WO2024018637A1 - Thermally conductive sheet, heat dissipation device, and method for producing thermally conductive sheet - Google Patents

Thermally conductive sheet, heat dissipation device, and method for producing thermally conductive sheet Download PDF

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Publication number
WO2024018637A1
WO2024018637A1 PCT/JP2022/028529 JP2022028529W WO2024018637A1 WO 2024018637 A1 WO2024018637 A1 WO 2024018637A1 JP 2022028529 W JP2022028529 W JP 2022028529W WO 2024018637 A1 WO2024018637 A1 WO 2024018637A1
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WO
WIPO (PCT)
Prior art keywords
thermally conductive
conductive sheet
heat
particles
adhesive layer
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PCT/JP2022/028529
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French (fr)
Japanese (ja)
Inventor
美香 小舩
リカルド ミゾグチ ゴルゴル
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株式会社レゾナック
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Priority to PCT/JP2022/028529 priority Critical patent/WO2024018637A1/en
Publication of WO2024018637A1 publication Critical patent/WO2024018637A1/en

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    • 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
    • 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
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon

Definitions

  • the present disclosure relates to a heat conductive sheet, a heat dissipation device, and a method for manufacturing a heat conductive sheet.
  • a heat dissipation device is generally conveniently used, which dissipates heat by sandwiching thermal conductive grease or a heat conductive sheet between a heat generating body such as a semiconductor package and a heat dissipating body such as aluminum or copper.
  • thermally conductive sheets are superior to thermally conductive grease in terms of workability when assembling a heat dissipation device.
  • Resin sheets filled with thermally conductive fillers are also known as thermally conductive sheets.
  • Various resin sheets have been proposed that are filled with thermally conductive fillers and have excellent thermal conductivity, in which highly thermally conductive inorganic particles are selected as the thermally conductive fillers, and the inorganic particles are oriented perpendicular to the sheet surface.
  • thermally conductive sheets in which thermally conductive fillers (boron nitride) are oriented in a direction substantially perpendicular to the sheet surface (for example, see Patent Document 1), and carbon fibers dispersed in a gel-like substance are oriented in a direction perpendicular to the sheet surface.
  • a thermally conductive sheet having an oriented structure has been proposed.
  • Patent Documents 1 and 2 consider a method of suppressing thermal resistance by orienting thermally conductive fillers, carbon fibers, etc. in a direction perpendicular to the sheet surface. In order to cope with the increase in heat generation due to the higher performance and larger size of semiconductors, it is desired to further reduce the thermal resistance of thermally conductive sheets. Therefore, it is preferable to aim at lowering the thermal resistance by considering methods other than the orientation of the thermally conductive filler, carbon fiber, etc. contained in the thermally conductive sheet.
  • An object of one aspect of the present invention is to provide a thermally conductive sheet with low thermal resistance, a heat dissipation device equipped with the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
  • ⁇ 1> Contains at least one type of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles, and rod-like particles, and in the case of the scale-like particles, in the plane direction, the ellipsoidal particles in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction; an adhesive layer containing a resin component and a thermally conductive filler and located on at least a portion of the main surface of the thermally conductive layer; A thermally conductive sheet with ⁇ 2> The thermally conductive sheet according to ⁇ 1>, wherein the resin component includes at least one selected from the group consisting of a curable resin component, an adhesive resin component, and a thermoplastic resin component.
  • the thermally conductive filler includes silver, aluminum oxide, aluminum hydroxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, aluminum fluoride, calcium fluoride, and zinc oxide.
  • thermoly conductive sheet according to any one of ⁇ 1> to ⁇ 5>, wherein the adhesive layer has an average thickness of 5 ⁇ m to 50 ⁇ m.
  • the adhesive layer is located on at least a portion of at least one of the main surface located on the heat generating body side and the main surface located on the heat radiating body side.
  • a method for manufacturing a thermally conductive sheet for manufacturing the thermally conductive sheet according to any one of ⁇ 1> to ⁇ 6> comprising: A step of preparing a composition containing the graphite particles (A), a step of forming the thermally conductive layer using the composition, and forming an adhesive layer on at least a portion of the main surface of the thermally conductive layer.
  • a method for manufacturing a thermally conductive sheet comprising the steps of:
  • thermoly conductive sheet with low thermal resistance a heat dissipation device including the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
  • FIG. 1 is a schematic configuration diagram of a thermally conductive sheet, which is an embodiment of the present invention.
  • FIG. 1 is a schematic cross-sectional view of a heat dissipation device according to an embodiment of the present invention, in which a heat generating body is a semiconductor chip and a heat dissipation body is a heat spreader.
  • FIG. 1 is a schematic configuration diagram of a heat conductive sheet incorporated in a heat dissipation device that is an embodiment of the present invention.
  • 2 is a diagram showing the state of the interface according to image analysis in Examples 1 to 2 and Comparative Example 1.
  • each component may contain multiple types of corresponding substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
  • each component may include a plurality of types of particles.
  • the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.
  • layer or film refers to the case where the layer or film is formed only in a part of the region, in addition to the case where the layer or film is formed in the entire region when observing the region where the layer or film is present. This also includes cases where it is formed.
  • laminate refers to stacking layers, and two or more layers may be bonded, or two or more layers may be removable.
  • the thermally conductive sheet of the present disclosure contains at least one graphite particle (A) selected from the group consisting of scale-like particles, ellipsoid-like particles, and rod-like particles, and in the case of the scale-like particles, in the planar direction; In the case of the ellipsoidal particles, the long axis direction is oriented in the thickness direction, and in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction. an adhesive layer located on at least a portion of the main surface of the heat conductive layer.
  • the thermally conductive sheet of the present disclosure is considered to have excellent thermal conductivity in the thickness direction and exhibit low thermal resistance because it includes a thermally conductive layer in which graphite particles (A) are oriented in the thickness direction.
  • the thermally conductive sheet exhibits lower thermal resistance by including the aforementioned adhesive layer together with the thermally conductive layer containing the graphite particles (A).
  • the reason for this is assumed to be as follows. Note that the present disclosure is not limited to the following speculations. In a thermally conductive sheet in which graphite particles (A) are oriented in the thickness direction, there are irregularities on the surface that contacts the adherend, and most of the thermal resistance is caused by contact between the thermally conductive sheet and the thermally conductive sheet. It originates from the resistance (also referred to as "contact thermal resistance") caused by gaps caused by contact with adherends such as heating elements and heat radiating elements.
  • the thermally conductive sheet of the present disclosure by disposing an adhesive layer containing a resin component and a thermally conductive filler on at least a part of the main surface of the thermally conductive layer, the thermally conductive sheet and the heating element, the heat radiating element, etc. are covered.
  • the adhesive layer softens, deforms, etc. due to heat, pressure, etc.
  • gaps that occur when the thermally conductive sheet and the adherend are bonded under heat and pressure are filled with the adhesive layer.
  • the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer while reducing the gap between the thermally conductive sheet and the adherend, so that the thermal contact resistance is significantly reduced.
  • thermally conductive sheet of the present disclosure the thermally conductive sheet and an adherend having irregularities on the surface can be brought into close contact via the adhesive layer.
  • the adhesive layer fills the gaps that occur when heat-pressing the thermally conductive sheet and the adherend (for example, gaps caused by unevenness of the adherend), significantly reducing contact thermal resistance. be done.
  • the thermally conductive layer included in the thermally conductive sheet of the present disclosure includes at least graphite particles (A), and may also include components described below within the range that produces the effects of the present disclosure.
  • the materials used for the thermally conductive layer of the present disclosure will be described below.
  • the thermally conductive layer included in the thermally conductive sheet contains graphite particles (A). It is believed that the graphite particles (A) primarily function as a highly thermally conductive filler.
  • the graphite particles (A) are at least one type selected from the group consisting of scaly particles, ellipsoidal particles, and rod-shaped particles.
  • the graphite particles (A) are oriented in the plane direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the thickness direction in the case of rod-like particles. .
  • the graphite particles (A) have six-membered ring planes in the crystal in the planar direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-like particles. is preferably oriented.
  • the six-membered ring plane is a plane in which a six-membered ring is formed in a hexagonal crystal system, and means a (0001) crystal plane.
  • the shape of the graphite particles (A) is more preferably scaly.
  • thermal conductivity tends to be further improved. This can be considered, for example, because the scale-like graphite particles are more easily oriented in a predetermined direction in the heat conductive layer.
  • the six-membered ring plane in the crystal of the graphite particle (A) is oriented in the plane direction of the scale-like particle, the long axis direction of the ellipsoidal particle, or the long axis direction of the rod-like particle can be determined by X-ray diffraction measurement. It can be confirmed. Specifically, the orientation direction of the six-membered ring plane in the crystal of the graphite particle (A) is confirmed by the following method.
  • a sample sheet for measurement is prepared in which the in-plane direction of the scale-like particles, the long-axis direction of the ellipsoidal particles, or the long-axis direction of the rod-like particles of the graphite particles (A) are oriented along the in-plane direction of the sheet.
  • the following method may be mentioned.
  • a mixture of a resin and graphite particles (A) in an amount of 10% by volume or more based on the resin is formed into a sheet.
  • the "resin” used here is not particularly limited as long as it is a material that does not exhibit peaks that interfere with X-ray diffraction and can be formed into a sheet.
  • an amorphous resin having cohesive strength as a binder can be used, such as acrylic rubber, NBR (acrylonitrile butadiene rubber), and SIBS (styrene-isobutylene-styrene copolymer).
  • a sheet of this mixture is pressed to a thickness of 1/10 or less of the original thickness, and a plurality of pressed sheets are laminated to form a laminate.
  • the operation of crushing this laminate to 1/10 or less is repeated three or more times to obtain a sample sheet for measurement.
  • the graphite particle (A) is a scale-like particle, the plane direction, if it is an ellipsoidal particle, the long axis direction, and if it is a rod-like particle, the long axis direction is , it is oriented along the surface direction of the sample sheet for measurement.
  • the value obtained by dividing H 1 by H 2 is 0 to 0.02.
  • the six-membered ring plane in the crystal of graphite particles (A) is in the plane direction in the case of scale-like particles, in the major axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-shaped particles.
  • X-ray diffraction measurements are performed under the following conditions.
  • Device For example, Bruker AXS Co., Ltd. “D8DISCOVER” X-ray source: CuK ⁇ with a wavelength of 1.5406 nm, 40 kV, 40 mA Step (measurement step width): 0.01° Step time: 720sec
  • the planar direction is oriented, in the case of ellipsoidal particles, the long axis direction is oriented, and in the case of rod-shaped particles, the long axis direction is oriented in the thickness direction of the thermally conductive layer.
  • "" means the direction between the surface (principal surface) of the thermally conductive layer and the surface direction (principal surface) of the thermally conductive layer. It means that the angle formed (hereinafter also referred to as "orientation angle”) is 60° or more.
  • the orientation angle is preferably 80° or more, more preferably 85° or more, and even more preferably 88° or more.
  • the orientation angle is determined by observing the cross section of the thermally conductive layer with a SEM (scanning electron microscope), and for any 50 graphite particles (A), the orientation angle is determined by the in-plane direction in the case of scaly particles and the in-plane direction in the case of ellipsoidal particles. is the average value when measuring the angle (orientation angle) between the long axis direction, and in the case of rod-shaped particles, the long axis direction and the surface (principal surface) of the thermally conductive layer.
  • the particle size of the graphite particles (A) is not particularly limited.
  • the average particle diameter of the graphite particles (A), as a mass average particle diameter, is preferably 1/2 or more and not more than the average thickness of the heat conductive layer.
  • the mass average particle diameter of the graphite particles (A) is 1/2 or more of the average thickness of the heat conductive layer, an efficient heat conduction path is formed in the heat conductive layer, and thermal conductivity tends to improve.
  • the mass average particle diameter of the graphite particles (A) is less than or equal to the average thickness of the thermally conductive layer, protrusion of the graphite particles (A) from the surface of the thermally conductive layer is suppressed, and the adhesion of the surface of the thermally conductive layer is excellent. There is a tendency.
  • thermoly conductive layer so that the plane direction is oriented in the case of scale-like particles, the long axis direction in the case of ellipsoidal particles, and the long axis direction in the case of rod-like particles is oriented in the thickness direction.
  • the method described in JP-A No. 2008-280496 can be used.
  • sheets are produced using the composition, the sheets are laminated to produce a laminate, and the side end surfaces of the laminate are aligned (for example, 0 with respect to the normal from the main surface of the laminate).
  • a slicing method (hereinafter also referred to as "layered slicing method”) can be used.
  • the particle size of the graphite particles (A) used as a raw material is preferably 1/2 or more of the average thickness of the thermally conductive layer as a mass average particle size, and the average thickness is You can exceed it.
  • the reason why the particle size of the graphite particles (A) used as a raw material may exceed the average thickness of the thermally conductive layer is that, for example, even if the graphite particles (A) have a particle size that exceeds the average thickness of the thermally conductive layer, This is because the graphite particles (A) are sliced together to form the thermally conductive layer, and as a result, the graphite particles (A) do not protrude from the surface of the thermally conductive layer.
  • the particle diameter of the graphite particles (A) used as a raw material is preferably 1 to 5 times, and 2 to 4 times, the average thickness of the thermally conductive layer as a mass average particle diameter. It is more preferable that When the mass average particle diameter of the graphite particles (A) is one or more times the average thickness of the heat conductive layer, a more efficient heat conduction path is formed and the heat conductivity is further improved. When the thickness is 5 times or less the average thickness of the thermally conductive layer, the area occupied by the graphite particles (A) on the surface portion can be prevented from becoming too large, and a decrease in adhesiveness can be suppressed.
  • the mass average particle diameter (D50) of the graphite particles (A) is measured using a laser diffraction particle size distribution device (for example, Nikkiso Co., Ltd. "Microtrack series MT3300") adapted to the laser diffraction/scattering method, and the mass cumulative When the particle size distribution curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
  • a laser diffraction particle size distribution device for example, Nikkiso Co., Ltd. "Microtrack series MT3300
  • the thermally conductive layer may contain graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, such as spherical graphite particles, artificial graphite particles, exfoliated graphite particles, acid-treated graphite particles, expanded graphite particles, and carbon. It may also contain fiber flakes and the like.
  • the graphite particles (A) are preferably scale-like particles, and from the viewpoint of having a high degree of crystallinity and easily obtaining scales with a large particle size, scale-like expanded graphite particles obtained by crushing expanded graphite in the form of a sheet are preferred. preferable.
  • the content of graphite particles (A) in the thermally conductive layer is preferably 15% to 50% by volume, and preferably 20% to 45% by volume from the viewpoint of the balance between thermal conductivity and adhesion. It is more preferable that the amount is 25% to 40% by volume.
  • the content of graphite particles (A) is 15% by volume or more, thermal conductivity tends to improve.
  • the content of graphite particles (A) is 50% by volume or less, deterioration in tackiness and adhesiveness tends to be suppressed.
  • the heat conductive layer contains graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, it is preferable that the content of the entire graphite particles is within the above range.
  • the content rate (volume %) of graphite particles (A) is a value determined by the following formula.
  • Content rate (volume %) of graphite particles (A) [(Aw/Ad)/ ⁇ (Aw/Ad)+(Xw/Xd) ⁇ ] ⁇ 100
  • Aw Mass composition (mass%) of graphite particles (A)
  • Xw mass composition of other arbitrary components (mass%)
  • Ad Density of graphite particles (A) (In this disclosure, Ad is calculated as 2.1.)
  • Xd Density of other arbitrary components
  • the thermally conductive layer included in the thermally conductive sheet of the present disclosure may contain a component that is liquid at 25° C. (hereinafter also referred to as “liquid component (B)").
  • liquid at 25°C means a substance that exhibits fluidity and viscosity at 25°C, and has a viscosity, which is a measure of viscosity, of 0.0001 Pa ⁇ s to 1000 Pa ⁇ s at 25°C. .
  • viscosity is defined as a value measured at 25° C. using a rheometer at a shear rate of 5.0 s ⁇ 1 . Specifically, “viscosity” is measured as shear viscosity at a temperature of 25° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0°).
  • the viscosity of the liquid component (B) at 25° C. is preferably 0.001 Pa ⁇ s to 100 Pa ⁇ s, more preferably 0.01 Pa ⁇ s to 10 Pa ⁇ s.
  • the liquid component (B) is not particularly limited as long as it is liquid at 25°C, and is preferably a high molecular compound (polymer).
  • the liquid component (B) include polybutene, polyisoprene, polysulfide, acrylonitrile rubber, silicone rubber, hydrocarbon resin, terpene resin, and acrylic resin. Among these, from the viewpoint of heat resistance, it is preferable that the liquid component (B) contains polybutene.
  • the liquid component (B) may be used alone or in combination of two or more.
  • polybutene refers to a polymer obtained by polymerizing isobutene or normal butene. It also includes polymers obtained by copolymerizing isobutene and normal butene. As for the structure, it refers to a polymer having a structural unit represented by "-CH 2 --C(CH 3 ) 2 --" or "-CH 2 --CH(CH 2 CH 3 )-". It is also sometimes called polyisobutylene.
  • the polybutene only needs to contain the above structure, and other structures are not particularly limited.
  • polybutenes examples include butene homopolymers and copolymers of butene and other monomer components.
  • copolymers with other monomer components examples include copolymers of isobutene and styrene or copolymers of isobutene and ethylene.
  • the copolymer may be a random copolymer, a block copolymer, or a graft copolymer.
  • polybutene examples include NOF Polybutene TM Emmawet (registered trademark) from NOF Corporation, Nisseki Polybutene from JXTG Energy Corporation, Tetrax from JXTG Energy Corporation, and Tetrax from JXTG Energy Corporation. Examples include “Himol” and “Polyisobutylene” manufactured by Tomoe Kogyo Co., Ltd.
  • the liquid component (B) mainly functions as, for example, a stress relieving agent with excellent heat resistance and humidity resistance, and a tackifying agent.
  • a hot melt agent (D) described below, it tends to be possible to further improve cohesive force and fluidity during heating.
  • the content of the liquid component (B) in the thermally conductive layer is preferably 10% by volume to 55% by volume, from the viewpoint of further enhancing adhesive strength, adhesion, sheet strength, hydrolysis resistance, etc. % to 50% by volume, and even more preferably 20% to 50% by volume.
  • the content of the liquid component (B) is 10% by volume or more, the tackiness and adhesiveness tend to be further improved.
  • the content of the liquid component (B) is 55% by volume or less, reductions in sheet strength and thermal conductivity tend to be more effectively suppressed.
  • the thermally conductive layer included in the thermally conductive sheet may contain an acrylic acid ester polymer (C). It is thought that the acrylic ester polymer (C) mainly functions as, for example, a tackifier and an elasticity-imparting agent that allows the thickness to be restored in order to follow warping.
  • the acrylic ester polymer (C) has, for example, butyl acrylate, ethyl acrylate, acrylonitrile, acrylic acid, glycidyl methacrylate, 2-ethylhexyl acrylate, etc. as main raw material components, and if necessary, methyl acrylate, etc.
  • An acrylic acid ester polymer (so-called acrylic rubber) copolymerized with is preferably used.
  • the acrylic ester polymer (C) may be used alone or in combination of two or more.
  • the weight average molecular weight of the acrylic ester polymer (C) is preferably 100,000 to 1,000,000, more preferably 250,000 to 700,000, and even more preferably 400,000 to 600. ,000. When the weight average molecular weight is 100,000 or more, the film tends to have excellent strength, and when it is 1,000,000 or less, it tends to have excellent flexibility.
  • the weight average molecular weight can be measured by gel permeation chromatography using a standard polystyrene calibration curve.
  • the glass transition temperature (Tg) of the acrylic ester polymer (C) is preferably 20°C or lower, more preferably -70°C to 0°C, even more preferably -50°C to -20°C. be. When the glass transition temperature is 20° C. or lower, flexibility and adhesiveness tend to be excellent.
  • the glass transition temperature (Tg) can be calculated from tan ⁇ derived from dynamic viscoelasticity measurement by tension.
  • the acrylic ester polymer (C) may be present in the entire thermally conductive layer by internal addition, or may be localized on the surface by coating or impregnating the surface. In particular, coating on one side or impregnating one side is preferable because strong tackiness can be imparted to only one side, resulting in a sheet with good handling properties.
  • the content of the acrylic ester polymer (C) in the thermally conductive layer is preferably from 3% by volume to 25% by volume, more preferably from 5% to 20% by volume, and from 7% by volume. More preferably, it is 15% by volume.
  • the heat conductive layer included in the heat conductive sheet may contain a hot melt agent (D).
  • the hot melt agent (D) has the effect of improving the strength of the heat conductive layer and improving the fluidity during heating.
  • hot melt agent (D) examples include aromatic petroleum resins, terpene phenol resins, and cyclopentadiene petroleum resins. Further, the hot melt agent (D) may be a hydrogenated aromatic petroleum resin or a hydrogenated terpene phenol resin. The hot melt agent (D) may be used alone or in combination of two or more.
  • the hot melt agent (D) when polybutene is used as the liquid component (B), the hot melt agent (D) should contain at least one selected from the group consisting of hydrogenated aromatic petroleum resins and hydrogenated terpene phenolic resins. is preferred. These hot melt agents (D) have high stability and excellent compatibility with polybutene, so when forming a thermally conductive layer, they can achieve better thermal conductivity, flexibility, and handling properties. There is a tendency.
  • hydrogenated aromatic petroleum resins include, for example, “Alcon” by Arakawa Chemical Co., Ltd. and “Imarv” by Idemitsu Kosan Co., Ltd.
  • examples of commercially available hydrogenated terpene phenol resins include “Clearon” manufactured by Yasuhara Chemical Co., Ltd.
  • commercially available cyclopentadiene petroleum resins include, for example, “Quinton” manufactured by Nippon Zeon Co., Ltd. and “Marcarez” manufactured by Maruzen Petrochemical Co., Ltd.
  • the hot melt agent (D) is solid at 25°C and has a softening temperature of 40°C to 150°C.
