WO2023190726A1 - Heat-conducting sheet and production method for heat-conducting sheet - Google Patents

Heat-conducting sheet and production method for heat-conducting sheet Download PDF

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WO2023190726A1
WO2023190726A1 PCT/JP2023/012900 JP2023012900W WO2023190726A1 WO 2023190726 A1 WO2023190726 A1 WO 2023190726A1 JP 2023012900 W JP2023012900 W JP 2023012900W WO 2023190726 A1 WO2023190726 A1 WO 2023190726A1
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Prior art keywords
thermally conductive
conductive sheet
less
polishing
sheet
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PCT/JP2023/012900
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French (fr)
Japanese (ja)
Inventor
圭佑 武笠
栄治 太田
真理奈 戸端
大地 森
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 JP2023052788A external-priority patent/JP2023152928A/en
Publication of WO2023190726A1 publication Critical patent/WO2023190726A1/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. 2022-055354 filed in Japan on March 30, 2022 and Japanese Patent Application No. 2023-052788 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 fibrous fillers (eg, carbon fibers) (see, eg, Patent Documents 1 to 5).
  • Carbon fiber which is an example of a fibrous filler, 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.
  • thermal resistance is thermal resistance that occurs between a thermally conductive sheet and an adherend.
  • 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.
  • 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.
  • the contact thermal resistance tends to increase as the thickness decreases.
  • the present technology has been proposed in view of such conventional circumstances, and provides a thermally conductive sheet with reduced contact thermal resistance.
  • the inventors of the present application have found that the above-mentioned problem can be solved by setting the average height Spk of the protruding peaks to a predetermined value or less for a thermally conductive sheet in which fibrous filler is oriented in the thickness direction. I found it.
  • the present technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler, in which the fibrous filler
  • the average height Spk of the protruding peaks of the thermally conductive sheet is 3 ⁇ m, which is oriented in the thickness direction of the conductive sheet and measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the contact thermal resistance when applying a pressure of 1.4 kgf/cm 2 and when applying a pressure of 2.1 kgf/cm 2 is 0.10° C.cm 2 /W or less, measured according to ASTM-D5470.
  • a method for manufacturing a thermally conductive sheet according to the present technology includes molding a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler into a predetermined shape and curing it.
  • a step of obtaining a molded body of the thermally conductive composition by doing so a step of cutting the molded body into sheet shapes to obtain a molded body sheet, and a process of polishing the molded body sheet with a polishing member to form a thermally conductive sheet.
  • a polishing residue containing a binder resin, a fibrous filler, and other thermally conductive fillers generated by the polishing is left on the surface of the thermally conductive sheet.
  • the present technology can provide a thermally conductive sheet with reduced contact thermal resistance.
  • 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 molded sheet 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 molded body sheets 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 of a polishing
  • 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 cross-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, a fibrous filler 3, and a thermally conductive filler 4 other than the fibrous filler 3.
  • a fibrous filler 3 and another thermally conductive filler 4 are dispersed in a binder resin 2, and the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1.
  • the fact that the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1 means that, for example, among all the fibrous fillers 3 in the thermally conductive sheet 1, the thickness of the thermally conductive sheet 1
  • the proportion of the fibrous filler 3 whose long axis is oriented in direction B is 50% or more, may be 55% or more, may be 60% or more, may be 65% or more, It may be 70% or more, 80% or more, 90% or more, 95% or more, or 99% or more.
  • the long axis of the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1 by 60° to The angle may be in the range of 120 degrees, may be in the range of 70 to 100 degrees, or may be 90 degrees (substantially vertical).
  • the thermally conductive sheet 1 has an average height Spk of protruding peaks of 3 ⁇ m 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.
  • the average height Spk of the protruding peaks is influenced by the objective lens magnification of the scanning white interference microscope.
  • it will also be simply referred to as "average height Spk of the protruding peaks measured according to ISO 25178" or "average height Spk of the protruding peaks”.
  • the thermally conductive sheet 1 has a contact thermal resistance of 0.10°C ⁇ cm 2 / when a pressure of 1.4 kgf/cm 2 is applied and when a pressure of 2.1 kgf/cm 2 is applied, which is measured according to ASTM-D5470. W or less. Note that the values measured according to ISO 25178, which will be described later, are also affected by the objective lens magnification of the scanning white interference microscope.
  • the thermally conductive sheet 1 Since the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 ⁇ m or less, the contact area between the thermally conductive sheet 1 and the adherend increases, and the contact area between the thermally conductive sheet 1 and the adherend increases. Since air is prevented from entering between the two, contact thermal resistance can be reduced. Specifically, the thermally conductive sheet 1 has an average height Spk of the protruding peaks of 3 ⁇ m or less, so that the thermally conductive sheet 1 has a pressure of 1.4 kgf/cm 2 and 2.1 kgf measured according to ASTM-D5470. /cm 2 The contact thermal resistance when pressurized can be 0.10° C.cm 2 /W or less. In this manner, since the average height Spk of the protruding peaks is 3 ⁇ m or less, the thermally conductive sheet 1 can reduce contact thermal resistance even under low load (low pressurization).
  • the thermally conductive sheet 1 has an average height Spk of the protruding peaks measured according to ISO 25178 of 3 ⁇ m or less, may be 2.5 ⁇ m or less, may be 2 ⁇ m or less, and may be 1.2 ⁇ m or less. 1.1 ⁇ m or less, 1.0 ⁇ m or less, 0.9 ⁇ m or less, 0.8 ⁇ m or less, 0.7 ⁇ m or less The thickness may be 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 2.342 ⁇ m, and may be in the range of 0.494 to 2.342 ⁇ m. ⁇ 1.212 ⁇ m, 0.494 ⁇ 1.143 ⁇ m, 0.494 ⁇ 0.887 ⁇ m, 0.494 ⁇ 0.566 ⁇ 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.
  • the thermally conductive sheet 1 may have an average depth Svk of the protruding valleys of 5.5 ⁇ m or less as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens; 4. 5 ⁇ m or less, 4.0 ⁇ m or less, 3.5 ⁇ m or less, 3.0 ⁇ m or less, 2.5 ⁇ m or less, 2. It may be 0 ⁇ m or less, 1.5 ⁇ m or less, or 1.2 ⁇ 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, or may be in the range of 1.165 to 4.490 ⁇ m, or may be in the range of 1.165 to 4.490 ⁇ m. It may be in the range of .165 to 4.291 ⁇ m, may be in the range of 1.165 to 3.711 ⁇ m, or may be in the range of 1.165 to 3.559 ⁇ m.
  • 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.
  • Thermal conductive sheet 1 has an average height Spk ( ⁇ m) of protruding peaks and an average depth Svk ( The value (Spk/(Spk+Svk)) of the average height Spk ( ⁇ m) of the protruding peaks relative to the sum of the peaks (Spk/(Spk+Svk)) is preferably 40% or less, may be 30% or less, and may be 25% or less. It may be 22% or less, 20% or less, or 18% 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 18% or more. It's okay.
  • (Spk/(Spk+Svk)) of the thermally conductive sheet 1 may be in the range of 18.14 to 39.78%, may be in the range of 18.14 to 39.69%, or may be in the range of 18.14 to 39.69%, or It may be in the range of .14 to 29.76%, it may be in the range of 18.14 to 27.58%, it may be in the range of 18.14 to 22.02%, It may range from 18.14% to 19.29%.
  • 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.
  • the thermally conductive sheet 1 preferably has 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 a 20x objective lens; It may be 0.12ml/ m2 or less, 0.10ml/ m2 or less, 0.08ml/ m2 or less, or 0.06ml/ m2 or less. Generally, it may be 0.04 ml/m 2 or less, or 0.03 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 thermally conductive sheet 1 may have a volume Vmp of the protruding peaks in the range of 0.025 to 0.137 ml/ m2 , or in the range of 0.025 to 0.114 ml/ m2 . It may be in the range of 0.025 to 0.058 ml/ m2 , it may be in the range of 0.025 to 0.055 ml/ m2 , or it may be in the range of 0.025 to 0.040 ml/m2.
  • 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 root mean square gradient Sdq of the thermally conductive sheet 1 is equal to or less than a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20 times.
  • the root mean square gradient Sdq of the thermally conductive sheet 1 represents the average size of the local gradient (differential of the shape) of the uneven shape on the surface of the thermally conductive sheet 1. 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 root mean square gradient Sdq of the thermally conductive sheet 1 is preferably less than 1.1, may be 0.8 or less, may be 0.7 or less, and may be 0.6 or less. It may be 0.5 or less, 0.4 or less, or 0.3 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, for example, in the range of 0.304 to 0.697, may be in the range of 0.304 to 0.578, or may be in the range of 0.304 to 0.578. 0.565, 0.304 to 0.508, 0.304 to 0.507, or 0.304 to 0.
  • 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 arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is less than or equal to a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the arithmetic mean curvature Spc of the peaks of the thermally conductive sheet 1 represents the average of the principal curvatures of the peaks of the surface of the thermally conductive sheet 1. 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.
  • the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is preferably 2500 (1/mm) or less, may be 2300 (1/mm) or less, and may be 2100 (1/mm) or less. 2000 (1/mm) or less, 1900 (1/mm) or less, 1700 (1/mm) or less, 1500 (1/mm) or less It may be 1300 (1/mm) or less, 1100 (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 951 to 2290 (1/mm), or may be in the range of 951 to 2105 (1/mm), It may be in the range of 951 to 1937 (1/mm), it may be in the range of 951 to 1879 (1/mm), it may be in the range of 951 to 1455 (1/mm), or it may be in the range of 951 to 1455 (1/mm). , 951 to 1399 (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 developed area ratio Sdr of the interface of the thermally conductive sheet 1 is equal to or less than a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • the developed area ratio Sdr of the interface of the thermally conductive sheet 1 represents how much the developed area (surface area) of the defined region of the thermally conductive sheet 1 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 development area ratio Sdr of 20% or less, which may be 15% or less, 10% or less, or 9% or less, It may be 7% or less, or 4% 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, or 2% or more.
  • the developed area ratio Sdr of the interface of the thermally conductive sheet 1 may be, for example, in the range of 3.56 to 15.55%, or may be in the range of 3.56 to 10.44%, It may be in the range of 3.56 to 10.32%, it may be in the range of 3.56 to 9.44%, or it may be in the range of 3.56 to 8.34%. 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.
  • Thermal conductive sheet 1 has the arithmetic mean curvature of the peak Spc (1/mm) and the developed area ratio of the interface Sdr (%), which are measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens.
  • Spc and Sdr satisfy the following formula 1.
  • the thermally conductive sheet 1 can more effectively reduce contact thermal resistance under low load by satisfying Formula 1 in addition to having an average height Spk of the protruding peaks of 3 ⁇ m or less.
  • Formula 1: Y 0.0153X-(15.547 ⁇ 10) (In formula 1, 0 ⁇ X ⁇ 2500 and 0 ⁇ Y ⁇ 20.)
  • the plotted values are as follows. Preferably, it exists within a region surrounded by Formula 1A and Formula 1B.
  • the thermally conductive sheet 1 has a contact thermal resistance of 0.10° C.cm 2 /W or less when 1.4 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.09° C.cm 2 /W. It may be below W, it may be below 0.08°C ⁇ cm 2 /W, it may be below 0.07°C ⁇ cm 2 /W, it may be below 0.06°C ⁇ cm 2 /W. It may be.
  • the lower limit of the contact thermal resistance 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, for example 0 It can be .02°C ⁇ cm 2 /W or more, or it can be 0.05°C ⁇ cm 2 /W or more.
  • the thermally conductive sheet 1 may have a contact thermal resistance when pressurized with 1.4 kgf/cm 2 in the range of 0.020 to 0.083° C.cm 2 /W, and may be in the range of 0.060 to 0.083.
  • It may be in the range of °C ⁇ cm 2 /W, it may be in the range of 0.060 to 0.082 °C ⁇ cm 2 /W, it may be in the range of 0.060 to 0.077 °C ⁇ cm 2 /W It may be in the range of 0.060 to 0.075°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 has a contact thermal resistance of 0.10° C.cm 2 /W or less when 2.1 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.08° C.cm 2 /W. It may be below W, may be below 0.07°C ⁇ cm 2 /W, and may be below 0.06°C ⁇ cm 2 /W.
  • the lower limit of the contact thermal resistance of the thermally conductive sheet 1 when pressurized with 2.1 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example 0 It can be .03°C ⁇ cm 2 /W or more, or it can be 0.05°C ⁇ cm 2 /W or more.
