導材料３と、無機フィラー４と、バインダ樹脂２とを含む熱伝導性組成物の硬化物からなり、上述した条件１～３の少なくとも１つを満たすため、熱伝導性シート１と被着体との接触面積が増大し、熱伝導性シート１と被着体との間にエアーが混入することが抑制されるため、接触熱抵抗を低減でき、結果として、全熱抵抗値を低減することができる。 As described above, the thermally conductive sheet 1 is made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material 3, an inorganic filler 4, and a binder resin 2, and satisfies the conditions 1 to 3 described above. Since at least one condition is satisfied, the contact area between the thermally conductive sheet 1 and the adherend increases, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, so the contact heat The resistance can be reduced, and as a result, the total thermal resistance value can be reduced.
　＜熱伝導性シートの製造方法＞
　次に、熱伝導性シート１の製造方法について説明する。熱伝導性シート１の製造方法は、以下の工程Ａと、工程Ｂと、工程Ｃとを有する。 <Method for manufacturing thermally conductive sheet>
Next, a method for manufacturing the thermally conductive sheet 1 will be explained. The method for manufacturing the thermally conductive sheet 1 includes the following steps A, B, and C.
　＜工程Ａ＞
　工程Ａでは、バインダ樹脂２と、異方性熱伝導材料３と、無機フィラー４とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性組成物の成型体（熱伝導性成形体）を得る。 <Process A>
In step A, a thermally conductive composition containing a binder resin 2, an anisotropic thermally conductive material 3, and an inorganic filler 4 is molded into a predetermined shape and cured to form a molded body of the thermally conductive composition (thermal A conductive molded body) is obtained.
　工程Ａの一例では、まず、異方性熱伝導材料３と無機フィラー４とをバインダ樹脂２に分散させることにより、バインダ樹脂２と、異方性熱伝導材料３と、無機フィラー４とを含む熱伝導性組成物を作製する。熱伝導性組成物は、バインダ樹脂２と、異方性熱伝導材料３と、無機フィラー４との他に、必要に応じて上述した他の成分を公知の手法により均一に混合することで調製できる。 In an example of process A, first, the anisotropic thermally conductive material 3 and the inorganic filler 4 are dispersed in the binder resin 2, thereby containing the binder resin 2, the anisotropic thermally conductive material 3, and the inorganic filler 4. A thermally conductive composition is produced. The thermally conductive composition is prepared by uniformly mixing the binder resin 2, the anisotropic thermally conductive material 3, the inorganic filler 4, and other components mentioned above as necessary using a known method. can.
　続いて、熱伝導性組成物を押出成形した後硬化し、柱状の硬化物（熱伝導性成形体）を得る。押出成形する方法は、特に制限されず、公知の各種押出成形法の中から、熱伝導性組成物の粘度や熱伝導性シート１に要求される特性等に応じて適宜採用できる。押出成形法において、熱伝導性組成物をダイより押し出す際、熱伝導性組成物中のバインダ樹脂２が流動し、その流動方向に沿って異方性熱伝導材料３が配向する。柱状の硬化物の大きさ・形状は、求められる熱伝導性シート１の大きさに応じて決めることができる。例えば、断面の縦の大きさが０．５～１５ｃｍで横の大きさが０．５～１５ｃｍの直方体が挙げられる。直方体の長さは必要に応じて決定すればよい。 Subsequently, the thermally conductive composition is extruded and then cured to obtain a columnar cured product (thermally conductive molded body). The extrusion molding method is not particularly limited, and can be appropriately adopted from various known extrusion molding methods depending on the viscosity of the thermally conductive composition, the characteristics required of the thermally conductive sheet 1, and the like. In the extrusion molding method, when extruding a thermally conductive composition from a die, the binder resin 2 in the thermally conductive composition flows, and the anisotropic thermally conductive material 3 is oriented along the flow direction. The size and shape of the columnar cured product can be determined depending on the required size of the thermally conductive sheet 1. For example, a rectangular parallelepiped with a vertical cross section of 0.5 to 15 cm and a horizontal cross section of 0.5 to 15 cm may be mentioned. The length of the rectangular parallelepiped may be determined as necessary.
　＜工程Ｂ＞
　工程Ｂでは、工程Ａで得られた熱伝導性成形体をシート状に切断し、シート状成形体を得る。工程Ｂの一例では、工程Ａで得た柱状の硬化物を柱の長さ方向に対し所定の厚みに切断してシート状成形体を得る。シート状成形体の表面（切断面）には、異方性熱伝導材料３が露出する。熱伝導性成形体の切断方法は、特に制限されず、熱伝導性成形体の大きさや機械的強度により、公知のスライス装置の中から適宜選択できる。熱伝導性成形体を得る際に押出成形法を採用する場合、押出し方向に異方性熱伝導材料３が配向しているものもあるため、熱伝導性成形体の切断方向としては、押出し方向に対して６０～１２０度であることが好ましく、７０～１００度の方向であることがより好ましく、９０度（略垂直）の方向であることがさらに好ましい。熱伝導性成形体の切断方向は、上記の他は特に制限はなく、熱伝導性シート１の使用目的等に応じて適宜選択できる。 <Process B>
In step B, the thermally conductive molded product obtained in step A is cut into sheet shapes to obtain sheet-like molded products. In an example of step B, the columnar cured product obtained in step A is cut into a predetermined thickness in the length direction of the column to obtain a sheet-like molded product. The anisotropic thermally conductive material 3 is exposed on the surface (cut surface) of the sheet-like molded body. The method for cutting the thermally conductive molded body is not particularly limited, and can be appropriately selected from known slicing devices depending on the size and mechanical strength of the thermally conductive molded body. When extrusion molding is used to obtain a thermally conductive molded body, the anisotropic thermally conductive material 3 may be oriented in the extrusion direction, so the cutting direction of the thermally conductive molded body must be in the extrusion direction. The angle is preferably 60 to 120 degrees, more preferably 70 to 100 degrees, and even more preferably 90 degrees (substantially perpendicular). The cutting direction of the thermally conductive molded body is not particularly limited other than the above, and can be appropriately selected depending on the intended use of the thermally conductive sheet 1 and the like.
　＜工程Ｃ＞
　通常、工程Ｂで得られるシート状成形体は、表面に凹凸が存在する。例えば、工程Ｂで得られるシート状成形体は、図２に示すように、表面に複数の凸部１ａと、凸部１ａに隣接した凹部とを有する。そのため、通常、工程Ｂで得られるシート状成形体は、上述した条件１～３を満たさない傾向にある。表面にこのような凹凸が存在するシート状成形体を用いると、シート状成形体と被着体との間にエアーが混入しやすくなり、シート状成形体の接触熱抵抗を低減するのが難しい傾向にある。 <Process C>
Usually, the sheet-like molded product obtained in step B has irregularities on its surface. For example, as shown in FIG. 2, the sheet-like molded product obtained in step B has a plurality of convex portions 1a on the surface and concave portions adjacent to the convex portions 1a. Therefore, the sheet-like molded product obtained in step B usually tends not to satisfy the above-mentioned conditions 1 to 3. When using a sheet-like molded product with such irregularities on its surface, air tends to get mixed in between the sheet-like molded product and the adherend, making it difficult to reduce the contact thermal resistance of the sheet-like molded product. There is a tendency.
　そこで、工程Ｃでは、工程Ｂで得られたシート状成形体の表面を研磨することにより、シート状成形体の表面の凸部１ａから削り出たバインダ樹脂２、異方性熱伝導材料３及び無機フィラー４によってシート状成形体の表面の凹部が被覆され（換言すると、凸部１ａから削り出された研磨残渣５が凹部に留まる）ことで、熱伝導性シート１の表面が上述した条件１～３の少なくとも１つを満たすことができ、熱伝導性シート１と被着体との接触面積が向上して、熱伝導性シート１と被着体との間にエアーが混入することを抑制し、熱伝導性シート１の接触熱抵抗を低減させることができる。また、これに加えて、ブリードしたバインダ樹脂２が熱伝導性シート１の表面を被覆することにより、熱伝導性シート１と被着体との接触面積がより向上し、熱伝導性シート１と被着体との間にエアーが混入することがより効果的に抑制され、熱伝導性シート１の接触熱抵抗をさらに低減させることができると考えられる。 Therefore, in step C, by polishing the surface of the sheet-like molded body obtained in step B, the binder resin 2, anisotropic thermally conductive material 3, and By covering the recesses on the surface of the sheet-like molded body with the inorganic filler 4 (in other words, the polishing residue 5 scraped from the projections 1a remains in the recesses), the surface of the thermally conductive sheet 1 meets the above-mentioned condition 1. - At least one of 3 can be satisfied, the contact area between the thermally conductive sheet 1 and the adherend is improved, and air is prevented from entering between the thermally conductive sheet 1 and the adherend. However, the contact thermal resistance of the thermally conductive sheet 1 can be reduced. In addition, by covering the surface of the thermally conductive sheet 1 with the bled binder resin 2, the contact area between the thermally conductive sheet 1 and the adherend is further improved, and the surface of the thermally conductive sheet 1 and the adherend are further improved. It is considered that the mixture of air with the adherend can be more effectively suppressed, and the contact thermal resistance of the thermally conductive sheet 1 can be further reduced.