  • a thermoplastic resin is used as the hot melt agent (D)
  • the softening fluidity during thermocompression bonding is improved, and as a result, the adhesion tends to be improved.
  • the softening temperature is 40° C. or higher, cohesive force can be maintained near room temperature, and as a result, it becomes easier to obtain the necessary sheet strength and tends to be excellent in handleability.
  • the softening temperature is 150° C. or less, the softening fluidity during thermocompression bonding increases, and as a result, the adhesion tends to improve.
  • the softening temperature is more preferably 60°C to 120°C. Note that the softening temperature is measured by the ring and ball method (JIS K 2207:1996).
  • the content of the hot melt agent (D) in the thermally conductive layer is preferably 3% to 25% by volume, and preferably 5% to 20% by volume from the viewpoint of increasing adhesive strength, adhesion, sheet strength, etc. It is more preferable that the amount is 5% by volume to 15% by volume.
  • adhesive strength, heat fluidity, sheet strength, etc. tend to be sufficient, and when the content is 25% by volume or less, flexibility is insufficient. They tend to have excellent handling properties and thermal cycle resistance.
  • the thermally conductive layer included in the thermally conductive sheet may contain an antioxidant (E), for example, for the purpose of imparting thermal stability at high temperatures.
  • examples of the antioxidant (E) include phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, hydrazine antioxidants, and amide antioxidants.
  • the antioxidant (E) may be appropriately selected depending on the temperature conditions used, etc., and phenolic antioxidants are more preferred.
  • the antioxidant (E) may be used alone or in combination of two or more.
  • phenolic antioxidants include, for example, ADEKA STAB AO-50, ADEKA STAB AO-60, and ADEKA STAB AO-80 manufactured by ADEKA Corporation.
  • the content of the antioxidant (E) in the thermally conductive layer is not particularly limited, and is preferably 0.1% to 5% by volume, more preferably 0.2% to 3% by volume. It is preferably 0.3% by volume to 1% by volume or less. When the content of the antioxidant (E) is 0.1% by volume or more, a sufficient antioxidant effect tends to be obtained. When the content of the antioxidant (E) is 5% by volume or less, the strength of the heat conductive layer tends to be prevented from decreasing.
  • the thermally conductive layer contained in the thermally conductive sheet contains graphite particles (A), liquid component (B), acrylic ester polymer (C), hot melt agent (D), and others other than antioxidant (E).
  • Components may be included depending on the purpose.
  • the heat conductive layer may contain a flame retardant from the viewpoint of flame retardancy.
  • the flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. Examples include red phosphorus flame retardants and phosphate ester flame retardants. Among these, phosphoric acid ester flame retardants are preferred from the viewpoint of excellent safety and improved adhesion due to the plasticizing effect.
  • red phosphorus flame retardant in addition to pure red phosphorus particles, those coated with various coatings for the purpose of increasing safety or stability, those made into masterbatches, etc. may be used. Specific examples include Nobared, Nova Excel, Novaquel, and Nova Pellet (all trade names) manufactured by Rin Kagaku Kogyo Co., Ltd.
  • Phosphate ester flame retardants include aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, and tributyl phosphate; triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tricylenyl phosphate, and cresyl di-2,6-oxy Aromatic phosphate esters such as renyl phosphate, tris (t-butylated phenyl) phosphate, tris (isopropylated phenyl) phosphate, triaryl isopropylated phosphate; resorcinol bisdiphenyl phosphate, bisphenol A bis (diphenyl phosphate), resorcinol Examples include aromatic condensed phosphoric acid esters such as bisdixylenyl phosphate. Among these, bisphenol A bis(diphenyl phosphate) is preferable from the viewpoints of excellent hydrolysis resistance
  • the content of the flame retardant in the heat conductive layer is not limited and can be used in an amount that exhibits flame retardancy, and is preferably about 30% by volume or less. From the viewpoint of suppressing deterioration of thermal resistance due to seepage, the content is preferably 20% by volume or less.
  • the average thickness of the thermally conductive layer is not particularly limited and can be appropriately selected depending on the purpose.
  • the thickness of the thermally conductive layer can be appropriately selected depending on the specifications of the semiconductor package used. As the thickness decreases, the thermal resistance tends to decrease, and as the thickness increases, the warp followability tends to improve.
  • the average thickness of the thermally conductive layer may be 20 ⁇ m to 3000 ⁇ m, preferably 30 ⁇ m to 500 ⁇ m, more preferably 50 to 400 ⁇ m from the viewpoint of thermal conductivity and adhesion.
  • the average thickness of the thermally conductive layer is determined by observing the cross section of the measurement target using an electron microscope, or by measuring the thickness at three random locations using a micrometer, and is given as the arithmetic mean value.
  • the thermally conductive sheet of the present disclosure includes a resin component and a thermally conductive filler, and includes an adhesive layer located on at least a portion of the main surface of the thermally conductive layer.
  • the resin component examples include a curable resin component, a sticky resin component, a thermoplastic resin component, and the like.
  • examples of the curable resin component include a thermosetting resin component, a photocurable resin component, and the like.
  • the resin component may include one or more curable resin components, one or more adhesive resin components, or one or more thermoplastic resin components. good. Further, the resin component may be a mixture of two or more resin components.
  • curable resin components include epoxy resins, phenol resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, urethane resins, polyimide resins such as bismaleimide resins, polyamide resins, polyamideimide resins, and silicone resins. and thermosetting (meth)acrylic resins.
  • epoxy resin is preferred from the viewpoint of adhesiveness.
  • thermoplastic resin components examples include polyethylene (PE), polypropylene (PP), polycarbonate (PC), polystyrene, polyvinyl chloride, vinyl polymer, polyester, polyamide, acrylonitrile-butadiene- Examples include styrene copolymer resin (ABS resin), thermoplastic (meth)acrylic resin, acrylonitrile-ethylene-propylene-diene-styrene copolymer resin (AES resin), and thermoplastic elastomer.
  • ABS resin styrene copolymer resin
  • AES resin acrylonitrile-ethylene-propylene-diene-styrene copolymer resin
  • thermoplastic elastomer examples include thermoplastic elastomer.
  • thermally conductive filler examples include metal-containing particles and non-metallic particles that have excellent thermal conductivity.
  • the thermally conductive filler may have a thermal conductivity of 10 W/(m ⁇ K) or more, for example.
  • the thermally conductive filler may be insulating or electrically conductive.
  • the thermally conductive filler is selected from silver, aluminum oxide, aluminum hydroxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, aluminum fluoride, calcium fluoride and zinc oxide. It may be at least one type of particle. Among them, silver particles are preferred from the viewpoint of thermal conductivity.
  • the particle size of the thermally conductive filler may be from 0.1 ⁇ m to 50 ⁇ m, and from 0.2 ⁇ m to 50 ⁇ m, from the viewpoint of excellent thermal conductivity and from the viewpoint of further reducing the gap between the adherend and the thermally conductive sheet. It may be 20 ⁇ m or 0.5 ⁇ m to 10 ⁇ m.
  • the particle diameter (D50) of the thermally conductive filler is measured using a laser diffraction type particle size distribution device adapted to the laser diffraction/scattering method (for example, "Microtrack Series MT3300" manufactured by Nikkiso Co., Ltd.), and the mass cumulative particle size distribution is When the curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
  • a laser diffraction type particle size distribution device adapted to the laser diffraction/scattering method
  • the adhesive layer only needs to be located on at least a part of the main surface of the thermally conductive layer, and the adhesive layer may be located on the entire main surface, or a part of the main surface. (For example, an adhesive layer may be located at a portion that comes into contact with an adherend such as a heating element or a heat radiating element).
  • the adhesive layer may be located on one main surface, or the adhesive layer may be located on two main surfaces.
  • the content of the resin component contained in the adhesive layer is preferably 1% by mass to 30% by mass, and 3% by mass to 30% by mass, based on the total amount of the adhesive layer, for example, from the viewpoint of the balance between thermal conductivity and adhesion. It is more preferably 25% by weight, and even more preferably 5% to 20% by weight.
  • the content of the thermally conductive filler contained in the adhesive layer is preferably 70% by mass to 99% by mass, and 75% by mass based on the total amount of the adhesive layer, for example, from the viewpoint of the balance between thermal conductivity and adhesion. % to 97% by mass, and even more preferably 80% to 95% by mass.
  • the total content of the resin component and the thermally conductive filler contained in the adhesive layer may be 80% by mass to 100% by mass, or 90% by mass to 100% by mass, based on the total amount of the adhesive layer. .
  • the adhesive layer may or may not contain components other than the resin component and the thermally conductive filler.
  • Components other than the resin component and the thermally conductive filler include the hot melt agent (D), antioxidant (E), and other components described in the section of the thermally conductive layer above.
  • the adhesive layer contains a thermosetting resin component
  • the adhesive layer is preferably in a semi-cured state from the viewpoint of improving handling properties.
  • a resin composition containing a thermosetting resin component and a thermally conductive filler to treatments such as heating and drying, an adhesive layer in a semi-cured state can be obtained.
  • a semi-cured state means that the adhesive layer has a viscosity of 10 4 Pa ⁇ s to 10 6 Pa ⁇ s at room temperature (25 to 30° C.).
  • the above viscosity is measured by DMA (dynamic viscoelasticity measuring device; frequency 1 Hz, load 10 g, temperature increase rate 20° C./min).
  • the method of obtaining the adhesive layer in a semi-cured state is not particularly limited.
  • a resin composition containing a thermosetting resin component, a thermally conductive filler, a solvent, etc. may be applied to the main surface of the heat conductive layer, and the applied resin composition may be heated, dried, etc.
  • a resin composition may be applied to a release film, then heated, dried, etc., and then an adhesive layer made of the heated, dried, etc. resin composition may be heat roll laminated on the main surface of the heat conductive layer. Examples of methods for heating, drying, etc. include hot vacuum press, hot roll lamination, and the like.
  • the average thickness of the adhesive layer is preferably 2 ⁇ m to 50 ⁇ m, more preferably 2 ⁇ m to 30 ⁇ m, and even more preferably 2 ⁇ m to 20 ⁇ m.
  • the average thickness of the adhesive layer is 2 ⁇ m or more, the gap between the adherend and the thermally conductive sheet tends to be further reduced and the contact thermal resistance can be further reduced.
  • the average thickness of the adhesive layer is 50 ⁇ m or less, the thermal conductivity of the thermally conductive sheet tends to be more excellent.
  • the thickness may be measured at three random locations by observing the cross section of the thermally conductive layer to be measured using an electron microscope, and the arithmetic mean value may be taken as the average thickness of the adhesive layer.
  • the thermally conductive layer that does not include an adhesive layer and the thermally conductive sheet that includes an adhesive layer measure the thickness at three random locations using a micrometer, and calculate the arithmetic mean value as the average thickness of the thermally conductive layer. and the average thickness of the heat conductive sheet. Then, the average thickness of the adhesive layer may be determined by subtracting the average thickness of the thermally conductive sheet from the average thickness of the thermally conductive layer.
  • the average thickness of the adhesive layer means the total thickness of the adhesive layers formed on the two main surfaces.
  • the surface roughness Ra of the thermally conductive sheet (before adhering to the adherend) is 10 ⁇ m or less from the viewpoint of further reducing the gap between the adherend and the thermally conductive sheet when adhering to the adherend. From the viewpoint of productivity of the heat conductive sheet, the thickness may be 2 ⁇ m to 20 ⁇ m. In the present disclosure, surface roughness Ra refers to a value measured based on JIS B0601:2013.
  • the thermal conductivity in the thickness direction of the thermally conductive layer is preferably larger than the thermal conductivity in the thickness direction of the adhesive layer.
  • the ratio of the thermal conductivity in the thickness direction of the thermal conductive layer to the thermal conductivity in the thickness direction of the adhesive layer needs to be larger than 1, for example. , may be greater than 1 and less than or equal to 20, and may be greater than 1 and less than or equal to 10.
  • the thermal conductivity in the thickness direction of the thermally conductive layer and the thermal conductivity of the adhesive layer can be measured by a xenon flash (Xe-flash) method. Note that when the resin component includes a curable resin component, the thermal conductivity of the adhesive layer means the thermal conductivity of the adhesive layer after curing.
  • the thermal conductivity of the adhesive layer may be 5.0 W/(m K) or more, may be 5.0 W/(m K) to 20 W/(m K), and may be 7.0 W/(m K). /(m ⁇ K) to 15W/(m ⁇ K).
  • the thermally conductive sheet may have a protective film on at least one side, and preferably has a protective film on both sides. Thereby, the adhesive surface of the heat conductive sheet can be protected.
  • the protective film for example, resin films such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyether naphthalate, and methylpentene, coated paper, coated cloth, and metal foils such as aluminum can be used. These protective films may be used alone or in combination of two or more to form a multilayer film.
  • the protective film is preferably surface-treated with a silicone-based, silica-based, or the like release agent.
  • thermally conductive sheet is not particularly limited.
  • the thermally conductive sheet of the present disclosure is particularly suitable as a thermally conductive sheet (TIM1; Thermal Interface Material 1) interposed between the semiconductor chip and the heat spreader when the semiconductor chip is used as the heat generating body and the heat spreader is used as the heat radiating body.
  • TIM1 Thermal Interface Material 1
  • the thermally conductive sheet 1A shown in FIG. 3 includes a thermally conductive layer 11A and adhesive layers 12A and 13A, with the adhesive layer 12A located on one main surface of the thermally conductive layer 11A, and the other main surface of the thermally conductive layer 11A.
  • An adhesive layer 13A is located on the surface.
  • the heat conductive layer 11A in the heat conductive sheet 1A does not have to be flat because its two main surfaces have an uneven shape.
  • the two main surfaces of the thermally conductive layer 11A in the thermally conductive sheet 1A may be flat (for example, see FIG. 3).
  • the method for manufacturing the thermally conductive sheet is not particularly limited as long as it can produce a thermally conductive sheet having the above configuration.
  • the method for manufacturing a thermally conductive sheet includes a step of preparing a composition containing the graphite particles (A) (also referred to as a "preparation step"), and a step of forming the thermally conductive layer using the composition (also referred to as a "forming step”). and a step of forming an adhesive layer on at least a portion of the main surface of the thermally conductive layer (also referred to as an "adhesive layer forming step").
  • ⁇ Preparation process> In the preparation step, graphite particles (A) and any other components (for example, component (B) that is liquid at 25°C, acrylic ester polymer (C), hot melt agent (D), antioxidant (E) ), other ingredients) are prepared.
  • the method for blending each component is not particularly limited, and any method may be used as long as each component can be mixed uniformly.
  • the composition may be prepared by obtaining a commercially available composition. For details on the preparation of the composition, reference can be made to paragraph [0033] of JP-A-2008-280496.
  • the thermally conductive layer is formed using a composition containing graphite particles (A) and arbitrary other components.
  • the thermally conductive layer may be formed by forming the above-mentioned composition into a sheet shape.
  • the forming step includes a step of forming the composition into a sheet to obtain a sheet (also referred to as a "sheet manufacturing step"), a step of manufacturing a laminate of the sheets (also referred to as a “laminate manufacturing step”), and a step of forming the laminate into a sheet. It is preferable to include a step of slicing the side end surface of the (also referred to as "slicing step").
  • the sheet production step is not particularly limited and may be performed by any method as long as the composition obtained in the previous step can be formed into a sheet.
  • at least one molding method selected from the group consisting of rolling, pressing, extrusion, and coating.
  • a laminate of sheets obtained in the previous step is formed.
  • the laminate may be produced by sequentially stacking a plurality of independent sheets, by folding a single sheet, or by winding one of the sheets. .
  • the laminate manufacturing process reference can be made to paragraphs [0035] to [0037] of JP-A No. 2008-280496.
  • the slicing step is not particularly limited and may be any method as long as it can slice the side end surface of the laminate obtained in the previous step.
  • the graphite particles (A) that penetrate in the thickness direction of the heat conductive layer form an extremely efficient heat conduction path, and from the viewpoint of further improving thermal conductivity, the mass average particle diameter of the graphite particles (A) is twice or less. It is preferable to slice with a thickness of .
  • JP-A-2008-280496 for details of the slicing process, reference can be made to paragraph [0038] of JP-A-2008-280496.
  • the adhesive layer forming step is not particularly limited and may be any method as long as it can form an adhesive layer on at least a portion of the main surface of the heat conductive layer (for example, a sliced sheet obtained by slicing).
  • a resin composition containing a thermosetting resin component, a thermally conductive filler, a solvent, etc. is applied to the main surface of the thermally conductive layer, and the applied resin composition is heated, dried, etc. to evaporate the solvent. That's fine.
  • a resin composition may be applied to a release film, then heated, dried, etc., and then an adhesive layer made of the heated, dried, etc. resin composition may be heat roll laminated on the main surface of the heat conductive layer. Examples of methods for heating, drying, etc. include hot vacuum pressing, hot roll lamination, and the like.
  • the adhesive layer formed on the main surface of the heat conductive layer may be in a semi-cured state.
  • the method for manufacturing a thermally conductive sheet may further include a step of attaching a protective film to the thermally conductive sheet and laminating it after the adhesive layer forming step (also referred to as a "laminate step").
  • the lamination step is not particularly limited and may be any method as long as the thermally conductive sheet obtained in the adhesive layer forming step can be attached to the protective film.
  • thermally conductive sheet By manufacturing a thermally conductive sheet using such a method, an efficient thermally conductive path is likely to be formed, and therefore a thermally conductive sheet with high thermal conductivity and excellent adhesion tends to be obtained.
  • the heat dissipation device of the present disclosure includes a heat generating body, a heat dissipating body, and a heat conductive sheet of the present disclosure disposed between the heat generating body and the heat dissipating body, the heat conductive sheet being located on the side of the heat generating body in the heat conductive layer.
  • the adhesive layer is located on at least a portion of at least one of the main surface and the main surface located on the side of the heat sink.
  • an adhesive layer is located on at least a part of the main surface located on the heating element side and at least a part of the main surface located on the heat radiating element side, and the adhesive layer is located on at least a part of the main surface located on the heating element side. It is more preferable that the adhesive layer is located in the facing region and in the region facing the heat radiator of the main surface located on the heat radiator side, respectively.
  • heating elements include semiconductor chips, semiconductor packages, power modules, etc.
  • heat radiator examples include a heat spreader, a heat sink, a water cooling pipe, and the like.
  • a heat radiating device using a semiconductor chip as a heat generating body and a heat spreader as a heat radiating body will be described.
  • a semiconductor chip and a heat spreader are examples of a heat generating body and a heat radiating body, respectively, and the present disclosure is not limited thereto.
  • a thermally conductive sheet 1 is used with one surface in close contact with a semiconductor chip 2 and the other surface in close contact with a heat spreader 3.
  • the semiconductor chip 2 is fixed to the substrate 4 using an underfill material 5, and the heat spreader 3 is fixed to the substrate 4 by a sealing material 6, which presses the adhesion between the thermally conductive sheet 1, the semiconductor chip 2, and the heat spreader 3.
  • one heating element and one heat radiating element are provided for one heat conductive sheet 1.
  • a plurality of semiconductor chips 2 may be provided for one heat conductive sheet 1
  • one semiconductor chip 2 may be provided for a plurality of heat conductive sheets 1
  • a plurality of semiconductor chips 2 may be provided for a plurality of heat conductive sheets 1.
  • a plurality of semiconductor chips 2 may be provided on the heat conductive sheet 1.
  • An adhesive layer is located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side and on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side. For example, in the thermally conductive sheet 1 shown in FIG.
  • the adhesive layer 13 is located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side, and the adhesive layer 12 is located on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side. are doing. Further, the adhesive layer 13 may be in contact with the semiconductor chip 2, and the adhesive layer 12 may be in contact with the heat spreader 3.
  • the heat radiating device includes the heat conductive sheet of the present disclosure disposed between a heat generating element and a heat radiating element. Since the heating element and the heat radiating element are laminated via the heat conductive sheet, heat from the heating element can be efficiently conducted to the heat radiating element. By being able to conduct heat efficiently, the lifespan of the heat dissipation device is improved, and a heat dissipation device that functions stably even during long-term use can be provided.
  • the temperature range in which the thermally conductive sheet can be particularly suitably used may be, for example, -10°C to 150°C, -10°C to 100°C, or -10°C to 80°C. .
  • suitable examples of the heating element include semiconductor packages, displays, LEDs, electric lights, automotive power modules, and industrial power modules.
  • the heat sink examples include a heat sink using aluminum or copper fins or plates, an aluminum or copper block connected to a heat pipe, an aluminum or copper block in which a cooling liquid is circulated by a pump, and a Peltier element and an aluminum or copper block equipped with the same.
  • the heat radiating device is constructed by bringing each surface of a heat conductive sheet into contact with a heat generating element and a heat radiating element.
  • the method of bringing the heating element into contact with one side of the heat conductive sheet and the method of bringing the heat radiating element into contact with the other side of the heat conductive sheet are especially suitable as long as they can be fixed in a sufficiently close state. Not restricted.
  • a heat conductive sheet may be placed between the heating element and the heat radiating element, fixed with a jig that can be pressurized to approximately 0.05 MPa to 1 MPa, and the heating element may be heated in this state, or the A method of heating to about .degree. C. to 200.degree. C. can be mentioned.
  • Another method is to use a press machine capable of heating and pressing at 80° C. to 200° C. and 0.05 MPa to 1 MPa.
  • the preferred pressure range for this method is 0.10 MPa to 1 MPa, and the preferred temperature range is 100°C to 180°C. Excellent adhesion tends to be obtained by setting the pressure to 0.10 MPa or higher or the heating temperature to 100° C. or higher.
  • the pressure is 1 MPa or less or the heating temperature is 180° C. or less, the reliability of adhesion tends to be further improved. This is thought to be because it is possible to prevent the thermally conductive sheet from being excessively compressed and becoming thinner, or from becoming too large in distortion or residual stress in peripheral members.
  • the heat conductive sheet disposed between the heating element and the heat radiating element is not particularly limited as long as it is the above-mentioned heat conductive sheet.