  • the thermally conductive sheet 1 may have a contact thermal resistance when pressurized with 2.1 kgf/cm 2 in the range of 0.039 to 0.093° C.cm 2 /W, or 0.055 to 0.075.
  • It may be in the range of °C ⁇ cm 2 /W, it may be in the range of 0.055 to 0.073 °C ⁇ cm 2 /W, it may be in the range of 0.055 to 0.070 °C ⁇ cm 2 /W It may be in the range of 0.055 to 0.069°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 may have a contact thermal resistance of 0.072°C ⁇ cm 2 /W or less when 2.8 kgf/cm 2 is applied, measured according to ASTM-D5470, and may have a contact thermal resistance of 0.065°C ⁇ cm 2 /W or less. It may be less than cm 2 /W.
  • the lower limit of the contact thermal resistance 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 0 It can be .04° C.cm 2 /W or more.
  • the thermally conductive sheet 1 may have a contact thermal resistance of 0.052 to 0.072° C.cm 2 /W when pressurized with 2.8 kgf/cm 2 , for example, and may have a contact thermal resistance of 0.052 to 0.072° C.cm 2 /W. It may be in the range of 0.071°C.cm 2 /W, it may be in the range of 0.052 to 0.065°C.cm 2 /W, it may be in the range of 0.052 to 0.064°C.cm 2 /W. It may be in the range of 0.052 to 0.061°C ⁇ cm 2 /W, or may be in the range of 0.052 to 0.054°C ⁇ cm 2 /W.
  • the thermally conductive sheet 1 may have a contact thermal resistance of 0.086° C.cm 2 /W or less when 3.5 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.068° C. cm 2 /W or less, or 0.062° C.cm 2 /W or less.
  • the lower limit of the contact thermal resistance 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 0 It can be .02°C ⁇ cm 2 /W or more, or it can be 0.04°C ⁇ cm 2 /W or more.
  • the thermally conductive sheet 1 may have a contact thermal resistance of, for example, 0.024 to 0.086° C.cm 2 /W when pressurized with 3.5 kgf/cm 2 , or 0.045 to 0.086° C.cm 2 /W. It may be in the range of 0.068°C.cm 2 /W, it may be in the range of 0.045 to 0.062°C.cm 2 /W, it may be in the range of 0.045 to 0.060°C.cm 2 /W. It may be within a range of 0.045 to 0.051° 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.
  • the polishing residue 5 is, for example, a lump made of a thermally conductive composition containing a binder resin 2, a fibrous filler 3, and another thermally conductive filler 4.
  • the surface of the thermally conductive sheet 1 can be made smoother, and as described above, the average height Spk of the protruding peaks of the thermally conductive sheet 1 can be made smoother. is 3 ⁇ m or less, and contact thermal resistances of 0.10° C.cm 2 /W or less when pressurized at 1.4 kgf/cm 2 and 2.1 kgf/cm 2 tend to be obtained.
  • the thermally conductive sheet 1 having polishing residue 5 means that the polishing residue 5 is present on the surface of the thermally conductive sheet 1 to such an extent that the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 ⁇ m or less. is preferable, and for example, it may have polishing residue 5 almost uniformly over the entire surface, or it may have polishing residue 5 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 height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 ⁇ m or less, and when a pressure of 1.4 kgf/cm 2 is applied, and when a pressure of 2.1 kgf/cm 2 is applied.
  • the average particle size and maximum particle size 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 setting the average height Spk of the protruding peaks of the thermally conductive sheet 1 to a predetermined value or less for the thermally conductive sheet 1 in which the fibrous filler 3 is oriented in the thickness direction. As a result, the total thermal resistance value can be reduced.
  • the binder resin 2, fibrous filler 3, and other thermally conductive filler 4 which are examples of the structure of the thermally conductive sheet 1, will be explained.
  • Binder resin 2 is for holding fibrous filler 3 and other thermally conductive 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.
  • the silicone resin is, for example, a two-component addition type, which is mainly composed of silicone (polyorganosiloxane) having an alkenyl group, a main resin containing a curing catalyst, and a curing agent having a hydrosilyl group (Si-H group).
  • Reactive silicone resins can be used.
  • silicone having an alkenyl group a polyorganosiloxane having at least two alkenyl groups in one molecule can be used.
  • 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.
  • 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 a mixing ratio 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, or more than 34% 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 may be, for example, in the range of 24 to 35% by volume, or may be in the range of 24 to 32% 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 fibrous filler 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. Below, the case where carbon fiber is used as a fibrous thermally conductive filler will be described in detail as an example.
  • the fibrous filler 3 has 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 long axis length / average short axis length) exceeds 1. including.
  • the fibrous filler 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 fibrous filler 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 fibrous filler 3 can be appropriately selected depending on the purpose, and can be, for example, 4 to 20 ⁇ m, or may be 5 to 14 ⁇ m.
  • the aspect ratio of the fibrous filler 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 fibrous filler 3 can be measured using, for example, a microscope or a scanning electron microscope (SEM).
  • the content of the fibrous filler 3 in the thermally conductive sheet 1 can be, for example, 5% by volume or more, and may be 10% by volume or more. , may be 14 volume% or more, may be 20 volume% or more, may be 22 volume% or more, may be 24 volume% or more, or may be 26 volume% or more. . Further, from the viewpoint of formability of the thermally conductive sheet 1, the content of the fibrous filler 3 in the thermally conductive sheet 1 can be, for example, 30% by volume or less, and even if it is 28% by volume or less. Generally, it may be 26% by volume or less, 20% by volume or less, or 18% by volume or less.
  • the content of the fibrous filler 3 in the thermally conductive sheet 1 may be, for example, in the range of 14 to 28% by volume, or may be in the range of 14 to 26% by volume.
  • the total amount thereof satisfies the above-mentioned content.
  • the other thermally conductive filler 4 is a thermally conductive filler other than the fibrous filler 3.
  • Other thermally conductive fillers 4 include, for example, spherical, powdery, granular, scale-like, and other thermally conductive fillers.
  • the material of the other thermally conductive filler 4 includes, for example, an inorganic filler, preferably a ceramic filler, and specific examples include aluminum oxide (alumina, sapphire), Examples include aluminum nitride, aluminum, aluminum hydroxide, and boron nitride.
  • the other thermally conductive fillers 4 may be used alone or in combination of two or more.
  • two or more types of thermally conductive fillers having different average particle diameters may be used in combination.
  • thermally conductive fillers 4 are selected from aluminum oxide, aluminum nitride, aluminum, and aluminum hydroxide, 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 at least one kind is selected.
  • the other thermally conductive filler 4 aluminum oxide and aluminum nitride may be used together, aluminum oxide, aluminum nitride and aluminum may be used together, or aluminum hydroxide may be used alone. good.
  • 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 hydroxide may be in the range of 0.1 to 10 ⁇ m, 0.5 to 5 ⁇ m, or 0.5 ⁇ m in terms of the specific gravity of the thermally conductive sheet 1, for example. 3 ⁇ m, or 0.5 to 2 ⁇ 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 other thermally conductive fillers 4 in the thermally conductive sheet 1 can be appropriately selected depending on the purpose.
  • the content of the other thermally conductive filler 4 in the thermally conductive sheet 1 may be, for example, 10% by volume or more, may be 15% by volume or more, or may be 20% by volume or more. , may be 25 volume% or more, may be 30 volume% or more, may be 35 volume% or more, may be 39 volume% or more, may be 45 volume% or more.
  • the upper limit of the content of the other thermally conductive filler 4 in the thermally conductive sheet 1 can be, for example, 55% by volume or less, 50% by volume or less, and 49% by volume or less.
  • the content may be 45% by volume or less, or may be 40% by volume or less.
  • the content of the other thermally conductive filler 4 in the thermally conductive sheet 1 may be in the range of 39 to 50% by volume, or may be in the range of 39 to 49% by volume, for example.
  • the content of aluminum nitride in the thermally conductive sheet 1 is in the range of 15 to 35% by volume, and the content of aluminum oxide is in the range of 15 to 35% by volume. It can range from 5 to 25% by volume.
  • the content of aluminum nitride in the thermally conductive sheet 1 should be in the range of 10 to 30% by volume, and aluminum oxide
  • the content of aluminum can be in the range of 1 to 20% by volume, and the content of aluminum can be in the range of 10 to 30% by volume.
  • the thermally conductive sheet 1 may further contain other components other than the above-mentioned components 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 may be treated with a fibrous filler 3 treated with a coupling agent and/or a coupling agent.
  • Other thermally conductive fillers 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 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, a fibrous filler 3, and a thermally conductive filler 4 other than the fibrous filler 3 is molded into a predetermined shape and cured. A molded body of the conductive composition is obtained.
  • process A first, by dispersing the fibrous filler 3 and other thermally conductive filler 4 into the binder resin 2, the binder resin 2, the fibrous filler 3, and the other thermally conductive filler 4 are combined.
  • a thermally conductive composition containing the following is produced.
  • the thermally conductive composition is prepared by uniformly mixing the binder resin 2, the fibrous filler 3, the other thermally conductive filler 4, and other components mentioned above as needed by a known method. Can be prepared.
  • the prepared thermally conductive composition is extruded and then cured to obtain a columnar cured product (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 the thermally conductive composition from a die, the binder resin 2 in the thermally conductive composition flows, and the fibrous filler 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 molded body of the thermally conductive composition obtained in step A is cut into sheets to obtain molded sheets.
  • the columnar cured product obtained in step A is cut into a predetermined thickness in the length direction of the column to obtain a molded sheet.
  • the fibrous filler 3 is exposed on the surface (cut surface) of the molded sheet obtained in step B.
  • the method for cutting the molded body is not particularly limited, and can be appropriately selected from known slicing devices depending on the size and mechanical strength of the molded body. When extrusion molding is used to obtain a molded product, the fibrous filler 3 may be oriented in the extrusion direction, so the cutting direction of the molded product is 60 to 120 degrees to the extrusion direction.
  • the direction is preferably 70 to 100 degrees, and even more preferably 90 degrees (substantially perpendicular).
  • the cutting direction of the molded body is not particularly limited other than the above, and can be appropriately selected depending on the purpose of use of the thermally conductive sheet 1 and the like.
  • the molded sheet obtained in step B has irregularities on its surface.
  • the molded sheet 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 molded sheet obtained in step B usually has an average height Spk of the protruding peaks measured according to ISO 25178 of more than 3 ⁇ m.
  • air tends to get mixed in between the molded sheet and the adherend, making it difficult to reduce the contact thermal resistance of the molded sheet. .
  • step C by polishing the molded sheet obtained in step B, binder resin 2, fibrous filler 3, and other thermally conductive filler 4 are removed from the convex portions 1a on the surface of the molded sheet.
  • the concave portions on the surface of the formed sheet are covered (in other words, the polishing residue 5 scraped from the convex portions 1a remains in the concave portions), so that the average height Spk of the protruding peaks of the thermally conductive sheet 1 is reduced to 3 ⁇ m.
  • the contact area between the thermally conductive sheet 1 and the adherend can be improved, suppressing the mixing of air between the thermally conductive sheet 1 and the adherend, and improving the thermal conductivity.
  • the contact thermal resistance of the sheet 1 can be reduced.
  • the thermally conductive sheet 1 by coating the surface of the thermally conductive sheet 1 with the bled binder resin 2, the reduction in the average height Spk of the protruding peaks of the thermally conductive sheet 1 is facilitated, and the thermal conduction The contact area between the thermally conductive sheet 1 and the adherend is further improved, and the mixture of air between the thermally conductive sheet 1 and the adherend is more effectively suppressed, and the contact heat of the thermally conductive sheet 1 is reduced. It is believed that the resistance can be further reduced.
  • step C for example, the molded sheet obtained in step B is polished with a polishing member.
  • the polishing member include those that can be brought into surface contact with the surface of the molded sheet for polishing.
  • examples of such abrasive members include sandpaper, wrapping films, brushes, etc., and 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 binder resin 2, fibrous filler 3, and others are scraped out from the convex portions 1a on the surface of the molded sheet.
  • the heat conductive filler 4 can more efficiently cover the recesses on the surface of the molded sheet.
  • 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 molded sheet 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 resilience, etc., nylon can be used.
  • 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. It is believed that the greater the number of times of polishing, the easier it is for the concave portions on the surface of the molded sheet 9 to be covered by the binder resin 2, fibrous filler 3, and other thermally conductive filler 4 scraped out from the convex portions 1a on the surface of the molded sheet. 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 is defined as one time of polishing in one direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9 in FIG. 4, for example.
