Thermally conductive sheet and method for mounting heat dissipating electronic component

Abstract

The present application relates to a heat conductive sheet characterized by being formed by laminating a heat conductive sheet having a hardness of 30 or less as measured with an ASKER C-type durometer, a surface initial adhesion of 30 gf (0.294 N) or more, a thickness of 0.3 mm or more, and a thermal conductivity of 0.8 W / mK or more, and an insulating resin film on one face of the heat conductive sheet, the heat conductive sheet containing an organic polysiloxane elastomer and a heat conductive filler, the insulating resin film having a thickness of 10 μm or more and 50 μm or less and an elastic modulus of 1 GPa or more. Thus, a heat conductive sheet having high surface slidability, easy mounting of heat releasing electronic components, and excellent heat conductivity can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a thermally conductive sheet and a mounting method of a heat dissipating electronic component. BACKGROUND

[0002] With high performance, high speed, miniaturization and high integration, the LSI chip itself such as CPU, driver IC and memory used in electronic devices such as personal computers and mobile phones generates a large amount of heat, and the temperature rise of the chip caused by the heat can cause failure or damage of the chip. In addition, in recent years, heat dissipation measures are also required for the battery of an electric vehicle, and various heat dissipation methods for suppressing temperature rise and heat dissipation members for these heat dissipation methods have been proposed.

[0003] When there is a certain degree of space between the heat dissipating electronic component and the cooling member such as a heat sink or a housing, the thermally conductive sheet can be used well. In addition, electrical insulation is required between most heat dissipating elements (heat dissipating electronic components) and heat sinks, housings, etc., and insulation is also required for most thermally conductive sheets. In addition, in this case, in order to absorb the thickness tolerance of the heat dissipating electronic component and the thickness tolerance of the cooling member such as a heat sink or a housing, etc., the thermally conductive sheet is mostly provided with a thickness and is set to have a low hardness. Thus, the tolerance of the components can be effectively absorbed, and the stress when compressed can be reduced.

[0004] As a mounting method of the thermally conductive sheet, in general, the thermally conductive sheet is attached to the cooling member, the heat dissipating electronic component is disposed from a direction perpendicular to the thermally conductive sheet, and fixed by applying pressure with a screw or the like.

[0005] However, it is sometimes difficult to dispose the heat dissipating electronic component from a direction perpendicular to the thermally conductive sheet due to factors of the mounting process or the structure of the heat dissipating electronic component. In such a case, after the thermally conductive sheet is disposed on the cooling member, it is sometimes necessary to mount it in such a way that the heat dissipating electronic component slides on the thermally conductive sheet. Then, the conventional thermally conductive sheet is soft, so if the heat dissipating electronic component is made to slide on the sheet, the thermally conductive sheet will be deformed or damaged. This is because the thermally conductive sheet is soft and lacks strength, and the sheet surface has a sticky feeling due to the softness and lacks sliding properties. The problem in terms of factors of the mounting process or the structure of the heat dissipating electronic component means, for example, a case where the direction in which the heat dissipating electronic component is mounted is limited due to the complex structure of the electronic device, or a case where the direction in which stress is applied at the time of mounting is limited due to the structural problem of the heat dissipating electronic component. In such a case, after the thermally conductive sheet is attached to the cooling member, it is necessary to dispose the heat dissipating electronic component by making it slide on the sheet.

[0006] In order to improve the slidability, it is known that the coefficient of friction can be reduced by adding an oil that does not affect the crosslinked structure of the rubber and has poor compatibility to the silicone material, and the oil exudes to the surface of the sheet, thereby reducing the coefficient of friction (Patent Literature 1). However, if the heat dissipation sheet is soft and has a sticky feeling, it is not effective. In addition, a method of adjusting the alkenyl content of a silicone base polymer to reduce the coefficient of friction is known, but this method is a method for a mixable silicone rubber material, and it is difficult to process the hardness of the cured sheet to be relatively soft (Patent Literature 2).