　例えば、工程Ｃでは、シート状成形体を研磨部材によって研磨する。研磨部材としては、例えば、シート状成形体の表面に面接触させ研磨することができるものが挙げられる。このような研磨部材としては、例えば、紙やすり、ラッピングフィルム、ブラシが挙げられ、耐久性や砥粒の粒度の精度、処理量に応じて適宜選択される。ラッピングフィルムとは、基材となる樹脂製フィルムに接着剤を用いて砥粒を固定したフィルムである。ラッピングフィルムのようにシート状成形体の表面に面接触させて研磨することができる研磨部材を用いることにより、シート状成形体の表面の凸部１ａから削り出たバインダ樹脂２、異方性熱伝導材料３及び無機フィラー４によってシート状成形体の表面の凹部をより効率的に被覆できる。 For example, in step C, the sheet-like molded body is polished with a polishing member. Examples of the polishing member include those that can be brought into surface contact with the surface of the sheet-like molded body for polishing. Examples of such abrasive members include sandpaper, wrapping films, and brushes, which are appropriately selected depending on durability, accuracy of abrasive grain size, and throughput. A lapping film is a film in which abrasive grains are fixed to a resin film as a base material using an adhesive. By using a polishing member such as a wrapping film that can be polished by bringing it into surface contact with the surface of the sheet-like molded body, the binder resin 2 scraped out from the convex portions 1a on the surface of the sheet-like molded body, and the anisotropic heat The conductive material 3 and the inorganic filler 4 can more efficiently cover the recesses on the surface of the sheet-like molded body.
　ラッピングフィルムは、例えば、基材としてポリエステルフィルムを用い、砥粒として平均粒子径２～４０μｍの酸化アルミニウムを用いたものを用いることができる。あるいは、砥粒の粒度を示すものとして公称値で＃４００～＃６０００のラッピングフィルムを用いることができる。ラッピングフィルムのサイズや厚みは、研磨するシート状成形体の大きさに応じて適宜変更することができる。例えば、ラッピングフィルムの厚みは、０．０１～０．５ｍｍとすることができる。 As the wrapping film, for example, one using a polyester film as the base material and aluminum oxide with an average particle size of 2 to 40 μm as the abrasive grains can be used. Alternatively, a lapping film with a nominal value of #400 to #6000 can be used as an indicator of the particle size of the abrasive grains. The size and thickness of the wrapping film can be changed as appropriate depending on the size of the sheet-like molded body to be polished. For example, the thickness of the wrapping film can be 0.01 to 0.5 mm.
　図３は、研磨部材の一例であるブラシ６の斜視図である。ブラシ６は、例えば図３に示すように、柱状の基材７の長さ方向に毛材８が配列した形状を有する。毛材８は、複数の毛の束であり、長さＢと、奥行きＣと、幅Ａを有する。ブラシ６の材質は、特に限定されず、例えば、汎用性、耐摩耗性、柔軟性、曲げ復元性等の観点では、ナイロン、アクリル、塩化ビニル、ポリプロピレン、ポリフェニレンスルファイド、銅、真鍮、ステンレス、馬、豚、羊などのブラシ用として扱われる材料が挙げられ、研磨効率を向上させる研磨剤、研磨紛のブラシへ汚染などを防止する静電処理、導通処理などを施したものも、使用することが可能である。なお、好ましくは毛の太さが０．０５ｍｍ～２．２ｍｍ、毛の長さが１～１００ｍｍであり、熱伝導性組成物の材料、硬さ、熱プレスなどの処理の有無、処理の程度、処理速度など、本発明を損なわない範囲にて適宜選択し組み合わせて使用することができる。 FIG. 3 is a perspective view of a brush 6, which is an example of a polishing member. The brush 6 has a shape in which bristles 8 are arranged in the length direction of a columnar base material 7, as shown in FIG. 3, for example. The hair material 8 is a bundle of a plurality of hairs, and has a length B, a depth C, and a width A. The material of the brush 6 is not particularly limited, and for example, from the viewpoint of versatility, abrasion resistance, flexibility, bending recovery, etc., nylon, acrylic, vinyl chloride, polypropylene, polyphenylene sulfide, copper, brass, stainless steel, Materials used for brushes include horses, pigs, sheep, etc., and materials that have been treated with abrasives to improve polishing efficiency, electrostatic treatment to prevent contamination of polishing powder brushes, conductive treatment, etc. are also used. Is possible. Preferably, the thickness of the hair is 0.05 mm to 2.2 mm, and the length of the hair is 1 to 100 mm. , processing speed, etc., can be appropriately selected and used in combination within a range that does not impair the present invention.
　図４は、成形体シート９の表面をブラシ６で研磨する方法の一例を説明するための斜視図である。研磨部材としてブラシ６を用いて、１枚ずつ成形体シート９において研磨処理を行なう場合、図示しない吸着パッドやテープなどの固定手段で、成形体シート９の研磨しようとする面の背面、または研磨処理を開始する側の端部を仮止めすることが好ましい。テープを用いた仮固定の例として、例えば図４中のＤ１の方向にブラシ６で研磨する場合は、成形体シート９の一端側９Ａを仮固定し、固定されていない他端側９Ｂに向かってブラシ６を移動する。成形体シート９の背面を仮固定する場合は、ブラシ６の移動方向に制限はない。ブラシ６の移動手段は、手動であっても自動であってもよい。成形体シート９を研磨する場合には、毛材８の先端がＡ方向全体で成形体シート９の表面に接触するようにしならせつつ、毛材８の先端で撫でるように、ブラシ６を移動させることが好ましい。 FIG. 4 is a perspective view for explaining an example of a method of polishing the surface of the molded sheet 9 with the brush 6. When polishing the molded sheet 9 one by one using the brush 6 as the polishing member, use a fixing means such as a suction pad or tape (not shown) to polish the back side of the surface of the molded sheet 9 to be polished or It is preferable to temporarily fasten the end on the side where processing is to be started. As an example of temporary fixing using tape, when polishing with the brush 6 in the direction of D1 in FIG. to move the brush 6. When temporarily fixing the back surface of the molded sheet 9, there is no restriction on the moving direction of the brush 6. The means for moving the brush 6 may be manual or automatic. When polishing the molded sheet 9, move the brush 6 so that the tips of the bristles 8 touch the surface of the molded sheet 9 in the entire direction A, and stroke with the tips of the bristles 8. It is preferable to let
　研磨方法は、成形体シート９表面の一端側９Ａから他端側９Ｂに一方向に研磨部材を移動させることに限定されない。例えば成形体シート９表面の一端側９Ａから他端側９Ｂに亘って研磨部材で研磨することと、成形体シート９表面の他端側９Ｂから一端側９Ａに亘って研磨部材で研磨することを繰り返す、すなわち、研磨部材を、成形体シート９表面の一端側９Ａと他端側９Ｂに亘って往復して研磨してもよい。一例としてブラシ６を用いる場合、図４において成形体シート９表面の一端側９Ａから他端側９Ｂに亘って、Ｄ１方向とＤ２方向に往復して研磨してもよい。図５は、複数の成形体シートの表面を連続してブラシで研磨する方法の一例を説明するための斜視図である。図５に示すように、複数の熱伝導性シート１を連続して研磨処理する場合には、例えば、研磨部材を固定し、成形体シート９をコンベア１０上に複数枚配置し、コンベア１０を移動させることで複数の成形体シート９を連続して研磨処理してもよい。コンベア１０の移動方向は、図５中のＤ３方向またはＤ４方向の一方向であってもよいし、Ｄ３方向とＤ４方向に往復してもよい。また、複数のブラシを設置して使用することも可能である。更には、ロール状ブラシを回転させて使用しても良い。 The polishing method is not limited to moving the polishing member in one direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9. For example, polishing the surface of the molded sheet 9 from one end 9A to the other end 9B with a polishing member, and polishing the surface of the molded sheet 9 from the other end 9B to one end 9A with a polishing member. In other words, the polishing member may be reciprocated to polish the surface of the molded sheet 9 from one end side 9A to the other end side 9B. As an example, when the brush 6 is used, it may be polished by reciprocating in the D1 direction and the D2 direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9 in FIG. FIG. 5 is a perspective view for explaining an example of a method of continuously polishing the surfaces of a plurality of molded body sheets with a brush. As shown in FIG. 5, when polishing a plurality of thermally conductive sheets 1 in succession, for example, the polishing member is fixed, a plurality of formed sheets 9 are placed on a conveyor 10, and the conveyor 10 is By moving, a plurality of molded sheets 9 may be polished continuously. The direction of movement of the conveyor 10 may be one direction, D3 direction or D4 direction in FIG. 5, or may be reciprocated in the D3 direction and D4 direction. It is also possible to install and use a plurality of brushes. Furthermore, a rolled brush may be rotated and used.