  • the thermally conductive sheet 1 obtained in step C has polishing residue 5 generated by polishing the convex portions 1a existing on the surface of the molded sheet with a polishing member.
  • the thermally conductive sheet 1 has the above-mentioned physical properties, that is, the average height Spk of the protruding peaks measured according to ISO 25178 is 3 ⁇ m or less, and the ASTM-D5470
  • the contact thermal resistance when pressurized with 1.4 kgf/cm 2 and when pressurized with 2.1 kgf/cm 2 is 0.10° C.cm 2 /W or less, which is measured according to the standard, tends to be easily satisfied.
  • 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.
  • the protruding peaks of the thermally conductive sheet 1 measured according to ISO 25178 By setting the average height Spk of 3 ⁇ m or less, the contact thermal resistance of the thermally conductive sheet 1 can be reduced.
  • the average height of the protruding peaks of the thermally conductive sheet 1 can be improved in polishing in step C without using two or more types of polishing members with different abrasive grain sizes. Since the thickness Spk can be reduced to 3 ⁇ m or less, 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.
  • 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 molded sheet 9 obtained in step B, and in step C, The thermally conductive sheet 1 may be obtained by polishing the surface of the molded sheet 9 pressed in step D.
  • the surface of the resulting thermally conductive sheet 1 can be made smoother, and its adhesion to other members can be further improved.
  • 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 heating element and a heat radiating element to allow the heat generated by the heating element to escape 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 thermally conductive sheet 1 and the adherend are The contact area with a certain heating element or heat radiating element is increased, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, so the contact heat during low load (low pressurization) is reduced. Resistance can be reduced more effectively.
  • 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 2 A thermally conductive sheet was obtained by polishing the surface of a molded sheet in the same manner as in Example 1, except that the thickness of the thermally conductive sheet was changed to 0.3 mm. Thus, the thermally conductive sheet obtained in Example 2 had a polished surface and had polishing residue on the surface.
  • Example 3 A thermally conductive sheet was obtained by polishing the surface of a molded sheet in the same manner as in Example 1, except that the thickness of the thermally conductive sheet was changed to 0.5 mm. Thus, the thermally conductive sheet obtained in Example 3 had a polished surface and had polishing residue on the surface.
  • Example 4 > 24% by volume of silicone resin, 10% by volume of aluminum oxide (average particle diameter: approximately 2 ⁇ m), 20% by volume of aluminum nitride (average particle diameter: approximately 1 ⁇ m), and 19% by volume of aluminum (average particle diameter: approximately 6 ⁇ m).
  • a thermally conductive composition was prepared by uniformly mixing 26% by volume of carbon fibers (average fiber length: about 150 ⁇ m) 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 5 Uniformly mix 35% by volume of silicone resin, 50% by volume of aluminum hydroxide (average particle diameter: approximately 1 ⁇ m), 14% by volume of carbon fiber (average fiber length: approximately 150 ⁇ m), and 1% by volume of coupling agent.
  • a thermally conductive composition was prepared. 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 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 by polishing the surface of the molded sheet in the same manner as in Example 6, except that the thickness of the molded sheet was changed to 2.0 mm.
  • the thermally conductive sheet obtained in Example 7 had a polished surface and had polishing residue on the surface.
  • Comparative Example 1 a molded sheet obtained in the same manner as in Example 2 in which carbon fibers were oriented in the thickness direction of the sheet was pressed.
  • the surface of a molded sheet obtained by slicing a columnar cured product into 0.3 mm thick sheets was pressed with a wrapping film without polishing it. Therefore, the molded sheet obtained in Comparative Example 1 did not have any polishing residue on its surface.
  • Comparative example 2 In Comparative Example 2, a composition in which 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 molded sheet oriented in the direction was obtained.
  • Comparative Example 2 after slicing the columnar cured product into 0.3 mm thick slices, the surface of the molded sheet was not polished with a wrapping film. Therefore, the molded sheet obtained in Comparative Example 2 did not have any polishing residue on its 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 4 A molded product sheet was obtained in the same manner as in Comparative Example 3, except that the thickness when cutting (slicing) the columnar cured product into sheet shapes was 2.0 mm. Thus, in Comparative Example 4, after slicing the columnar cured product into 2.0 mm thick slices, the surface of the molded sheet was not polished with a wrapping film. Therefore, the molded sheet obtained in Comparative Example 4 did not have any polishing residue on its surface.
  • ⁇ Surface property parameters of thermally conductive sheet> The surface property parameters of the thermally conductive sheets obtained in each example and the molded sheets obtained in each comparative example were measured. Specifically, the average height Spk ( ⁇ m) of the protruding peaks of the thermally conductive sheet (molded body sheet), the average depth Svk ( ⁇ m) of the protruding valleys, and the volume Vmp (ml/m 2 ) of the protruding peaks ), the root mean square gradient Sdq, the arithmetic mean curvature of the peak Spc (1/mm), and the developed area ratio Sdr (%) of the interface were measured.
  • the total thermal resistance was measured using a thermal resistance measuring device (manufactured by Dexerials Co., Ltd.) compliant with 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 bulk thermal conductivity [W/(m ⁇ K)] is determined for the thermally conductive sheet obtained in each example and the molded sheet obtained in each comparative example at a sheet thickness of 0.5 mm and 1.0 mm. , 1.5 mm respectively, and the horizontal axis is the thickness [mm] when compressed by 4 to 12% from the initial thickness of each sheet, and the total when compressed from 4 to 12% from the initial thickness of each sheet.
  • the obtained data was plotted with the thermal resistance value [° C.cm 2 /W] as the vertical axis, and the data was calculated from the reciprocal of the slope of the approximate straight line.
  • the total thermal resistance value is the total thermal resistance value of the bulk thermal resistance value and the contact thermal resistance value measured in accordance with ASTM D5470
  • the bulk thermal resistance value is the thermal resistance value of the thermal conductive sheet itself. It is a value.
  • Bulk thermal conductivity [W/(m ⁇ K)] indicates the thermal conductivity of the thermally conductive sheet itself, without considering contact with a jig during measurement. The results are shown in Table 1.
  • a thermally conductive sheet made of a cured product of a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler,
  • the filler is oriented in the thickness direction of the thermally conductive sheet, and the average height Spk of the protruding peaks of the thermally conductive sheet measured according to ISO 25178 is 3 ⁇ m or less, as measured according to ASTM-D5470. It was found that the contact thermal resistance when applying a pressure of 1.4 kgf/cm 2 and when applying a pressure of 2.1 kgf/cm 2 was 0.10° C.cm 2 /W or less.
  • thermally conductive sheets obtained in Examples 1 to 7 have a contact thermal resistance of 0.072° C.cm 2 /W or less when 2.8 kgf/cm 2 is applied, as measured in accordance with ASTM-D5470. That's what I found out.
  • the thermally conductive sheets obtained in Examples 1 to 7 had polished surfaces and had polishing residues on the surfaces. This polishing residue was confirmed to be a lump containing silicone resin, carbon fiber, and other thermally conductive fillers (aluminum oxide, aluminum nitride, aluminum, aluminum hydroxide, etc.) caused by polishing.
  • 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 the arithmetic mean curvature Spc (1/mm) of the peak measured according to ISO 25178 and the developed area ratio Sdr (%) of the interface. It was found that when a graph was created in which the values were plotted with Spc on the horizontal axis and Sdr on the vertical axis, Spc and Sdr satisfied Equation 1 described above.
  • the molded sheets obtained in Comparative Examples 1 and 2 had an average height Spk of the protruding peaks measured according to ISO 25178 of less than 3 ⁇ m, and an average height Spk of 1.4 kgf/cm 2 measured according to ASTM-D5470. It was found that the contact thermal resistance under pressure and when 2.1 kgf/cm 2 was applied did not satisfy 0.10° C.cm 2 /W or less. Furthermore, it was found that the average height Spk of the protruding peaks measured according to ISO 25178 did not satisfy 3 ⁇ m or less in the molded sheets obtained in Comparative Examples 3 and 4. This is thought to be because in Comparative Examples 1 to 4, the molded sheet was not polished with a polishing member (wrapping film), so no polishing residue remained on the surface of the molded sheet.
  • the molded sheets obtained in Comparative Examples 1 to 4 have the arithmetic mean curvature of the peak Spc (1/mm) measured according to ISO 25178 and the developed area ratio Sdr (%) of the interface.
  • Spc and Sdr do not satisfy the above formula 1 (in formula 1, 0 ⁇ X ⁇ 2500 and 0 ⁇ Y ⁇ 20).

Abstract

Provided is a heat-conducting sheet having a reduced contact thermal resistance.　This heat-conducting sheet 1 comprises a cured product of a heat-conducting composition containing a binder resin 2, a fibrous filler 3, and a heat-conducting filler 4 other than the fibrous filler 3. In the heat-conducting sheet 1, the fibrous filler 3 is aligned in the thickness direction B. The average height Spk of peaks on the heat-conducting sheet 1 as measured using a scanning white-light interference microscope having a 20x objective lens in accordance with ISO 25178 is at most 3 μm. The contact thermal resistances of the heat-conducting sheet 1 as measured in accordance with ASTM-D5470 when applied with pressure at 1.4 kgf/cm2 and 2.1 kgf/cm2 are at most 0.10°C·cm2/W.

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３０日に出願された日本特許出願番号特願２０２２－０５５３５４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２０２３－０５２７８８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. 2022-055354 filed in Japan on March 30, 2022 and Japanese Patent Application No. 2023-052788 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、繊維状フィラー（例えば炭素繊維）を用いた熱伝導性シートが挙げられる（例えば、特許文献１～５を参照）。繊維状フィラー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 fibrous fillers (eg, carbon fibers) (see, eg, Patent Documents 1 to 5). Carbon fiber, which is an example of a fibrous filler, 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。接触熱抵抗とは、熱伝導シートと被着体の間に生じる熱抵抗である。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. Contact thermal resistance is thermal resistance that occurs between a thermally conductive sheet and an adherend. 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。特に、炭素繊維のような繊維状フィラー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る。 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. In particular, in a thermally conductive sheet in which fibrous filler such as carbon fiber is oriented in the thickness direction, the contact thermal resistance tends to increase as the thickness decreases.
特許５７５２２９９号Patent No. 5752299 特許４８１４５５０号Patent No. 4814550 特許６６５０１７５号Patent No. 6650175 特許６６７１７３５号Patent No. 6671735 国際公開第２０２０／０６７１４１号公報International Publication No. 2020/067141
　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、接触熱抵抗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 reduced contact thermal resistance.
　本願発明者らは、鋭意検討の結果、繊維状フィラーが厚み方向に配向した熱伝導性シートについて、突出山部の平均高さＳｐｋを所定値以下とすることにより、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 found that the above-mentioned problem can be solved by setting the average height Spk of the protruding peaks to a predetermined value or less for a thermally conductive sheet in which fibrous filler is oriented in the thickness direction. I found it.
　本技術は、バインダ樹脂と、繊維状フィラーと、繊維状フィラー以外の他の熱伝導性フィラー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、繊維状フィラーが熱伝導性シートの厚み方向に配向しており、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、熱伝導性シートの突出山部の平均高さＳｐｋが３μｍ以下であり、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下である。 The present technology is a thermally conductive sheet made of a cured product of a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler, in which the fibrous filler The average height Spk of the protruding peaks of the thermally conductive sheet is 3 μm, which is oriented in the thickness direction of the conductive sheet and measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. The contact thermal resistance when applying a pressure of 1.4 kgf/cm 2 and when applying a pressure of 2.1 kgf/cm 2 is 0.10° C.cm 2 /W or less, measured according to ASTM-D5470.
　本技術に係る熱伝導性シートの製造方法は、バインダ樹脂と、繊維状フィラーと、繊維状フィラー以外の他の熱伝導性フィラーとを含む熱伝導性組成物を所定の形状に成型して硬化することにより、熱伝導性組成物の成型体を得る工程と、成型体をシート状に切断し、成型体シートを得る工程と、成形体シートを研磨部材によって研磨することにより、熱伝導性シートを得る工程とを含み、熱伝導性シートの表面には、上記研磨によって生じた、バインダ樹脂、繊維状フィラー及び他の熱伝導性フィラーを含む研磨残渣が残留する。 A method for manufacturing a thermally conductive sheet according to the present technology includes molding a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler into a predetermined shape and curing it. A step of obtaining a molded body of the thermally conductive composition by doing so, a step of cutting the molded body into sheet shapes to obtain a molded body sheet, and a process of polishing the molded body sheet with a polishing member to form a thermally conductive sheet. A polishing residue containing a binder resin, a fibrous filler, and other thermally conductive fillers generated by the polishing is left on the surface of the thermally conductive sheet.