  • the thermally conductive sheet shown in FIG. 1 may be placed between a heat generating element and a heat radiating element.
  • thermally conductive sheet 1A shown in FIG. 1 When using the thermally conductive sheet 1A shown in FIG. 1, by heating and pressurizing the thermally conductive sheet 1A with the thermally conductive sheet 1A arranged between the heat generating element and the heat dissipating element, an adhesive layer located on the main surface of the thermally conductive sheet 1A is formed. 12A and 13A are softened or deformed. A gap that occurs when heat-compression bonding the thermally conductive sheet 1A and the heating element and the heat radiating element is bonded is filled with a softened, deformed, etc. adhesive layer. Thereby, the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer while reducing the gap between the thermally conductive sheet and the adherend.
  • thermosetting resin component the adhesive layer deformed by heat compression fills the gap between the thermally conductive sheet and the adherend, and the thermosetting resin component hardens by heating. do.
  • the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer.
  • the adhesive layer softened by heat-pressing fills the gap between the thermally conductive sheet and the adherend.
  • the gap between the heat conductive sheet and the heat generating element or the heat radiating element is reduced, and the contact thermal resistance is significantly reduced.
  • the thermally conductive sheet may have a reduced thickness (compression rate) of 1% to 35% after the heat-conducting sheet is placed between the heat-generating element and the heat-dissipating body relative to its initial thickness before being press-bonded.
  • jigs such as screws and springs may be used for fixing, and it is preferable to further fix with commonly used means such as adhesives in order to maintain close contact.
  • the porosity calculated as the ratio of the area of the gas region to the area of the measurement region is 0% to 25.0%. is preferable, and more preferably 0% to 20.0%. This reduces gaps that occur when heat-compression bonding the thermal conductive sheet and the heat generating element or the heat dissipating body (for example, gaps resulting from unevenness of the heat conductive sheet and gaps resulting from unevenness of the heat generating element or heat dissipating body). . As a result, it is estimated that the contact thermal resistance is significantly reduced.
  • the porosity satisfies the above numerical range both on the main surface side of the thermally conductive layer where the adhesive layer is located and on the main surface side of the thermally conductive layer where the adhesive layer is not located.
  • the above-mentioned porosity is preferably 0% to 10.0%, more preferably 0% to 5.0%, and 0% to 2%. More preferably, it is .0%.
  • the numerical range of the porosity at the interface can be adjusted by, for example, adjusting the thickness of the adhesive layer, the composition of the resin composition forming the adhesive layer, the compressibility of the thermally conductive sheet, etc.
  • Example 1 to Example 2 The following materials were put into a kneader (Moriyama Co., Ltd., DS3-SGHM-E type pressurized double-arm kneader) so that the mixing ratio (volume %) was as shown in Table 1, and kneaded at a temperature of 150°C. , a composition was obtained.
  • a kneader Moka Co., Ltd., DS3-SGHM-E type pressurized double-arm kneader
  • the composition obtained by kneading was put into an extrusion molding machine (Parker Co., Ltd., product name: HKS40-15 type extruder) and extruded into a flat plate shape with a width of 20 cm and a thickness of 1.5 mm to 1.6 mm to obtain a primary sheet.
  • the obtained primary sheet was press punched using a 40 mm x 150 mm die blade, and 61 of the punched sheets were stacked and heated at 90°C in the stacking direction with a spacer 80 mm in height in between so that the height was 80 mm. Pressure was applied for 30 minutes to obtain a 40 mm x 150 mm x 80 mm laminate.
  • the 80 mm x 150 mm side end face of this laminate was sliced with a wood slicer to obtain a thermally conductive layer with a thickness of 0.11 mm.
  • thermoly conductive sheet (Preparation of thermally conductive sheet) (Example 1) Thermosetting resin components (bisphenol F type epoxy resin) 6 parts by mass, (cresol novolac type epoxy resin) 4 parts by mass, (phenol resin) 8 parts by mass, (acrylic acid ester resin) 6 parts by mass, thermal conductivity A resin composition containing 76 parts by mass of filler (silver particles, particle size 1.5 ⁇ m) and 39 parts by mass of a solvent (cyclohexanone) was prepared. The prepared resin composition was applied onto a release film, and the resin composition was dried in an oven at 130°C. A thermally conductive sheet with an adhesive layer (adhesive layer 1 in Table 2) formed on one main surface was obtained by thermal roll lamination at 70 ° C.
  • bisphenol F type epoxy resin bisphenol F type epoxy resin
  • phenol resin cresol novolac type epoxy resin
  • phenol resin phenol resin
  • acrylic acid ester resin 6 parts by mass
  • thermal conductivity A resin composition containing 76 parts by
  • Example 2 Thermosetting resin components (bisphenol F type epoxy resin) 4 parts by weight, (cresol novolac type epoxy resin) 3 parts by weight, (phenol resin) 6 parts by weight, (acrylic acid ester resin) 5 parts by weight, thermal conductivity
  • a resin composition containing 83 parts by mass of filler (silver particles, particle size 1.5 ⁇ m) and 39 parts by mass of a solvent (cyclohexanone) was prepared. The prepared resin composition was applied onto a release film, and the resin composition was dried in an oven at 130°C.
  • a thermally conductive sheet with an adhesive layer (adhesive layer 2 in Table 2) formed on one main surface was obtained by hot roll laminating at 70 ° C. on one main surface of the thermally conductive layer obtained as described above.
  • Thermal resistance was measured using a tabletop xenon flash analyzer (LFA 467 Hyper Flash).
  • a sample with a three-layer structure was prepared by sandwiching a thermally conductive sheet with a diameter of 14 mm between 1 mm copper plates.
  • the sample preparation conditions were a temperature of 150° C. and a pressure of 0.14 MPa for 3 minutes.
  • a thermosetting resin was included, in order to harden the resin, it was heated in an oven at 175° C. for 1 hour, and then sufficiently cooled to room temperature.
  • the copper surface was blackened using carbon spray, and then measured.

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Abstract

A thermally conductive sheet is provided with: a thermally conductive layer containing at least one kind of graphite particles (A) selected from the group consisting of scale shaped particles, ellipsoidal particles, and rod shaped particles, in which the face direction in the case of a scale-like particle, the longitudinal axis direction in the case of an ellipsoidal particle, and the longitudinal axis direction in the case of a rod shaped particle, is oriented in the thickness direction of said thermally conductive layer; and an adhesive layer containing a resin component and a thermally conductive filler, wherein said adhesive layer is located on at least one part of the main face of the thermally conductive layer.

Description

熱伝導シート、放熱装置及び熱伝導シートの製造方法Thermal conductive sheet, heat dissipation device, and method for manufacturing the thermal conductive sheet
　本開示は、熱伝導シート、放熱装置及び熱伝導シートの製造方法に関する。 The present disclosure relates to a heat conductive sheet, a heat dissipation device, and a method for manufacturing a heat conductive sheet.
　近年、多層配線板を用いた半導体パッケージにおける配線及び電子部品の搭載密度の高密度化による発熱量が増大し、半導体素子の高集積化による単位面積当たりの発熱量が増大しており、半導体パッケージからの熱放散性を高めることが望まれている。 In recent years, the amount of heat generated by the mounting density of wiring and electronic components in semiconductor packages using multilayer wiring boards has increased, and the amount of heat generated per unit area has increased due to the high integration of semiconductor elements. It is desired to improve heat dissipation from the
　半導体パッケージ等の発熱体とアルミ、銅等の放熱体との間に、熱伝導グリース又は熱伝導シートを挟んで密着させることにより熱を放散する放熱装置が一般に簡便に使用されている。通常、熱伝導グリースよりも熱伝導シートの方が、放熱装置を組み立てる際の作業性に優れている。 A heat dissipation device is generally conveniently used, which dissipates heat by sandwiching thermal conductive grease or a heat conductive sheet between a heat generating body such as a semiconductor package and a heat dissipating body such as aluminum or copper. Normally, thermally conductive sheets are superior to thermally conductive grease in terms of workability when assembling a heat dissipation device.
　近年、ＣＰＵ（中央処理装置、Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）のチップはマルチコア化及びマルチチップ化により大面積化する傾向にある。また、発熱体であるＣＰＵと放熱体との圧着圧力を低くする傾向にある。そのため、熱伝導シートには圧着時の柔軟性が求められている。また、チップ段差によって熱伝導シートが厚くなっても低熱抵抗となるよう、熱伝導シートは熱伝導性に優れることが求められている。 In recent years, the area of CPU (Central Processing Unit) chips has tended to increase due to multi-core and multi-chip technology. Additionally, there is a tendency to lower the compression pressure between the CPU, which is a heat generating body, and a heat radiating body. Therefore, thermally conductive sheets are required to have flexibility during pressure bonding. In addition, the heat conductive sheet is required to have excellent thermal conductivity so that even if the heat conductive sheet becomes thick due to the difference in chip height, it has low thermal resistance.
　熱伝導シートとして、熱伝導フィラを充填した樹脂シートも知られている。熱伝導フィラを充填した熱伝導性に優れる樹脂シートとして、熱伝導性の高い無機粒子を熱伝導フィラとして選択し、さらに無機粒子をシート面に対し垂直に配向させた樹脂シートが種々提案されている。
　例えば、シート面に関してほぼ垂直な方向に熱伝導フィラ（窒化ホウ素）が配向した熱伝導シート（例えば、特許文献１参照）、及びゲル状物質に分散された炭素繊維がシート面に対して垂直に配向した構造の熱伝導シート（例えば、特許文献２参照）が提案されている。 Resin sheets filled with thermally conductive fillers are also known as thermally conductive sheets. Various resin sheets have been proposed that are filled with thermally conductive fillers and have excellent thermal conductivity, in which highly thermally conductive inorganic particles are selected as the thermally conductive fillers, and the inorganic particles are oriented perpendicular to the sheet surface. There is.
For example, there are thermally conductive sheets in which thermally conductive fillers (boron nitride) are oriented in a direction substantially perpendicular to the sheet surface (for example, see Patent Document 1), and carbon fibers dispersed in a gel-like substance are oriented in a direction perpendicular to the sheet surface. A thermally conductive sheet having an oriented structure (see, for example, Patent Document 2) has been proposed.
特開２００２－２６２０２号公報Japanese Patent Application Publication No. 2002-26202 特開２００１－２５０８９４号公報Japanese Patent Application Publication No. 2001-250894
　特許文献１及び２では、シート面に対して垂直な方向に熱伝導フィラ、炭素繊維等を配向させることで熱抵抗を抑制する方法が検討されている。半導体の高性能化及び大型化に伴う発熱量の増大に対応するため、熱伝導シートのさらなる低熱抵抗化が望まれている。そのため、熱伝導シートに含まれる熱伝導フィラ、炭素繊維等の配向以外の手法も踏まえた上で低熱抵抗化を図ることが好ましい。 Patent Documents 1 and 2 consider a method of suppressing thermal resistance by orienting thermally conductive fillers, carbon fibers, etc. in a direction perpendicular to the sheet surface. In order to cope with the increase in heat generation due to the higher performance and larger size of semiconductors, it is desired to further reduce the thermal resistance of thermally conductive sheets. Therefore, it is preferable to aim at lowering the thermal resistance by considering methods other than the orientation of the thermally conductive filler, carbon fiber, etc. contained in the thermally conductive sheet.
　本発明の一態様の目的は、熱抵抗が小さい熱伝導シート、これを備える放熱装置及び熱抵抗が小さい熱伝導シートを製造可能な熱伝導シートの製造方法を提供することである。 An object of one aspect of the present invention is to provide a thermally conductive sheet with low thermal resistance, a heat dissipation device equipped with the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
　上記課題を解決するための具体的手段は、以下の態様を含む。
＜１＞　鱗片状粒子、楕円体状粒子及び棒状粒子からなる群より選択される少なくとも１種の黒鉛粒子（Ａ）を含有し、前記鱗片状粒子の場合には面方向、前記楕円体状粒子の場合には長軸方向、前記棒状粒子の場合には長軸方向が、厚み方向に配向している熱伝導層と、
　樹脂成分と、熱伝導性フィラとを含み、前記熱伝導層の主面の少なくとも一部に位置する接着層と、
　を備える熱伝導シート。
＜２＞　前記樹脂成分は、硬化性の樹脂成分、粘着性の樹脂成分及び熱可塑性の樹脂成分からなる群より選択される少なくとも１種を含む＜１＞に記載の熱伝導シート。
＜３＞　前記樹脂成分は、硬化性の樹脂成分であり、前記接着層は、半硬化された状態である＜２＞に記載の熱伝導シート。
＜４＞　前記樹脂成分は、熱可塑性の樹脂成分を含む＜１＞～＜３＞のいずれか１つに記載の熱伝導シート。
＜５＞　前記熱伝導性フィラは、銀、酸化アルミニウム、水酸化アルミニウム、酸化マグネシウム、酸化ベリリウム、窒化ホウ素、窒化アルミニウム、窒化ケイ素、炭化ケイ素、二酸化ケイ素、フッ化アルミニウム、フッ化カルシウム及び酸化亜鉛から選択される少なくとも１種の粒子である＜１＞～＜４＞のいずれか１つに記載の熱伝導シート。
＜６＞　前記接着層の平均厚みは、５μｍ～５０μｍである＜１＞～＜５＞のいずれか１つに記載の熱伝導シート。
＜７＞　発熱体と、放熱体と、前記発熱体及び前記放熱体の間に配置される＜１＞～＜６＞のいずれか１つに記載の熱伝導シートとを備え、
　前記熱伝導層において、前記発熱体側に位置する主面及び前記放熱体側に位置する主面の少なくとも一方の主面の少なくとも一部に前記接着層が位置する放熱装置。
＜８＞　＜１＞～＜６＞のいずれか１つに記載の熱伝導シートを製造する熱伝導シートの製造方法であって、
　前記黒鉛粒子（Ａ）を含有する組成物を準備する工程と、前記組成物を用いて前記熱伝導層を形成する工程と、前記熱伝導層の主面の少なくとも一部に接着層を形成する工程と、を有する熱伝導シートの製造方法。 Specific means for solving the above problems include the following aspects.
<1> Contains at least one type of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles, and rod-like particles, and in the case of the scale-like particles, in the plane direction, the ellipsoidal particles in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction;
an adhesive layer containing a resin component and a thermally conductive filler and located on at least a portion of the main surface of the thermally conductive layer;
A thermally conductive sheet with
<2> The thermally conductive sheet according to <1>, wherein the resin component includes at least one selected from the group consisting of a curable resin component, an adhesive resin component, and a thermoplastic resin component.
<3> The thermally conductive sheet according to <2>, wherein the resin component is a curable resin component, and the adhesive layer is in a semi-cured state.
<4> The thermally conductive sheet according to any one of <1> to <3>, wherein the resin component includes a thermoplastic resin component.
<5> The thermally conductive filler includes silver, aluminum oxide, aluminum hydroxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, aluminum fluoride, calcium fluoride, and zinc oxide. The thermally conductive sheet according to any one of <1> to <4>, which is at least one type of particle selected from.
<6> The thermally conductive sheet according to any one of <1> to <5>, wherein the adhesive layer has an average thickness of 5 μm to 50 μm.
<7> A heating element, a heat radiating element, and the thermally conductive sheet according to any one of <1> to <6> disposed between the heating element and the heat radiating element,
In the thermally conductive layer, the adhesive layer is located on at least a portion of at least one of the main surface located on the heat generating body side and the main surface located on the heat radiating body side.
<8> A method for manufacturing a thermally conductive sheet for manufacturing the thermally conductive sheet according to any one of <1> to <6>, comprising:
A step of preparing a composition containing the graphite particles (A), a step of forming the thermally conductive layer using the composition, and forming an adhesive layer on at least a portion of the main surface of the thermally conductive layer. A method for manufacturing a thermally conductive sheet, comprising the steps of:
　本開示によれば、熱抵抗が小さい熱伝導シート、これを備える放熱装置及び熱抵抗が小さい熱伝導シートを製造可能な熱伝導シートの製造方法を提供することができる。 According to the present disclosure, it is possible to provide a thermally conductive sheet with low thermal resistance, a heat dissipation device including the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
本発明の一実施形態である、熱伝導シートの概略構成図である。1 is a schematic configuration diagram of a thermally conductive sheet, which is an embodiment of the present invention. 本発明の一実施形態である、発熱体が半導体チップ、放熱体がヒートスプレッダである放熱装置の概略断面図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a heat dissipation device according to an embodiment of the present invention, in which a heat generating body is a semiconductor chip and a heat dissipation body is a heat spreader. 本発明の一実施形態である放熱装置に組み込まれた熱伝導シートの概略構成図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a heat conductive sheet incorporated in a heat dissipation device that is an embodiment of the present invention. 実施例１～２及び比較例１において、画像解析による界面の状態を示す図である。2 is a diagram showing the state of the interface according to image analysis in Examples 1 to 2 and Comparative Example 1. FIG.
　以下、本発明を実施するための形態について詳細に説明する。但し、本発明は以下の実施形態に限定されるものではない。以下の実施形態において、その構成要素（要素ステップ等も含む）は、特に明示した場合を除き、必須ではない。数値及びその範囲についても同様であり、本発明を制限するものではない。
　本開示において「工程」との語には、他の工程から独立した工程に加え、他の工程と明確に区別できない場合であってもその工程の目的が達成されれば、当該工程も含まれる。
　本開示において「～」を用いて示された数値範囲には、「～」の前後に記載される数値がそれぞれ最小値及び最大値として含まれる。
　本開示中に段階的に記載されている数値範囲において、一つの数値範囲で記載された上限値又は下限値は、他の段階的な記載の数値範囲の上限値又は下限値に置き換えてもよい。また、本開示中に記載されている数値範囲において、その数値範囲の上限値又は下限値は、実施例に示されている値に置き換えてもよい。
　本開示において各成分は該当する物質を複数種含んでいてもよい。組成物中に各成分に該当する物質が複数種存在する場合、各成分の含有率又は含有量は、特に断らない限り、組成物中に存在する当該複数種の物質の合計の含有率又は含有量を意味する。
　本開示において各成分に該当する粒子は複数種含んでいてもよい。組成物中に各成分に該当する粒子が複数種存在する場合、各成分の粒子径は、特に断らない限り、組成物中に存在する当該複数種の粒子の混合物についての値を意味する。
　本開示において「層」又は「膜」との語には、当該層又は膜が存在する領域を観察したときに、当該領域の全体に形成されている場合に加え、当該領域の一部にのみ形成されている場合も含まれる。
　本開示において「積層」との語は、層を積み重ねることを示し、二以上の層が結合されていてもよく、二以上の層が着脱可能であってもよい。 EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including elemental steps and the like) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the present invention.
In this disclosure, the term "step" includes not only a step that is independent from other steps, but also a step that cannot be clearly distinguished from other steps, as long as the purpose of the step is achieved. .
In the present disclosure, numerical ranges indicated using "~" include the numerical values written before and after "~" as minimum and maximum values, respectively.
In the numerical ranges described step by step in this disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. . Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the Examples.
In the present disclosure, each component may contain multiple types of corresponding substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
In the present disclosure, each component may include a plurality of types of particles. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.
In this disclosure, the term "layer" or "film" refers to the case where the layer or film is formed only in a part of the region, in addition to the case where the layer or film is formed in the entire region when observing the region where the layer or film is present. This also includes cases where it is formed.
In this disclosure, the term "laminate" refers to stacking layers, and two or more layers may be bonded, or two or more layers may be removable.
〔熱伝導シート〕
　本開示の熱伝導シートは、鱗片状粒子、楕円体状粒子及び棒状粒子からなる群より選択される少なくとも１種の黒鉛粒子（Ａ）を含有し、前記鱗片状粒子の場合には面方向、前記楕円体状粒子の場合には長軸方向、前記棒状粒子の場合には長軸方向が、厚み方向に配向している熱伝導層と、樹脂成分と、熱伝導性フィラとを含み、前記熱伝導層の主面の少なくとも一部に位置する接着層と、を備える。 [Thermal conductive sheet]
The thermally conductive sheet of the present disclosure contains at least one graphite particle (A) selected from the group consisting of scale-like particles, ellipsoid-like particles, and rod-like particles, and in the case of the scale-like particles, in the planar direction; In the case of the ellipsoidal particles, the long axis direction is oriented in the thickness direction, and in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction. an adhesive layer located on at least a portion of the main surface of the heat conductive layer.
　本開示の熱伝導シートは、黒鉛粒子（Ａ）が厚み方向に配向している熱伝導層を備えることにより、厚み方向の熱伝導性に優れ、低い熱抵抗を示すと考えられる。 The thermally conductive sheet of the present disclosure is considered to have excellent thermal conductivity in the thickness direction and exhibit low thermal resistance because it includes a thermally conductive layer in which graphite particles (A) are oriented in the thickness direction.