　研磨方法について、成形体シート９の片面のみを研磨処理してもよいし、成形体シート９の片面を研磨処理した後、他方の面も研磨処理してもよい。 Regarding the polishing method, only one side of the molded sheet 9 may be polished, or after one side of the molded sheet 9 is polished, the other side may also be polished.
　研磨部材としてラッピングフィルムを用いる場合、成形体シート９の表面にラッピングフィルムを接触させ、成形体シート９及びラッピングフィルムの少なくともいずれか一方を移動させる限りにおいては、上述のブラシ６における研磨方法と同様に、移動方法や移動方向、配置や形状において各種の変形が可能である。 When using a wrapping film as the polishing member, the polishing method is the same as the polishing method for the brush 6 described above, as long as the wrapping film is brought into contact with the surface of the molded sheet 9 and at least one of the molded sheet 9 and the wrapping film is moved. In addition, various modifications can be made in the movement method, movement direction, arrangement, and shape.
　研磨回数は、研磨方法や、研磨部材の種類、研磨部材の粒度などに応じて適宜変更することができる。研磨回数は、多いほどシート状成形体９の表面の凸部１ａから削り出たバインダ樹脂２、異方性熱伝導材料３及び無機フィラー４によってシート状成形体９の表面の凹部が被覆されやすいと考えられるため、一定回数以上とすることが好ましい。研磨回数は、例えば、１回以上とすることができ、１０回以上としてもよく、２０回以上としてもよく、３０回以上としてもよく、４０回以上としてもよく、５０回以上としてもよく、６０回以上としてもよく、７０回以上としてもよく、８０回以上としてもよく、９０回以上としてもよく、１００回以上としてもよく、２００回以上としてもよく、３００回以上としてもよく、４００回以上としてもよく、１００～１０００回の範囲としてもよく、１００～４００回の範囲としてもよい。なお、本明細書において、研磨回数とは、例えば図４において、シート状成形体９表面の一端側９Ａから他端側９Ｂに亘って一方向に研磨することを１回とする。 The number of times of polishing can be changed as appropriate depending on the polishing method, the type of polishing member, the particle size of the polishing member, etc. The greater the number of times of polishing, the more easily the concave portions on the surface of the sheet-like molded body 9 are covered with the binder resin 2, anisotropic heat conductive material 3, and inorganic filler 4 carved out from the convex portions 1a on the surface of the sheet-like molded body 9. Therefore, it is preferable to set the number of times to a certain number or more. The number of times of polishing can be, for example, 1 or more times, 10 times or more, 20 times or more, 30 or more times, 40 times or more, 50 times or more, It may be more than 60 times, it may be more than 70 times, it may be more than 80 times, it may be more than 90 times, it may be more than 100 times, it may be more than 200 times, it may be more than 300 times, it may be more than 400 times. The number of times may be more than 1,000 times, or may be in the range of 100 to 1,000 times, or may be in the range of 100 to 400 times. In this specification, the number of times of polishing refers to one time of polishing in one direction from one end side 9A to the other end side 9B of the surface of the sheet-like molded body 9 in FIG. 4, for example.
　熱伝導性シート１が表面に有する研磨残渣５の大きさは、使用する研磨部材の材質や粒度により適宜変更できる。例えば、研磨部材としてラッピングフィルムやブラシ６を用いる場合は、研磨残渣５の最大サイズを１００μｍ以下とすることができ、０．５～１００μｍの範囲とすることもできる。 The size of the polishing residue 5 that the thermally conductive sheet 1 has on the surface can be changed as appropriate depending on the material and particle size of the polishing member used. For example, when a lapping film or brush 6 is used as the polishing member, the maximum size of the polishing residue 5 can be 100 μm or less, and can also be in the range of 0.5 to 100 μm.
　研磨部材は、研磨する工程（工程Ｃ）において同一の粗さを持つ研磨部材であってもよい。研磨する工程において同一の粗さを持つ研磨部材とは、例えば、工程Ｃにおいて、砥粒の粒度が異なる２種以上の研磨部材を併用するのではなく、砥粒の粒度が同一の研磨部材を用いることを意味する。熱伝導性シート１の製造方法では、工程Ｃにおいて、同一の粗さを持つ研磨部材を用いてシート状成形体９を研磨した場合でも、上述した条件１～３を満たすことができ、熱伝導性シート１の全熱抵抗値を低減することができる。このように、熱伝導性シート１の製造方法では、工程Ｃにおける研磨について、砥粒の粒度が異なる２種以上の研磨部材を併用しなくても、熱伝導性シート１が上述した条件１～３を満たすことができるため、工程を簡素化できる。なお、熱伝導性シート１の製造方法の工程Ｃでは、砥粒の粒度が異なる２種以上の研磨部材を併用してもよい。 The polishing member may have the same roughness in the polishing step (step C). Polishing members having the same roughness in the polishing process mean, for example, polishing members with the same abrasive grain size in step C, rather than using two or more types of polishing members with different abrasive grain sizes together. It means to use. In the method for manufacturing the thermally conductive sheet 1, even when the sheet-like molded body 9 is polished using a polishing member having the same roughness in step C, conditions 1 to 3 described above can be satisfied, and the thermal conductivity is improved. The total thermal resistance value of the adhesive sheet 1 can be reduced. In this way, in the method for manufacturing the thermally conductive sheet 1, the thermally conductive sheet 1 can be polished under the conditions 1 to 1 without using two or more types of polishing members having different abrasive grain sizes in combination in step C. 3 can be satisfied, the process can be simplified. In addition, in step C of the method for manufacturing the thermally conductive sheet 1, two or more types of polishing members having different abrasive grain sizes may be used together.
　このような工程Ａと、工程Ｂと、工程Ｃとを有する熱伝導性シートの製造方法によれば、上述した熱伝導性シート１が得られる。 According to the method for manufacturing a thermally conductive sheet having such steps A, B, and C, the thermally conductive sheet 1 described above can be obtained.
　熱伝導性シート１の製造方法は、上述した例に限定されず、プレスする工程Ｄをさらに有していてもよい。工程Ｄは、工程Ｂと工程Ｃとの間であってもよく、工程Ｃの後であってもよい。例えば、熱伝導性シート１の製造方法の一例は、上述した工程Ａ～Ｃの他に、工程Ｂで得られたシート状成形体９の表面をプレスする工程Ｄをさらに有し、工程Ｃでは、工程Ｄでプレスしたシート状成形体９の表面を研磨して熱伝導性シート１を得るようにしてもよい。このような工程Ｄをさらに有することで、得られる熱伝導性シート１の表面がより平滑化され、他の部材との密着性をより向上させることができる。プレスの方法としては、平盤と表面が平坦なプレスヘッドとからなる一対のプレス装置を使用することができる。また、ピンチロールでプレスしてもよい。プレスの際の圧力としては、例えば、０．１～１００ＭＰａとすることができる。プレスの効果をより高め、プレス時間を短縮するために、プレスは、バインダ樹脂２のガラス転移温度（Ｔｇ）以上で行うことが好ましい。例えば、プレス温度は、０～１８０℃とすることができ、室温（例えば２５℃）～１００℃の温度範囲内であってもよく、３０～１００℃であってもよい。 The method for manufacturing the thermally conductive sheet 1 is not limited to the above-mentioned example, and may further include a pressing step D. Process D may be between process B and process C, or may be after process C. For example, an example of the method for manufacturing the thermally conductive sheet 1 includes, in addition to the above-mentioned steps A to C, a step D of pressing the surface of the sheet-like molded body 9 obtained in step B; The thermally conductive sheet 1 may be obtained by polishing the surface of the sheet-like molded body 9 pressed in step D. By further including such a step D, the surface of the resulting thermally conductive sheet 1 is smoothed, and the adhesion to other members can be further improved. As a pressing method, a pair of press devices consisting of a flat plate and a press head with a flat surface can be used. Alternatively, it may be pressed using pinch rolls. The pressure during pressing can be, for example, 0.1 to 100 MPa. In order to further enhance the pressing effect and shorten the pressing time, the pressing is preferably performed at a temperature equal to or higher than the glass transition temperature (Tg) of the binder resin 2. For example, the pressing temperature can be from 0 to 180°C, may be within the temperature range of room temperature (eg, 25°C) to 100°C, or may be from 30 to 100°C.