　本技術は、接触熱抵抗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 reduced contact thermal resistance.
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、成形体シート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 molded sheet with a brush. 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。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. 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.
　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、繊維状フィラー３と、繊維状フィラー３以外の他の熱伝導性フィラー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、繊維状フィラー３と他の熱伝導性フィラー４とがバインダ樹脂２に分散しており、繊維状フィラー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に繊維状フィラー３が配向しているとは、例えば、熱伝導性シート１中の全ての繊維状フィラー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繊維状フィラー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。繊維状フィラー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、繊維状フィラー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。 FIG. 1 is a cross-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, a fibrous filler 3, and a thermally conductive filler 4 other than the fibrous filler 3. In the thermally conductive sheet 1, a fibrous filler 3 and another thermally conductive filler 4 are dispersed in a binder resin 2, and the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1. Here, the fact that the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1 means that, for example, among all the fibrous fillers 3 in the thermally conductive sheet 1, the thickness of the thermally conductive sheet 1 The proportion of the fibrous filler 3 whose long axis is oriented in direction B is 50% or more, may be 55% or more, may be 60% or more, may be 65% or more, It may be 70% or more, 80% or more, 90% or more, 95% or more, or 99% or more. When the long axis of the fibrous filler 3 is oriented in the thickness direction B of the thermally conductive sheet 1, for example, the long axis of the fibrous filler 3 is oriented in the direction A of the thermally conductive sheet 1 by 60° to The angle may be in the range of 120 degrees, may be in the range of 70 to 100 degrees, or may be 90 degrees (substantially vertical).
　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３μｍ以下である。突出山部の平均高さＳｐｋは、走査型白色干渉顕微鏡の対物レンズ倍率に影響を受ける。以下では、単に「ＩＳＯ　２５１７８に従って測定される、突出山部の平均高さＳｐｋ」や「突出山部の平均高さＳｐｋ」ともいう。さらに、熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下である。なお、後述する、ＩＳＯ　２５１７８に従って測定される値についても、走査型白色干渉顕微鏡の対物レンズ倍率に影響を受ける。 The thermally conductive sheet 1 has an average height Spk of protruding peaks of 3 μm 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. The average height Spk of the protruding peaks is influenced by the objective lens magnification of the scanning white interference microscope. Hereinafter, it will also be simply referred to as "average height Spk of the protruding peaks measured according to ISO 25178" or "average height Spk of the protruding peaks". Furthermore, the thermally conductive sheet 1 has a contact thermal resistance of 0.10°C·cm 2 / when a pressure of 1.4 kgf/cm 2 is applied and when a pressure of 2.1 kgf/cm 2 is applied, which is measured according to ASTM-D5470. W or less. Note that the values measured according to ISO 25178, which will be described later, are also affected by the objective lens magnification of the scanning white interference microscope.
　熱伝導性シート１は、突出山部の平均高さＳｐｋが３μｍ以下であることにより、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る。具体的には、熱伝導性シート１は、突出山部の平均高さＳｐｋが３μｍ以下であることにより、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗を０．１０℃・ｃｍ２／Ｗ以下とすることができる。このように、熱伝導性シート１は、突出山部の平均高さＳｐｋが３μｍ以下であることにより、低荷重（低加圧）時でも接触熱抵抗を低減できる。 Since the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 μm or less, the contact area between the thermally conductive sheet 1 and the adherend increases, and the contact area between the thermally conductive sheet 1 and the adherend increases. Since air is prevented from entering between the two, contact thermal resistance can be reduced. Specifically, the thermally conductive sheet 1 has an average height Spk of the protruding peaks of 3 μm or less, so that the thermally conductive sheet 1 has a pressure of 1.4 kgf/cm 2 and 2.1 kgf measured according to ASTM-D5470. /cm 2 The contact thermal resistance when pressurized can be 0.10° C.cm 2 /W or less. In this manner, since the average height Spk of the protruding peaks is 3 μm or less, the thermally conductive sheet 1 can reduce contact thermal resistance even under low load (low pressurization).
　熱伝導性シート１は、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３μｍ以下であり、２．５μｍ以下であってもよく、２μｍ以下であってもよく、１．２μｍ以下であってもよく、１．１μｍ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、０．４９４～２．３４２μｍの範囲であってもよく、０．４９４～１．２１２μｍの範囲であってもよく、０．４９４～１．１４３μｍの範囲であってもよく、０．４９４～０．８８７μｍの範囲であってもよく、０．４９４～０．５６６μｍ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。 The thermally conductive sheet 1 has an average height Spk of the protruding peaks measured according to ISO 25178 of 3 μm or less, may be 2.5 μm or less, may be 2 μm or less, and may be 1.2 μm or less. 1.1 μm or less, 1.0 μm or less, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less The thickness may be 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 2.342 μm, and may be in the range of 0.494 to 2.342 μm. ~1.212μm, 0.494~1.143μm, 0.494~0.887μm, 0.494~0.566μm 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.
　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、１．２μｍ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。また、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。 The thermally conductive sheet 1 may have an average depth Svk of the protruding valleys of 5.5 μm or less as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens; 4. 5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2. It may be 0 μm or less, 1.5 μm or less, or 1.2 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. Further, 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, or may be in the range of 1.165 to 4.490 μm, or may be in the range of 1.165 to 4.490 μm. It may be in the range of .165 to 4.291 μm, may be in the range of 1.165 to 3.711 μm, or may be in the range of 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（μｍ）と突出谷部の平均深さＳｖｋ（μｍ）の和に対する突出山部の平均高さＳｐｋ（μｍ）の値（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））が、４０％以下であることが好ましく、３０％以下であってもよく、２５％以下であってもよく、２２％以下であってもよく、２０％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（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、１８％以上であってもよい。熱伝導性シート１の（Ｓｐｋ／（Ｓｐｋ＋Ｓｖｋ））は、１８．１４～３９．７８％の範囲であってもよいし、１８．１４～３９．６９％の範囲であってもよいし、１８．１４～２９．７６％の範囲であってもよいし、１８．１４～２７．５８％の範囲であってもよいし、１８．１４～２２．０２％の範囲であってもよいし、１８．１４～１９．２９％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。 Thermal conductive sheet 1 has an average height Spk (μm) of protruding peaks and an average depth Svk ( The value (Spk/(Spk+Svk)) of the average height Spk (μm) of the protruding peaks relative to the sum of the peaks (Spk/(Spk+Svk)) is preferably 40% or less, may be 30% or less, and may be 25% or less. It may be 22% or less, 20% or less, or 18% 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 18% or more. It's okay. (Spk/(Spk+Svk)) of the thermally conductive sheet 1 may be in the range of 18.14 to 39.78%, may be in the range of 18.14 to 39.69%, or may be in the range of 18.14 to 39.69%, or It may be in the range of .14 to 29.76%, it may be in the range of 18.14 to 27.58%, it may be in the range of 18.14 to 22.02%, It may range from 18.14% to 19.29%. 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、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以下であることが好ましく、０．１２ｍｌ／ｍ２以下であってもよく、０．１０ｍｌ／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、０．０３ｍｌ／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、０．０２５～０．１３７ｍｌ／ｍ２の範囲であってもよいし、０．０２５～０．１１４ｍｌ／ｍ２の範囲であってもよいし、０．０２５～０．０５８ｍｌ／ｍ２の範囲であってもよいし、０．０２５～０．０５５ｍｌ／ｍ２の範囲であってもよいし、０．０２５～０．０４０ｍｌ／ｍ２の範囲であってもよいし、０．０２５～０．０２７ｍｌ／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 preferably has 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 a 20x objective lens; It may be 0.12ml/ m2 or less, 0.10ml/ m2 or less, 0.08ml/ m2 or less, or 0.06ml/ m2 or less. Generally, it may be 0.04 ml/m 2 or less, or 0.03 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 thermally conductive sheet 1 may have a volume Vmp of the protruding peaks in the range of 0.025 to 0.137 ml/ m2 , or in the range of 0.025 to 0.114 ml/ m2 . It may be in the range of 0.025 to 0.058 ml/ m2 , it may be in the range of 0.025 to 0.055 ml/ m2 , or it may be in the range of 0.025 to 0.040 ml/m2. 2 or 0.025 to 0.027 ml/m 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、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二乗平均平方根勾配Ｓｄｑが所定値以下であることが好ましい。熱伝導性シート１の二乗平均平方根勾配Ｓｄｑとは、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１．１未満であることが好ましく、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以下であってもよく、０．３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、０．３０４～０．６９７の範囲であってもよいし、０．３０４～０．５７８の範囲であってもよいし、０．３０４～０．５６５の範囲であってもよいし、０．３０４～０．５０８の範囲であってもよいし、０．３０４～０．５０７の範囲であってもよいし、０．３０４～０．０．３１６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。 It is preferable that the root mean square gradient Sdq of the thermally conductive sheet 1 is equal to or less than a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20 times. The root mean square gradient Sdq of the thermally conductive sheet 1 represents the average size of the local gradient (differential of the shape) of the uneven shape on the surface of the thermally conductive sheet 1. 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 root mean square gradient Sdq of the thermally conductive sheet 1 is preferably less than 1.1, may be 0.8 or less, may be 0.7 or less, and may be 0.6 or less. It may be 0.5 or less, 0.4 or less, or 0.3 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, for example, in the range of 0.304 to 0.697, may be in the range of 0.304 to 0.578, or may be in the range of 0.304 to 0.578. 0.565, 0.304 to 0.508, 0.304 to 0.507, or 0.304 to 0. It may be in the range of .0.316. 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が所定値以下であることが好ましい。熱伝導性シート１の山頂の算術平均曲率Ｓｐｃとは、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。熱伝導性シート１は、山頂の算術平均曲率Ｓｐｃが２５００（１／ｍｍ）以下であることが好ましく、２３００（１／ｍｍ）以下であってもよく、２１００（１／ｍｍ）以下であってもよく、２０００（１／ｍｍ）以下であってもよく、１９００（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、１３００（１／ｍｍ）以下であってもよく、１１００（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、９５１～２２９０（１／ｍｍ）の範囲であってもよいし、９５１～２１０５（１／ｍｍ）の範囲であってもよいし、９５１～１９３７（１／ｍｍ）の範囲であってもよいし、９５１～１８７９（１／ｍｍ）の範囲であってもよいし、９５１～１４５５（１／ｍｍ）の範囲であってもよいし、９５１～１３９９（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。 It is preferable that the arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is less than or equal to a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens. The arithmetic mean curvature Spc of the peaks of the thermally conductive sheet 1 represents the average of the principal curvatures of the peaks of the surface of the thermally conductive sheet 1. 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. The arithmetic mean curvature Spc of the peak of the thermally conductive sheet 1 is preferably 2500 (1/mm) or less, may be 2300 (1/mm) or less, and may be 2100 (1/mm) or less. 2000 (1/mm) or less, 1900 (1/mm) or less, 1700 (1/mm) or less, 1500 (1/mm) or less It may be 1300 (1/mm) or less, 1100 (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 951 to 2290 (1/mm), or may be in the range of 951 to 2105 (1/mm), It may be in the range of 951 to 1937 (1/mm), it may be in the range of 951 to 1879 (1/mm), it may be in the range of 951 to 1455 (1/mm), or it may be in the range of 951 to 1455 (1/mm). , 951 to 1399 (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、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界面の展開面積比Ｓｄｒが所定値以下であることが好ましい。熱伝導性シート１の界面の展開面積比Ｓｄｒとは、熱伝導性シート１の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。熱伝導性シート１は、界面の展開面積比Ｓｄｒが２０％以下であることが好ましく、１５％以下であってもよく、１０％以下であってもよく、９％以下であってもよく、７％以下であってもよく、４％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。熱伝導性シート１の界面の展開面積比Ｓｄｒは、例えば、３．５６～１５．５５％の範囲であってもよいし、３．５６～１０．４４％の範囲であってもよいし、３．５６～１０．３２％の範囲であってもよいし、３．５６～９．４４％の範囲であってもよいし、３．５６～８．３４％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。 It is preferable that the developed area ratio Sdr of the interface of the thermally conductive sheet 1 is equal to or less than a predetermined value, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens. The developed area ratio Sdr of the interface of the thermally conductive sheet 1 represents how much the developed area (surface area) of the defined region of the thermally conductive sheet 1 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 development area ratio Sdr of 20% or less, which may be 15% or less, 10% or less, or 9% or less, It may be 7% or less, or 4% 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, or 2% or more. The developed area ratio Sdr of the interface of the thermally conductive sheet 1 may be, for example, in the range of 3.56 to 15.55%, or may be in the range of 3.56 to 10.44%, It may be in the range of 3.56 to 10.32%, it may be in the range of 3.56 to 9.44%, or it may be in the range of 3.56 to 8.34%. 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。熱伝導性シート１は、突出山部の平均高さＳｐｋが３μｍ以下であることに加えて式１を満たすことにより、より効果的に低荷重時の接触熱抵抗を低減させることができる。
式１：Ｙ＝０．０１５３Ｘ－（１５．５４７±１０）
（式１中、０≦Ｘ≦２５００、かつ、０≦Ｙ≦２０である。） Thermal conductive sheet 1 has the arithmetic mean curvature of the peak Spc (1/mm) and the developed area ratio of the interface Sdr (%), which are measured according to ISO 25178 using a scanning white interference microscope with a 20x objective lens. When a graph is created in which the values are plotted with Spc as the horizontal axis and Sdr as the vertical axis, it is preferable that Spc and Sdr satisfy the following formula 1. The thermally conductive sheet 1 can more effectively reduce contact thermal resistance under low load by satisfying Formula 1 in addition to having an average height Spk of the protruding peaks of 3 μm or less.