[0007] As another method, a method of laminating a rubber sheet having high hardness to one surface of a low hardness sheet is also considered (Patent Literature 3), but abrasion of the rubber sheet occurs when the heat releasing electronic component is slid.

[0008] A method of dusting the surface of the sheet is also considered. Dusting does improve the smoothness of the surface of the sheet, but it is only temporary, and the effect of the dusting gradually decreases. Furthermore, the strength of the surface of the sheet does not change and thus the breakage of the sheet cannot be avoided.

[0009] Prior Art Documents

[0010] Patent Literature

[0011] Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-185254

[0012] Patent Literature 2: Japanese Patent Application Laid-Open No. 2016-164281

[0013] Patent Literature 3: Japanese Patent Application Laid-Open No. 2019-071380 SUMMARY

[0014] Technical Problem to be Solved by the Invention

[0015] The present invention was made in view of the above circumstances, and aims to provide a heat dissipation composite sheet in which the slidability of the surface is high, the installation of a heat releasing electronic component is easy, and the heat dissipation property is also excellent.

[0016] Technical Means for Solving the Technical Problem

[0017] To solve the above-described technical problem, the present application provides a heat conductive composite sheet which is formed by laminating a heat conductive sheet and an insulating resin film on one surface of the heat conductive sheet, the hardness of the heat conductive sheet measured by an ASKER C-type durometer is 30 or less, the surface tack force is 30 gf (0.294 N) or more, the thickness is 0.3 mm or more, and the thermal conductivity is 0.8 W / mK or more, the heat conductive sheet contains an organic polysiloxane elastomer and a heat conductive filler, and the thickness of the insulating resin film is 10 μm or more and 50 μm or less, and the elastic modulus is 1 GPa or more.

[0018] Such a heat conductive composite sheet has a high surface sliding property, is easy to mount a heat releasing electronic component, and has excellent heat conductivity.

[0019] Further, it is preferable that the insulating resin film is a polyester resin film.

[0020] If such a heat conductive composite sheet is used, it is easy to obtain and the cost can be suppressed.

[0021] Further, it is preferable that the thermal conductivity of the heat conductive sheet is 3.0 W / mK or more.

[0022] If such a heat conductive composite sheet is used, the heat generated from a heat releasing electronic component can be more effectively conducted to a cooling member.

[0023] In addition, it is preferable that the heat conductive sheet is a cured product of a heat conductive silicone composition containing the following (A) to (D) components:

[0024] (A) an organic polysiloxane having two or more alkenyl groups in one molecule, which is 100 parts by mass;

[0025] (B) an organohydrogen polysiloxane having two or more hydrogen atoms directly bonded to a silicon atom, which is in an amount such that the number of moles of the hydrogen atoms directly bonded to the silicon atom is 0.1 to 5.0 times the number of moles of the alkenyl groups from the (A) component;

[0026] (C) a heat conductive filler, which is 1200 to 6500 parts by mass; and

[0027] (D) a platinum group metal-based curing catalyst, which is 0.1 to 2000 ppm relative to the (A) component, in terms of platinum group metal element mass.

[0028] As long as it is a cured product of such a composition, it can be suitably used as a heat conductive sheet.

[0029] Further, it is preferable that the heat conductive filler of the (C) component is composed of the following three components:

[0030] (C-i) amorphous alumina having an average particle diameter of 10 to 30 μm, which is 500 to 1500 parts by mass;

[0031] (C-ii) spherical alumina having an average particle diameter of 30 to 85 μm, which is 150 to 4000 parts by mass;

[0032] (C-iii) insulating inorganic filler having an average particle diameter of 0.1 to 6 μm, which is 500 to 2000 parts by mass.

[0033] By using the (C) component in the above blending ratio, the effects of the present application described above can be more favorably and more reliably achieved.