　＜電子機器＞
　熱伝導性シート１は、例えば、発熱体と放熱体との間に配置させることにより、発熱体で生じた熱を放熱体に逃がすためにそれらの間に配された構造の電子機器（サーマルデバイス）とすることができる。電子機器は、発熱体と放熱体と熱伝導性シート１とを少なくとも有し、必要に応じて、その他の部材をさらに有していてもよい。このように、熱伝導性シート１を適用した電子機器は、発熱体と放熱体との間に熱伝導性シート１が挟持されているため、熱伝導性シート１により高熱伝導性を実現しつつ、発熱体への熱伝導性シート１の密着性に優れ、熱伝導性シート１からのバインダ樹脂２の過剰なブリードを抑制できる。 <Electronic equipment>
The thermally conductive sheet 1 is, for example, placed between a heat generating element and a heat radiating element, so that the heat generated by the heating element is dissipated to the heat radiating element. ). The electronic device includes at least a heating element, a heat radiating element, and a thermally conductive sheet 1, and may further include other members as necessary. In this way, electronic devices to which the thermally conductive sheet 1 is applied can achieve high thermal conductivity due to the thermally conductive sheet 1 because the thermally conductive sheet 1 is sandwiched between the heating element and the heat radiating element. , the thermally conductive sheet 1 has excellent adhesion to the heating element, and excessive bleeding of the binder resin 2 from the thermally conductive sheet 1 can be suppressed.
　特に、熱伝導性シート１を適用した電子機器は、上述のように、熱伝導性シート１が上述した条件１～３の少なくとも１つを満たすため、熱伝導性シート１と被着体である発熱体や放熱体との接触面積がより増大し、熱伝導性シート１と被着体との間にエアーが混入することが抑制され、熱伝導性シート１の接触熱抵抗の低減に寄与し、結果として、全熱抵抗値を低減することができる。 In particular, as described above, the electronic device to which the thermally conductive sheet 1 is applied is such that the thermally conductive sheet 1 and the adherend meet at least one of the conditions 1 to 3 described above. The contact area with the heating element and the heat radiating element is further increased, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, contributing to a reduction in the contact thermal resistance of the thermally conductive sheet 1. , As a result, the total thermal resistance value can be reduced.
　発熱体としては、特に限定されず、例えば、ＣＰＵ、ＧＰＵ（Graphics Processing Unit）、ＤＲＡＭ（Dynamic Random Access Memory）、フラッシュメモリなどの集積回路素子、トランジスタ、抵抗器など、電気回路において発熱する電子部品等が挙げられる。また、発熱体には、通信機器における光トランシーバ等の光信号を受信する部品も含まれる。 The heating element is not particularly limited, and examples include electronic components that generate heat in electric circuits, such as CPUs, GPUs (Graphics Processing Units), DRAMs (Dynamic Random Access Memory), integrated circuit elements such as flash memories, transistors, and resistors. etc. The heating element also includes components that receive optical signals, such as optical transceivers in communication equipment.
　放熱体としては、特に限定されず、例えば、ヒートシンクやヒートスプレッダなど、集積回路素子やトランジスタ、光トランシーバ筐体などと組み合わされて用いられるものが挙げられる。ヒートシンクやヒートスプレッダの材質としては、例えば、銅、アルミニウムなどが挙げられる。放熱体としては、ヒートスプレッダやヒートシンク以外にも、熱源から発生する熱を伝導して外部に放散させるものであればよく、例えば、放熱器、冷却器、ダイパッド、プリント基板、冷却ファン、ペルチェ素子、ヒートパイプ、ベーパーチャンバー、金属カバー、筐体等が挙げられる。ヒートパイプは、例えば、円筒状、略円筒状又は扁平筒状の中空構造体である。 The heat sink is not particularly limited, and includes, for example, heat sinks, heat spreaders, and other heat sinks that are used in combination with integrated circuit elements, transistors, optical transceiver casings, and the like. Examples of the material for the heat sink and heat spreader include copper and aluminum. In addition to heat spreaders and heat sinks, the heat dissipation body may be anything that conducts heat generated from a heat source and dissipates it to the outside, such as a heat dissipator, cooler, die pad, printed circuit board, cooling fan, Peltier element, etc. Examples include heat pipes, vapor chambers, metal covers, and casings. A heat pipe is, for example, a cylindrical, substantially cylindrical, or flat cylindrical hollow structure.
　図６は、熱伝導性シートを適用した半導体装置の一例を示す断面図である。例えば、熱伝導性シート１は、図６に示すように、各種電子機器に内蔵される半導体装置５０に実装され、発熱体と放熱体との間に挟持される。図６に示す半導体装置５０は、電子部品５１と、ヒートスプレッダ５２と、熱伝導性シート１とを備え、熱伝導性シート１がヒートスプレッダ５２と電子部品５１との間に挟持される。熱伝導性シート１が、ヒートスプレッダ５２とヒートシンク５３との間に挟持されることにより、ヒートスプレッダ５２とともに、電子部品５１の熱を放熱する放熱部材を構成する。熱伝導性シート１の実装場所は、ヒートスプレッダ５２と電子部品５１との間や、ヒートスプレッダ５２とヒートシンク５３との間に限らず、電子機器や半導体装置の構成に応じて、適宜選択できる。ヒートスプレッダ５２は、例えば方形板状に形成され、電子部品５１と対峙する主面５２ａと、主面５２ａの外周に沿って立設された側壁５２ｂとを有する。ヒートスプレッダ５２は、側壁５２ｂに囲まれた主面５２ａに熱伝導性シート１が設けられ、主面５２ａと反対側の他面５２ｃに熱伝導性シート１を介してヒートシンク５３が設けられる。 FIG. 6 is a cross-sectional view showing an example of a semiconductor device to which a thermally conductive sheet is applied. For example, as shown in FIG. 6, the thermally conductive sheet 1 is mounted on a semiconductor device 50 built into various electronic devices, and is sandwiched between a heat generating body and a heat radiating body. A semiconductor device 50 shown in FIG. 6 includes an electronic component 51, a heat spreader 52, and a thermally conductive sheet 1, and the thermally conductive sheet 1 is sandwiched between the heat spreader 52 and the electronic component 51. The thermally conductive sheet 1 is sandwiched between the heat spreader 52 and the heat sink 53, thereby forming a heat radiating member that radiates heat from the electronic component 51 together with the heat spreader 52. The mounting location of the thermally conductive sheet 1 is not limited to between the heat spreader 52 and the electronic component 51 or between the heat spreader 52 and the heat sink 53, and can be appropriately selected depending on the configuration of the electronic device or semiconductor device. The heat spreader 52 is formed into a rectangular plate shape, for example, and has a main surface 52a facing the electronic component 51, and a side wall 52b erected along the outer periphery of the main surface 52a. In the heat spreader 52, a thermally conductive sheet 1 is provided on a main surface 52a surrounded by side walls 52b, and a heat sink 53 is provided on the other surface 52c opposite to the main surface 52a via the thermally conductive sheet 1.
　以下、本技術の実施例について説明する。なお、本技術は、これらの実施例に限定されるものではない。 Examples of the present technology will be described below. Note that the present technology is not limited to these examples.
　＜実施例１＞
　シリコーン樹脂３２体積％と、酸化アルミニウム（平均粒子径：約２μｍ）１４体積％と、窒化アルミニウム（平均粒子径：約１μｍ）２５体積％と、炭素繊維（平均繊維長：約１５０μｍ）２８体積％と、カップリング剤１体積％とを均一に混合することにより熱伝導性組成物を調製した。この熱伝導性組成物を、押出成形法により、直方体状の内部空間を有する金型（開口部：５０ｍｍ×５０ｍｍ）中に流し込み、１００℃のオーブンで６時間加熱して、柱状の硬化物（成形体ブロック）を形成した。なお、金型の内面には、剥離処理を行なったポリエチレンテレフタレートフィルムを、剥離処理面が内側となるように貼り付けておいた。得られた柱状の硬化物を柱の長さ方向に対し略直交する方向に、柱状の硬化物をスライサーで０．３ｍｍ厚のシート状に切断（スライス）することにより、炭素繊維が厚み方向に配向したシート状成形体を得た。 <Example 1>
32% by volume of silicone resin, 14% by volume of aluminum oxide (average particle diameter: approximately 2 μm), 25% by volume of aluminum nitride (average particle diameter: approximately 1 μm), and 28% by volume of carbon fiber (average fiber length: approximately 150 μm). A thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed. Note that a polyethylene terephthalate film that had been subjected to a peeling treatment was pasted on the inner surface of the mold so that the peeled surface was on the inside. By cutting (slicing) the obtained columnar cured product into a 0.3 mm thick sheet with a slicer in a direction substantially perpendicular to the length direction of the column, the carbon fibers are cut in the thickness direction. An oriented sheet-like molded body was obtained.