Formula 1: Y=0.0153X-(15.547±10)
(In formula 1, 0≦X≦2500 and 0≦Y≦20.)
　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、界面の展開面積比Ｓｄｒ（％）を縦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＝０．０１５３Ｘ－２５．５４７
式１Ｂ：Ｙ＝０．０１５３Ｘ－５．５４７
（式１Ａ及び式１Ｂ中、０≦Ｘ≦２５００、かつ、０≦Ｙ≦２０である。） That is, when the values of the thermally conductive sheet 1 are plotted with the arithmetic mean curvature Spc (1/mm) of the peak on the horizontal axis and the developed area ratio Sdr (%) of the interface on the vertical axis, the plotted values are as follows. Preferably, it exists within a region surrounded by Formula 1A and Formula 1B.
Formula 1A: Y=0.0153X-25.547
Formula 1B: Y=0.0153X-5.547
(In Formula 1A and Formula 1B, 0≦X≦2500 and 0≦Y≦20.)
　熱伝導性シート１は、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下であり、０．０９℃・ｃｍ２／Ｗ以下であってもよく、０．０８℃・ｃｍ２／Ｗ以下であってもよく、０．０７℃・ｃｍ２／Ｗ以下であってもよく、０．０６℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の１．４ｋｇｆ／ｃｍ２加圧時の接触熱抵抗の下限値は、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０．０２℃・ｃｍ２／Ｗ以上となり得るし、０．０５℃・ｃｍ２／Ｗ以上ともなり得る。熱伝導性シート１は、１．４ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が、０．０２０～０．０８３℃・ｃｍ２／Ｗの範囲であってもよく、０．０６０～０．０８３℃・ｃｍ２／Ｗの範囲であってもよく、０．０６０～０．０８２℃・ｃｍ２／Ｗの範囲であってもよく、０．０６０～０．０７７℃・ｃｍ２／Ｗの範囲であってもよく、０．０６０～０．０７５℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 has a contact thermal resistance of 0.10° C.cm 2 /W or less when 1.4 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.09° C.cm 2 /W. It may be below W, it may be below 0.08°C·cm 2 /W, it may be below 0.07°C·cm 2 /W, it may be below 0.06°C·cm 2 /W. It may be. The lower limit of the contact thermal resistance 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, for example 0 It can be .02°C·cm 2 /W or more, or it can be 0.05°C·cm 2 /W or more. The thermally conductive sheet 1 may have a contact thermal resistance when pressurized with 1.4 kgf/cm 2 in the range of 0.020 to 0.083° C.cm 2 /W, and may be in the range of 0.060 to 0.083. It may be in the range of °C·cm 2 /W, it may be in the range of 0.060 to 0.082 °C·cm 2 /W, it may be in the range of 0.060 to 0.077 °C·cm 2 /W It may be in the range of 0.060 to 0.075°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加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下であり、０．０８℃・ｃｍ２／Ｗ以下であってもよく、０．０７℃・ｃｍ２／Ｗ以下であってもよく、０．０６℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗の下限値は、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０．０３℃・ｃｍ２／Ｗ以上となり得るし、０．０５℃・ｃｍ２／Ｗ以上ともなり得る。熱伝導性シート１は、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が、０．０３９～０．０９３℃・ｃｍ２／Ｗの範囲であってもよく、０．０５５～０．０７５℃・ｃｍ２／Ｗの範囲であってもよく、０．０５５～０．０７３℃・ｃｍ２／Ｗの範囲であってもよく、０．０５５～０．０７０℃・ｃｍ２／Ｗの範囲であってもよく、０．０５５～０．０６９℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 has a contact thermal resistance of 0.10° C.cm 2 /W or less when 2.1 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.08° C.cm 2 /W. It may be below W, may be below 0.07°C·cm 2 /W, and may be below 0.06°C·cm 2 /W. The lower limit of the contact thermal resistance of the thermally conductive sheet 1 when pressurized with 2.1 kgf/cm 2 is not particularly limited, and is preferably a lower value, exceeding 0° C.cm 2 /W, for example 0 It can be .03°C·cm 2 /W or more, or it can be 0.05°C·cm 2 /W or more. The thermally conductive sheet 1 may have a contact thermal resistance when pressurized with 2.1 kgf/cm 2 in the range of 0.039 to 0.093° C.cm 2 /W, or 0.055 to 0.075. It may be in the range of °C·cm 2 /W, it may be in the range of 0.055 to 0.073 °C·cm 2 /W, it may be in the range of 0.055 to 0.070 °C·cm 2 /W It may be in the range of 0.055 to 0.069°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加圧時の接触熱抵抗が０．０７２℃・ｃｍ２／Ｗ以下であってもよく、０．０６５℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の２．８ｋｇｆ／ｃｍ２加圧時の接触熱抵抗の下限値は、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０．０４℃・ｃｍ２／Ｗ以上となり得る。熱伝導性シート１は、例えば、２．８ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．０５２～０．０７２℃・ｃｍ２／Ｗの範囲であってもよく、０．０５２～０．０７１℃・ｃｍ２／Ｗの範囲であってもよく、０．０５２～０．０６５℃・ｃｍ２／Ｗの範囲であってもよく、０．０５２～０．０６４℃・ｃｍ２／Ｗの範囲であってもよく、０．０５２～０．０６１℃・ｃｍ２／Ｗの範囲であってもよく、０．０５２～０．０５４℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 may have a contact thermal resistance of 0.072°C·cm 2 /W or less when 2.8 kgf/cm 2 is applied, measured according to ASTM-D5470, and may have a contact thermal resistance of 0.065°C·cm 2 /W or less. It may be less than cm 2 /W. The lower limit of the contact thermal resistance 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 0 It can be .04° C.cm 2 /W or more. The thermally conductive sheet 1 may have a contact thermal resistance of 0.052 to 0.072° C.cm 2 /W when pressurized with 2.8 kgf/cm 2 , for example, and may have a contact thermal resistance of 0.052 to 0.072° C.cm 2 /W. It may be in the range of 0.071°C.cm 2 /W, it may be in the range of 0.052 to 0.065°C.cm 2 /W, it may be in the range of 0.052 to 0.064°C.cm 2 /W. It may be in the range of 0.052 to 0.061°C·cm 2 /W, or may be in the range of 0.052 to 0.054°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加圧時の接触熱抵抗が０．０８６℃・ｃｍ２／Ｗ以下であってもよく、０．０６８℃・ｃｍ２／Ｗ以下であってもよく、０．０６２℃・ｃｍ２／Ｗ以下であってもよい。熱伝導性シート１の３．５ｋｇｆ／ｃｍ２加圧時の接触熱抵抗の下限値は、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０．０２℃・ｃｍ２／Ｗ以上となり得るし、０．０４℃・ｃｍ２／Ｗ以上ともなり得る。熱伝導性シート１は、例えば、３．５ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．０２４～０．０８６℃・ｃｍ２／Ｗの範囲であってもよく、０．０４５～０．０６８℃・ｃｍ２／Ｗの範囲であってもよく、０．０４５～０．０６２℃・ｃｍ２／Ｗの範囲であってもよく、０．０４５～０．０６０℃・ｃｍ２／Ｗの範囲であってもよく、０．０４５～０．０５１℃・ｃｍ２／Ｗの範囲であってもよい。 The thermally conductive sheet 1 may have a contact thermal resistance of 0.086° C.cm 2 /W or less when 3.5 kgf/cm 2 is applied, measured according to ASTM-D5470, and 0.068° C. cm 2 /W or less, or 0.062° C.cm 2 /W or less. The lower limit of the contact thermal resistance 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 0 It can be .02°C·cm 2 /W or more, or it can be 0.04°C·cm 2 /W or more. The thermally conductive sheet 1 may have a contact thermal resistance of, for example, 0.024 to 0.086° C.cm 2 /W when pressurized with 3.5 kgf/cm 2 , or 0.045 to 0.086° C.cm 2 /W. It may be in the range of 0.068°C.cm 2 /W, it may be in the range of 0.045 to 0.062°C.cm 2 /W, it may be in the range of 0.045 to 0.060°C.cm 2 /W. It may be within a range of 0.045 to 0.051° 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。研磨残渣５は、例えば、バインダ樹脂２、繊維状フィラー３及び他の熱伝導性フィラー４を含む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の突出山部の平均高さＳｐｋが３μｍ以下であって、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下が得られやすい傾向にある。 FIG. 2 is a cross-sectional view showing an example of the surface of the thermally conductive sheet 1. As shown in FIG. 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. The polishing residue 5 is, for example, a lump made of a thermally conductive composition containing a binder resin 2, a fibrous filler 3, and another thermally conductive 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 as described above, the average height Spk of the protruding peaks of the thermally conductive sheet 1 can be made smoother. is 3 μm or less, and contact thermal resistances of 0.10° C.cm 2 /W or less when pressurized at 1.4 kgf/cm 2 and 2.1 kgf/cm 2 tend to be obtained.
　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の突出山部の平均高さＳｐｋが３μｍ以下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。 The thermally conductive sheet 1 having polishing residue 5 means that the polishing residue 5 is present on the surface of the thermally conductive sheet 1 to such an extent that the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 μm or less. is preferable, and for example, it may have polishing residue 5 almost uniformly over the entire surface, or it may have polishing residue 5 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の突出山部の平均高さＳｐｋを３μｍ以下とし、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗を０．１０℃・ｃｍ２／Ｗ以下とするためには、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, as described above, the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 μm or less, and when a pressure of 1.4 kgf/cm 2 is applied, and when a pressure of 2.1 kgf/cm 2 is applied. In order to keep the contact thermal resistance at 0.10° C.cm 2 /W or less, it is preferable that the average particle size and maximum particle size 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、繊維状フィラー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の突出山部の平均高さＳｐｋを所定値以下とすることにより、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 setting the average height Spk of the protruding peaks of the thermally conductive sheet 1 to a predetermined value or less for the thermally conductive sheet 1 in which the fibrous filler 3 is oriented in the thickness direction. 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、繊維状フィラー３と、他の熱伝導性フィラー４について説明する。 Next, the binder resin 2, fibrous filler 3, and other thermally conductive 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、繊維状フィラー３と他の熱伝導性フィラー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 fibrous filler 3 and other thermally conductive 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、硬化触媒を含む主剤と、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. The silicone resin is, for example, a two-component addition type, which is mainly composed of silicone (polyorganosiloxane) having an alkenyl group, a main resin containing a curing catalyst, and a curing agent having a hydrosilyl group (Si-H group). Reactive 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 a mixing ratio 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％以上であってもよく、３４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、２４～３５体積％の範囲であってもよいし、２４～３２体積％の範囲であってもよい。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, or more than 34% 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 may be, for example, in the range of 24 to 35% by volume, or may be in the range of 24 to 32% 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.
　＜繊維状フィラー＞
　繊維状フィラー３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、繊維状の熱伝導性フィラーとして、炭素繊維を用いた場合を例に挙げて詳述する。繊維状フィラー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。繊維状フィラー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。 <Fibrous filler>
The fibrous filler 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. Below, the case where carbon fiber is used as a fibrous thermally conductive filler will be described in detail as an example. The fibrous filler 3 has 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 long axis length / average short axis length) exceeds 1. including. The fibrous filler 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.