[0034] It is further preferred that the (C) component is treated with the following (F) surface treatment agent, which is one or more selected from the group consisting of (F-1) an alkoxysilane compound represented by the following general formula (1) and (F-2) a dimethylpolysiloxane having a molecular chain single end terminated with a trialkoxysilyl group represented by the following general formula (2),

[0035] R 1 a R 2 b Si(OR 3 ) 4-a-b (1)

[0036] (In the general formula (1), R 1 is independently an alkyl group having 6 to 15 carbon atoms, R 2 is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, R 3 is independently an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, and a + b is an integer of 1 to 3);

[0037] [Chemical Formula 1]

[0038]

[0039] (In the general formula (2), R 4 is independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100).

[0040] By hydrophobically treating the (C) component with such a (F) component, the wettability of the (C) component with the organopolysiloxane as the (A) component can be improved, and the thermally conductive filler material as the (C) component can be uniformly dispersed in the matrix composed of the (A) component.

[0041] In addition, the blending amount of the (F) component is preferably 0.01 to 300 parts by mass with respect to 100 parts by mass of the (A) component.

[0042] If the ratio is such, oil separation will not be induced.

[0043] Furthermore, the present invention provides a method for mounting a heat-exothermic electronic component, which involves sliding the heat-exothermic electronic component on the insulating resin film of the thermally conductive composite sheet of the present invention and adjusting it to a target position, and then fixing the heat-exothermic electronic component.

[0044] If this is the installation method for heat-dissipating electronic components, then when installing heat-dissipating electronic components in electronic devices, the sliding properties of one side of the heat-conducting sheet are excellent, so the sheet will not peel or break, and the heat-dissipating electronic components can be slid for installation, thereby expanding the scope of application of the installation method.

[0045] Invention Effects

[0046] For example, when installing heat-generating electronic components in electronic devices, the present invention provides a thermally conductive sheet with excellent sliding properties on one side, allowing the heat-generating electronic components to be installed by sliding. Specifically, a thermally conductive composite sheet with excellent sliding properties on one side is formed by laminating an insulating resin film on one side of the thermally conductive sheet. Even when the heat-generating component slides on the thermally conductive composite sheet, the sheet will not peel or break, expanding the application range of the installation method and effectively suppressing the increase in thermal resistance. The thermally conductive sheet has a hardness of 30 or less as measured by an ASKER C-type hardness tester, an initial surface tack of 30 gf or more, a thickness of 0.3 mm or more, and a thermal conductivity of 0.8 W / mK or more. It is composed of an organosilicon polymer and a thermally conductive filler material, and the thickness of the insulating resin film layer is 10 μm or more and 50 μm or less, with an elastic modulus of 1 GPa or more. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the thermally conductive composite sheet of the present invention. Detailed Implementation

[0048] As described above, the aim is to develop a thermally conductive composite sheet with high surface slippage, easy mounting of exothermic electronic components, and excellent thermal conductivity.

[0049] Therefore, the inventors of this application conducted in-depth research and found that by laminating an insulating resin film with a thickness of 10 μm to 50 μm and an elastic modulus of 1 GPa or more on one side of the heat-conducting sheet, the sliding properties are improved, the surface of the heat-conducting sheet is not damaged, and the heat-generating electronic components can be installed in a sliding manner.

[0050] That is, the present invention is a thermally conductive composite sheet, which is formed by stacking a thermally conductive sheet and an insulating resin film located on one side of the thermally conductive sheet. The thermally conductive sheet has a hardness of less than 30, an initial surface tack of more than 30 gf (0.294 N), a thickness of more than 0.3 mm, and a thermal conductivity of more than 0.8 W / mK, as measured by an ASKER C-type hardness tester. The thermally conductive sheet contains an organopolysiloxane elastomer and a thermally conductive filler material. The insulating resin film has a thickness of more than 10 μm and less than 50 μm and an elastic modulus of more than 1 GPa.