　実施例１では、図３に示すように、毛太さ０．２ｍｍ、毛長さ（図３中のＢ）２５ｍｍ、毛束（奥行：図３中のＣ）４ｍｍ、幅（図３中のＡ）７０ｍｍのナイロン製のブラシ６（角田ブラシ社製）を用いた。そして、図４に示すように、ブラシ６の毛先（毛材８の先端）がＡ方向全体でシート状成形体９に接触するようにブラシ６の毛先をしならせつつ、毛先で撫でるように、シート状成形体９の表面の一端側から他端側にわたって一方向に１００回ブラシ６を移動させた。このようにシート状成形体９の表面を研磨することにより、熱伝導性シートを得た。研磨は、シート状成形体の両面に対して行った。実施例１で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨により脱離した熱伝導性組成物の構成材料を有していた。 In Example 1, as shown in Fig. 3, the hair thickness is 0.2 mm, the hair length (B in Fig. 3) is 25 mm, the hair bundle (depth: C in Fig. 3) is 4 mm, and the width (B in Fig. 3) is 4 mm. A) A 70 mm nylon brush 6 (manufactured by Kakuda Brush Co., Ltd.) was used. Then, as shown in FIG. 4, while bending the bristles of the brush 6 so that the bristles of the brush 6 (the tips of the bristles 8) contact the sheet-like molded body 9 in the entire direction A, The brush 6 was moved in one direction 100 times from one end to the other end of the surface of the sheet-like molded body 9 in a caressing motion. By polishing the surface of the sheet-like molded body 9 in this manner, a thermally conductive sheet was obtained. Polishing was performed on both sides of the sheet-like molded body. The thermally conductive sheet obtained in Example 1 had a polished surface, and had the constituent material of the thermally conductive composition detached from the surface by polishing.
　＜実施例２＞
　実施例２では、研磨回数を１０００回に変更したこと以外は、実施例１と同様に熱伝導性シートを得た。実施例２で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨により脱離した熱伝導性組成物の構成材料を有していた。 <Example 2>
In Example 2, a thermally conductive sheet was obtained in the same manner as in Example 1, except that the number of times of polishing was changed to 1000 times. The thermally conductive sheet obtained in Example 2 had a polished surface, and contained the constituent material of the thermally conductive composition detached by polishing on the surface.
　＜実施例３＞
　実施例３では、シート状成形体を２枚の単板の間に挟み、７０℃、０．５ＭＰａ、３０秒の条件でプレスし、プレス後のシート状成形体９を研磨したこと以外は、実施例１と同様に熱伝導性シートを得た。実施例３で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨により脱離した熱伝導性組成物の構成材料を有していた。 <Example 3>
In Example 3, the sheet-like molded body was sandwiched between two veneers and pressed under the conditions of 70° C., 0.5 MPa, and 30 seconds, and the sheet-like molded body 9 after pressing was polished. A thermally conductive sheet was obtained in the same manner as in Example 1. The thermally conductive sheet obtained in Example 3 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
　＜実施例４＞
　実施例４では、シリコーン樹脂２４体積％と、酸化アルミニウム（平均粒子径：約２μｍ）１０体積％と、窒化アルミニウム（平均粒子径：約１μｍ）２０体積％と、アルミニウム（平均粒子径：約６μｍ）１９体積％と、炭素繊維（平均繊維長：約１５０μｍ）２６体積％と、カップリング剤１体積％とを均一に混合することにより熱伝導性組成物を調製したことと、ナイロン製のブラシに替えて厚みが約１００μｍである４０００番（＃４０００）のラッピングフィルム（３Ｍ社製）を用いて、シート状成形体９の表面の一端側から他端側にわたって一方向に１００回研磨した（擦った）こと以外は、実施例１と同様に熱伝導性シートを得た。実施例４で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨により脱離した熱伝導性組成物の構成材料を有していた。 <Example 4>
In Example 4, 24% by volume of silicone resin, 10% by volume of aluminum oxide (average particle size: about 2 μm), 20% by volume of aluminum nitride (average particle size: about 1 μm), and aluminum (average particle size: about 6 μm) ), 26 volume % of carbon fibers (average fiber length: approximately 150 μm), and 1 volume % of a coupling agent, and a nylon brush. Instead, using a #4000 wrapping film (manufactured by 3M) with a thickness of about 100 μm, the surface of the sheet-like molded body 9 was polished 100 times in one direction from one end to the other end ( A thermally conductive sheet was obtained in the same manner as in Example 1, except that the sheet was rubbed. The thermally conductive sheet obtained in Example 4 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
　＜実施例５＞
　実施例５では、ナイロン製のブラシに替えて厚みが約１００μｍである２０００番（＃２０００）のラッピングフィルム（３Ｍ社製）を用いて、シート状成形体９の表面の一端側から他端側にわたって一方向に１００回研磨したこと以外は、実施例１と同様に熱伝導性シートを得た。実施例５で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨により脱離した熱伝導性組成物の構成材料を有していた。 <Example 5>
In Example 5, a #2000 wrapping film (manufactured by 3M) with a thickness of about 100 μm was used instead of the nylon brush to cover the surface of the sheet-like molded body 9 from one end to the other end. A thermally conductive sheet was obtained in the same manner as in Example 1, except that it was polished 100 times in one direction over the entire area. The thermally conductive sheet obtained in Example 5 had a polished surface, and had the constituent material of the thermally conductive composition removed by polishing on the surface.
　＜実施例６＞
　シリコーン樹脂２８体積％と、酸化アルミニウム（平均粒子径：約２μｍ）２２体積％と、窒化アルミニウム（平均粒子径：約１μｍ）２３体積％と、炭素繊維（平均繊維長：約１５０μｍ）２６体積％と、カップリング剤１体積％とを均一に混合することにより熱伝導性組成物を調製した。この熱伝導性組成物を、押出成形法により、直方体状の内部空間を有する金型（開口部：５０ｍｍ×５０ｍｍ）中に流し込み、１００℃のオーブンで６時間加熱して、柱状の硬化物（成形体ブロック）を形成した。なお、金型の内面には、剥離処理を行なったポリエチレンテレフタレートフィルムを、剥離処理面が内側となるように貼り付けておいた。得られた柱状の硬化物を柱の長さ方向に対し略直交する方向に、柱状の硬化物をスライサーで１．０ｍｍ厚のシート状に切断（スライス）することにより、炭素繊維がシートの厚み方向に配向したシート状成形体を得た。このシート状成形体の表面の一端側から他端側にわたって一方向に、厚みが約１００μｍである４０００番（＃４０００）のラッピングフィルム（３Ｍ社製）により２００回擦ることで研磨を行ない、熱伝導性シートを得た。研磨はシート状成形体の両面に対して行なった。のこのように、実施例６で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨残渣を有していた。 <Example 6>
28% by volume of silicone resin, 22% by volume of aluminum oxide (average particle diameter: approximately 2 μm), 23% by volume of aluminum nitride (average particle diameter: approximately 1 μm), and 26% by volume of carbon fiber (average fiber length: approximately 150 μm). A thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed. Note that a polyethylene terephthalate film that had been subjected to a peeling treatment was pasted on the inner surface of the mold so that the peeled surface was on the inside. By cutting (slicing) the obtained columnar cured product into a 1.0 mm thick sheet with a slicer in a direction substantially perpendicular to the length direction of the column, the carbon fibers are cut into sheets with a thickness of 1.0 mm. A sheet-like molded body oriented in the direction was obtained. The surface of this sheet-like molded product was polished by rubbing it 200 times in one direction from one end to the other with a #4000 wrapping film (manufactured by 3M) with a thickness of about 100 μm, and then heated. A conductive sheet was obtained. Polishing was performed on both sides of the sheet-shaped molded body. As described above, the thermally conductive sheet obtained in Example 6 had a polished surface and had polishing residue on the surface.
　＜実施例７＞
　実施例７では、シート状成形体の厚みを２ｍｍとしたこと以外は、実施例６と同様にして熱伝導性シートを得た。このように、実施例７で得られた熱伝導性シートは、表面が研磨面であり、表面に研磨残渣を有していた。 <Example 7>
In Example 7, a thermally conductive sheet was obtained in the same manner as in Example 6 except that the thickness of the sheet-like molded body was 2 mm. Thus, the thermally conductive sheet obtained in Example 7 had a polished surface and had polishing residue on the surface.