　繊維状フィラー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、繊維状フィラー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。繊維状フィラー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。繊維状フィラー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 fibrous filler 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 fibrous filler 3 can be appropriately selected depending on the purpose, and can be, for example, 4 to 20 μm, or may be 5 to 14 μm. The aspect ratio of the fibrous filler 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 fibrous filler 3 can be measured using, for example, a microscope or a scanning electron microscope (SEM).
　熱伝導性シート１中の繊維状フィラー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中の繊維状フィラー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％以下であってもよく、２６体積％以下であってもよく、２０体積％以下であってもよく、１８体積％以下であってもよい。熱伝導性シート１中の繊維状フィラー３の含有量は、例えば、１４～２８体積％の範囲であってもよく、１４～２６体積％の範囲であってもよい。２種以上の繊維状フィラー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 fibrous filler 3 in the thermally conductive sheet 1 can be, for example, 5% by volume or more, and may be 10% by volume or more. , may be 14 volume% or more, may be 20 volume% or more, may be 22 volume% or more, may be 24 volume% or more, or may be 26 volume% or more. . Further, from the viewpoint of formability of the thermally conductive sheet 1, the content of the fibrous filler 3 in the thermally conductive sheet 1 can be, for example, 30% by volume or less, and even if it is 28% by volume or less. Generally, it may be 26% by volume or less, 20% by volume or less, or 18% by volume or less. The content of the fibrous filler 3 in the thermally conductive sheet 1 may be, for example, in the range of 14 to 28% by volume, or may be in the range of 14 to 26% by volume. When using two or more types of fibrous fillers 3, it is preferable that the total amount thereof satisfies the above-mentioned content.
　＜他の熱伝導性フィラー＞
　他の熱伝導性フィラー４は、繊維状フィラー３以外の熱伝導性フィラーである。他の熱伝導性フィラー４には、例えば、球状、粉末状、顆粒状、鱗片状などの熱伝導性フィラーが含まれる。他の熱伝導性フィラー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、無機フィラーが挙げられ、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。他の熱伝導性フィラー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、他の熱伝導性フィラー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。 <Other thermally conductive fillers>
The other thermally conductive filler 4 is a thermally conductive filler other than the fibrous filler 3. Other thermally conductive fillers 4 include, for example, spherical, powdery, granular, scale-like, and other thermally conductive fillers. From the viewpoint of thermal conductivity of the thermally conductive sheet 1, the material of the other thermally conductive filler 4 includes, for example, an inorganic filler, preferably a ceramic filler, and specific examples include aluminum oxide (alumina, sapphire), Examples include aluminum nitride, aluminum, aluminum hydroxide, and boron nitride. The other thermally conductive fillers 4 may be used alone or in combination of two or more. For example, as the other thermally conductive filler 4, two or more types of thermally conductive fillers having different average particle diameters may be used in combination.
　特に、他の熱伝導性フィラー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、アルミニウム及び水酸化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、他の熱伝導性フィラー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く、水酸化アルミニウムを単独で使用してもよい。 In particular, other thermally conductive fillers 4 are selected from aluminum oxide, aluminum nitride, aluminum, and aluminum hydroxide, 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 at least one kind is selected. For example, as the other thermally conductive filler 4, aluminum oxide and aluminum nitride may be used together, aluminum oxide, aluminum nitride and aluminum may be used together, or aluminum hydroxide may be used alone. good.
　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。水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。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 hydroxide may be in the range of 0.1 to 10 μm, 0.5 to 5 μm, or 0.5 μm in terms of the specific gravity of the thermally conductive sheet 1, for example. 3 μm, or 0.5 to 2 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中の他の熱伝導性フィラー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中における他の熱伝導性フィラー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中の他の熱伝導性フィラー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％以下とすることができ、４９体積％以下とすることができ、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中における他の熱伝導性フィラー４の含有量は、例えば、３９～５０体積％の範囲であってもよく、３９～４９体積％の範囲であってもよい。 The content of other thermally conductive fillers 4 in the thermally conductive sheet 1 can be appropriately selected depending on the purpose. The content of the other thermally conductive filler 4 in the thermally conductive sheet 1 may be, for example, 10% by volume or more, may be 15% by volume or more, or may be 20% by volume or more. , may be 25 volume% or more, may be 30 volume% or more, may be 35 volume% or more, may be 39 volume% or more, may be 45 volume% or more. . Further, the upper limit of the content of the other thermally conductive filler 4 in the thermally conductive sheet 1 can be, for example, 55% by volume or less, 50% by volume or less, and 49% by volume or less. The content may be 45% by volume or less, or may be 40% by volume or less. The content of the other thermally conductive filler 4 in the thermally conductive sheet 1 may be in the range of 39 to 50% by volume, or may be in the range of 39 to 49% by volume, for example.
　他の熱伝導性フィラー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１５～３５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る。また、他の熱伝導性フィラー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 using aluminum oxide and aluminum nitride together as the other thermally conductive filler 4, the content of aluminum nitride in the thermally conductive sheet 1 is in the range of 15 to 35% by volume, and the content of aluminum oxide is in the range of 15 to 35% by volume. It can range from 5 to 25% by volume. In addition, when using aluminum oxide, aluminum nitride, and aluminum together as other thermally conductive filler 4, for example, the content of aluminum nitride in the thermally conductive sheet 1 should be in the range of 10 to 30% by volume, and aluminum oxide The content of aluminum can be in the range of 1 to 20% by volume, and the content of aluminum 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んでもよい。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、繊維状フィラー３及び他の熱伝導性フィラー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繊維状フィラー３及び／又はカップリング剤で処理した他の熱伝導性フィラー４を用いてもよい。 <Other ingredients>
The thermally conductive sheet 1 may further contain other components other than the above-mentioned components 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 fibrous filler 3 and other thermally conductive fillers 4, the thermally conductive sheet 1 may be treated with a fibrous filler 3 treated with a coupling agent and/or a coupling agent. Other thermally conductive fillers 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.
　＜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、繊維状フィラー３と、繊維状フィラー３以外の他の熱伝導性フィラー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することにより、熱伝導性組成物の成型体を得る。 <Process A>
In step A, a thermally conductive composition containing a binder resin 2, a fibrous filler 3, and a thermally conductive filler 4 other than the fibrous filler 3 is molded into a predetermined shape and cured. A molded body of the conductive composition is obtained.
　工程Ａの一例では、まず、繊維状フィラー３と他の熱伝導性フィラー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、繊維状フィラー３と、他の熱伝導性フィラー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、繊維状フィラー３と、他の熱伝導性フィラー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, by dispersing the fibrous filler 3 and other thermally conductive filler 4 into the binder resin 2, the binder resin 2, the fibrous filler 3, and the other thermally conductive filler 4 are combined. A thermally conductive composition containing the following is produced. The thermally conductive composition is prepared by uniformly mixing the binder resin 2, the fibrous filler 3, the other thermally conductive filler 4, and other components mentioned above as needed by a known method. Can be prepared.
　続いて、調製した熱伝導性組成物を押出成形した後硬化し、柱状の硬化物（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繊維状フィラー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 prepared thermally conductive composition is extruded and then cured to obtain a columnar cured product (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 the thermally conductive composition from a die, the binder resin 2 in the thermally conductive composition flows, and the fibrous filler 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組成物の成型体をシート状に切断し、成型体シートを得る。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成形体シートを得る。工程Ｂで得られる成形体シートの表面（切断面）には、繊維状フィラー３が露出する。成形体の切断方法は、特に制限されず、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。成形体を得る際に押出成形法を採用する場合、押出し方向に繊維状フィラー３が配向しているものもあるため、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。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 molded body of the thermally conductive composition obtained in step A is cut into sheets to obtain molded sheets. 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 molded sheet. The fibrous filler 3 is exposed on the surface (cut surface) of the molded sheet obtained in step B. The method for cutting the molded body is not particularly limited, and can be appropriately selected from known slicing devices depending on the size and mechanical strength of the molded body. When extrusion molding is used to obtain a molded product, the fibrous filler 3 may be oriented in the extrusion direction, so the cutting direction of the molded product is 60 to 120 degrees to the extrusion direction. The direction is preferably 70 to 100 degrees, and even more preferably 90 degrees (substantially perpendicular). The cutting direction of the molded body is not particularly limited other than the above, and can be appropriately selected depending on the purpose of use of the thermally conductive sheet 1 and the like.
　＜工程Ｃ＞
　通常、工程Ｂで得られる成形体シートは、表面に凹凸が存在する。例えば、工程Ｂで得られる成形体シートは、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で得られる成形体シートは、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３μｍ超である。表面にこのような凹凸が存在する成形体シートを用いると、成形体シートと被着体との間にエアーが混入しやすくなり、成形体シート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 molded sheet obtained in step B has irregularities on its surface. For example, as shown in FIG. 2, the molded sheet 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 molded sheet obtained in step B usually has an average height Spk of the protruding peaks measured according to ISO 25178 of more than 3 μm. When using a molded sheet with such irregularities on its surface, air tends to get mixed in between the molded sheet and the adherend, making it difficult to reduce the contact thermal resistance of the molded sheet. .
　そこで、工程Ｃでは、工程Ｂで得られた成形体シートを研磨することにより、成形体シートの表面の凸部１ａから削り出たバインダ樹脂２、繊維状フィラー３及び他の熱伝導性フィラー４によって成形体シート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の突出山部の平均高さＳｐｋを３μｍ以下とすることができ、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の突出山部の平均高さＳｐｋの低減が促進されやすくなり、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できると考えられる。 Therefore, in step C, by polishing the molded sheet obtained in step B, binder resin 2, fibrous filler 3, and other thermally conductive filler 4 are removed from the convex portions 1a on the surface of the molded sheet. As a result, the concave portions on the surface of the formed sheet are covered (in other words, the polishing residue 5 scraped from the convex portions 1a remains in the concave portions), so that the average height Spk of the protruding peaks of the thermally conductive sheet 1 is reduced to 3 μm. The contact area between the thermally conductive sheet 1 and the adherend can be improved, suppressing the mixing of air between the thermally conductive sheet 1 and the adherend, and improving the thermal conductivity. The contact thermal resistance of the sheet 1 can be reduced. In addition to this, by coating the surface of the thermally conductive sheet 1 with the bled binder resin 2, the reduction in the average height Spk of the protruding peaks of the thermally conductive sheet 1 is facilitated, and the thermal conduction The contact area between the thermally conductive sheet 1 and the adherend is further improved, and the mixture of air between the thermally conductive sheet 1 and the adherend is more effectively suppressed, and the contact heat of the thermally conductive sheet 1 is reduced. It is believed that the resistance can be further reduced.
　工程Ｃでは、例えば、工程Ｂで得られた成形体シートを研磨部材で研磨する。研磨部材としては、例えば、成形体シート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、ブラシなどが挙げられ、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成形体シート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、成形体シートの表面の凸部１ａから削り出たバインダ樹脂２、繊維状フィラー３及び他の熱伝導性フィラー４によって成形体シートの表面の凹部をより効率的に被覆できる。 In step C, for example, the molded sheet obtained in step B 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 molded sheet for polishing. Examples of such abrasive members include sandpaper, wrapping films, brushes, etc., and 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 molded sheet, the binder resin 2, fibrous filler 3, and others are scraped out from the convex portions 1a on the surface of the molded sheet. The heat conductive filler 4 can more efficiently cover the recesses on the surface of the molded sheet.
　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、研磨する成形体シート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 molded sheet 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、ナイロンが挙げられる。 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 resilience, etc., nylon can be used.
　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、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、多いほど成形体シートの表面の凸部１ａから削り出たバインダ樹脂２、繊維状フィラー３及び他の熱伝導性フィラー４によって成形体シート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、成形体シート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. It is believed that the greater the number of times of polishing, the easier it is for the concave portions on the surface of the molded sheet 9 to be covered by the binder resin 2, fibrous filler 3, and other thermally conductive filler 4 scraped out from the convex portions 1a on the surface of the molded sheet. 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 is defined as one time of polishing in one direction from one end side 9A to the other end side 9B of the surface of the molded sheet 9 in FIG. 4, for example.