[0051] The present invention will be described in detail below, but the present invention is not limited thereto.

[0052] [Thermal Conductive Composite Sheet]

[0053] The thermally conductive composite sheet of the present invention is, for example, Figure 1 As shown. In Figure 1 In this process, the thermally conductive composite sheet 1 is formed by laminating an insulating resin film 2 onto one surface of a thermally conductive sheet 3. The thermally conductive sheet 3 imparts thermal conductivity to the thermally conductive composite sheet 1. The insulating resin film 2 imparts sliding properties to the surface on which the insulating resin film 2 is laminated.

[0054] [Thermal Conductive Sheet]

[0055] As a thermally conductive sheet, there are no particular limitations as long as the hardness, initial surface tack, thickness, and thermal conductivity are within the following ranges. For example, it can be a cured product obtained by forming the thermally conductive silicone composition described later into a sheet and then curing it. In addition, commercially available thermally conductive sheets can also be used.

[0056] [Hardness of the thermal conductive sheet]

[0057] The hardness of the heat-conducting sheet is characterized by being 30 or less, preferably 20 or less, when measured using an ASKERC type hardness tester according to the method described in Annex 2 of JIS K 7312:1996. The lower limit of hardness is not particularly limited, but is preferably 1 or more, and more preferably 5 or more. If the hardness is greater than 30, it becomes difficult to compress when fixing heat-generating electronic components to the heat-conducting sheet, thereby applying stress to the heat-generating electronic components and causing damage.

[0058] [Thickness of the heat-conducting sheet]

[0059] The thickness of the heat-conducting sheet is characterized by being 0.3 mm or more, preferably 0.4 mm or more. There is no particular upper limit to the thickness; for example, it can be 5 mm or less, preferably 3 mm or less, and more preferably 2 mm or less. If it is less than 0.3 mm, as mentioned above, it is largely unable to absorb the tolerances of electronic components.

[0060] [Initial Surface Adhesion of the Thermal Conductor]

[0061] The initial tack of the thermal conductive sheet is characterized by being 30 gf (0.294 N) or higher, preferably 60 gf (0.588 N) or higher. There is no particular upper limit to the initial tack, but it is preferably 500 gf (4.903 N) or lower, more preferably 200 gf (1.961 N) or lower, and even more preferably 100 gf (0.981 N) or lower. This is because if it is less than 30 gf (0.294 N), it is difficult to achieve sufficient adhesion between the thermal conductive sheet and the substrate, and it also becomes easy to peel off when laminated with an insulating resin film. In this invention, the initial tack can be a value measured using a viscosity meter (manufactured by MALCOM CO.,LTD.) using a constant pressure immersion method.

[0062] [Thermal conductivity of the heat-conducting sheet]

[0063] The thermal conductivity of the heat-conducting sheet is 0.8 W / mK or higher. Preferably, it is 1.5 W / mK or higher, more preferably 3.0 W / mK or higher. There is no particular upper limit to the thermal conductivity; for example, it can be 10 W / mK or lower, preferably 5 W / mK or lower. If the thermal conductivity is less than 0.8 W / mK, the heat generated by the exothermic electronic components cannot be effectively conducted to the cooling components. In this invention, the thermal conductivity can be a value measured using the hot disk method.

[0064] [Insulating resin film]

[0065] Insulating resin films refer to products made by molding organic resins with an organic framework and high molecular weight through polymerization into a film form. Manufacturing methods include applying heat above the softening point to soften and stretch the resin, and coating it onto a supporting substrate and then heating and curing it. Examples of resins include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PEEK (polyetheretherketone), PPS (polyphenylene sulfide), and PI (polyimide).

[0066] Considering characteristics, availability, and cost, compounds derived from polyester resins are preferred, specifically PET film. However, the choice of insulating resin film depends on the environment in which the thermally conductive composite sheet is used. For long-term use in environments such as above 150°C, PPS film, PI film, etc., can be selected from the perspective of heat resistance.