　＜比較例１＞
　比較例１では、実施例１で得られたシート状成形体をそのまま用いた。すなわち、比較例１では、シート状成形体の表面を研磨しなかったこと以外は、実施例１と同様に行った。比較例１で得られたシート状成形体は、表面が研磨面ではなく、表面に研磨により脱離した熱伝導性組成物の構成材料を有していなかった。 <Comparative example 1>
In Comparative Example 1, the sheet-like molded product obtained in Example 1 was used as it was. That is, in Comparative Example 1, the same procedure as in Example 1 was carried out except that the surface of the sheet-like molded body was not polished. The sheet-like molded article obtained in Comparative Example 1 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached from the surface by polishing.
　＜比較例２＞
　比較例２では、実施例３で得られたプレス後のシート状成形体をそのまま用いた。すなわち、比較例２では、プレス後のシート状成形体の表面を研磨しなかったこと以外は、実施例３と同様に行った。比較例２で得られたシート状成形体は、表面が研磨面ではなく、表面に研磨により脱離した熱伝導性組成物の構成材料を有していなかった。 <Comparative example 2>
In Comparative Example 2, the pressed sheet-shaped molded product obtained in Example 3 was used as it was. That is, in Comparative Example 2, the same procedure as in Example 3 was carried out except that the surface of the sheet-shaped molded body after pressing was not polished. The sheet-like molded article obtained in Comparative Example 2 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached from the surface by polishing.
　＜比較例３＞
　比較例３では、シリコーン樹脂と、炭素繊維と、他の無機フィラーとを混合した組成物を、金型に注入し、磁場を厚さ方向に印加して炭素繊維を厚さ方向に磁場配向させた後に硬化して、柱状の硬化物を形成した。得られた柱状の硬化物を柱の長さ方向に対し略直交する方向に、柱状の硬化物をスライサーで０．３ｍｍ厚のシート状に切断（スライス）することにより、炭素繊維がシートの厚み方向に配向したシート状成形体を得た。このように、比較例３では、柱状の硬化物を０．３ｍｍ厚にスライスした後に、シート状成形体の表面を研磨しなかった。比較例３で得られたシート状成形体は、表面が研磨面ではなく、表面に研磨により脱離した熱伝導性組成物の構成材料を有していなかった。 <Comparative example 3>
In Comparative Example 3, a composition in which a silicone resin, carbon fibers, and other inorganic fillers were mixed was injected into a mold, and a magnetic field was applied in the thickness direction to orient the carbon fibers in the thickness direction. After that, it was cured to form a columnar cured product. By cutting (slicing) the obtained columnar cured product into a sheet with a thickness of 0.3 mm using a slicer in a direction substantially perpendicular to the length direction of the column, the carbon fibers are cut into sheets with a thickness of 0.3 mm. A sheet-like molded body oriented in the direction was obtained. Thus, in Comparative Example 3, after slicing the columnar cured product into 0.3 mm thick pieces, the surface of the sheet-like molded product was not polished. The sheet-like molded article obtained in Comparative Example 3 did not have a polished surface, and did not have the constituent material of the thermally conductive composition detached by polishing on the surface.
　＜比較例４＞
　シリコーン樹脂２８体積％と、酸化アルミニウム（平均粒子径：約２μｍ）２２体積％と、窒化アルミニウム（平均粒子径：約１μｍ）２３体積％と、炭素繊維（平均繊維長：約１５０μｍ）２６体積％と、カップリング剤１体積％とを均一に混合することにより熱伝導性組成物を調製した。この熱伝導性組成物を、押出成形法により、直方体状の内部空間を有する金型（開口部：５０ｍｍ×５０ｍｍ）中に流し込み、１００℃のオーブンで６時間加熱して、柱状の硬化物（成形体ブロック）を形成した。なお、金型の内面には、剥離処理を行なったポリエチレンテレフタレートフィルムを、剥離処理面が内側となるように貼り付けておいた。得られた柱状の硬化物を柱の長さ方向に対し略直交する方向に、柱状の硬化物をスライサーで１．０ｍｍ厚のシート状に切断（スライス）することにより、炭素繊維がシートの厚み方向に配向したシート状成形体を得た。 <Comparative example 4>
28% by volume of silicone resin, 22% by volume of aluminum oxide (average particle diameter: approximately 2 μm), 23% by volume of aluminum nitride (average particle diameter: approximately 1 μm), and 26% by volume of carbon fiber (average fiber length: approximately 150 μm). A thermally conductive composition was prepared by uniformly mixing the above and 1% by volume of a coupling agent. This thermally conductive composition was poured into a mold (opening: 50 mm x 50 mm) having a rectangular parallelepiped internal space by extrusion molding, and heated in an oven at 100°C for 6 hours to form a columnar cured product ( A molded body block) was formed. Note that a polyethylene terephthalate film that had been subjected to a peeling treatment was pasted on the inner surface of the mold so that the peeled surface was on the inside. By cutting (slicing) the obtained columnar cured product into a 1.0 mm thick sheet with a slicer in a direction substantially perpendicular to the length direction of the column, the carbon fibers are cut into sheets with a thickness of 1.0 mm. A sheet-like molded body oriented in the direction was obtained.
　＜比較例５＞
　比較例５では、シート状成形体の厚みを２ｍｍとしたこと以外は、比較例４と同様にしてシート状成形体を得た。 <Comparative example 5>
In Comparative Example 5, a sheet-like molded product was obtained in the same manner as Comparative Example 4, except that the thickness of the sheet-like molded product was 2 mm.
　＜熱伝導性シートの表面性状パラメータ＞
　各実施例で得られた熱伝導性シート及び各比較例で得られたシート状成形体の表面性状パラメータを測定した。具体的には、熱伝導性シートの突出山部の平均高さＳｐｋ（μｍ）、突出谷部の平均深さＳｖｋ（μｍ）、突出山部の体積Ｖｍｐ（ｍｌ／ｍ２）、二乗平均平方根勾配Ｓｄｑ、山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）、界面の展開面積比Ｓｄｒ（％）を測定した。これらは、走査型白色干渉顕微鏡である、ナノ３Ｄ光干渉計測システム（装置名：ＶＳ－１８００、日立ハイテク社製、測定モード：ｗａｖｅモード）を用いて、ＩＳＯ　２５１７８に従って測定した。レンズ倍率は鏡筒内レンズ０．５倍、対物レンズ２０倍であり、５６２μｍ×５６２μｍのＸＹ領域に対し、Ｚ軸の高さ方向５０μｍ、深さ方向５０μｍの範囲で表面性状パラメータを測定した。突出山部の体積Ｖｍｐは、不可面積率１０％値を適用した。結果を表１に示す。 <Surface property parameters of thermally conductive sheet>
The surface quality parameters of the thermally conductive sheet obtained in each Example and the sheet-like molded article obtained in each Comparative Example were measured. Specifically, the average height Spk (μm) of the protruding peaks of the thermally conductive sheet, the average depth Svk (μm) of the protruding valleys, the volume Vmp (ml/m 2 ) of the protruding peaks, and the root mean square of the heat conductive sheet. The slope Sdq, the arithmetic mean curvature Spc (1/mm) of the mountain top, and the developed area ratio Sdr (%) of the interface were measured. These were measured in accordance with ISO 25178 using a nano 3D optical interference measurement system (apparatus name: VS-1800, manufactured by Hitachi High-Tech Corporation, measurement mode: wave mode), which is a scanning white interference microscope. The lens magnification was 0.5 times for the lens inside the lens barrel and 20 times for the objective lens, and surface texture parameters were measured in a range of 50 μm in the height direction and 50 μm in the depth direction of the Z axis in an XY region of 562 μm×562 μm. For the volume Vmp of the protruding peak part, a value of 10% of the impossible area ratio was applied. The results are shown in Table 1.
　＜熱インピーダンス（全熱抵抗値）＞
　実施例で得られた熱伝導性シート及び比較例で得られたシート状成形体を直径２０ｍｍのサイズに打ち抜き加工し、所定の圧力（０．７０ｋｆｇ／ｃｍ２、１．４ｋｆｇ／ｃｍ２、２．１ｋｆｇ／ｃｍ２、２．８ｋｆｇ／ｃｍ２又は３．５ｋｆｇ／ｃｍ２）での加圧条件下、ＡＳＴＭ－Ｄ５４７０に従って熱インピーダンス（全熱抵抗値）を測定した。なお、測定時の加圧時間は２５０秒間とし、２０１秒から２５０秒の間の測定値の平均値を測定値とした。測定は、１枚の熱伝導性シートに対して、順次加圧条件を変えながら行なった。結果を表１に示す。 <Thermal impedance (total thermal resistance value)>
The thermally conductive sheets obtained in the Examples and the sheet-like molded bodies obtained in the Comparative Examples were punched to a size of 20 mm in diameter, and subjected to predetermined pressures (0.70 kfg/cm 2 , 1.4 kfg/cm 2 , 2 Thermal impedance (total thermal resistance value) was measured under pressurized conditions (.1 kfg/cm 2 , 2.8 kfg/cm 2 or 3.5 kfg/cm 2 ) according to ASTM-D5470. The pressurization time during the measurement was 250 seconds, and the average value of the measured values from 201 seconds to 250 seconds was taken as the measured value. The measurements were performed on one thermally conductive sheet while sequentially changing the pressure conditions. The results are shown in Table 1.