　さらに、熱伝導シートは、黒鉛粒子（Ａ）を含む熱伝導層とともに前述の接着層を備えることで、より低い熱抵抗を示すと考えられる。この理由は以下のように推測される。なお、本開示は以下の推測に限定されない。黒鉛粒子（Ａ）が厚み方向に配向している熱伝導シートでは、被着体と接触する表面に凹凸が存在しており、熱抵抗の大部分が、熱伝導シートと熱伝導シートに接触する発熱体、放熱体等の被着体との接触により生じる隙間による抵抗（「接触熱抵抗」ともいう）に由来する。本開示の熱伝導シートでは、樹脂成分と、熱伝導性フィラとを含む接着層を熱伝導層の主面の少なくとも一部に配置することで、熱伝導シートと発熱体、放熱体等の被着体とを加熱圧着させる際に熱、圧力等によって接着層が軟化、変形等する。接着層が軟化、変形等することで熱伝導シートと被着体とを加熱圧着する際に生じる隙間（例えば、熱伝導シートの凹凸に由来する隙間）が当該接着層で埋められる。これにより、熱伝導シートと被着体との隙間を低減しつつ、接着層を介して熱伝導シートと被着体とを密着させることができるため、接触熱抵抗が大幅に低減される。 Furthermore, it is thought that the thermally conductive sheet exhibits lower thermal resistance by including the aforementioned adhesive layer together with the thermally conductive layer containing the graphite particles (A). The reason for this is assumed to be as follows. Note that the present disclosure is not limited to the following speculations. In a thermally conductive sheet in which graphite particles (A) are oriented in the thickness direction, there are irregularities on the surface that contacts the adherend, and most of the thermal resistance is caused by contact between the thermally conductive sheet and the thermally conductive sheet. It originates from the resistance (also referred to as "contact thermal resistance") caused by gaps caused by contact with adherends such as heating elements and heat radiating elements. In the thermally conductive sheet of the present disclosure, by disposing an adhesive layer containing a resin component and a thermally conductive filler on at least a part of the main surface of the thermally conductive layer, the thermally conductive sheet and the heating element, the heat radiating element, etc. are covered. When heat-pressing the adhesive layer to the adhered body, the adhesive layer softens, deforms, etc. due to heat, pressure, etc. As the adhesive layer softens, deforms, etc., gaps that occur when the thermally conductive sheet and the adherend are bonded under heat and pressure (for example, gaps resulting from unevenness of the thermally conductive sheet) are filled with the adhesive layer. Thereby, the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer while reducing the gap between the thermally conductive sheet and the adherend, so that the thermal contact resistance is significantly reduced.
　発熱体、放熱体等の被着体の表面に凹凸が存在する場合にも、接触熱抵抗が生じやすくなる。この場合、熱伝導シートに含まれる熱伝導フィラ等の配向を調整させる方法では熱抵抗を低減させることは困難である。一方、本開示の熱伝導シートを用いることで、接着層を介して熱伝導シートと、表面に凹凸が存在する被着体とを密着させることができる。このとき、熱伝導シートと被着体とを加熱圧着する際に生じる隙間（例えば、被着体の凹凸に由来する隙間）が接着層で埋められることになるため、接触熱抵抗が大幅に低減される。 Contact thermal resistance is also likely to occur when there are irregularities on the surface of an adherend such as a heating element or a heat radiating element. In this case, it is difficult to reduce the thermal resistance by adjusting the orientation of thermally conductive fillers and the like included in the thermally conductive sheet. On the other hand, by using the thermally conductive sheet of the present disclosure, the thermally conductive sheet and an adherend having irregularities on the surface can be brought into close contact via the adhesive layer. At this time, the adhesive layer fills the gaps that occur when heat-pressing the thermally conductive sheet and the adherend (for example, gaps caused by unevenness of the adherend), significantly reducing contact thermal resistance. be done.
　本開示の熱伝導シートに含まれる熱伝導層は、黒鉛粒子（Ａ）を少なくとも含み、本開示の効果を奏する範囲において、後述する成分を含んでいてもよい。以下、本開示の熱伝導層に用いられる材料を説明する。 The thermally conductive layer included in the thermally conductive sheet of the present disclosure includes at least graphite particles (A), and may also include components described below within the range that produces the effects of the present disclosure. The materials used for the thermally conductive layer of the present disclosure will be described below.
＜黒鉛粒子（Ａ）＞
　熱伝導シートに含まれる熱伝導層は、黒鉛粒子（Ａ）を含有する。黒鉛粒子（Ａ）は、高熱伝導性フィラとして主に機能すると考えられる。黒鉛粒子（Ａ）は、鱗片状粒子、楕円体状粒子及び棒状粒子からなる群より選択される少なくとも１種である。また、黒鉛粒子（Ａ）は、鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向が、厚み方向に配向している。また、黒鉛粒子（Ａ）は、鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向に、結晶中の六員環面が配向していることが好ましい。六員環面とは、六方晶系において六員環が形成されている面であり、（０００１）結晶面を意味する。 <Graphite particles (A)>
The thermally conductive layer included in the thermally conductive sheet contains graphite particles (A). It is believed that the graphite particles (A) primarily function as a highly thermally conductive filler. The graphite particles (A) are at least one type selected from the group consisting of scaly particles, ellipsoidal particles, and rod-shaped particles. In addition, the graphite particles (A) are oriented in the plane direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the thickness direction in the case of rod-like particles. . In addition, the graphite particles (A) have six-membered ring planes in the crystal in the planar direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-like particles. is preferably oriented. The six-membered ring plane is a plane in which a six-membered ring is formed in a hexagonal crystal system, and means a (0001) crystal plane.
　黒鉛粒子（Ａ）の形状は、鱗片状がより好ましい。鱗片状の黒鉛粒子を選択することで、熱伝導性がより向上する傾向にある。これは例えば、鱗片状の黒鉛粒子は、熱伝導層中で、所定の方向へより容易に配向するためと考えることができる。 The shape of the graphite particles (A) is more preferably scaly. By selecting scale-like graphite particles, thermal conductivity tends to be further improved. This can be considered, for example, because the scale-like graphite particles are more easily oriented in a predetermined direction in the heat conductive layer.
　黒鉛粒子（Ａ）の結晶中の六員環面が、鱗片状粒子の面方向、楕円体状粒子の長軸方向又は棒状粒子の長軸方向に配向しているかどうかは、Ｘ線回折測定により確認することができる。黒鉛粒子（Ａ）の結晶中の六員環面の配向方向は、具体的には以下の方法で確認する。 Whether the six-membered ring plane in the crystal of the graphite particle (A) is oriented in the plane direction of the scale-like particle, the long axis direction of the ellipsoidal particle, or the long axis direction of the rod-like particle can be determined by X-ray diffraction measurement. It can be confirmed. Specifically, the orientation direction of the six-membered ring plane in the crystal of the graphite particle (A) is confirmed by the following method.
　まず、黒鉛粒子（Ａ）の鱗片状粒子の面方向、楕円体状粒子の長軸方向又は棒状粒子の長軸方向が、シートの面方向に沿って配向した測定用サンプルシートを作製する。測定用サンプルシートの具体的な作製方法としては、例えば、以下の方法が挙げられる。 First, a sample sheet for measurement is prepared in which the in-plane direction of the scale-like particles, the long-axis direction of the ellipsoidal particles, or the long-axis direction of the rod-like particles of the graphite particles (A) are oriented along the in-plane direction of the sheet. As a specific method for producing the measurement sample sheet, for example, the following method may be mentioned.
　樹脂と、樹脂に対して１０体積％以上の量の黒鉛粒子（Ａ）との混合物をシート化する。ここで用いる「樹脂」とは、Ｘ線回折の妨げになるピークが現れない材料で、かつシート物を形成可能な材料であれば特に制限されない。具体的には、アクリルゴム、ＮＢＲ（アクリロニトリルブタジエンゴム）、ＳＩＢＳ（スチレン－イソブチレン－スチレン共重合体）等、バインダとしての凝集力を有する非晶質樹脂を使用することができる。 A mixture of a resin and graphite particles (A) in an amount of 10% by volume or more based on the resin is formed into a sheet. The "resin" used here is not particularly limited as long as it is a material that does not exhibit peaks that interfere with X-ray diffraction and can be formed into a sheet. Specifically, an amorphous resin having cohesive strength as a binder can be used, such as acrylic rubber, NBR (acrylonitrile butadiene rubber), and SIBS (styrene-isobutylene-styrene copolymer).
　この混合物のシートを、元の厚みの１／１０以下となるようにプレスし、プレスしたシートの複数枚を積層して積層体を形成する。この積層体をさらに１／１０以下まで押し潰す操作を３回以上繰り返して測定用サンプルシートを得る。この操作により、測定用サンプルシート中では、黒鉛粒子（Ａ）が鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向が、測定用サンプルシートの面方向に沿って配向した状態になる。 A sheet of this mixture is pressed to a thickness of 1/10 or less of the original thickness, and a plurality of pressed sheets are laminated to form a laminate. The operation of crushing this laminate to 1/10 or less is repeated three or more times to obtain a sample sheet for measurement. By this operation, in the sample sheet for measurement, if the graphite particle (A) is a scale-like particle, the plane direction, if it is an ellipsoidal particle, the long axis direction, and if it is a rod-like particle, the long axis direction is , it is oriented along the surface direction of the sample sheet for measurement.
　上記のように作製した測定用サンプルシートの表面に対してＸ線回折測定を行う。２θ＝７７°付近に現れる黒鉛の（１１０）面に対応するピークの高さＨ１と、２θ＝２７°付近に現れる黒鉛の（００２）面に対応するピークの高さＨ２とを測定する。このように作製した測定用サンプルシートでは、Ｈ１をＨ２で割った値が０～０．０２となる。 X-ray diffraction measurement is performed on the surface of the sample sheet for measurement produced as described above. Measure the height H1 of the peak corresponding to the (110) plane of graphite appearing around 2θ = 77° and the height H2 of the peak corresponding to the (002) plane of graphite appearing around 2θ = 27°. . In the measurement sample sheet prepared in this manner, the value obtained by dividing H 1 by H 2 is 0 to 0.02.
　このことより、「黒鉛粒子（Ａ）の結晶中の六員環面が、鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向に配向している」とは、黒鉛粒子（Ａ）を含有するシートの表面に対し、Ｘ線回折測定を行い、２θ＝７７°付近に現れる黒鉛粒子（Ａ）の（１１０）面に対応するピークの高さを、２θ＝２７°付近に現れる黒鉛粒子（Ａ）の（００２）面に対応するピークの高さで割った値が０～０．０２となる状態をいう。 From this, it can be concluded that "the six-membered ring plane in the crystal of graphite particles (A) is in the plane direction in the case of scale-like particles, in the major axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-shaped particles. "Oriented in the axial direction" means that X-ray diffraction measurement is performed on the surface of the sheet containing the graphite particles (A), and the (110) plane of the graphite particles (A) that appears around 2θ = 77° A state in which the value obtained by dividing the height of the corresponding peak by the height of the peak corresponding to the (002) plane of the graphite particle (A) appearing around 2θ=27° is 0 to 0.02.
　本開示において、Ｘ線回折測定は以下の条件で行なう。
　装置：例えば、ブルカー・エイエックスエス株式会社「Ｄ８ＤＩＳＣＯＶＥＲ」
　Ｘ線源：波長１．５４０６ｎｍのＣｕＫα、４０ｋＶ、４０ｍＡ
　ステップ（測定刻み幅）：０．０１°
　ステップタイム：７２０ｓｅｃ In the present disclosure, X-ray diffraction measurements are performed under the following conditions.
Device: For example, Bruker AXS Co., Ltd. “D8DISCOVER”
X-ray source: CuKα with a wavelength of 1.5406 nm, 40 kV, 40 mA
Step (measurement step width): 0.01°
Step time: 720sec
　ここで、「黒鉛粒子が鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向が熱伝導層の厚み方向に配向している」とは、鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸方向、及び棒状粒子の場合には長軸方向と、熱伝導層の表面（主面）とのなす角度（以下、「配向角度」ともいう）が、６０°以上であることをいう。配向角度は、８０°以上であることが好ましく、８５°以上であることがより好ましく、８８°以上であることがさらに好ましい。 Here, ``if the graphite particles are scale-like particles, the planar direction is oriented, in the case of ellipsoidal particles, the long axis direction is oriented, and in the case of rod-shaped particles, the long axis direction is oriented in the thickness direction of the thermally conductive layer. "" means the direction between the surface (principal surface) of the thermally conductive layer and the surface direction (principal surface) of the thermally conductive layer. It means that the angle formed (hereinafter also referred to as "orientation angle") is 60° or more. The orientation angle is preferably 80° or more, more preferably 85° or more, and even more preferably 88° or more.
　配向角度は、熱伝導層の断面をＳＥＭ（走査型電子顕微鏡）で観察し、任意の５０個の黒鉛粒子（Ａ）について、鱗片状粒子の場合には面方向と、楕円体状粒子の場合には長軸方向と、及び棒状粒子の場合には長軸方向と、熱伝導層表面（主面）とのなす角度（配向角度）を測定したときの平均値である。 The orientation angle is determined by observing the cross section of the thermally conductive layer with a SEM (scanning electron microscope), and for any 50 graphite particles (A), the orientation angle is determined by the in-plane direction in the case of scaly particles and the in-plane direction in the case of ellipsoidal particles. is the average value when measuring the angle (orientation angle) between the long axis direction, and in the case of rod-shaped particles, the long axis direction and the surface (principal surface) of the thermally conductive layer.
　黒鉛粒子（Ａ）の粒子径は特に制限されない。黒鉛粒子（Ａ）の平均粒子径は、質量平均粒子径として、熱伝導層の平均厚みの１／２以上平均厚み以下であることが好ましい。黒鉛粒子（Ａ）の質量平均粒子径が熱伝導層の平均厚みの１／２以上であると、熱伝導層中に効率的な熱伝導パスが形成され、熱伝導率が向上する傾向にある。黒鉛粒子（Ａ）の質量平均粒子径が熱伝導層の平均厚み以下であると、熱伝導層の表面からの黒鉛粒子（Ａ）の突出が抑えられ、熱伝導層の表面の密着性に優れる傾向にある。 The particle size of the graphite particles (A) is not particularly limited. The average particle diameter of the graphite particles (A), as a mass average particle diameter, is preferably 1/2 or more and not more than the average thickness of the heat conductive layer. When the mass average particle diameter of the graphite particles (A) is 1/2 or more of the average thickness of the heat conductive layer, an efficient heat conduction path is formed in the heat conductive layer, and thermal conductivity tends to improve. . When the mass average particle diameter of the graphite particles (A) is less than or equal to the average thickness of the thermally conductive layer, protrusion of the graphite particles (A) from the surface of the thermally conductive layer is suppressed, and the adhesion of the surface of the thermally conductive layer is excellent. There is a tendency.
　鱗片状粒子の場合には面方向、楕円体状粒子の場合には長軸、及び棒状粒子の場合には長軸方向が、厚み方向に配向するように熱伝導層を作製する方法は特に制限されず、例えば特開２００８－２８０４９６号公報に記載されている方法を用いることができる。具体的には、組成物を用いてシートを作製し、当該シートを積層して積層体を作製し、当該積層体の側端面を（例えば、積層体の主面から出る法線に対して０°～３０°の角度で）スライスする方法（以下、「積層スライス法」ともいう）を用いることができる。 There are particular restrictions on the method of producing a thermally conductive layer so that the plane direction is oriented in the case of scale-like particles, the long axis direction in the case of ellipsoidal particles, and the long axis direction in the case of rod-like particles is oriented in the thickness direction. For example, the method described in JP-A No. 2008-280496 can be used. Specifically, sheets are produced using the composition, the sheets are laminated to produce a laminate, and the side end surfaces of the laminate are aligned (for example, 0 with respect to the normal from the main surface of the laminate). A slicing method (hereinafter also referred to as "layered slicing method") can be used.
　尚、上記積層スライス法を用いる場合、原料として用いる黒鉛粒子（Ａ）の粒子径は、質量平均粒子径として、熱伝導層の平均厚みの１／２倍以上であることが好ましく、平均厚みを超えてもよい。原料として用いる黒鉛粒子（Ａ）の粒子径が熱伝導層の平均厚みを超えてもよい理由は、例えば、熱伝導層の平均厚みを超える粒子径の黒鉛粒子（Ａ）を含んでいても、黒鉛粒子（Ａ）ごとスライスして熱伝導層を形成するため、結果的に黒鉛粒子（Ａ）が熱伝導層の表面から突出しないからである。またこのように黒鉛粒子（Ａ）ごとスライスすると、熱伝導層の厚み方向に貫通する黒鉛粒子（Ａ）が多数生じ、極めて効率的な熱伝導パスが形成され、熱伝導性がより向上する傾向にある。 In addition, when using the above laminated slicing method, the particle size of the graphite particles (A) used as a raw material is preferably 1/2 or more of the average thickness of the thermally conductive layer as a mass average particle size, and the average thickness is You can exceed it. The reason why the particle size of the graphite particles (A) used as a raw material may exceed the average thickness of the thermally conductive layer is that, for example, even if the graphite particles (A) have a particle size that exceeds the average thickness of the thermally conductive layer, This is because the graphite particles (A) are sliced together to form the thermally conductive layer, and as a result, the graphite particles (A) do not protrude from the surface of the thermally conductive layer. In addition, when slicing each graphite particle (A) in this way, a large number of graphite particles (A) penetrating the heat conductive layer in the thickness direction are generated, forming an extremely efficient heat conduction path, which tends to further improve thermal conductivity. It is in.
　積層スライス法を用いる場合、原料として用いる黒鉛粒子（Ａ）の粒子径は、質量平均粒子径として、熱伝導層の平均厚みの１倍～５倍であることがより好ましく、２倍～４倍であることが、さらに好ましい。黒鉛粒子（Ａ）の質量平均粒子径が、熱伝導層の平均厚みの１倍以上であると、さらに効率的な熱伝導パスが形成され、熱伝導性がより向上する。熱伝導層の平均厚みの５倍以下であると、黒鉛粒子（Ａ）の表面部に占める面積が大きくなりすぎるのが抑えられ、密着性の低下が抑制できる。 When using the laminated slicing method, the particle diameter of the graphite particles (A) used as a raw material is preferably 1 to 5 times, and 2 to 4 times, the average thickness of the thermally conductive layer as a mass average particle diameter. It is more preferable that When the mass average particle diameter of the graphite particles (A) is one or more times the average thickness of the heat conductive layer, a more efficient heat conduction path is formed and the heat conductivity is further improved. When the thickness is 5 times or less the average thickness of the thermally conductive layer, the area occupied by the graphite particles (A) on the surface portion can be prevented from becoming too large, and a decrease in adhesiveness can be suppressed.
　黒鉛粒子（Ａ）の質量平均粒子径（Ｄ５０）は、レーザー回折・散乱法を適応したレーザー回折式粒度分布装置（例えば、日機装株式会社「マイクロトラックシリーズＭＴ３３００」）を用いて測定され、質量累積粒度分布曲線を小粒径側から描いた場合に、質量累積が５０％となる粒子径に対応する。 The mass average particle diameter (D50) of the graphite particles (A) is measured using a laser diffraction particle size distribution device (for example, Nikkiso Co., Ltd. "Microtrack series MT3300") adapted to the laser diffraction/scattering method, and the mass cumulative When the particle size distribution curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
　熱伝導層は、鱗片状粒子、楕円体状粒子及び棒状粒子以外の黒鉛粒子を含んでいてもよく、球状黒鉛粒子、人造黒鉛粒子、薄片化黒鉛粒子、酸処理黒鉛粒子、膨張黒鉛粒子、炭素繊維フレーク等を含んでいてもよい。
　黒鉛粒子（Ａ）としては、鱗片状粒子が好ましく、結晶化度が高くかつ大粒径の鱗片が得やすい観点から、シート化した膨張黒鉛を粉砕して得られる、鱗片状の膨張黒鉛粒子が好ましい。 The thermally conductive layer may contain graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, such as spherical graphite particles, artificial graphite particles, exfoliated graphite particles, acid-treated graphite particles, expanded graphite particles, and carbon. It may also contain fiber flakes and the like.
The graphite particles (A) are preferably scale-like particles, and from the viewpoint of having a high degree of crystallinity and easily obtaining scales with a large particle size, scale-like expanded graphite particles obtained by crushing expanded graphite in the form of a sheet are preferred. preferable.
　熱伝導層中の黒鉛粒子（Ａ）の含有率は、例えば、熱伝導性と密着性のバランスの観点から、１５体積％～５０体積％であることが好ましく、２０体積％～４５体積％であることがより好ましく、２５体積％～４０体積％であることがさらに好ましい。
　黒鉛粒子（Ａ）の含有率が１５体積％以上であると、熱伝導性が向上する傾向にある。また、黒鉛粒子（Ａ）の含有率が５０体積％以下であると、粘着性及び密着性の低下を抑制できる傾向にある。
　尚、熱伝導層が鱗片状粒子、楕円体状粒子及び棒状粒子以外の黒鉛粒子を含有する場合には、黒鉛粒子全体の含有率が上記範囲であることが好ましい。 The content of graphite particles (A) in the thermally conductive layer is preferably 15% to 50% by volume, and preferably 20% to 45% by volume from the viewpoint of the balance between thermal conductivity and adhesion. It is more preferable that the amount is 25% to 40% by volume.
When the content of graphite particles (A) is 15% by volume or more, thermal conductivity tends to improve. Furthermore, when the content of graphite particles (A) is 50% by volume or less, deterioration in tackiness and adhesiveness tends to be suppressed.
In addition, when the heat conductive layer contains graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, it is preferable that the content of the entire graphite particles is within the above range.
　黒鉛粒子（Ａ）の含有率（体積％）は、次式により求めた値である。
　黒鉛粒子（Ａ）の含有率（体積％）＝［（Ａｗ／Ａｄ）／｛（Ａｗ／Ａｄ）＋（Ｘｗ／Ｘｄ）｝］×１００
　　Ａｗ：黒鉛粒子（Ａ）の質量組成（質量％）
　　Ｘｗ：その他の任意成分の質量組成（質量％）
　　Ａｄ：黒鉛粒子（Ａ）の密度（本開示においてＡｄは２．１で計算する。）
　　Ｘｄ：その他の任意成分の密度 The content rate (volume %) of graphite particles (A) is a value determined by the following formula.
Content rate (volume %) of graphite particles (A) = [(Aw/Ad)/{(Aw/Ad)+(Xw/Xd)}]×100
Aw: Mass composition (mass%) of graphite particles (A)
Xw: mass composition of other arbitrary components (mass%)
Ad: Density of graphite particles (A) (In this disclosure, Ad is calculated as 2.1.)