[0067] [Thickness of the insulating resin film]

[0068] The thickness of the insulating resin film is characterized by being 10 μm to 50 μm, preferably 20 μm to 40 μm. If the thickness is less than 10 μm, sufficient lubrication cannot be provided. On the other hand, when the thickness is greater than 50 μm, heat from exothermic electronic components cannot be effectively conducted to cooling components. This is because insulating resin films typically have low thermal conductivity, hindering heat conduction; therefore, a thinner insulating resin film is preferred. However, even if it is too thin, sufficient lubrication still cannot be provided.

[0069] [Elastic modulus of insulating resin film]

[0070] The elastic modulus of the insulating resin film is 1 GPa or more, preferably 2 GPa or more, and more preferably 3 GPa or more. There is no particular upper limit, but it can be, for example, 10 GPa or less, preferably 7 GPa or less, and even more preferably 5 GPa or less. If it is less than 1 GPa, the strength of the resin film is insufficient to provide adequate sliding properties. In this invention, the elastic modulus can be a value determined according to ASTM D882.

[0071] [Molding method of thermally conductive composite sheet]

[0072] One method for forming the thermally conductive composite sheet is, for example, by laminating an insulating resin film onto the thermally conductive sheet. In this case, it is preferable to manufacture it in a manner where no air layer is present at the interface of the insulating resin film and the thermally conductive sheet. Alternatively, an uncured thermally conductive silicone composition can be coated onto the insulating resin film and then cured by heating. However, the forming method of the thermally conductive composite sheet is not particularly limited to these methods. Furthermore, to improve the adhesion between the thermally conductive sheet and the insulating resin film, a primer treatment or plasma treatment can be applied to the insulating resin film.

[0073] [Thermoconductive silicone composition]

[0074] The thermally conductive silicone composition used to form the thermally conductive sheet used in this invention is not particularly limited, but preferably contains the following components (A) to (D). Each component will be described in detail below.

[0075] [(A) Organopolysiloxane]

[0076] The alkenyl-containing organopolysiloxane, which is a component (A), is an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule, and is the main agent of the cured product of this composition. Generally, the main chain portion is basically composed of repeating diorganosiloxane units, but it may also contain branched structures in part of the molecular structure, and may also be cyclic. From the perspective of the mechanical strength and other physical properties of the cured product, linear diorganopolysiloxanes are preferred.

[0077] Alkenyl groups bonded to silicon atoms can be categorized into those with 2 to 8 carbon atoms, such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl. Among these, lower alkenyl groups such as vinyl and allyl are preferred, and vinyl is particularly preferred.

[0078] Furthermore, as functional groups other than the alkenyl group bonded to silicon atoms, monovalent hydrocarbon groups can be listed, wherein the monovalent hydrocarbon group is selected from alkyl groups having 1 to 12 carbon atoms, preferably 1 to 7; aryl groups having 6 to 15 carbon atoms, preferably 6 to 12; and aralkyl groups having 7 to 15 carbon atoms, preferably 7 to 12. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, etc., and may also include cyclopentyl, cyclohexyl, cycloheptyl, etc. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, biphenyl. Examples of aralkyl groups include benzyl, phenethyl, phenylpropyl, methylbenzyl, etc. Among these, methyl, ethyl, propyl, and phenyl are preferred. Furthermore, these functional groups may all be the same or all different.

[0079] The kinematic viscosity of this organopolysiloxane at 25°C is preferably 10–30,000 mm⁻¹. 2 The range of / s is more preferably 50 to 1000 mm. 2 The range of kinematic viscosity is specified. If an organopolysiloxane with a kinematic viscosity within this range is used, the flowability of the resulting composition will not be impaired, and the filling of thermally conductive fillers becomes easier. Furthermore, in this specification, kinematic viscosity refers to the kinematic viscosity at 25°C measured using a Cannon-Fenske viscometer as described in JIS Z 8803:2011.