　実施例１～７で得られた熱伝導性シートは、異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなり、上述した条件１～３の少なくとも１つを満たすことにより、全熱抵抗値を低減できることが分かった。特に、実施例１～５で得られた熱伝導性シートは、低荷重時の全熱抵抗値を低減でき、具体的には、荷重０．７０ｋｇｆ/ｃｍ２おける全熱抵抗値が０．２３０℃ｃｍ２／Ｗ未満であることが分かった。 The thermally conductive sheets obtained in Examples 1 to 7 are made of cured products of thermally conductive compositions containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin, and meet the conditions 1 to 3 described above. It has been found that the total thermal resistance value can be reduced by satisfying at least one of the conditions. In particular, the thermally conductive sheets obtained in Examples 1 to 5 can reduce the total thermal resistance value at low loads, and specifically, the total thermal resistance value at a load of 0.70 kgf/ cm2 is 0.230. It was found that the temperature was less than ℃cm 2 /W.
　実施例１～５で得られた熱伝導性シートは、荷重１．４ｋｇｆ/ｃｍ２おける全熱抵抗値が０．１７９℃ｃｍ２／Ｗ以下であることが分かった。 It was found that the thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.179°C cm 2 /W or less at a load of 1.4 kgf/cm 2 .
　実施例１～５で得られた熱伝導性シートは、荷重２．１ｋｇｆ/ｃｍ２おける全熱抵抗値が０．１６１℃ｃｍ２／Ｗ以下であることが分かった。 It was found that the thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.161°C cm 2 /W or less under a load of 2.1 kgf/cm 2 .
　実施例１～５で得られた熱伝導性シートは、荷重２．８ｋｇｆ/ｃｍ２おける全熱抵抗値が０．１５７℃ｃｍ２／Ｗ以下であることが分かった。 It was found that the thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.157°C cm 2 /W or less at a load of 2.8 kgf/cm 2 .
　実施例１～５で得られた熱伝導性シートは、荷重３．５ｋｇｆ/ｃｍ２おける全熱抵抗値が０．１５６℃ｃｍ２／Ｗ以下であることが分かった。 It was found that the thermally conductive sheets obtained in Examples 1 to 5 had a total thermal resistance value of 0.156°C cm 2 /W or less at a load of 3.5 kgf/cm 2 .
　実施例１～７で得られた熱伝導性シートは、表面が研磨面であり、研磨面に研磨により脱離した熱伝導性組成物の構成材料（研磨残渣）を有していた。この研磨残渣は、研磨によって生じた、シリコーン樹脂、炭素繊維及び他の無機フィラー（酸化アルミニウム、窒化アルミニウム、アルミニウムなど）を含有する塊状物であることが確認された。 The thermally conductive sheets obtained in Examples 1 to 7 had a polished surface, and had constituent materials (polishing residue) of the thermally conductive composition released by polishing on the polished surface. This polishing residue was confirmed to be a lump containing silicone resin, carbon fiber, and other inorganic fillers (aluminum oxide, aluminum nitride, aluminum, etc.) produced by polishing.
　実施例１～７で得られた熱伝導性シートは、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、熱伝導性シートの界面の展開面積比Ｓｄｒが４５％以下であり、且つ、熱伝導性シートの山頂の算術平均曲率Ｓｐｃが３５００（１／ｍｍ）以下であることが分かった。 The thermally conductive sheets obtained in Examples 1 to 7 have a developed area ratio Sdr of the interface of the thermally conductive sheet, which is measured according to ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20. 45% or less, and the arithmetic mean curvature Spc of the peak of the thermally conductive sheet was found to be 3500 (1/mm) or less.
　図７は、熱伝導性シートの山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）を横軸、熱伝導性シートの界面の展開面積比Ｓｄｒ（％）を縦軸として実施例及び比較例の結果をプロットしたグラフである。図７に示すように、実施例１～７で得られた熱伝導性シートは、対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）と、界面の展開面積比Ｓｄｒ（％）とを、Ｓｐｃを横軸、Ｓｄｒを縦軸として値をプロットしたグラフを作成した場合に、ＳｐｃとＳｄｒが上述した式１を満たすことが分かった。 FIG. 7 shows the results of Examples and Comparative Examples with the horizontal axis representing the arithmetic mean curvature Spc (1/mm) of the peak of the thermally conductive sheet and the vertical axis representing the developed area ratio Sdr (%) of the interface of the thermally conductive sheet. This is a plotted graph. As shown in FIG. 7, the thermally conductive sheets obtained in Examples 1 to 7 have an arithmetic mean curvature of the peak Spc measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. (1/mm) and the developed area ratio Sdr (%) of the interface, when a graph is created in which the values are plotted with Spc on the horizontal axis and Sdr on the vertical axis, Spc and Sdr satisfy Equation 1 above. That's what I found out.
　一方、比較例１～５で得られたシート状成形体は、上述した条件１～３を満たさないことが分かった。また、比較例１～５で得られたシート状成形体は、実施例１～７の熱伝導性シートと比べて全熱抵抗値が高いことが分かった。比較例１～５で得られたシート状成形体は、表面が研磨面ではなく、表面に研磨により脱離した熱伝導性組成物の構成材料を有していなかったことが原因と考えられる。 On the other hand, it was found that the sheet-like molded bodies obtained in Comparative Examples 1 to 5 did not satisfy the above-mentioned conditions 1 to 3. Furthermore, it was found that the sheet-like molded bodies obtained in Comparative Examples 1 to 5 had higher total thermal resistance values than the thermally conductive sheets of Examples 1 to 7. This is thought to be due to the fact that the sheet-like molded bodies obtained in Comparative Examples 1 to 5 did not have a polished surface and did not have the constituent material of the thermally conductive composition detached by polishing on the surface.
　比較例１，３～５で得られたシート状成形体は、界面の展開面積比Ｓｄｒが４５％以下、且つ、山頂の算術平均曲率Ｓｐｃが３５００（１／ｍｍ）以下であることを満たさないことが分かった。 The sheet-like molded bodies obtained in Comparative Examples 1, 3 to 5 do not satisfy the requirements that the developed area ratio Sdr of the interface is 45% or less and the arithmetic mean curvature Spc of the peak is 3500 (1/mm) or less. That's what I found out.
　実施例６、７で得られた熱伝導性シートと、比較例４、５で得られた成形体シートは、それぞれ実施例１～５、比較例１～３よりも厚みが厚いものである。実施例６、７でも、山頂の算術平均曲率Ｓｐｃ、熱伝導性シートの界面の展開面積比Ｓｄｒ、熱伝導性シートの突出山部の体積Ｖｍｐなどが改善され、全熱抵抗が低下することが明らかとなった。 The thermally conductive sheets obtained in Examples 6 and 7 and the molded sheets obtained in Comparative Examples 4 and 5 are thicker than Examples 1 to 5 and Comparative Examples 1 to 3, respectively. In Examples 6 and 7, the arithmetic mean curvature Spc of the peak, the developed area ratio Sdr of the interface of the thermally conductive sheet, the volume Vmp of the protruding peak of the thermally conductive sheet, etc. were improved, and the total thermal resistance was reduced. It became clear.
１　熱伝導性シート、１ａ　凸部、２　バインダ樹脂、３　異方性熱伝導材料、４　無機フィラー、５　研磨残渣、６　ブラシ、７　基材、８　毛材、９　シート状成形体、１０　コンベア、５０　半導体装置、５１　電子部品、５２　ヒートスプレッダ、５２ａ　主面、５２ｂ　側壁、５２ｃ　他面、５３　ヒートシンク 1 thermally conductive sheet, 1a convex portion, 2 binder resin, 3 anisotropic thermally conductive material, 4 inorganic filler, 5 polishing residue, 6 brush, 7 base material, 8 bristle material, 9 sheet-shaped molded body, 10 conveyor, 50 Semiconductor device, 51 Electronic component, 52 Heat spreader, 52a Main surface, 52b Side wall, 52c Other surface, 53 Heat sink

Claims (15)

  1. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、
    　対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、当該熱伝導性シートの突出山部の平均高さＳｐｋが３．５μｍ未満である、熱伝導性シート。     A thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin,
    A thermally conductive sheet having an average height Spk of protruding peaks of less than 3.5 μm, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  2. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、
    　対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、当該熱伝導性シートの突出山部の体積Ｖｍｐが０．１６ｍｌ／ｍ２以下である、熱伝導性シート。     A thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin,
    A thermally conductive sheet having a volume Vmp of a protruding peak of the thermally conductive sheet of 0.16 ml/m 2 or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens. .