Xd: Density of other arbitrary components
＜２５℃で液状の成分（Ｂ）＞
　本開示の熱伝導シートに含まれる熱伝導層は、２５℃で液状の成分（以下、「液状成分（Ｂ）」ともいう）を含有してもよい。本開示において「２５℃で液状」とは、２５℃において流動性と粘性とを示し、かつ粘性を示す尺度である粘度が２５℃において０．０００１Ｐａ・ｓ～１０００Ｐａ・ｓである物質を意味する。本開示において「粘度」とは、２５℃でレオメーターを用いて５．０ｓ－１のせん断速度で測定したときの値と定義する。詳細には、「粘度」は、せん断粘度として、コーンプレート（直径４０ｍｍ、コーン角０°）を装着した回転式のせん断粘度計を用いて、温度２５℃で測定される。 <Component (B) that is liquid at 25°C>
The thermally conductive layer included in the thermally conductive sheet of the present disclosure may contain a component that is liquid at 25° C. (hereinafter also referred to as "liquid component (B)"). In the present disclosure, "liquid at 25°C" means a substance that exhibits fluidity and viscosity at 25°C, and has a viscosity, which is a measure of viscosity, of 0.0001 Pa·s to 1000 Pa·s at 25°C. . In the present disclosure, "viscosity" is defined as a value measured at 25° C. using a rheometer at a shear rate of 5.0 s −1 . Specifically, "viscosity" is measured as shear viscosity at a temperature of 25° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0°).
　液状成分（Ｂ）の２５℃における粘度は０．００１Ｐａ・ｓ～１００Ｐａ・ｓであることが好ましく、０．０１Ｐａ・ｓ～１０Ｐａ・ｓであることがより好ましい。 The viscosity of the liquid component (B) at 25° C. is preferably 0.001 Pa·s to 100 Pa·s, more preferably 0.01 Pa·s to 10 Pa·s.
　液状成分（Ｂ）は２５℃で液状である限り特に制限されず、高分子化合物（ポリマー）であることが好ましい。液状成分（Ｂ）としては、ポリブテン、ポリイソプレン、ポリサルファイド、アクリロニトリルゴム、シリコーンゴム、炭化水素樹脂、テルペン樹脂、アクリル樹脂等が挙げられる。中でも、耐熱性の観点から、液状成分（Ｂ）はポリブテンを含むことが好ましい。液状成分（Ｂ）は１種を単独で用いても２種以上を併用してもよい。 The liquid component (B) is not particularly limited as long as it is liquid at 25°C, and is preferably a high molecular compound (polymer). Examples of the liquid component (B) include polybutene, polyisoprene, polysulfide, acrylonitrile rubber, silicone rubber, hydrocarbon resin, terpene resin, and acrylic resin. Among these, from the viewpoint of heat resistance, it is preferable that the liquid component (B) contains polybutene. The liquid component (B) may be used alone or in combination of two or more.
　ここで、ポリブテンはイソブテン又はノルマルブテンを重合して得られる重合体をいう。イソブテンとノルマルブテンを共重合して得られる重合体も含む。構造としては、「－ＣＨ２－Ｃ（ＣＨ３）２－」又は、「－ＣＨ２－ＣＨ（ＣＨ２ＣＨ３）－」で表される構造単位を有する重合体をいう。ポリイソブチレンと称されることもある。ポリブテンは上記構造を含んでいればよく、その他の構造については特に制限されない。 Here, polybutene refers to a polymer obtained by polymerizing isobutene or normal butene. It also includes polymers obtained by copolymerizing isobutene and normal butene. As for the structure, it refers to a polymer having a structural unit represented by "-CH 2 --C(CH 3 ) 2 --" or "-CH 2 --CH(CH 2 CH 3 )-". It is also sometimes called polyisobutylene. The polybutene only needs to contain the above structure, and other structures are not particularly limited.
　ポリブテンとしてはブテンの単独重合体、及びブテンと他のモノマー成分との共重合体が挙げられる。他のモノマー成分との共重合体の例としては、イソブテンとスチレンとの共重合体又はイソブテンとエチレンとの共重合体が挙げられる。共重合体は、ランダム共重合体、ブロック共重合体及びグラフト共重合体のいずれであってもよい。 Examples of polybutenes include butene homopolymers and copolymers of butene and other monomer components. Examples of copolymers with other monomer components include copolymers of isobutene and styrene or copolymers of isobutene and ethylene. The copolymer may be a random copolymer, a block copolymer, or a graft copolymer.
　ポリブテンとしては、例えば、日油株式会社の「日油ポリブテンＴＭ・エマウエット（登録商標）」、ＪＸＴＧエネルギー株式会社の「日石ポリブテン」、ＪＸＴＧエネルギー株式会社の「テトラックス」、ＪＸＴＧエネルギー株式会社の「ハイモール」、及び巴工業株式会社の「ポリイソブチレン」が挙げられる。 Examples of polybutene include NOF Polybutene TM Emmawet (registered trademark) from NOF Corporation, Nisseki Polybutene from JXTG Energy Corporation, Tetrax from JXTG Energy Corporation, and Tetrax from JXTG Energy Corporation. Examples include "Himol" and "Polyisobutylene" manufactured by Tomoe Kogyo Co., Ltd.
　液状成分（Ｂ）は、例えば、耐熱性及び耐湿度性に優れた応力緩和剤と粘着性付与剤とを兼ねて主に機能すると考えられる。また、後述するホットメルト剤（Ｄ）と併用することにより、凝集力及び加熱時の流動性をより高めることができる傾向にある。 It is thought that the liquid component (B) mainly functions as, for example, a stress relieving agent with excellent heat resistance and humidity resistance, and a tackifying agent. In addition, by using it in combination with a hot melt agent (D) described below, it tends to be possible to further improve cohesive force and fluidity during heating.
　熱伝導層中、液状成分（Ｂ）の含有率は、粘着力、密着性、シート強度、耐加水分解性等をより高める観点から、１０体積％～５５体積％であることが好ましく、１５体積％～５０体積％であることがより好ましく、２０体積％～５０体積％であることがさらに好ましい。
　液状成分（Ｂ）の含有率が１０体積％以上であると、粘着性及び密着性がより向上する傾向にある。液状成分（Ｂ）の含有率が５５体積％以下であると、シート強度及び熱伝導性の低下をより効果的に抑制できる傾向にある。 The content of the liquid component (B) in the thermally conductive layer is preferably 10% by volume to 55% by volume, from the viewpoint of further enhancing adhesive strength, adhesion, sheet strength, hydrolysis resistance, etc. % to 50% by volume, and even more preferably 20% to 50% by volume.
When the content of the liquid component (B) is 10% by volume or more, the tackiness and adhesiveness tend to be further improved. When the content of the liquid component (B) is 55% by volume or less, reductions in sheet strength and thermal conductivity tend to be more effectively suppressed.
＜アクリル酸エステル系高分子（Ｃ）＞
　熱伝導シートに含まれる熱伝導層はアクリル酸エステル系高分子（Ｃ）を含有してもよい。アクリル酸エステル系高分子（Ｃ）は、例えば、粘着性付与剤と、反りに追従するために厚みが復元するような弾性付与剤とを兼ねて主に機能すると考えられる。 <Acrylic acid ester polymer (C)>
The thermally conductive layer included in the thermally conductive sheet may contain an acrylic acid ester polymer (C). It is thought that the acrylic ester polymer (C) mainly functions as, for example, a tackifier and an elasticity-imparting agent that allows the thickness to be restored in order to follow warping.
　アクリル酸エステル系高分子（Ｃ）は、例えば、アクリル酸ブチル、アクリル酸エチル、アクリロニトリル、アクリル酸、グリシジルメタクリレート、アクリル酸２－エチルヘキシル等を主要な原料成分とし、必要に応じてアクリル酸メチル等を共重合させたアクリル酸エステル系高分子（所謂アクリルゴム）が好適に用いられる。アクリル酸エステル系高分子（Ｃ）は１種を単独で用いても２種以上を併用してもよい。 The acrylic ester polymer (C) has, for example, butyl acrylate, ethyl acrylate, acrylonitrile, acrylic acid, glycidyl methacrylate, 2-ethylhexyl acrylate, etc. as main raw material components, and if necessary, methyl acrylate, etc. An acrylic acid ester polymer (so-called acrylic rubber) copolymerized with is preferably used. The acrylic ester polymer (C) may be used alone or in combination of two or more.
　アクリル酸エステル系高分子（Ｃ）の重量平均分子量は１００，０００～１，０００，０００であることが好ましく、より好ましくは２５０，０００～７００，０００であり、さらに好ましくは４００，０００～６００，０００である。重量平均分子量が、１００，０００以上であると膜強度に優れる傾向にあり、１，０００，０００以下であると柔軟性に優れる傾向にある。
　重量平均分子量は、ゲルパーミエーションクロマトグラフィーにより、標準ポリスチレンの検量線を用いて測定することができる。 The weight average molecular weight of the acrylic ester polymer (C) is preferably 100,000 to 1,000,000, more preferably 250,000 to 700,000, and even more preferably 400,000 to 600. ,000. When the weight average molecular weight is 100,000 or more, the film tends to have excellent strength, and when it is 1,000,000 or less, it tends to have excellent flexibility.
The weight average molecular weight can be measured by gel permeation chromatography using a standard polystyrene calibration curve.
　アクリル酸エステル系高分子（Ｃ）のガラス転移温度（Ｔｇ）は、２０℃以下であることが好ましく、より好ましくは－７０℃～０℃であり、さらに好ましくは－５０℃～－２０℃である。ガラス転移温度が２０℃以下であると、柔軟性及び粘着性に優れる傾向にある。
　ガラス転移温度（Ｔｇ）は、引張による動的粘弾性測定を行い、それによって導き出されるｔａｎδより算出できる。 The glass transition temperature (Tg) of the acrylic ester polymer (C) is preferably 20°C or lower, more preferably -70°C to 0°C, even more preferably -50°C to -20°C. be. When the glass transition temperature is 20° C. or lower, flexibility and adhesiveness tend to be excellent.
The glass transition temperature (Tg) can be calculated from tan δ derived from dynamic viscoelasticity measurement by tension.
　アクリル酸エステル系高分子（Ｃ）は内部添加により熱伝導層全体に存在させてもよく、表面に塗布又は含浸することにより表面に局在化させてもよい。特に、片面に塗布、又は片面に含浸すると、片面のみに強いタック性を付与できるため、ハンドリング性の良いシートが得られる点で好ましい。 The acrylic ester polymer (C) may be present in the entire thermally conductive layer by internal addition, or may be localized on the surface by coating or impregnating the surface. In particular, coating on one side or impregnating one side is preferable because strong tackiness can be imparted to only one side, resulting in a sheet with good handling properties.
　熱伝導層中、アクリル酸エステル系高分子（Ｃ）の含有率は、３体積％～２５体積％であることが好ましく、５体積％～２０体積％であることがより好ましく、７体積％～１５体積％であることがさらに好ましい。 The content of the acrylic ester polymer (C) in the thermally conductive layer is preferably from 3% by volume to 25% by volume, more preferably from 5% to 20% by volume, and from 7% by volume. More preferably, it is 15% by volume.
＜ホットメルト剤（Ｄ）＞
　熱伝導シートに含まれる熱伝導層はホットメルト剤（Ｄ）を含有していてもよい。ホットメルト剤（Ｄ）は、熱伝導層の強度向上、及び加熱時の流動性を向上する効果がある。 <Hot melt agent (D)>
The heat conductive layer included in the heat conductive sheet may contain a hot melt agent (D). The hot melt agent (D) has the effect of improving the strength of the heat conductive layer and improving the fluidity during heating.
　ホットメルト剤（Ｄ）としては、例えば、芳香族系石油樹脂、テルペンフェノール樹脂、及びシクロペンタジエン系石油樹脂が挙げられる。また、ホットメルト剤（Ｄ）は水素化芳香族系石油樹脂、又は水素化テルペンフェノール樹脂であってもよい。ホットメルト剤（Ｄ）は１種を単独で用いても２種以上を併用してもよい。 Examples of the hot melt agent (D) include aromatic petroleum resins, terpene phenol resins, and cyclopentadiene petroleum resins. Further, the hot melt agent (D) may be a hydrogenated aromatic petroleum resin or a hydrogenated terpene phenol resin. The hot melt agent (D) may be used alone or in combination of two or more.
　中でも、液状成分（Ｂ）としてポリブテンを用いる場合には、ホットメルト剤（Ｄ）は、水素化芳香族系石油樹脂、及び水素化テルペンフェノール樹脂からなる群から選択される少なくとも１種を含むことが好ましい。これらのホットメルト剤（Ｄ）は、安定性が高く、かつポリブテンとの相溶性に優れるため、熱伝導層を構成した場合に、より優れた熱伝導性、柔軟性、及びハンドリング性が達成できる傾向にある。 Among them, when polybutene is used as the liquid component (B), the hot melt agent (D) should contain at least one selected from the group consisting of hydrogenated aromatic petroleum resins and hydrogenated terpene phenolic resins. is preferred. These hot melt agents (D) have high stability and excellent compatibility with polybutene, so when forming a thermally conductive layer, they can achieve better thermal conductivity, flexibility, and handling properties. There is a tendency.
　市販で入手可能な水素化芳香族系石油樹脂としては、例えば、荒川化学工業株式会社の「アルコン」、及び出光興産株式会社の「アイマーブ」が挙げられる。また、市販で入手可能な水素化テルペンフェノール樹脂としては、例えば、ヤスハラケミカル株式会社の「クリアロン」が挙げられる。また、市販で入手可能なシクロペンタジエン系石油樹脂としては、例えば、日本ゼオン株式会社の「クイントン」、及び丸善石油化学株式会社の「マルカレッツ」が挙げられる。 Commercially available hydrogenated aromatic petroleum resins include, for example, "Alcon" by Arakawa Chemical Co., Ltd. and "Imarv" by Idemitsu Kosan Co., Ltd. Furthermore, examples of commercially available hydrogenated terpene phenol resins include "Clearon" manufactured by Yasuhara Chemical Co., Ltd. Commercially available cyclopentadiene petroleum resins include, for example, "Quinton" manufactured by Nippon Zeon Co., Ltd. and "Marcarez" manufactured by Maruzen Petrochemical Co., Ltd.
　ホットメルト剤（Ｄ）は、２５℃で固形であり、軟化温度が４０℃～１５０℃であることが好ましい。ホットメルト剤（Ｄ）として熱可塑性の樹脂を使用すると、熱圧着時の軟化流動性が向上する結果、密着性が向上する傾向にある。また、軟化温度が４０℃以上であると、室温付近での凝集力を保つことができる結果、必要なシート強度が得やすくなって取扱い性に優れる傾向にある。軟化温度が１５０℃以下であると、熱圧着時の軟化流動性が高くなる結果、密着性が向上する傾向にある。軟化温度は、６０℃～１２０℃であることがより好ましい。尚、軟化温度は、環球法（ＪＩＳ　Ｋ　２２０７：１９９６）で測定される。 It is preferable that the hot melt agent (D) is solid at 25°C and has a softening temperature of 40°C to 150°C. When a thermoplastic resin is used as the hot melt agent (D), the softening fluidity during thermocompression bonding is improved, and as a result, the adhesion tends to be improved. Further, when the softening temperature is 40° C. or higher, cohesive force can be maintained near room temperature, and as a result, it becomes easier to obtain the necessary sheet strength and tends to be excellent in handleability. When the softening temperature is 150° C. or less, the softening fluidity during thermocompression bonding increases, and as a result, the adhesion tends to improve. The softening temperature is more preferably 60°C to 120°C. Note that the softening temperature is measured by the ring and ball method (JIS K 2207:1996).
　熱伝導層中のホットメルト剤（Ｄ）の含有率は、粘着力、密着性、シート強度等を高める観点から、３体積％～２５体積％であることが好ましく、５体積％～２０体積％であることがより好ましく、５体積％～１５体積％であることがさらに好ましい。
　ホットメルト剤（Ｄ）の含有率が３体積％以上であると、粘着力、加熱流動性、シート強度等が十分となる傾向にあり、２５体積％以下であると、柔軟性が十分となってハンドリング性及び耐サーマルサイクル性に優れる傾向にある。 The content of the hot melt agent (D) in the thermally conductive layer is preferably 3% to 25% by volume, and preferably 5% to 20% by volume from the viewpoint of increasing adhesive strength, adhesion, sheet strength, etc. It is more preferable that the amount is 5% by volume to 15% by volume.
When the content of the hot melt agent (D) is 3% by volume or more, adhesive strength, heat fluidity, sheet strength, etc. tend to be sufficient, and when the content is 25% by volume or less, flexibility is insufficient. They tend to have excellent handling properties and thermal cycle resistance.
＜酸化防止剤（Ｅ）＞
　熱伝導シートに含まれる熱伝導層は、例えば高温時の熱安定性を付与する目的で、酸化防止剤（Ｅ）を含有していてもよい。酸化防止剤（Ｅ）としては、フェノール系酸化防止剤、リン系酸化防止剤、アミン系酸化防止剤、イオウ系酸化防止剤、ヒドラジン系酸化防止剤、アミド系酸化防止剤等が挙げられる。酸化防止剤（Ｅ）は、使用される温度条件等により適宜選択してよく、フェノール系酸化防止剤がより好ましい。酸化防止剤（Ｅ）は１種を単独で用いても２種以上を併用してもよい。 <Antioxidant (E)>
The thermally conductive layer included in the thermally conductive sheet may contain an antioxidant (E), for example, for the purpose of imparting thermal stability at high temperatures. Examples of the antioxidant (E) include phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, hydrazine antioxidants, and amide antioxidants. The antioxidant (E) may be appropriately selected depending on the temperature conditions used, etc., and phenolic antioxidants are more preferred. The antioxidant (E) may be used alone or in combination of two or more.
　市販で入手可能なフェノール系酸化防止剤としては、例えば、株式会社ＡＤＥＫＡのアデカスタブＡＯ－５０、アデカスタブＡＯ－６０、及びアデカスタブＡＯ－８０が挙げられる。 Commercially available phenolic antioxidants include, for example, ADEKA STAB AO-50, ADEKA STAB AO-60, and ADEKA STAB AO-80 manufactured by ADEKA Corporation.
　熱伝導層中の酸化防止剤（Ｅ）の含有率は特に制限されず、０．１体積％～５体積％であることが好ましく、０．２体積％～３体積％以下であることがより好ましく、０．３体積％～１体積％以下であることがさらに好ましい。酸化防止剤（Ｅ）の含有率が０．１体積％以上であると、酸化防止効果が十分に得られる傾向にある。酸化防止剤（Ｅ）の含有率が５体積％以下であると熱伝導層の強度が低下することを抑制できる傾向にある。 The content of the antioxidant (E) in the thermally conductive layer is not particularly limited, and is preferably 0.1% to 5% by volume, more preferably 0.2% to 3% by volume. It is preferably 0.3% by volume to 1% by volume or less. When the content of the antioxidant (E) is 0.1% by volume or more, a sufficient antioxidant effect tends to be obtained. When the content of the antioxidant (E) is 5% by volume or less, the strength of the heat conductive layer tends to be prevented from decreasing.
＜その他の成分＞
　熱伝導シートに含まれる熱伝導層は、黒鉛粒子（Ａ）、液状成分（Ｂ）、アクリル酸エステル系高分子（Ｃ）、ホットメルト剤（Ｄ）、及び酸化防止剤（Ｅ）以外のその他の成分を、目的に応じて含有していてもよい。例えば、熱伝導層は難燃性の観点から、難燃剤を含有していてもよい。難燃剤は特に限定されず、通常用いられる難燃剤から適宜選択することができる。例えば、赤りん系難燃剤及びりん酸エステル系難燃剤が挙げられる。中でも、安全性に優れ、可塑化効果により密着性が向上する観点から、りん酸エステル系難燃剤が好ましい。 <Other ingredients>
The thermally conductive layer contained in the thermally conductive sheet contains graphite particles (A), liquid component (B), acrylic ester polymer (C), hot melt agent (D), and others other than antioxidant (E). Components may be included depending on the purpose. For example, the heat conductive layer may contain a flame retardant from the viewpoint of flame retardancy. The flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. Examples include red phosphorus flame retardants and phosphate ester flame retardants. Among these, phosphoric acid ester flame retardants are preferred from the viewpoint of excellent safety and improved adhesion due to the plasticizing effect.
　赤りん系難燃剤としては、純粋な赤りん粒子の他に、安全性又は安定性を高める目的で種々のコーティングを施したもの、マスターバッチ化したもの等を用いてもよい。具体的には、燐化学工業株式会社のノーバレッド、ノーバエクセル、ノーバクエル、ノーバペレット（いずれも商品名）等が挙げられる。 As the red phosphorus flame retardant, in addition to pure red phosphorus particles, those coated with various coatings for the purpose of increasing safety or stability, those made into masterbatches, etc. may be used. Specific examples include Nobared, Nova Excel, Novaquel, and Nova Pellet (all trade names) manufactured by Rin Kagaku Kogyo Co., Ltd.
　りん酸エステル系難燃剤としては、トリメチルホスフェート、トリエチルホスフェート、トリブチルホスフェート等の脂肪族リン酸エステル；トリフェニルホスフェート、トリクレジルホスフェート、クレジルジフェニルホスフェート、トリキシレニルホスフェート、クレジルジ２，６－キシレニルホスフェート、トリス（ｔ－ブチル化フェニル）ホスフェート、トリス（イソプロピル化フェニル）ホスフェート、リン酸トリアリールイソプロピル化物等の芳香族リン酸エステル；レゾルシノールビスジフェニルホスフェート、ビスフェノールＡビス（ジフェニルホスフェート）、レゾルシノールビスジキシレニルホスフェート等の芳香族縮合リン酸エステルなどが挙げられる。
　これらの中でもビスフェノールＡビス（ジフェニルホスフェート）が、耐加水分解性に優れ、かつ可塑化効果により密着性を向上する効果に優れる観点から好ましい。 Phosphate ester flame retardants include aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, and tributyl phosphate; triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tricylenyl phosphate, and cresyl di-2,6-oxy Aromatic phosphate esters such as renyl phosphate, tris (t-butylated phenyl) phosphate, tris (isopropylated phenyl) phosphate, triaryl isopropylated phosphate; resorcinol bisdiphenyl phosphate, bisphenol A bis (diphenyl phosphate), resorcinol Examples include aromatic condensed phosphoric acid esters such as bisdixylenyl phosphate.