　工程Ｃで得られる熱伝導性シート１は、上述のように、成形体シートの表面に存在していた凸部１ａが研磨部材で研磨されたことにより発生した研磨残渣５を有する。このように、熱伝導性シート１は、表面に研磨残渣５を有することによって、上述した物性、すなわち、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３μｍ以下であり、ＡＳＴＭ－Ｄ５４７０に従って測定される１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下であることを満たしやすい傾向にある。 As described above, the thermally conductive sheet 1 obtained in step C has polishing residue 5 generated by polishing the convex portions 1a existing on the surface of the molded sheet with a polishing member. As described above, by having the polishing residue 5 on the surface, the thermally conductive sheet 1 has the above-mentioned physical properties, that is, the average height Spk of the protruding peaks measured according to ISO 25178 is 3 μm or less, and the ASTM-D5470 The contact thermal resistance when pressurized with 1.4 kgf/cm 2 and when pressurized with 2.1 kgf/cm 2 is 0.10° C.cm 2 /W or less, which is measured according to the standard, tends to be easily satisfied.
　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成形体シート９を研磨した場合でも、ＩＳＯ　２５１７８に従って測定される熱伝導性シート１の突出山部の平均高さＳｐｋを３μｍ以下とし、熱伝導性シート１の接触熱抵抗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の突出山部の平均高さＳｐｋを３μｍ以下にすることができるため、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 molded sheet 9 is polished using a polishing member having the same roughness in step C, the protruding peaks of the thermally conductive sheet 1 measured according to ISO 25178 By setting the average height Spk of 3 μm or less, the contact thermal resistance of the thermally conductive sheet 1 can be reduced. In this way, in the method for manufacturing the thermally conductive sheet 1, the average height of the protruding peaks of the thermally conductive sheet 1 can be improved in polishing in step C without using two or more types of polishing members with different abrasive grain sizes. Since the thickness Spk can be reduced to 3 μm or less, 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で得られた成形体シート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でプレスした成形体シート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。プレスする工程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 molded sheet 9 obtained in step B, and in step C, The thermally conductive sheet 1 may be obtained by polishing the surface of the molded sheet 9 pressed in step D. By further including the pressing step D, the surface of the resulting thermally conductive sheet 1 can be made smoother, and its 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 heating element and a heat radiating element to allow the heat generated by the heating element to escape 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の突出山部の平均高さＳｐｋが３μｍ以下であるため、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るため、低荷重（低加圧）時の接触熱抵抗をより効果的に低減できる。 In particular, in electronic devices to which the thermally conductive sheet 1 is applied, since the average height Spk of the protruding peaks of the thermally conductive sheet 1 is 3 μm or less, as described above, the thermally conductive sheet 1 and the adherend are The contact area with a certain heating element or heat radiating element is increased, and air is prevented from entering between the thermally conductive sheet 1 and the adherend, so the contact heat during low load (low pressurization) is reduced. Resistance can be reduced more effectively.
　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０．２ｍｍ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成形体シートを得た。この成形体シートの表面の両表面につき、片面ずつ、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４００回擦り、熱伝導性シートを得た。このように、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、表面に研磨残渣を有していた。 <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 sheet with a thickness of 0.2 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 0.2 mm. A molded sheet oriented in the direction was obtained. Both surfaces of this molded sheet were rubbed 400 times in one direction from one end to the other with a #4000 wrapping film (manufactured by 3M) having a thickness of about 100 μm. A thermally conductive sheet was obtained. Thus, the thermally conductive sheet obtained in Example 1 had a polished surface and had polishing residue on the surface.
　＜実施例２＞
　熱伝導性シートの厚みを０．３ｍｍに変更したこと以外は、実施例１と同様に成形体シートの表面を研磨した熱伝導性シートを得た。このように、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、表面に研磨残渣を有していた。 <Example 2>
A thermally conductive sheet was obtained by polishing the surface of a molded sheet in the same manner as in Example 1, except that the thickness of the thermally conductive sheet was changed to 0.3 mm. Thus, the thermally conductive sheet obtained in Example 2 had a polished surface and had polishing residue on the surface.
　＜実施例３＞
　熱伝導性シートの厚みを０．５ｍｍに変更したこと以外は、実施例１と同様に成形体シートの表面を研磨した熱伝導性シートを得た。このように、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、表面に研磨残渣を有していた。 <Example 3>
A thermally conductive sheet was obtained by polishing the surface of a molded sheet in the same manner as in Example 1, except that the thickness of the thermally conductive sheet was changed to 0.5 mm. Thus, the thermally conductive sheet obtained in Example 3 had a polished surface and had polishing residue on the surface.
　＜実施例４＞
　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、炭素繊維がシートの厚み方向に配向した成形体シートを得た。この成形体シートの両表面につき、片面ずつ、表面の一端側から他端側にわたって一方向に、表面を４０００番（＃４０００）のラッピングフィルム（３Ｍ社製）により１００回擦り、熱伝導性シートを得た。このように、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、表面に研磨残渣を有していた。 <Example 4>
24% by volume of silicone resin, 10% by volume of aluminum oxide (average particle diameter: approximately 2 μm), 20% by volume of aluminum nitride (average particle diameter: approximately 1 μm), and 19% by volume of aluminum (average particle diameter: approximately 6 μm). A thermally conductive composition was prepared by uniformly mixing 26% by volume of carbon fibers (average fiber length: about 150 μm) 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 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 molded sheet oriented in the direction was obtained. Both surfaces of this molded sheet were rubbed 100 times in one direction from one end of the surface to the other end with a #4000 wrapping film (manufactured by 3M) to form a thermally conductive sheet. I got it. Thus, the thermally conductive sheet obtained in Example 4 had a polished surface and had polishing residue on the surface.
　＜実施例５＞
　シリコーン樹脂３５体積％と、水酸化アルミニウム（平均粒子径：約１μｍ）５０体積％と、炭素繊維（平均繊維長：約１５０μｍ）１４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、炭素繊維がシートの厚み方向に配向した成形体シートを得た。この成形体シートの両表面につき、片面ずつ、表面を４０００番（＃４０００）のラッピングフィルム（３Ｍ社製）により４００回擦り、熱伝導性シートを得た。このように、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、表面に研磨残渣を有していた。 <Example 5>
Uniformly mix 35% by volume of silicone resin, 50% by volume of aluminum hydroxide (average particle diameter: approximately 1 μm), 14% by volume of carbon fiber (average fiber length: approximately 150 μm), and 1% by volume of coupling agent. A thermally conductive composition was prepared. 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 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 molded sheet oriented in the direction was obtained. Both surfaces of this molded sheet were rubbed 400 times with a No. 4000 (#4000) wrapping film (manufactured by 3M Company) to obtain a thermally conductive sheet. Thus, the thermally conductive sheet obtained in Example 5 had a polished surface and had polishing residue 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成形体シートを得た。この成形体シートの両表面につき、片面ずつ、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回擦り、熱伝導性シートを得た。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 molded sheet oriented in the direction was obtained. Both surfaces of this molded sheet were rubbed 200 times in one direction from one end of the surface to the other with a #4000 wrapping film (manufactured by 3M) having a thickness of about 100 μm. A thermally conductive sheet was obtained. Thus, the thermally conductive sheet obtained in Example 6 had a polished surface and had polishing residue on the surface.
　＜実施例７＞
　成形体シートの厚みを２．０ｍｍ厚に変更したこと以外は、実施例６と同様に成形体シートの表面を研磨した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>
A thermally conductive sheet was obtained by polishing the surface of the molded sheet in the same manner as in Example 6, except that the thickness of the molded sheet was changed to 2.0 mm. 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２と同様の方法で得られた、炭素繊維がシートの厚み方向に配向した成形体シートをプレスした。このように、比較例１では、柱状の硬化物を０．３ｍｍ厚にスライスした成形体シートの表面をラッピングフィルムで研磨せずにプレスを行った。そのため、比較例１で得られた成形体シートは、表面に研磨残渣を有していなかった。 <Comparative example 1>
In Comparative Example 1, a molded sheet obtained in the same manner as in Example 2 in which carbon fibers were oriented in the thickness direction of the sheet was pressed. Thus, in Comparative Example 1, the surface of a molded sheet obtained by slicing a columnar cured product into 0.3 mm thick sheets was pressed with a wrapping film without polishing it. Therefore, the molded sheet obtained in Comparative Example 1 did not have any polishing residue on its surface.
　＜比較例２＞
　比較例２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成形体シートを得た。このように、比較例２では、柱状の硬化物を０．３ｍｍ厚にスライスした後に、成形体シートの表面をラッピングフィルムで研磨しなかった。そのため、比較例２で得られた成形体シートは、表面に研磨残渣を有していなかった。 <Comparative example 2>
In Comparative Example 2, a composition in which 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 molded sheet oriented in the direction was obtained. Thus, in Comparative Example 2, after slicing the columnar cured product into 0.3 mm thick slices, the surface of the molded sheet was not polished with a wrapping film. Therefore, the molded sheet obtained in Comparative Example 2 did not have any polishing residue on its surface.
　＜比較例３＞
　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成形体シートを得た。このように、比較例３では、柱状の硬化物を１．０ｍｍ厚にスライスした後に、成形体シートの表面をラッピングフィルムで研磨しなかった。そのため、比較例３で得られた成形体シートは、表面に研磨残渣を有していなかった。 <Comparative example 3>
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 molded sheet oriented in the direction was obtained. Thus, in Comparative Example 3, after slicing the columnar cured product into 1.0 mm thick slices, the surface of the molded sheet was not polished with a wrapping film. Therefore, the molded sheet obtained in Comparative Example 3 did not have any polishing residue on its surface.
　＜比較例４＞
　柱状の硬化物をシート状に切断（スライス）する際の厚みを２．０ｍｍ厚としたほかは、比較例３と同様に成形体シートを得た。このように、比較例４では、柱状の硬化物を２．０ｍｍ厚にスライスした後に、成形体シートの表面をラッピングフィルムで研磨しなかった。そのため、比較例４で得られた成形体シートは、表面に研磨残渣を有していなかった。 <Comparative example 4>
A molded product sheet was obtained in the same manner as in Comparative Example 3, except that the thickness when cutting (slicing) the columnar cured product into sheet shapes was 2.0 mm. Thus, in Comparative Example 4, after slicing the columnar cured product into 2.0 mm thick slices, the surface of the molded sheet was not polished with a wrapping film. Therefore, the molded sheet obtained in Comparative Example 4 did not have any polishing residue on its surface.
　＜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と、各比較例で得られた成形体シート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（成形体シート）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（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 property parameters of the thermally conductive sheets obtained in each example and the molded sheets obtained in each comparative example were measured. Specifically, the average height Spk (μm) of the protruding peaks of the thermally conductive sheet (molded body sheet), the average depth Svk (μm) of the protruding valleys, and the volume Vmp (ml/m 2 ) of the protruding peaks ), the root mean square gradient Sdq, the arithmetic mean curvature of the peak Spc (1/mm), and the developed area ratio Sdr (%) of the interface were measured. These were measured in accordance with ISO 25178 using a scanning white interference microscope (Nano 3D optical interference measurement system, device name: VS-1800, manufactured by Hitachi High-Tech Corporation, measurement mode: wave mode). 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.
　＜接触熱抵抗＞
　各実施例で得られた熱伝導性シートと、各比較例で得られた成形体シートについて、ＡＳＴＭ－Ｄ５４７０に従って測定される、所定の加圧時（１．４ｋｇｆ／ｃｍ２加圧時、２．１ｋｇｆ／ｃｍ２加圧時、２．８ｋｇｆ／ｃｍ２加圧時、３．５ｋｇｆ／ｃｍ２加圧時）の総熱抵抗値［℃・ｃｍ２／Ｗ］からバルク熱抵抗［℃・ｃｍ２／Ｗ］を差し引くことで接触熱抵抗［℃・ｃｍ２／Ｗ］を求めた。前記の測定において、直接測定されるのが総熱抵抗値である。接触熱抵抗の算出時に使用する式を下記の式Ａ、式Ｂに示す。なお、総熱抵抗の測定は、ＡＳＴＭ－Ｄ５４７０に準拠した熱抵抗測定装置（デクセリアルズ株式会社製）を用いて行った。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。 <Contact thermal resistance>
The thermally conductive sheet obtained in each Example and the molded sheet obtained in each Comparative Example were measured in accordance with ASTM-D5470 at a predetermined pressure (1.4 kgf/cm 2 pressure, 2 Bulk thermal resistance [℃・cm 2 /W] is calculated from the total thermal resistance value [℃・cm 2 / W ] of The contact thermal resistance [°C·cm 2 /W] was determined by subtracting 2 /W]. In the above measurements, what is directly measured is the total thermal resistance value. The formulas used to calculate the contact thermal resistance are shown in the following formulas A and B. The total thermal resistance was measured using a thermal resistance measuring device (manufactured by Dexerials Co., Ltd.) compliant with 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.