  3. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、
    　対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、当該熱伝導性シートの突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が４０％以下であり、
    　当該熱伝導性シートの二乗平均平方根勾配Ｓｄｑが１．１以下である、熱伝導性シート。     A thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin,
    The sum of the average height Spk of the protruding peaks and the average depth Svk of the protruding troughs of the thermally conductive sheet (Spk+Svk) is measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. ), the value of the average height Spk of the protruding peak portion (Spk/(Spk+Svk)) is 40% or less,
    A thermally conductive sheet having a root mean square gradient Sdq of 1.1 or less.
  4. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物の硬化物からなる熱伝導性シートであって、
    　対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、当該熱伝導性シートの界面の展開面積比Ｓｄｒが４５％以下であり、且つ、当該熱伝導性シートの山頂の算術平均曲率Ｓｐｃが３５００（１／ｍｍ）以下である、請求項１～３のいずれか１項に記載の熱伝導性シート。     A thermally conductive sheet made of a cured product of a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin,
    The developed area ratio Sdr of the interface of the thermally conductive sheet is 45% or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens; The thermally conductive sheet according to any one of claims 1 to 3, wherein the arithmetic mean curvature Spc of the mountain peak is 3500 (1/mm) or less.
  5. 　対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、当該熱伝導性シートの山頂の算術平均曲率Ｓｐｃ（１／ｍｍ）と、界面の展開面積比Ｓｄｒ（％）とを、Ｓｐｃを横軸、Ｓｄｒを縦軸として値をプロットしたグラフを作成した場合に、ＳｐｃとＳｄｒが下記式１を満たす、請求項４に記載の熱伝導性シート。
    式１：Ｙ＝０．０１４３Ｘ－（１２．３２９±１０）     The arithmetic mean curvature Spc (1/mm) of the peak of the thermally conductive sheet and the developed area ratio Sdr (% ), the thermally conductive sheet according to claim 4, wherein when a graph is created in which the values are plotted with Spc as the horizontal axis and Sdr as the vertical axis, Spc and Sdr satisfy the following formula 1.
    Formula 1: Y=0.0143X-(12.329±10)
  6. 　厚みを０．３ｍｍとしたときに、ＡＳＴＭ－Ｄ５４７０に従って測定される、荷重０．７０ｋｇｆ/ｃｍ２における全熱抵抗値が０．２３０℃・ｃｍ２／Ｗ未満である、請求項１又は２に記載の熱伝導性シート。 Claim 1 or 2, wherein the total thermal resistance value at a load of 0.70 kgf/cm 2 is less than 0.230°C cm 2 /W when the thickness is 0.3 mm, measured according to ASTM-D5470. Thermal conductive sheet described.
  7. 　ＡＳＴＭ－Ｄ５４７０に従って測定される、厚みを１．０ｍｍとしたときに、荷重０．７０ｋｇｆ/ｃｍ２における全熱抵抗値が０．３１２℃・ｃｍ２／Ｗ以下である、請求項１又は２に記載の熱伝導性シート。 According to claim 1 or 2, the total thermal resistance value at a load of 0.70 kgf/cm 2 is 0.312° C.cm 2 /W or less when the thickness is 1.0 mm, measured according to ASTM-D5470. Thermal conductive sheet described.
  8. 　ＡＳＴＭ－Ｄ５４７０に従って測定される、厚みを２．０ｍｍとしたときに、荷重０．７０ｋｇｆ/ｃｍ２における全熱抵抗値が０．５２５℃・ｃｍ２／Ｗ以下である、請求項１又は２に記載の熱伝導性シート。 According to claim 1 or 2, the total thermal resistance value at a load of 0.70 kgf/cm 2 is 0.525° C.cm 2 /W or less when the thickness is 2.0 mm, measured according to ASTM-D5470. Thermal conductive sheet described.
  9. 　上記異方性熱伝導材料が厚み方向に配向した、請求項１又は２に記載の熱伝導性シート。 The thermally conductive sheet according to claim 1 or 2, wherein the anisotropic thermally conductive material is oriented in the thickness direction.
  10. 　上記異方性熱伝導材料が炭素繊維である、請求項９に記載の熱伝導性シート。 The thermally conductive sheet according to claim 9, wherein the anisotropic thermally conductive material is carbon fiber.
  11. 　表面が研磨面であり、上記研磨面に、研磨により脱離した上記熱伝導性組成物の構成材料を有する、請求項１又は２に記載の熱伝導性シート。 The thermally conductive sheet according to claim 1 or 2, wherein the surface is a polished surface, and the polished surface has a constituent material of the thermally conductive composition detached by polishing.
  12. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、
    　上記熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、
    　上記シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、
    　上記熱伝導性シートを得る工程では、上記熱伝導性シートの表面が以下の条件１を満たすように、上記シート状成形体の表面を研磨する、熱伝導性シートの製造方法。
    （条件１）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋが３．５μｍ未満である。     forming a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive molded body;
    slicing the thermally conductive molded body into sheet shapes to obtain a sheet-like molded body;
    a step of polishing the surface of the sheet-like molded body to obtain a thermally conductive sheet;
    In the step of obtaining the thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 1 below.
    (Condition 1) The average height Spk of the protruding peaks is less than 3.5 μm, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  13. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、
    　上記熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、
    　上記シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、
    　上記熱伝導性シートを得る工程では、上記熱伝導性シートの表面が以下の条件２を満たすように、上記シート状成形体の表面を研磨する、熱伝導性シートの製造方法。
    （条件２）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の体積Ｖｍｐが０．１６ｍｌ／ｍ２以下である。     forming a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive molded body;
    slicing the thermally conductive molded body into sheet shapes to obtain a sheet-like molded body;
    a step of polishing the surface of the sheet-like molded body to obtain a thermally conductive sheet;
    In the step of obtaining the thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 2 below.
    (Condition 2) The volume Vmp of the protruding peak is 0.16 ml/m 2 or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  14. 　異方性熱伝導材料と、無機フィラーと、バインダ樹脂とを含む熱伝導性組成物を所定の形状に成型して硬化させ、熱伝導性成形体を形成する工程と、
    　上記熱伝導性成形体をシート状にスライスして、シート状成形体を得る工程と、
    　上記シート状成形体の表面を研磨して熱伝導性シートを得る工程とを有し、
    　上記熱伝導性シートを得る工程では、上記熱伝導性シートの表面が以下の条件３を満たすように、上記シート状成形体の表面を研磨する、熱伝導性シートの製造方法。
    （条件３）対物レンズを２０倍とした走査型白色干渉顕微鏡を用いて、ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋと突出谷部の平均深さＳｖｋの和（Ｓｐｋ＋Ｓｖｋ）に対する、突出山部の平均高さＳｐｋの値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が４０％以下であり、かつ、二乗平均平方根勾配Ｓｄｑが１．１以下である。     forming a thermally conductive composition containing an anisotropic thermally conductive material, an inorganic filler, and a binder resin into a predetermined shape and curing it to form a thermally conductive molded body;
    slicing the thermally conductive molded body into sheet shapes to obtain a sheet-like molded body;
    a step of polishing the surface of the sheet-like molded body to obtain a thermally conductive sheet;
    In the step of obtaining the thermally conductive sheet, the surface of the sheet-like molded body is polished so that the surface of the thermally conductive sheet satisfies Condition 3 below.
    (Condition 3) Regarding the sum of the average height Spk of the protruding peaks and the average depth Svk of the protruding valleys (Spk+Svk), measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. , the value of the average height Spk of the protruding peak portion (Spk/(Spk+Svk)) is 40% or less, and the root mean square gradient Sdq is 1.1 or less.
  15. 　上記熱伝導性シートの研磨面には、研磨によって生じた、上記バインダ樹脂、上記異方性熱伝導材料、上記無機フィラーを含む研磨残渣が残留する、請求項１２～１４のいずれか１項に記載の熱伝導性シートの製造方法。
          According to any one of claims 12 to 14, a polishing residue containing the binder resin, the anisotropic thermally conductive material, and the inorganic filler generated by polishing remains on the polished surface of the thermally conductive sheet. A method for manufacturing the thermally conductive sheet described above.
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JP2019186555A (en) * 2016-04-11 2019-10-24 積水ポリマテック株式会社 Heat conductive sheet and manufacturing method of heat conductive sheet
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WO2021025089A1 (en) * 2019-08-08 2021-02-11 積水ポリマテック株式会社 Thermally conductive sheet and production method therefor
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