Among these, bisphenol A bis(diphenyl phosphate) is preferable from the viewpoints of excellent hydrolysis resistance and excellent effect of improving adhesion through a plasticizing effect.
　熱伝導層中の難燃剤の含有率は制限されず、難燃性が発揮される量で用いることができ、３０体積％以下程度とすることが好ましく、難燃剤成分が熱伝導層の表面に染み出すことによる熱抵抗の悪化を抑制する観点から、２０体積％以下とすることが好ましい。 The content of the flame retardant in the heat conductive layer is not limited and can be used in an amount that exhibits flame retardancy, and is preferably about 30% by volume or less. From the viewpoint of suppressing deterioration of thermal resistance due to seepage, the content is preferably 20% by volume or less.
　熱伝導層の平均厚みは特に制限されず、目的に応じて適宜選択することができる。熱伝導層の厚みは使用される半導体パッケージ等の仕様により適宜選択することができる。厚みが小さいほど熱抵抗が低下する傾向にあり、厚みが大きいほど反り追従性が向上する傾向にある。熱伝導層の平均厚みは、２０μｍ～３０００μｍであってもよく、熱伝導性及び密着性の観点から、３０μｍ～５００μｍであることが好ましく、５０～４００μｍであることがより好ましい。
　熱伝導層の平均厚みは、電子顕微鏡を用いて、測定対象の断面を観察すること、あるいは、マイクロメータを用いることで無作為に３箇所の厚みを測定し、その算術平均値として与えられる。 The average thickness of the thermally conductive layer is not particularly limited and can be appropriately selected depending on the purpose. The thickness of the thermally conductive layer can be appropriately selected depending on the specifications of the semiconductor package used. As the thickness decreases, the thermal resistance tends to decrease, and as the thickness increases, the warp followability tends to improve. The average thickness of the thermally conductive layer may be 20 μm to 3000 μm, preferably 30 μm to 500 μm, more preferably 50 to 400 μm from the viewpoint of thermal conductivity and adhesion.
The average thickness of the thermally conductive layer is determined by observing the cross section of the measurement target using an electron microscope, or by measuring the thickness at three random locations using a micrometer, and is given as the arithmetic mean value.
＜接着層＞
　本開示の熱伝導シートは、樹脂成分と、熱伝導性フィラとを含み、前記熱伝導層の主面の少なくとも一部に位置する接着層を備える。 <Adhesive layer>
The thermally conductive sheet of the present disclosure includes a resin component and a thermally conductive filler, and includes an adhesive layer located on at least a portion of the main surface of the thermally conductive layer.
　樹脂成分としては、硬化性の樹脂成分、粘着性の樹脂成分、熱可塑性の樹脂成分等が挙げられる。硬化性の樹脂成分としては、熱硬化性の樹脂成分、光硬化性の樹脂成分等が挙げられる。樹脂成分は、１種以上の硬化性の樹脂成分を含んでいてもよく、１種以上の粘着性の樹脂成分を含んでいてもよく、１種以上の熱可塑性の樹脂成分を含んでいてもよい。また、樹脂成分は、２種以上の樹脂成分の混合物であってもよい。 Examples of the resin component include a curable resin component, a sticky resin component, a thermoplastic resin component, and the like. Examples of the curable resin component include a thermosetting resin component, a photocurable resin component, and the like. The resin component may include one or more curable resin components, one or more adhesive resin components, or one or more thermoplastic resin components. good. Further, the resin component may be a mixture of two or more resin components.
　硬化性の樹脂成分としては、例えば、エポキシ樹脂、フェノール樹脂、メラミン樹脂、尿素樹脂、不飽和ポリエステル樹脂、アルキド樹脂、ウレタン樹脂、ビスマレイミド樹脂等のポリイミド樹脂、ポリアミド樹脂、ポリアミドイミド樹脂、シリコーン樹脂及び熱硬化型（メタ）アクリル樹脂が挙げられる。中でも、密着性の観点から、エポキシ樹脂が好ましい。 Examples of curable resin components include epoxy resins, phenol resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, urethane resins, polyimide resins such as bismaleimide resins, polyamide resins, polyamideimide resins, and silicone resins. and thermosetting (meth)acrylic resins. Among these, epoxy resin is preferred from the viewpoint of adhesiveness.
　粘着性の樹脂成分、熱可塑性の樹脂成分等としては、例えば、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、ポリカーボネート（ＰＣ）、ポリスチレン、ポリ塩化ビニル、ビニル系ポリマー、ポリエステル、ポリアミド、アクリロニトリル－ブタジエン－スチレン共重合体樹脂（ＡＢＳ樹脂）、熱可塑型（メタ）アクリル樹脂、アクリロニトリル－エチレン－プロピレン－ジエン－スチレン共重合体樹脂（ＡＥＳ樹脂）及び熱可塑性エラストマーが挙げられる。 Examples of adhesive resin components, thermoplastic resin components, etc. include polyethylene (PE), polypropylene (PP), polycarbonate (PC), polystyrene, polyvinyl chloride, vinyl polymer, polyester, polyamide, acrylonitrile-butadiene- Examples include styrene copolymer resin (ABS resin), thermoplastic (meth)acrylic resin, acrylonitrile-ethylene-propylene-diene-styrene copolymer resin (AES resin), and thermoplastic elastomer.
　熱伝導性フィラとしては、熱伝導性に優れる金属含有粒子、非金属粒子等が挙げられる。熱伝導性フィラは、例えば、熱伝導率が１０Ｗ／（ｍ・Ｋ）以上のフィラであってもよい。熱伝導性フィラは、絶縁性であってよく、導電性であってもよい。 Examples of the thermally conductive filler include metal-containing particles and non-metallic particles that have excellent thermal conductivity. The thermally conductive filler may have a thermal conductivity of 10 W/(m·K) or more, for example. The thermally conductive filler may be insulating or electrically conductive.
　熱伝導性フィラは、銀、酸化アルミニウム、水酸化アルミニウム、酸化マグネシウム、酸化ベリリウム、窒化ホウ素、窒化アルミニウム、窒化ケイ素、炭化ケイ素、二酸化ケイ素、フッ化アルミニウム、フッ化カルシウム及び酸化亜鉛から選択される少なくとも１種の粒子であってもよい。中でも、熱伝導性の観点から、銀粒子が好ましい。 The thermally conductive filler is selected from silver, aluminum oxide, aluminum hydroxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, aluminum fluoride, calcium fluoride and zinc oxide. It may be at least one type of particle. Among them, silver particles are preferred from the viewpoint of thermal conductivity.
　熱伝導性フィラの粒子径は、熱伝導性に優れる観点及び被着体と熱伝導シートとの間の隙間をより低減させる観点から、０．１μｍ～５０μｍであってもよく、０．２μｍ～２０μｍであってもよく、０．５μｍ～１０μｍであってもよい。 The particle size of the thermally conductive filler may be from 0.1 μm to 50 μm, and from 0.2 μm to 50 μm, from the viewpoint of excellent thermal conductivity and from the viewpoint of further reducing the gap between the adherend and the thermally conductive sheet. It may be 20 μm or 0.5 μm to 10 μm.
　熱伝導性フィラの粒子径（Ｄ５０）は、レーザー回折・散乱法を適応したレーザー回折式粒度分布装置（例えば、日機装株式会社製「マイクロトラックシリーズＭＴ３３００」）を用いて測定され、質量累積粒度分布曲線を小粒径側から描いた場合に、質量累積が５０％となる粒子径に対応する。 The particle diameter (D50) of the thermally conductive filler is measured using a laser diffraction type particle size distribution device adapted to the laser diffraction/scattering method (for example, "Microtrack Series MT3300" manufactured by Nikkiso Co., Ltd.), and the mass cumulative particle size distribution is When the curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
　本開示の熱伝導シートにおいて、接着層は熱伝導層の主面の少なくとも一部に位置していればよく、当該主面全体に接着層が位置していてもよく、当該主面の一部（例えば、発熱体、放熱体等の被着体と接触する部分）に接着層が位置していてもよい。 In the thermally conductive sheet of the present disclosure, the adhesive layer only needs to be located on at least a part of the main surface of the thermally conductive layer, and the adhesive layer may be located on the entire main surface, or a part of the main surface. (For example, an adhesive layer may be located at a portion that comes into contact with an adherend such as a heating element or a heat radiating element).
　１つの主面に接着層が位置していてもよく、２つの主面に接着層が位置していてもよい。 The adhesive layer may be located on one main surface, or the adhesive layer may be located on two main surfaces.
　接着層に含まれる樹脂成分の含有率は、例えば、熱伝導性と密着性のバランスの観点から、接着層全量に対して、１質量％～３０質量％であることが好ましく、３質量％～２５質量％であることがより好ましく、５質量％～２０質量％であることがさらに好ましい。 The content of the resin component contained in the adhesive layer is preferably 1% by mass to 30% by mass, and 3% by mass to 30% by mass, based on the total amount of the adhesive layer, for example, from the viewpoint of the balance between thermal conductivity and adhesion. It is more preferably 25% by weight, and even more preferably 5% to 20% by weight.
　接着層に含まれる熱伝導性フィラの含有率は、例えば、熱伝導性と密着性のバランスの観点から、接着層全量に対して、７０質量％～９９質量％であることが好ましく、７５質量％～９７質量％であることがより好ましく、８０質量％～９５質量％であることがさらに好ましい。 The content of the thermally conductive filler contained in the adhesive layer is preferably 70% by mass to 99% by mass, and 75% by mass based on the total amount of the adhesive layer, for example, from the viewpoint of the balance between thermal conductivity and adhesion. % to 97% by mass, and even more preferably 80% to 95% by mass.
　接着層に含まれる樹脂成分及び熱伝導性フィラの合計含有率は、接着層全量に対して、８０質量％～１００質量％であってもよく、９０質量％～１００質量％であってもよい。 The total content of the resin component and the thermally conductive filler contained in the adhesive layer may be 80% by mass to 100% by mass, or 90% by mass to 100% by mass, based on the total amount of the adhesive layer. .
　接着層は、樹脂成分及び熱伝導性フィラ以外の成分を含んでいてもよく、含んでいなくてもよい。樹脂成分及び熱伝導性フィラ以外の成分としては、前述の熱伝導層の項目にて説明されたホットメルト剤（Ｄ）、酸化防止剤（Ｅ）、その他の成分等が挙げられる。 The adhesive layer may or may not contain components other than the resin component and the thermally conductive filler. Components other than the resin component and the thermally conductive filler include the hot melt agent (D), antioxidant (E), and other components described in the section of the thermally conductive layer above.
　接着層が熱硬化性の樹脂成分を含む場合、取り扱い性を高める観点から、接着層は半硬化された状態であることが好ましい。例えば、熱硬化性の樹脂成分及び熱伝導性フィラを含む樹脂組成物に対して加熱、乾燥等の処理を施すことで半硬化された状態である接着層が得られる。 When the adhesive layer contains a thermosetting resin component, the adhesive layer is preferably in a semi-cured state from the viewpoint of improving handling properties. For example, by subjecting a resin composition containing a thermosetting resin component and a thermally conductive filler to treatments such as heating and drying, an adhesive layer in a semi-cured state can be obtained.
　本開示において、半硬化された状態とは、接着層の粘度が常温（２５～３０℃）で１０４Ｐａ・ｓ～１０６Ｐａ・ｓであることを意味する。なお、上記粘度はＤＭＡ（動的粘弾性測定装置；周波数１Ｈｚ、荷重１０ｇ：昇温速度２０℃／分）によって測定される。 In the present disclosure, a semi-cured state means that the adhesive layer has a viscosity of 10 4 Pa·s to 10 6 Pa·s at room temperature (25 to 30° C.). The above viscosity is measured by DMA (dynamic viscoelasticity measuring device; frequency 1 Hz, load 10 g, temperature increase rate 20° C./min).
　半硬化された状態の接着層を得る方法は特に限定されない。例えば、熱伝導層の主面に熱硬化性の樹脂成分、熱伝導性フィラ、溶剤等を含む樹脂組成物を付与し、付与された樹脂組成物を加熱、乾燥等すればよい。あるいは、剥離フィルムに樹脂組成物を付与し、次いで加熱、乾燥等した後、加熱、乾燥等させた樹脂組成物からなる接着層を熱伝導層の主面に熱ロールラミネートしてもよい。加熱、乾燥等の手法としては、熱真空プレス、熱ロールラミネートなどが挙げられる。 The method of obtaining the adhesive layer in a semi-cured state is not particularly limited. For example, a resin composition containing a thermosetting resin component, a thermally conductive filler, a solvent, etc. may be applied to the main surface of the heat conductive layer, and the applied resin composition may be heated, dried, etc. Alternatively, a resin composition may be applied to a release film, then heated, dried, etc., and then an adhesive layer made of the heated, dried, etc. resin composition may be heat roll laminated on the main surface of the heat conductive layer. Examples of methods for heating, drying, etc. include hot vacuum press, hot roll lamination, and the like.
　前記接着層の平均厚みは、２μｍ～５０μｍであることが好ましく、２μｍ～３０μｍであることがより好ましく、２μｍ～２０μｍであることがさらに好ましい。接着層の平均厚みが２μｍ以上であることにより、被着体と熱伝導シートとの間の隙間をより低減されて接触熱抵抗をより低減することができる傾向にある。接着層の平均厚みが５０μｍ以下であることにより、熱伝導シートの熱伝導性により優れる傾向にある。
　電子顕微鏡を用いて、測定対象となる熱伝導層の断面を観察することで無作為に３箇所の厚みを測定し、その算術平均値を接着層の平均厚みとしてもよい。あるいは、接着層を含まない熱伝導層、及び、接着層を含む熱伝導シートについて、マイクロメータを用いることで無作為に３箇所の厚みを測定し、その算術平均値を熱伝導層の平均厚み及び熱伝導シートの平均厚みとしてそれぞれ求めてもよい。そして、熱伝導シートの平均厚みを熱伝導層の平均厚みから差し引くことで接着層の平均厚みを求めてもよい。
　熱伝導層の２つの主面に接着層が形成されている場合、接着層の平均厚みは、２つの主面に形成された接着層の厚みの合計値を意味する。 The average thickness of the adhesive layer is preferably 2 μm to 50 μm, more preferably 2 μm to 30 μm, and even more preferably 2 μm to 20 μm. When the average thickness of the adhesive layer is 2 μm or more, the gap between the adherend and the thermally conductive sheet tends to be further reduced and the contact thermal resistance can be further reduced. When the average thickness of the adhesive layer is 50 μm or less, the thermal conductivity of the thermally conductive sheet tends to be more excellent.
The thickness may be measured at three random locations by observing the cross section of the thermally conductive layer to be measured using an electron microscope, and the arithmetic mean value may be taken as the average thickness of the adhesive layer. Alternatively, for the thermally conductive layer that does not include an adhesive layer and the thermally conductive sheet that includes an adhesive layer, measure the thickness at three random locations using a micrometer, and calculate the arithmetic mean value as the average thickness of the thermally conductive layer. and the average thickness of the heat conductive sheet. Then, the average thickness of the adhesive layer may be determined by subtracting the average thickness of the thermally conductive sheet from the average thickness of the thermally conductive layer.
When adhesive layers are formed on two main surfaces of the thermally conductive layer, the average thickness of the adhesive layer means the total thickness of the adhesive layers formed on the two main surfaces.
　熱伝導シート（被着体との接着前）の表面粗さＲａは、被着体との接着時に被着体と熱伝導シートとの間の隙間をより低減させる観点から、１０μｍ以下であってもよく、熱伝導シートの生産性の観点から、２μｍ～２０μｍであってもよい。
　本開示において、表面粗さＲａは、ＪＩＳ　Ｂ０６０１：２０１３に基づいて測定された値をいう。 The surface roughness Ra of the thermally conductive sheet (before adhering to the adherend) is 10 μm or less from the viewpoint of further reducing the gap between the adherend and the thermally conductive sheet when adhering to the adherend. From the viewpoint of productivity of the heat conductive sheet, the thickness may be 2 μm to 20 μm.
In the present disclosure, surface roughness Ra refers to a value measured based on JIS B0601:2013.
　熱伝導シートにおいて、熱伝導層の厚み方向における熱伝導率は、接着層の厚み方向における熱伝導率よりも大きいことが好ましい。例えば、接着層の厚み方向における熱伝導率に対する熱伝導層の厚み方向における熱伝導率の比率（熱伝導層の熱伝導率／接着層の熱伝導率）は、１よりも大きければよく、例えば、１よりも大きく２０以下であってもよく、１よりも大きく１０以下であってもよい。
　熱伝導層の厚み方向における熱伝導率及び接着層の熱伝導率は、キセノンフラッシュ（Ｘｅ－ｆｌａｓｈ）法により測定することができる。なお、樹脂成分が硬化性の樹脂成分を含む場合、接着層の熱伝導率は、硬化後の接着層の熱伝導率を意味する。 In the thermally conductive sheet, the thermal conductivity in the thickness direction of the thermally conductive layer is preferably larger than the thermal conductivity in the thickness direction of the adhesive layer. For example, the ratio of the thermal conductivity in the thickness direction of the thermal conductive layer to the thermal conductivity in the thickness direction of the adhesive layer (thermal conductivity of the thermal conductive layer/thermal conductivity of the adhesive layer) needs to be larger than 1, for example. , may be greater than 1 and less than or equal to 20, and may be greater than 1 and less than or equal to 10.
The thermal conductivity in the thickness direction of the thermally conductive layer and the thermal conductivity of the adhesive layer can be measured by a xenon flash (Xe-flash) method. Note that when the resin component includes a curable resin component, the thermal conductivity of the adhesive layer means the thermal conductivity of the adhesive layer after curing.
　接着層の熱伝導率は、５．０Ｗ／（ｍ・Ｋ）以上であってもよく、５．０Ｗ／（ｍ・Ｋ）～２０Ｗ／（ｍ・Ｋ）であってもよく、７．０Ｗ／（ｍ・Ｋ）～１５Ｗ／（ｍ・Ｋ）であってもよい。 The thermal conductivity of the adhesive layer may be 5.0 W/(m K) or more, may be 5.0 W/(m K) to 20 W/(m K), and may be 7.0 W/(m K). /(m·K) to 15W/(m·K).
　熱伝導シートは、少なくとも一方の面に保護フィルムを有していてもよく、両面に保護フィルムを有していることが好ましい。これにより、熱伝導シートの粘着面を保護することができる。 The thermally conductive sheet may have a protective film on at least one side, and preferably has a protective film on both sides. Thereby, the adhesive surface of the heat conductive sheet can be protected.
　保護フィルムは、例えば、ポリエチレン、ポリエステル、ポリプロピレン、ポリエチレンテレフタレート、ポリイミド、ポリエーテルイミド、ポリエーテルナフタレート、メチルペンテン等の樹脂フィルム、コート紙、コート布、及びアルミ等の金属箔が使用できる。これらの保護フィルムは、１種単独で使用しても、２種以上組み合わせて多層フィルムとしてもよい。保護フィルムは、シリコーン系、シリカ系等の離型剤などで表面処理されていることが好ましい。 As the protective film, for example, resin films such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyether naphthalate, and methylpentene, coated paper, coated cloth, and metal foils such as aluminum can be used. These protective films may be used alone or in combination of two or more to form a multilayer film. The protective film is preferably surface-treated with a silicone-based, silica-based, or the like release agent.
　熱伝導シートの用途は特に限定されない。本開示の熱伝導シートは、半導体チップを発熱体とし、ヒートスプレッダを放熱体とした場合の、半導体チップとヒートスプレッダを介在する熱伝導シート（ＴＩＭ１；Ｔｈｅｒｍａｌ　Ｉｎｔｅｒｆａｃｅ　Ｍａｔｅｒｉａｌ　１）として特に好適である。 The use of the thermally conductive sheet is not particularly limited. The thermally conductive sheet of the present disclosure is particularly suitable as a thermally conductive sheet (TIM1; Thermal Interface Material 1) interposed between the semiconductor chip and the heat spreader when the semiconductor chip is used as the heat generating body and the heat spreader is used as the heat radiating body.
　熱伝導シートの実施形態について図１を用いて説明する。本開示の熱伝導シートは以下の実施形態に限定されない。
　図３に示す熱伝導シート１Ａは、熱伝導層１１Ａ及び接着層１２Ａ，１３Ａを備え、熱伝導層１１Ａの一方の主面に接着層１２Ａが位置し、かつ、熱伝導層１１Ａの他方の主面に接着層１３Ａが位置している。
　図１に示すように、熱伝導シート１Ａにおける熱伝導層１１Ａは、２つの主面が凹凸形状を有することで平坦になっていなくてもよい。あるいは、熱伝導シート１Ａにおける熱伝導層１１Ａは、２つの主面が平坦になっていてもよい（例えば、図３参照）。 An embodiment of a thermally conductive sheet will be described using FIG. 1. The thermally conductive sheet of the present disclosure is not limited to the following embodiments.
The thermally conductive sheet 1A shown in FIG. 3 includes a thermally conductive layer 11A and adhesive layers 12A and 13A, with the adhesive layer 12A located on one main surface of the thermally conductive layer 11A, and the other main surface of the thermally conductive layer 11A. An adhesive layer 13A is located on the surface.
As shown in FIG. 1, the heat conductive layer 11A in the heat conductive sheet 1A does not have to be flat because its two main surfaces have an uneven shape. Alternatively, the two main surfaces of the thermally conductive layer 11A in the thermally conductive sheet 1A may be flat (for example, see FIG. 3).
〔熱伝導シートの製造方法〕
　熱伝導シートの製造方法は、上記の構成を有する熱伝導シートが得られる方法であれば特に制限されない。熱伝導シートの製造方法は、前記黒鉛粒子（Ａ）を含有する組成物を準備する工程（「準備工程」ともいう）と、前記組成物を用いて前記熱伝導層を形成する工程（「形成工程」ともいう）と、前記熱伝導層の主面の少なくとも一部に接着層を形成する工程（「接着層形成工程」ともいう）と、を有する。 [Method for manufacturing thermally conductive sheet]
The method for manufacturing the thermally conductive sheet is not particularly limited as long as it can produce a thermally conductive sheet having the above configuration. The method for manufacturing a thermally conductive sheet includes a step of preparing a composition containing the graphite particles (A) (also referred to as a "preparation step"), and a step of forming the thermally conductive layer using the composition (also referred to as a "forming step"). and a step of forming an adhesive layer on at least a portion of the main surface of the thermally conductive layer (also referred to as an "adhesive layer forming step").