式Ａ：接触熱抵抗［℃・ｃｍ２／Ｗ］＝総熱抵抗値［℃・ｃｍ２／Ｗ］―バルク熱抵抗［℃・ｃｍ２／Ｗ］
式Ｂ：バルク熱抵抗［℃・ｃｍ２／Ｗ］＝シート厚み［ｍ］／バルク熱伝導率［Ｗ／（ｍ・Ｋ）］＝１０－４×℃・ｍ２／Ｗ Formula A: Contact thermal resistance [℃・cm 2 /W] = Total thermal resistance value [℃・cm 2 /W] - Bulk thermal resistance [℃・cm 2 /W]
Formula B: Bulk thermal resistance [℃・cm 2 /W] = Sheet thickness [m] / Bulk thermal conductivity [W/(m・K)] = 10 -4 ×℃・m 2 /W
　バルク熱伝導率［Ｗ／（ｍ・Ｋ）］は、各実施例で得られた熱伝導性シートと、各比較例で得られた成形体シートについて、シート厚みを０．５ｍｍ、１．０ｍｍ、１．５ｍｍにそれぞれ変更したものを作製し、各シートの初期厚みから４～１２％圧縮したときの厚み［ｍｍ］を横軸に、シートの初期厚みから４～１２％圧縮したときの総熱抵抗値［℃・ｃｍ２／Ｗ］を縦軸にして、得られたデータをプロットし、近似直線の傾きの逆数から算出した。ここで、総熱抵抗値は、ＡＳＴＭ　Ｄ５４７０に準拠して測定された、バルク熱抵抗値と接触熱抵抗値の合計の熱抵抗値であり、バルク熱抵抗値は熱伝導シートそのものが有する熱抵抗値である。バルク熱伝導率［Ｗ／（ｍ・Ｋ）］は、測定における治具との接触などを考慮しない、熱伝導シートそのものが有する熱伝導率を示す。結果を表１に示す。 The bulk thermal conductivity [W/(m・K)] is determined for the thermally conductive sheet obtained in each example and the molded sheet obtained in each comparative example at a sheet thickness of 0.5 mm and 1.0 mm. , 1.5 mm respectively, and the horizontal axis is the thickness [mm] when compressed by 4 to 12% from the initial thickness of each sheet, and the total when compressed from 4 to 12% from the initial thickness of each sheet. The obtained data was plotted with the thermal resistance value [° C.cm 2 /W] as the vertical axis, and the data was calculated from the reciprocal of the slope of the approximate straight line. Here, the total thermal resistance value is the total thermal resistance value of the bulk thermal resistance value and the contact thermal resistance value measured in accordance with ASTM D5470, and the bulk thermal resistance value is the thermal resistance value of the thermal conductive sheet itself. It is a value. Bulk thermal conductivity [W/(m·K)] indicates the thermal conductivity of the thermally conductive sheet itself, without considering contact with a jig during measurement. The results are shown in Table 1.
　実施例１～７の結果から、バインダ樹脂と、繊維状フィラーと、繊維状フィラー以外の熱伝導性フィラー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、繊維状フィラーが熱伝導性シートの厚み方向に配向しており、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３μｍ以下であることにより、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下であることが分かった。 From the results of Examples 1 to 7, a thermally conductive sheet made of a cured product of a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler, The filler is oriented in the thickness direction of the thermally conductive sheet, and the average height Spk of the protruding peaks of the thermally conductive sheet measured according to ISO 25178 is 3 μm or less, as measured according to ASTM-D5470. It was found that the contact thermal resistance when applying a pressure of 1.4 kgf/cm 2 and when applying a pressure of 2.1 kgf/cm 2 was 0.10° C.cm 2 /W or less.
　また、実施例１～７で得られた熱伝導性シートは、ＡＳＴＭ－Ｄ５４７０に従って測定される２．８ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．０７２℃・ｃｍ２／Ｗ以下であることが分かった。 Furthermore, the thermally conductive sheets obtained in Examples 1 to 7 have a contact thermal resistance of 0.072° C.cm 2 /W or less when 2.8 kgf/cm 2 is applied, as measured in accordance with ASTM-D5470. That's what I found out.
　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、表面に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、炭素繊維及び他の熱伝導性フィラー（酸化アルミニウム、窒化アルミニウム、アルミニウム、水酸化アルミニウムなど）を含む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 polished surfaces and had polishing residues on the surfaces. This polishing residue was confirmed to be a lump containing silicone resin, carbon fiber, and other thermally conductive fillers (aluminum oxide, aluminum nitride, aluminum, aluminum hydroxide, etc.) caused by polishing.
　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、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 the arithmetic mean curvature Spc (1/mm) of the peak measured according to ISO 25178 and the developed area ratio Sdr (%) of the interface. It was found that when a graph was created in which the values were plotted with Spc on the horizontal axis and Sdr on the vertical axis, Spc and Sdr satisfied Equation 1 described above.
　比較例１，２で得られた成形体シートは、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３μｍ以下を満たさず、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下を満たさないことが分かった。また、比較例３，４で得られた成形体シートは、ＩＳＯ　２５１７８に従って測定される突出山部の平均高さＳｐｋが３μｍ以下を満たさないことが分かった。比較例１～４では、成形体シートを研磨部材（ラッピングフィルム）によって研磨しなかったため、成形体シートの表面には研磨残渣が残留しなかったことが原因と考えられる。 The molded sheets obtained in Comparative Examples 1 and 2 had an average height Spk of the protruding peaks measured according to ISO 25178 of less than 3 μm, and an average height Spk of 1.4 kgf/cm 2 measured according to ASTM-D5470. It was found that the contact thermal resistance under pressure and when 2.1 kgf/cm 2 was applied did not satisfy 0.10° C.cm 2 /W or less. Furthermore, it was found that the average height Spk of the protruding peaks measured according to ISO 25178 did not satisfy 3 μm or less in the molded sheets obtained in Comparative Examples 3 and 4. This is thought to be because in Comparative Examples 1 to 4, the molded sheet was not polished with a polishing member (wrapping film), so no polishing residue remained on the surface of the molded sheet.
　図７に示すように、比較例１～４で得られた成形体シートは、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を満たさない（式１中、０≦Ｘ≦２５００、かつ、０≦Ｙ≦２０を満たさない）ことが分かった。 As shown in FIG. 7, the molded sheets obtained in Comparative Examples 1 to 4 have the arithmetic mean curvature of the peak Spc (1/mm) measured according to ISO 25178 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 do not satisfy the above formula 1 (in formula 1, 0≦X≦2500 and 0≦Y ≦20).
１　熱伝導性シート、１ａ　凸部、２　バインダ樹脂、３　繊維状フィラー、４　他の熱伝導性フィラー、５　研磨残渣、６　ブラシ、７　基材、８　毛材、９　成形体シート、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 fibrous filler, 4 other thermally conductive filler, 5 polishing residue, 6 brush, 7 base material, 8 bristle material, 9 molded sheet, 10 conveyor, 50 Semiconductor device, 51 Electronic component, 52 Heat spreader, 52a Main surface, 52b Side wall, 52c Other surface, 53 Heat sink

Claims (13)

  1. 　バインダ樹脂と、繊維状フィラーと、上記繊維状フィラー以外の他の熱伝導性フィラー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、
    　上記繊維状フィラーが当該熱伝導性シートの厚み方向に配向しており、
    　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、当該熱伝導性シートの突出山部の平均高さＳｐｋが３μｍ以下であり、
    　ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ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 a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler,
    The fibrous filler is oriented in the thickness direction of the thermally conductive sheet,
    The average height Spk of the protruding peaks of the thermally conductive sheet is 3 μm or less, as measured in accordance with ISO 25178 using a scanning white interference microscope with a 20x objective lens;
    A thermally conductive sheet having a contact thermal resistance of 0.10° C. cm 2 /W or less when applying a pressure of 1.4 kgf/cm 2 and 2.1 kgf/cm 2 as measured according to ASTM-D5470. .
  2. 　ＡＳＴＭ－Ｄ５４７０に従って測定される、２．８ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．０７２℃・ｃｍ２／Ｗ以下である、請求項１に記載の熱伝導性シート。 The thermally conductive sheet according to claim 1, having a contact thermal resistance of 0.072° C.cm 2 /W or less when 2.8 kgf/cm 2 is applied, as measured in accordance with ASTM-D5470.
  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、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１又は２に記載の熱伝導性シート。
    式１：Ｙ＝０．０１５３Ｘ－（１５．５４７±１０）
    （式１中、０≦Ｘ≦２５００、かつ、０≦Ｙ≦２０である。）     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 1 or 2, 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=0.0153X-(15.547±10)
    (In formula 1, 0≦X≦2500 and 0≦Y≦20.)
  4. 　表面が研磨面である、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.
  5. 　表面に研磨残渣を有する、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, which has polishing residue on the surface.
  6. 　上記研磨残渣は、上記バインダ樹脂、上記繊維状フィラー及び上記他の熱伝導性フィラーを含む、請求項５に記載の熱伝導性シート。 The thermally conductive sheet according to claim 5, wherein the polishing residue includes the binder resin, the fibrous filler, and the other thermally conductive filler.
  7. 　上記繊維状フィラーが炭素繊維である、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 fibrous filler is carbon fiber.
  8. 　バインダ樹脂と、繊維状フィラーと、上記繊維状フィラー以外の他の熱伝導性フィラーとを含む熱伝導性組成物を所定の形状に成型して硬化することにより、上記熱伝導性組成物の成型体を得る工程と、
    　上記成型体をシート状に切断し、成型体シートを得る工程と、
    　上記成形体シートを研磨部材によって研磨することにより、熱伝導性シートを得る工程とを含み、
    　上記熱伝導性シートの表面には、上記研磨によって生じた、上記バインダ樹脂、上記繊維状フィラー及び上記他の熱伝導性フィラーを含む研磨残渣が残留する、熱伝導性シートの製造方法。     Molding the thermally conductive composition by molding a thermally conductive composition containing a binder resin, a fibrous filler, and a thermally conductive filler other than the fibrous filler into a predetermined shape and curing it. The process of obtaining a body,
    cutting the molded body into sheet shapes to obtain a molded body sheet;
    obtaining a thermally conductive sheet by polishing the molded sheet with a polishing member,
    A method for producing a thermally conductive sheet, wherein a polishing residue generated by the polishing and containing the binder resin, the fibrous filler, and the other thermally conductive filler remains on the surface of the thermally conductive sheet.
  9. 　上記研磨部材がラッピングフィルムである、請求項８に記載の熱伝導性シートの製造方法。 The method for manufacturing a thermally conductive sheet according to claim 8, wherein the polishing member is a wrapping film.
  10. 　上記研磨部材が、上記研磨する工程において同一の粗さを持つ研磨部材である、請求項８又は９に記載の熱伝導性シートの製造方法。 The method for manufacturing a thermally conductive sheet according to claim 8 or 9, wherein the polishing member is a polishing member having the same roughness in the polishing step.
  11. 　上記繊維状フィラーが炭素繊維である、請求項８又は９に記載の熱伝導性シートの製造方法。 The method for producing a thermally conductive sheet according to claim 8 or 9, wherein the fibrous filler is carbon fiber.
  12. 　上記繊維状フィラーが上記熱伝導性シートの厚み方向に配向している、請求項８又は９に記載の熱伝導性シートの製造方法。 The method for manufacturing a thermally conductive sheet according to claim 8 or 9, wherein the fibrous filler is oriented in the thickness direction of the thermally conductive sheet.
  13. 　上記熱伝導性シートは、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、突出山部の平均高さＳｐｋが３μｍ以下であり、ＡＳＴＭ－Ｄ５４７０に従って測定される、１．４ｋｇｆ／ｃｍ２加圧時と、２．１ｋｇｆ／ｃｍ２加圧時の接触熱抵抗が０．１０℃・ｃｍ２／Ｗ以下である、請求項８に記載の熱伝導性シートの製造方法。
          The thermally conductive sheet has an average height Spk of the protruding peaks of 3 μm or less, which is measured in accordance with ISO 25178 using a scanning white interference microscope with an objective lens set at a magnification of 20 times, and which is measured in accordance with ASTM-D5470. The thermally conductive sheet according to claim 8, wherein the thermally conductive sheet has a contact thermal resistance of 0.10° C.cm 2 /W or less when a pressure of 1.4 kgf/cm 2 is applied and when a pressure of 2.1 kgf/cm 2 is applied. manufacturing method.
PCT/JP2023/012900 2022-03-30 2023-03-29 Heat-conducting sheet and production method for heat-conducting sheet WO2023190726A1 (en)

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