＜準備工程＞
　準備工程では、黒鉛粒子（Ａ）と任意のその他の成分（例えば、２５℃で液状の成分（Ｂ）、アクリル酸エステル系高分子（Ｃ）、ホットメルト剤（Ｄ）、酸化防止剤（Ｅ）、その他の成分）を含有する組成物を準備する。各成分を配合する方法としては、各成分を均一に混合することが可能であれば、いずれの方法を用いてもよく、特に限定されない。また、組成物は市販のものを入手して準備してもよい。組成物の調製の詳細は、特開２００８－２８０４９６号公報の段落［００３３］を参照することができる。 <Preparation process>
In the preparation step, graphite particles (A) and any other components (for example, component (B) that is liquid at 25°C, acrylic ester polymer (C), hot melt agent (D), antioxidant (E) ), other ingredients) are prepared. The method for blending each component is not particularly limited, and any method may be used as long as each component can be mixed uniformly. Alternatively, the composition may be prepared by obtaining a commercially available composition. For details on the preparation of the composition, reference can be made to paragraph [0033] of JP-A-2008-280496.
＜形成工程＞
　形成工程では、黒鉛粒子（Ａ）と任意のその他の成分を含有する組成物を用いて前記熱伝導層を形成する。例えば、前述の組成物をシート状に成形して熱伝導層を形成すればよい。 <Formation process>
In the forming step, the thermally conductive layer is formed using a composition containing graphite particles (A) and arbitrary other components. For example, the thermally conductive layer may be formed by forming the above-mentioned composition into a sheet shape.
　形成工程は、前記組成物をシート化してシートを得る工程（「シート作製工程」ともいう）と、前記シートの積層体を作製する工程（「積層体作製工程」ともいう）と、前記積層体の側端面をスライスする工程（「スライシング工程」ともいう）と、を有することが好ましい。 The forming step includes a step of forming the composition into a sheet to obtain a sheet (also referred to as a "sheet manufacturing step"), a step of manufacturing a laminate of the sheets (also referred to as a "laminate manufacturing step"), and a step of forming the laminate into a sheet. It is preferable to include a step of slicing the side end surface of the (also referred to as "slicing step").
≪シート作製工程≫
　シート作製工程は、先の工程で得られた組成物をシート化できれば、いずれの方法で行ってもよく、特に限定されない。例えば、圧延、プレス、押出、及び塗工からなる群から選択される少なくとも１つの成形方法を用いて実施することが好ましい。シート作製工程の詳細は、特開２００８－２８０４９６号公報の段落［００３４］を参照することができる。 ≪Sheet production process≫
The sheet production step is not particularly limited and may be performed by any method as long as the composition obtained in the previous step can be formed into a sheet. For example, it is preferable to use at least one molding method selected from the group consisting of rolling, pressing, extrusion, and coating. For details of the sheet manufacturing process, reference can be made to paragraph [0034] of JP-A-2008-280496.
≪積層体作製工程≫
　積層体作製工程は、先の工程で得られたシートの積層体を形成する。積層体は、例えば、独立した複数枚のシートを順に重ね合わせて作製してもよく、１枚のシートを折り畳んで作製してもよく、シートの１枚を捲回させて作製してもよい。積層体作製工程の詳細は、特開２００８－２８０４９６号公報の段落［００３５］～［００３７］を参照することができる。 ≪Laminated body production process≫
In the laminate production step, a laminate of sheets obtained in the previous step is formed. For example, the laminate may be produced by sequentially stacking a plurality of independent sheets, by folding a single sheet, or by winding one of the sheets. . For details of the laminate manufacturing process, reference can be made to paragraphs [0035] to [0037] of JP-A No. 2008-280496.
≪スライシング工程≫
　スライシング工程は、先の工程で得られた積層体の側端面をスライスできれば、いずれの方法であってもよく、特に限定されない。熱伝導層の厚み方向に貫通する黒鉛粒子（Ａ）によって極めて効率的な熱伝導パスが形成され、熱伝導性がより向上する観点から、黒鉛粒子（Ａ）の質量平均粒子径の２倍以下の厚みでスライスすることが好ましい。スライシング工程の詳細は、特開２００８－２８０４９６号公報の段落［００３８］を参照することができる。 ≪Slicing process≫
The slicing step is not particularly limited and may be any method as long as it can slice the side end surface of the laminate obtained in the previous step. The graphite particles (A) that penetrate in the thickness direction of the heat conductive layer form an extremely efficient heat conduction path, and from the viewpoint of further improving thermal conductivity, the mass average particle diameter of the graphite particles (A) is twice or less. It is preferable to slice with a thickness of . For details of the slicing process, reference can be made to paragraph [0038] of JP-A-2008-280496.
＜接着層形成工程＞
　接着層形成工程は、熱伝導層（例えば、スライスして得られたスライスシート）の主面の少なくとも一部に接着層を形成できれば、いずれの方法であってもよく、特に限定されない。例えば、熱伝導層の主面に熱硬化性の樹脂成分、熱伝導性フィラ、溶剤等を含む樹脂組成物を付与し、付与された樹脂組成物を加熱、乾燥等することで溶剤を揮発させればよい。あるいは、剥離フィルムに樹脂組成物を付与し、次いで加熱、乾燥等した後、加熱、乾燥等させた樹脂組成物からなる接着層を熱伝導層の主面に熱ロールラミネートしてもよい。加熱、乾燥等の手法としては、熱真空プレス、熱ロールラミネート等が挙げられる。熱伝導層の主面に形成される接着層は、半硬化された状態であってもよい。 <Adhesive layer formation process>
The adhesive layer forming step is not particularly limited and may be any method as long as it can form an adhesive layer on at least a portion of the main surface of the heat conductive layer (for example, a sliced sheet obtained by slicing). For example, a resin composition containing a thermosetting resin component, a thermally conductive filler, a solvent, etc. is applied to the main surface of the thermally conductive layer, and the applied resin composition is heated, dried, etc. to evaporate the solvent. That's fine. Alternatively, a resin composition may be applied to a release film, then heated, dried, etc., and then an adhesive layer made of the heated, dried, etc. resin composition may be heat roll laminated on the main surface of the heat conductive layer. Examples of methods for heating, drying, etc. include hot vacuum pressing, hot roll lamination, and the like. The adhesive layer formed on the main surface of the heat conductive layer may be in a semi-cured state.
　熱伝導シートの製造方法は、接着層形成工程後に熱伝導シートに保護フィルムを貼り付けてラミネートする工程（「ラミネート工程」ともいう）をさらに有していてもよい。 The method for manufacturing a thermally conductive sheet may further include a step of attaching a protective film to the thermally conductive sheet and laminating it after the adhesive layer forming step (also referred to as a "laminate step").
＜ラミネート工程＞
　ラミネート工程は、接着層形成工程にて得られた熱伝導シートを保護フィルムに貼り付けられれば、いずれの方法であってもよく、特に限定されない。 <Lamination process>
The lamination step is not particularly limited and may be any method as long as the thermally conductive sheet obtained in the adhesive layer forming step can be attached to the protective film.
　熱伝導シートをかかる方法で製造することで、効率的な熱伝導パスが形成され易く、そのため高熱伝導性と密着性に優れる熱伝導シートが得られる傾向にある。 By manufacturing a thermally conductive sheet using such a method, an efficient thermally conductive path is likely to be formed, and therefore a thermally conductive sheet with high thermal conductivity and excellent adhesion tends to be obtained.
〔放熱装置〕
　本開示の放熱装置は、発熱体と、放熱体と、前記発熱体及び前記放熱体の間に配置される本開示の熱伝導シートとを備え、前記熱伝導層において、前記発熱体側に位置する主面及び前記放熱体側に位置する主面の少なくとも一方の主面の少なくとも一部に前記接着層が位置している装置である。熱伝導層において、発熱体側に位置する主面の少なくとも一部及び放熱体側に位置する主面の少なくとも一部に接着層がそれぞれ位置することが好ましく、発熱体側に位置する主面の発熱体と対面する領域及び放熱体側に位置する主面の放熱体と対面する領域に接着層がそれぞれ位置することがより好ましい。 [Heat dissipation device]
The heat dissipation device of the present disclosure includes a heat generating body, a heat dissipating body, and a heat conductive sheet of the present disclosure disposed between the heat generating body and the heat dissipating body, the heat conductive sheet being located on the side of the heat generating body in the heat conductive layer. The adhesive layer is located on at least a portion of at least one of the main surface and the main surface located on the side of the heat sink. In the thermally conductive layer, it is preferable that an adhesive layer is located on at least a part of the main surface located on the heating element side and at least a part of the main surface located on the heat radiating element side, and the adhesive layer is located on at least a part of the main surface located on the heating element side. It is more preferable that the adhesive layer is located in the facing region and in the region facing the heat radiator of the main surface located on the heat radiator side, respectively.
　発熱体としては、半導体チップ、半導体パッケージ、パワーモジュール等が挙げられる。放熱体としては、ヒートスプレッダ、ヒートシンク、水冷パイプ等が挙げられる。 Examples of heating elements include semiconductor chips, semiconductor packages, power modules, etc. Examples of the heat radiator include a heat spreader, a heat sink, a water cooling pipe, and the like.
　以下、放熱装置の一例を図２を用いてより具体的に説明する。発熱体として半導体チップを用い、放熱体としてヒートスプレッダを用いた放熱装置について説明する。半導体チップ及びヒートスプレッダは、それぞれ発熱体及び放熱体の一例であり、本開示はこれらに限定されない。熱伝導シート１を、半導体チップ２に対しその一方の面を密着させ、他方の面をヒートスプレッダ３に密着させて使用する。半導体チップ２は基板４にアンダーフィル材５を用いて固定されており、ヒートスプレッダ３はシール材６により基板４に固着され、熱伝導シート１と半導体チップ２及びヒートスプレッダ３との密着性を、押しつけることで向上させている。尚、１枚の熱伝導シート１に対し、発熱体及び放熱体が各々１個である必要はない。例えば、１枚の熱伝導シート１に対して複数の半導体チップ２が設けられてもよく、複数枚の熱伝導シート１に対して１個の半導体チップ２が設けられてもよく、複数枚の熱伝導シート１に対して複数の半導体チップ２が設けられてもよい。熱伝導シート１の半導体チップ２側の主面及び熱伝導シート１のヒートスプレッダ３側の主面には、接着層が位置している。例えば、図３に示される熱伝導シート１では、接着層１３が熱伝導シート１の半導体チップ２側の主面に位置し、接着層１２が熱伝導シート１のヒートスプレッダ３側の主面に位置している。さらに、接着層１３が半導体チップ２と接触していてもよく、接着層１２がヒートスプレッダ３と接触していてもよい。 Hereinafter, an example of the heat dissipation device will be described in more detail using FIG. 2. A heat radiating device using a semiconductor chip as a heat generating body and a heat spreader as a heat radiating body will be described. A semiconductor chip and a heat spreader are examples of a heat generating body and a heat radiating body, respectively, and the present disclosure is not limited thereto. A thermally conductive sheet 1 is used with one surface in close contact with a semiconductor chip 2 and the other surface in close contact with a heat spreader 3. The semiconductor chip 2 is fixed to the substrate 4 using an underfill material 5, and the heat spreader 3 is fixed to the substrate 4 by a sealing material 6, which presses the adhesion between the thermally conductive sheet 1, the semiconductor chip 2, and the heat spreader 3. This is what makes it better. Note that it is not necessary that one heating element and one heat radiating element are provided for one heat conductive sheet 1. For example, a plurality of semiconductor chips 2 may be provided for one heat conductive sheet 1, one semiconductor chip 2 may be provided for a plurality of heat conductive sheets 1, and a plurality of semiconductor chips 2 may be provided for a plurality of heat conductive sheets 1. A plurality of semiconductor chips 2 may be provided on the heat conductive sheet 1. An adhesive layer is located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side and on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side. For example, in the thermally conductive sheet 1 shown in FIG. 3, the adhesive layer 13 is located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side, and the adhesive layer 12 is located on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side. are doing. Further, the adhesive layer 13 may be in contact with the semiconductor chip 2, and the adhesive layer 12 may be in contact with the heat spreader 3.
　放熱装置は、発熱体と放熱体の間に、本開示の熱伝導シートを配置させてなる。熱伝導シートを介して発熱体と放熱体とが積層されていることで、発熱体からの熱を放熱体に効率よく伝導することができる。効率よく熱伝導することができることで、放熱装置の使用において寿命が向上し、長期使用においても安定して機能する放熱装置が提供できる。 The heat radiating device includes the heat conductive sheet of the present disclosure disposed between a heat generating element and a heat radiating element. Since the heating element and the heat radiating element are laminated via the heat conductive sheet, heat from the heating element can be efficiently conducted to the heat radiating element. By being able to conduct heat efficiently, the lifespan of the heat dissipation device is improved, and a heat dissipation device that functions stably even during long-term use can be provided.
　熱伝導シートを特に好適に使用できる温度範囲は、例えば、－１０℃～１５０℃であってもよく、－１０℃～１００℃であってもよく、－１０℃～８０℃であってもよい。このことから、発熱体としては、例えば、半導体パッケージ、ディスプレイ、ＬＥＤ、電灯、自動車用パワーモジュール及び産業用パワーモジュールを好適な発熱体の例として挙げることができる。 The temperature range in which the thermally conductive sheet can be particularly suitably used may be, for example, -10°C to 150°C, -10°C to 100°C, or -10°C to 80°C. . For this reason, suitable examples of the heating element include semiconductor packages, displays, LEDs, electric lights, automotive power modules, and industrial power modules.
　放熱体としては、例えば、アルミ又は銅のフィン、板等を利用したヒートシンク、ヒートパイプに接続されているアルミ又は銅のブロック、内部に冷却液体をポンプで循環させているアルミ又は銅のブロック、並びにペルチェ素子及びこれを備えたアルミ又は銅のブロックが挙げられる。 Examples of the heat sink include a heat sink using aluminum or copper fins or plates, an aluminum or copper block connected to a heat pipe, an aluminum or copper block in which a cooling liquid is circulated by a pump, and a Peltier element and an aluminum or copper block equipped with the same.
　放熱装置は、発熱体と放熱体とに熱伝導シートの各々の面を接触させることで構成される。発熱体と熱伝導シートの一方の面とを接触させる方法、及び放熱体と熱伝導シートの他方の面とを接触させる方法は、それぞれを十分に密着させた状態で固定できる方法であれば特に制限されない。 The heat radiating device is constructed by bringing each surface of a heat conductive sheet into contact with a heat generating element and a heat radiating element. The method of bringing the heating element into contact with one side of the heat conductive sheet and the method of bringing the heat radiating element into contact with the other side of the heat conductive sheet are especially suitable as long as they can be fixed in a sufficiently close state. Not restricted.
　例えば、発熱体と放熱体との間に熱伝導シートを配置し、０．０５ＭＰａ～１ＭＰａ程度に加圧可能な治具で固定し、この状態で発熱体を発熱させるか、又はオーブン等により８０℃～２００℃程度に加熱する方法が挙げられる。また、８０℃～２００℃、０．０５ＭＰａ～１ＭＰａで加熱加圧できるプレス機を用いる方法が挙げられる。この方法で好ましい圧力の範囲は、０．１０ＭＰａ～１ＭＰａであり、好ましい温度の範囲は、１００℃～１８０℃である。圧力を０．１０ＭＰａ以上又は加熱温度を１００℃以上とすることで、優れた密着性が得られる傾向にある。また、圧力が１ＭＰａ以下又は加熱温度が１８０℃以下であることで、密着の信頼性がより向上する傾向にある。これは熱伝導シートが過度に圧縮されて厚みが薄くなったり、周辺部材の歪み又は残留応力が大きくなりすぎたりすることを抑制できるためと考えられる。 For example, a heat conductive sheet may be placed between the heating element and the heat radiating element, fixed with a jig that can be pressurized to approximately 0.05 MPa to 1 MPa, and the heating element may be heated in this state, or the A method of heating to about .degree. C. to 200.degree. C. can be mentioned. Another method is to use a press machine capable of heating and pressing at 80° C. to 200° C. and 0.05 MPa to 1 MPa. The preferred pressure range for this method is 0.10 MPa to 1 MPa, and the preferred temperature range is 100°C to 180°C. Excellent adhesion tends to be obtained by setting the pressure to 0.10 MPa or higher or the heating temperature to 100° C. or higher. Further, when the pressure is 1 MPa or less or the heating temperature is 180° C. or less, the reliability of adhesion tends to be further improved. This is thought to be because it is possible to prevent the thermally conductive sheet from being excessively compressed and becoming thinner, or from becoming too large in distortion or residual stress in peripheral members.
　発熱体と放熱体との間に配置される熱伝導シートとしては、前述の熱伝導シートであれば特に限定されない。例えば、図１に示される熱伝導シートを発熱体と放熱体との間に配置してもよい。 The heat conductive sheet disposed between the heating element and the heat radiating element is not particularly limited as long as it is the above-mentioned heat conductive sheet. For example, the thermally conductive sheet shown in FIG. 1 may be placed between a heat generating element and a heat radiating element.
　図１に示される熱伝導シート１Ａを用いた場合、発熱体と放熱体との間に熱伝導シート１Ａを配置した状態で加熱加圧することで、熱伝導シート１Ａの主面に位置する接着層１２Ａ及び１３Ａが軟化したり、変形したりする。熱伝導シート１Ａと発熱体及び放熱体とを加熱圧着する際に生じる隙間が軟化、変形等した接着層で埋められる。これにより、熱伝導シートと被着体との隙間を低減しつつ、接着層を介して熱伝導シートと被着体とを密着させることができる。図１に示すような表面が平坦でない熱伝導シート１Ａを用いた場合も、発熱体と放熱体との間に熱伝導シート１Ａを配置した状態で加熱加圧される。これにより、平坦でない熱伝導シート１Ａが加圧により平坦化され、放熱装置が製造された際は、図３に示すように平坦な熱伝導シート１になっているため、熱伝導シートと被着体との隙間の発生が抑制される。
　例えば、熱硬化性の樹脂成分を含む接着層を適用することで、加熱圧着により変形した接着層が熱伝導シートと被着体との隙間を埋め、かつ加熱により熱硬化性の樹脂成分が硬化する。これにより、接着層を介して熱伝導シートと被着体とを密着させることができる。
　例えば、熱可塑性の樹脂成分を含む接着層を適用することで、加熱圧着により軟化した接着層が熱伝導シートと被着体との隙間を埋める。
　以上により、熱伝導シートと発熱体又は放熱体との間の隙間が低減されて接触熱抵抗が大幅に低減される。 When using the thermally conductive sheet 1A shown in FIG. 1, by heating and pressurizing the thermally conductive sheet 1A with the thermally conductive sheet 1A arranged between the heat generating element and the heat dissipating element, an adhesive layer located on the main surface of the thermally conductive sheet 1A is formed. 12A and 13A are softened or deformed. A gap that occurs when heat-compression bonding the thermally conductive sheet 1A and the heating element and the heat radiating element is bonded is filled with a softened, deformed, etc. adhesive layer. Thereby, the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer while reducing the gap between the thermally conductive sheet and the adherend. Even when a heat conductive sheet 1A with an uneven surface as shown in FIG. 1 is used, heating and pressure are applied with the heat conductive sheet 1A disposed between a heat generating element and a heat radiating element. As a result, the thermally conductive sheet 1A which is not flat is flattened by pressure, and when the heat dissipation device is manufactured, the thermally conductive sheet 1 is flat as shown in FIG. The generation of gaps with the body is suppressed.
For example, by applying an adhesive layer containing a thermosetting resin component, the adhesive layer deformed by heat compression fills the gap between the thermally conductive sheet and the adherend, and the thermosetting resin component hardens by heating. do. Thereby, the thermally conductive sheet and the adherend can be brought into close contact with each other via the adhesive layer.
For example, by applying an adhesive layer containing a thermoplastic resin component, the adhesive layer softened by heat-pressing fills the gap between the thermally conductive sheet and the adherend.
As described above, the gap between the heat conductive sheet and the heat generating element or the heat radiating element is reduced, and the contact thermal resistance is significantly reduced.
　熱伝導シートは、発熱体と放熱体との間に配置して圧着する前の初期厚みに対する、圧着後により減少した厚みの割合（圧縮率）が、１％～３５％であってもよい。 The thermally conductive sheet may have a reduced thickness (compression rate) of 1% to 35% after the heat-conducting sheet is placed between the heat-generating element and the heat-dissipating body relative to its initial thickness before being press-bonded.
　固定は、クリップの他、ネジ、バネ等の治具を用いてもよく、接着剤等の通常用いられる手段でさらに固定されていることが、密着を持続させる上で好ましい。 In addition to clips, jigs such as screws and springs may be used for fixing, and it is preferable to further fix with commonly used means such as adhesives in order to maintain close contact.
　発熱体と熱伝導シートとの界面及び放熱体と熱伝導シートとの界面にて、測定領域の面積に対する気体領域の面積の割合で算出される空隙率が０％～２５．０％であることが好ましく、０％～２０．０％であることがより好ましい。これにより、熱伝導シートと発熱体又は放熱体とを加熱圧着する際に生じる隙間（例えば、熱伝導シートの凹凸に由来する隙間及び発熱体又は放熱体の凹凸に由来する隙間）が低減される。その結果、接触熱抵抗が大幅に低減されると推測される。
　本開示では、接着層が位置する熱伝導層の主面側及び接着層が位置していない熱伝導層の主面側の両方の場合において、空隙率が前述の数値範囲を満たすことが好ましい。 At the interface between the heating element and the heat conductive sheet and at the interface between the heat radiating body and the heat conductive sheet, the porosity calculated as the ratio of the area of the gas region to the area of the measurement region is 0% to 25.0%. is preferable, and more preferably 0% to 20.0%. This reduces gaps that occur when heat-compression bonding the thermal conductive sheet and the heat generating element or the heat dissipating body (for example, gaps resulting from unevenness of the heat conductive sheet and gaps resulting from unevenness of the heat generating element or heat dissipating body). . As a result, it is estimated that the contact thermal resistance is significantly reduced.
In the present disclosure, it is preferable that the porosity satisfies the above numerical range both on the main surface side of the thermally conductive layer where the adhesive layer is located and on the main surface side of the thermally conductive layer where the adhesive layer is not located.
　接着層が位置する熱伝導層の主面側において、前述の空隙率が０％～１０．０％であることが好ましく、０％～５．０％であることがより好ましく、０％～２．０％であることがさらに好ましい。 On the main surface side of the thermally conductive layer where the adhesive layer is located, the above-mentioned porosity is preferably 0% to 10.0%, more preferably 0% to 5.0%, and 0% to 2%. More preferably, it is .0%.
　本開示において、界面の空隙率は、以下のようにして求めることができる。まず、超音波画像診断装置（例えば、Ｉｎｓｉｇｈｔ－３００、インサイト株式会社）を用いて、反射法、３５ＭＨｚの条件で界面の貼り付き状態を観察する。貼り付いていない気体領域の面積の割合を算出し、以下の式に基づいて界面の空隙率を求めればよい。
　界面の空隙率（％）＝１００×（気体領域の面積／測定領域の面積） In the present disclosure, the porosity of the interface can be determined as follows. First, using an ultrasonic image diagnostic apparatus (for example, Insight-300, manufactured by Insight Co., Ltd.), the adhesion state of the interface is observed using a reflection method at 35 MHz. The ratio of the area of the non-adhered gas region may be calculated, and the porosity of the interface may be determined based on the following formula.
Interfacial porosity (%) = 100 x (area of gas region/area of measurement region)
　界面の空隙率は、例えば、接着層の厚み、接着層を形成する樹脂組成物の組成、熱伝導シートの圧縮率等を調整することで、その数値範囲が調整可能となる。 The numerical range of the porosity at the interface can be adjusted by, for example, adjusting the thickness of the adhesive layer, the composition of the resin composition forming the adhesive layer, the compressibility of the thermally conductive sheet, etc.
　以下、実施例により本発明を詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.
（実施例１～実施例２）
　下記材料を表１に示す混合比率（体積％）になるように、混練機（株式会社モリヤマ、ＤＳ３－ＳＧＨＭ－Ｅ型加圧双腕型ニーダー）に投入し、温度１５０℃の条件で混練し、組成物を得た。 (Example 1 to Example 2)
The following materials were put into a kneader (Moriyama Co., Ltd., DS3-SGHM-E type pressurized double-arm kneader) so that the mixing ratio (volume %) was as shown in Table 1, and kneaded at a temperature of 150°C. , a composition was obtained.
＜黒鉛粒子（Ａ）＞
（Ａ）－１：鱗片状の膨張黒鉛粒子（昭和電工マテリアルズ株式会社「ＨＧＦ－Ｌ」、質量平均粒子径：２７０μｍ、前述のＸ線回折測定を用いた方法により、結晶中の六員環面が、鱗片状粒子の面方向に配向していることを確認した）。
＜液状成分（Ｂ）＞
（Ｂ）－１：イソブテン・ノルマルブテン共重合体（日油株式会社「日油ポリブテンＴＭ　・エマウエット（登録商標）、グレード３Ｎ」）
（Ｂ）－２：イソブテン・ノルマルブテン共重合体（日油株式会社「日油ポリブテンＴＭ　・エマウエット（登録商標）、グレード３０Ｎ」）
（Ｂ）－３：イソブテンの単独重合体（新日本石油株式会社「テトラックス６Ｔ」）
＜アクリル酸エステル系高分子（Ｃ）＞
（Ｃ）－１：アクリル酸エステル共重合樹脂（アクリル酸ブチル／アクリル酸エチル／アクリロニトリル／アクリル酸共重合体、重量平均分子量：５３万、Ｔｇ＝－３９℃）
＜ホットメルト剤（Ｄ）＞
（Ｄ）－１：水素化石油樹脂（荒川化学工業株式会社「アルコンＰ９０」）
＜酸化防止剤（Ｅ）＞
（Ｅ）－１：ヒンダードフェノール系酸化防止剤（株式会社ＡＤＥＫＡ「アデカスタブＡＯ－６０」） <Graphite particles (A)>
(A)-1: Scale-like expanded graphite particles (Showa Denko Materials Co., Ltd. "HGF-L", mass average particle diameter: 270 μm, six-membered rings in the crystal by the method using the aforementioned X-ray diffraction measurement) It was confirmed that the planes were oriented in the plane direction of the scaly particles).
<Liquid component (B)>
(B)-1: Isobutene/normal butene copolymer (NOF Polybutene TM Emmawet (registered trademark), Grade 3N) by NOF Corporation
(B)-2: Isobutene/normal butene copolymer (NOF Polybutene TM Emmawet (registered trademark), Grade 30N) by NOF Corporation
(B)-3: Isobutene homopolymer (Nippon Oil Co., Ltd. “Tetrax 6T”)
<Acrylic acid ester polymer (C)>
(C)-1: Acrylic acid ester copolymer resin (butyl acrylate/ethyl acrylate/acrylonitrile/acrylic acid copolymer, weight average molecular weight: 530,000, Tg = -39°C)
<Hot melt agent (D)>
(D)-1: Hydrogenated petroleum resin (Arakawa Chemical Co., Ltd. “Alcon P90”)
<Antioxidant (E)>
(E)-1: Hindered phenolic antioxidant (ADEKA Co., Ltd. “ADEKA STAB AO-60”)
（熱伝導層の作製）
　混練して得た組成物を押し出し成形機（株式会社パーカー、商品名：ＨＫＳ４０－１５型押し出し機）に入れ、幅２０ｃｍ、厚み１．５ｍｍ～１．６ｍｍの平板形状に押出して一次シートを得た。得られた一次シートを、４０ｍｍ×１５０ｍｍの型刃を用いてプレス打ち抜きし、打ち抜いたシートを６１枚積層し、高さが８０ｍｍになるよう、高さ８０ｍｍのスペーサを挟んで積層方向に９０℃で３０分間圧力をかけ、４０ｍｍ×１５０ｍｍ×８０ｍｍの積層体を得た。次いで、この積層体の８０ｍｍ×１５０ｍｍの側端面を木工用スライサーでスライスし、厚み０．１１ｍｍの熱伝導層を得た。 (Preparation of thermally conductive layer)
The composition obtained by kneading was put into an extrusion molding machine (Parker Co., Ltd., product name: HKS40-15 type extruder) and extruded into a flat plate shape with a width of 20 cm and a thickness of 1.5 mm to 1.6 mm to obtain a primary sheet. Ta. The obtained primary sheet was press punched using a 40 mm x 150 mm die blade, and 61 of the punched sheets were stacked and heated at 90°C in the stacking direction with a spacer 80 mm in height in between so that the height was 80 mm. Pressure was applied for 30 minutes to obtain a 40 mm x 150 mm x 80 mm laminate. Next, the 80 mm x 150 mm side end face of this laminate was sliced with a wood slicer to obtain a thermally conductive layer with a thickness of 0.11 mm.
（熱伝導シートの作製）
（実施例１）
　熱硬化性の樹脂成分（ビスフェノールＦ型エポキシ樹脂）６質量部、（クレゾールノボラック型エポキシ樹脂）４質量部、（フェノール樹脂）８質量部、（アクリル酸エステル系樹脂）６質量部、熱伝導性フィラ（銀粒子、粒子径１．５μｍ）７６質量部及び溶剤（シクロヘキサノン）３９質量部を含む樹脂組成物を準備した。準備した樹脂組成物を剥離フィルムの上に塗布し、１３０℃のオーブンで樹脂組成物を乾燥させた。前述のようにして得た熱伝導層の１つの主面に７０℃で熱ロールラミネートすることで１つの主面に接着層（表２中の接着層１）が形成された熱伝導シートを得た。
（実施例２）
　熱硬化性の樹脂成分（ビスフェノールＦ型エポキシ樹脂）４質量部、（クレゾールノボラック型エポキシ樹脂）３質量部、（フェノール樹脂）６質量部、（アクリル酸エステル系樹脂）５質量部、熱伝導性フィラ（銀粒子、粒子径１．５μｍ）８３質量部及び溶剤（シクロヘキサノン）３９質量部を含む樹脂組成物を準備した。準備した樹脂組成物を剥離フィルムの上に塗布し、１３０℃のオーブンで樹脂組成物を乾燥させた。前述のようにして得た熱伝導層の１つの主面に７０℃で熱ロールラミネートすることで１つの主面に接着層（表２中の接着層２）が形成された熱伝導シートを得た。 (Preparation of thermally conductive sheet)
(Example 1)
Thermosetting resin components (bisphenol F type epoxy resin) 6 parts by mass, (cresol novolac type epoxy resin) 4 parts by mass, (phenol resin) 8 parts by mass, (acrylic acid ester resin) 6 parts by mass, thermal conductivity A resin composition containing 76 parts by mass of filler (silver particles, particle size 1.5 μm) and 39 parts by mass of a solvent (cyclohexanone) was prepared. The prepared resin composition was applied onto a release film, and the resin composition was dried in an oven at 130°C. A thermally conductive sheet with an adhesive layer (adhesive layer 1 in Table 2) formed on one main surface was obtained by thermal roll lamination at 70 ° C. on one main surface of the thermally conductive layer obtained as described above. Ta.
(Example 2)
Thermosetting resin components (bisphenol F type epoxy resin) 4 parts by weight, (cresol novolac type epoxy resin) 3 parts by weight, (phenol resin) 6 parts by weight, (acrylic acid ester resin) 5 parts by weight, thermal conductivity A resin composition containing 83 parts by mass of filler (silver particles, particle size 1.5 μm) and 39 parts by mass of a solvent (cyclohexanone) was prepared. The prepared resin composition was applied onto a release film, and the resin composition was dried in an oven at 130°C. A thermally conductive sheet with an adhesive layer (adhesive layer 2 in Table 2) formed on one main surface was obtained by hot roll laminating at 70 ° C. on one main surface of the thermally conductive layer obtained as described above. Ta.
（比較例１）
　表１に示す各材料を表１の混合比率（体積％）となるよう、実施例１～実施例２と同じ工程で混練、積層、プレス、及びスライスし、熱伝導層を作製した。各比較例では、接着層を形成せずに熱伝導層を熱伝導シートとして用いた。 (Comparative example 1)
Each material shown in Table 1 was kneaded, laminated, pressed, and sliced in the same steps as in Examples 1 and 2 so that the mixing ratio (volume %) in Table 1 was achieved, and a thermally conductive layer was produced. In each comparative example, a thermally conductive layer was used as a thermally conductive sheet without forming an adhesive layer.
　実施例１～２及び比較例１の熱伝導シートにおいて、各評価は以下の方法により行った。結果を表２及び図４に示す。 Regarding the thermally conductive sheets of Examples 1 to 2 and Comparative Example 1, each evaluation was performed by the following method. The results are shown in Table 2 and FIG. 4.
（熱抵抗の測定）
　熱抵抗は卓上型キセノンフラッシュアナライザー（LFA 467 Hyper Flash）を用いて測定した。Φ１４ｍｍの熱伝導シートを１ｍｍの銅板に挟み、３層構造のサンプルを作製した。サンプル作製条件としては、温度１５０℃、圧力０．１４ＭＰａで３分加圧した。熱硬化性樹脂が含まれる場合は、樹脂を硬化するために、１７５℃のオーブンで１時間加熱し、常温で十分に冷却した。また、測定の前処理としてカーボンスプレーで銅表面に黒化処理を加え、測定した。３層構造から銅板分の影響を除いた熱伝導率λが得られ、得られた熱伝導率λと厚みｔから、以下の式で単位面積（１ｃｍ２）当たりの熱抵抗値Ｘ（Ｋ・ｃｍ２／Ｗ）を以下のように算出した。
Ｘ＝（１０×ｔ）／λ
ｔ：実施例１～４又は比較例１の熱伝導シートの厚み（ｍｍ）
λ：熱伝導率（Ｗ／（ｍ・Ｋ）） (Measurement of thermal resistance)
Thermal resistance was measured using a tabletop xenon flash analyzer (LFA 467 Hyper Flash). A sample with a three-layer structure was prepared by sandwiching a thermally conductive sheet with a diameter of 14 mm between 1 mm copper plates. The sample preparation conditions were a temperature of 150° C. and a pressure of 0.14 MPa for 3 minutes. When a thermosetting resin was included, in order to harden the resin, it was heated in an oven at 175° C. for 1 hour, and then sufficiently cooled to room temperature. In addition, as a pretreatment for measurement, the copper surface was blackened using carbon spray, and then measured. The thermal conductivity λ excluding the influence of the copper plate is obtained from the three-layer structure, and from the obtained thermal conductivity λ and the thickness t , the thermal resistance value X (K・cm 2 /W) was calculated as follows.
X=(10×t)/λ
t: Thickness (mm) of the thermally conductive sheet of Examples 1 to 4 or Comparative Example 1
λ: Thermal conductivity (W/(m・K))
（界面の空隙率の評価）
　（熱抵抗の測定）に記載の方法で作製した３層構造のサンプルにおいて、界面の空隙率の評価は以下のように評価した。超音波画像診断装置（Ｉｎｓｉｇｈｔ－３００、インサイト株式会社）を用いて、反射法、３５ＭＨｚ、ゲインレベルを１０ｄＢ、コントラスト閾値３０％～７０％の条件で界面の貼り付き状態を観察した。さらに、その画像を画像解析ソフト（ＩｍａｇｅＪ）により２値化（具体的には、ヒストグラムの０～８３を黒色部、８４～２５５を白色部として白黒化）し、Φ１１ｍｍの面積（測定領域の面積、なお、図４では、Φ１４ｍｍの画像を示す）のうち、貼り付いていない気体領域の面積の割合を算出し、以下の式に基づいて界面の空隙率（％）を求めた。
　界面の空隙率（％）＝１００×（気体領域の面積／測定領域の面積） (Evaluation of interface porosity)
(Measurement of thermal resistance) In the three-layer structure sample prepared by the method described in (Measurement of thermal resistance), the porosity of the interface was evaluated as follows. Using an ultrasonic diagnostic imaging device (Insight-300, Insight Co., Ltd.), the adhesion state of the interface was observed using the reflection method, 35 MHz, gain level of 10 dB, and contrast threshold of 30% to 70%. Furthermore, the image is binarized using image analysis software (ImageJ) (specifically, 0 to 83 of the histogram is black and 84 to 255 is white), and the area of Φ11 mm (area of the measurement area) is converted to black and white. (In FIG. 4, an image of Φ14 mm is shown), the area ratio of the non-adhered gas region was calculated, and the porosity (%) of the interface was determined based on the following formula.
Interfacial porosity (%) = 100 x (area of gas region/area of measurement region)
（厚みの評価）
　実施例１～２にてマイクロメータを用い、熱ロールラミネートする前の接着層の厚みを測定した。次に、実施例１～２及び比較例１の熱伝導シートについて同一の条件で圧縮を行った。次に、マイクロメータを用い、圧縮後の熱伝導シートの最大厚み（表２中の「圧縮後の厚み」）を測定した。 (Thickness evaluation)
In Examples 1 and 2, the thickness of the adhesive layer before hot roll lamination was measured using a micrometer. Next, the thermally conductive sheets of Examples 1 and 2 and Comparative Example 1 were compressed under the same conditions. Next, the maximum thickness of the thermally conductive sheet after compression ("thickness after compression" in Table 2) was measured using a micrometer.
　樹脂成分と、熱伝導性フィラとを含む樹脂組成物を用いて、熱伝導層の主面に接着層を形成した実施例１～２では、熱伝導層の主面に当該接着層を形成していない比較例１よりも熱抵抗を低減可能であることが確認された。 In Examples 1 and 2, in which an adhesive layer was formed on the main surface of the thermally conductive layer using a resin composition containing a resin component and a thermally conductive filler, the adhesive layer was formed on the main surface of the thermally conductive layer. It was confirmed that the thermal resistance could be reduced more than in Comparative Example 1, which did not have any heat resistance.
　本明細書に記載された全ての文献、特許出願、及び技術規格は、個々の文献、特許出願、及び技術規格が参照により取り込まれることが具体的かつ個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. Incorporated herein by reference.

Claims (8)

  1. 　鱗片状粒子、楕円体状粒子及び棒状粒子からなる群より選択される少なくとも１種の黒鉛粒子（Ａ）を含有し、前記鱗片状粒子の場合には面方向、前記楕円体状粒子の場合には長軸方向、前記棒状粒子の場合には長軸方向が、厚み方向に配向している熱伝導層と、
    　樹脂成分と、熱伝導性フィラとを含み、前記熱伝導層の主面の少なくとも一部に位置する接着層と、
    　を備える熱伝導シート。     Contains at least one type of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoid-like particles, and rod-like particles, in the case of the scale-like particles, in the in-plane direction, and in the case of the above-mentioned ellipsoid-like particles. is a long axis direction, and in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction,
    an adhesive layer containing a resin component and a thermally conductive filler and located on at least a portion of the main surface of the thermally conductive layer;
    A thermally conductive sheet with
  2. 　前記樹脂成分は、硬化性の樹脂成分、粘着性の樹脂成分及び熱可塑性の樹脂成分からなる群より選択される少なくとも１種を含む請求項１に記載の熱伝導シート。 The heat conductive sheet according to claim 1, wherein the resin component includes at least one selected from the group consisting of a curable resin component, a sticky resin component, and a thermoplastic resin component.
  3. 　前記樹脂成分は、硬化性の樹脂成分であり、前記接着層は、半硬化された状態である請求項２に記載の熱伝導シート。 The heat conductive sheet according to claim 2, wherein the resin component is a curable resin component, and the adhesive layer is in a semi-cured state.
  4. 　前記樹脂成分は、熱可塑性の樹脂成分を含む請求項１～請求項３のいずれか１項に記載の熱伝導シート。 The heat conductive sheet according to any one of claims 1 to 3, wherein the resin component includes a thermoplastic resin component.
  5. 　前記熱伝導性フィラは、銀、酸化アルミニウム、水酸化アルミニウム、酸化マグネシウム、酸化ベリリウム、窒化ホウ素、窒化アルミニウム、窒化ケイ素、炭化ケイ素、二酸化ケイ素、フッ化アルミニウム、フッ化カルシウム及び酸化亜鉛から選択される少なくとも１種の粒子である請求項１～請求項４のいずれか１項に記載の熱伝導シート。 The thermally conductive filler is selected from silver, aluminum oxide, aluminum hydroxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, silicon dioxide, aluminum fluoride, calcium fluoride and zinc oxide. The thermally conductive sheet according to any one of claims 1 to 4, which is at least one type of particle.
  6. 　前記接着層の平均厚みは、２μｍ～５０μｍである請求項１～請求項５のいずれか１項に記載の熱伝導シート。 The thermally conductive sheet according to any one of claims 1 to 5, wherein the adhesive layer has an average thickness of 2 μm to 50 μm.
  7. 　発熱体と、放熱体と、前記発熱体及び前記放熱体の間に配置される請求項１～請求項６のいずれか１項に記載の熱伝導シートとを備え、
    　前記熱伝導層において、前記発熱体側に位置する主面及び前記放熱体側に位置する主面の少なくとも一方の主面の少なくとも一部に前記接着層が位置する放熱装置。     comprising a heating element, a heat radiating element, and the thermally conductive sheet according to any one of claims 1 to 6 disposed between the heating element and the heat radiating element,
    In the thermally conductive layer, the adhesive layer is located on at least a portion of at least one of the main surface located on the heat generating body side and the main surface located on the heat radiating body side.
  8. 　請求項１～請求項６のいずれか１項に記載の熱伝導シートを製造する熱伝導シートの製造方法であって、
    　前記黒鉛粒子（Ａ）を含有する組成物を準備する工程と、前記組成物を用いて前記熱伝導層を形成する工程と、前記熱伝導層の主面の少なくとも一部に接着層を形成する工程と、を有する熱伝導シートの製造方法。     A method for manufacturing a thermally conductive sheet for manufacturing the thermally conductive sheet according to any one of claims 1 to 6, comprising:
    A step of preparing a composition containing the graphite particles (A), a step of forming the thermally conductive layer using the composition, and forming an adhesive layer on at least a portion of the main surface of the thermally conductive layer. A method for manufacturing a thermally conductive sheet, comprising the steps of:
PCT/JP2022/028529 2022-07-22 2022-07-22 Thermally conductive sheet, heat dissipation device, and method for producing thermally conductive sheet WO2024018637A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008300476A (en) * 2007-05-30 2008-12-11 Sumitomo Electric Ind Ltd Power module
JP2011040565A (en) * 2009-08-11 2011-02-24 Fuji Electric Systems Co Ltd Thermal conductive sheet, semiconductor device using the same, and method of manufacturing the same
JP2014067926A (en) * 2012-09-26 2014-04-17 Sumitomo Bakelite Co Ltd Method for manufacturing thermal conductive sheet
JP2016103611A (en) * 2014-11-28 2016-06-02 デンカ株式会社 Boron nitride resin composite circuit board

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008300476A (en) * 2007-05-30 2008-12-11 Sumitomo Electric Ind Ltd Power module
JP2011040565A (en) * 2009-08-11 2011-02-24 Fuji Electric Systems Co Ltd Thermal conductive sheet, semiconductor device using the same, and method of manufacturing the same
JP2014067926A (en) * 2012-09-26 2014-04-17 Sumitomo Bakelite Co Ltd Method for manufacturing thermal conductive sheet
JP2016103611A (en) * 2014-11-28 2016-06-02 デンカ株式会社 Boron nitride resin composite circuit board

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