[0080] The organopolysiloxane used as component (A) can be used alone or in combination with two or more organopolysiloxanes of different viscosities.

[0081] [(B) Organohydrogen polysiloxane]

[0082] The organohydropolysiloxane, as component (B), is an organohydropolysiloxane having an average of two or more, preferably 2 to 100, hydrogen atoms (hydrosilyl groups) directly bonded to silicon atoms in one molecule, and is used as a crosslinking agent for component (A). That is, the hydrosilyl group in component (B) and the alkenyl group in component (A) undergo addition via a hydrosilylation reaction promoted by a platinum group metal curing catalyst, which will be described later as component (D), thereby providing a three-dimensional network structure with a crosslinked structure. Furthermore, when the number of hydrosilyl groups is less than two, curing is not performed.

[0083] As an organohydrogen polysiloxane, the compound represented by the average structural formula (4) below is preferred, but not limited thereto.

[0084] [Chemical Formula 2]

[0085]

[0086] (In general formula (4), R) 6 Independently a hydrogen atom or a group selected from alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 15 carbon atoms, and aralkyl groups having 7 to 15 carbon atoms, R 6 Two or more of them are hydrogen atoms, preferably R 6 Of these, 2 to 10 are hydrogen atoms, and e is an integer greater than or equal to 1, preferably an integer between 10 and 200.

[0087] In general formula (4), R is used as 6 The group other than hydrogen atoms can be selected from alkyl groups having 1 to 12 carbon atoms, preferably 1 to 7; aryl groups having 6 to 15 carbon atoms, preferably 6 to 12; and aralkyl groups having 7 to 15 carbon atoms, preferably 7 to 12. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, etc., and may also include cyclopentyl, cyclohexyl, cycloheptyl, etc. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, biphenyl, etc. Examples of aralkyl groups include benzyl, phenethyl, phenylpropyl, methylbenzyl, etc. Methyl, ethyl, propyl, and phenyl are preferred. In addition, R 6 They can all be the same, or they can all be different.

[0088] The amount of component (B) added is as follows: relative to 1 mole of alkenyl group from component (A), the amount of hydrosilyl group from component (B) is preferably 0.1 to 5.0 moles, more preferably 0.3 to 2.0 moles, and even more preferably 0.5 to 1.0 moles. If the amount of hydrosilyl group from component (B) is 0.1 moles or more relative to 1 mole of alkenyl group from component (A), curing can be performed and the cured product has sufficient strength, can maintain the shape as a molded body, and becomes easy to handle. Furthermore, if it is 5.0 moles or less, the cured product can maintain its flexibility and will not become brittle.

[0089] [(C) Thermally conductive filler material]

[0090] The thermally conductive filler material, as component (C), preferably mainly contains alumina, for example, thermally conductive filler materials composed of the following components (Ci) to (C-iii):

[0091] (Ci) Amorphous alumina with an average particle size of 10–30 μm;

[0092] (C-ii) Spherical alumina with an average particle size of 30–85 μm;

[0093] (C-iii) Insulating inorganic fillers with an average particle size of 0.1 to 6 μm.

[0094] Furthermore, in this invention, the aforementioned average particle size is the cumulative average particle size (median particle size) of the volume reference, determined using a Microtrac MT3300EX particle size analyzer manufactured by MicrotracBEL Corp. via laser diffraction scattering (Microtrac method).

[0095] Amorphous alumina, as a (Ci) component, preferentially improves thermal conductivity. The average particle size of the amorphous alumina is preferably 10–30 μm, more preferably 15–25 μm. If the average particle size is 10 μm or more, the effect of improving thermal conductivity is sufficiently enhanced, and the viscosity of the composition does not increase, resulting in good processability. Furthermore, if the average particle size is 30 μm or less, wear on the reaction vessel and stirring blades is less likely, and there is no concern about a decrease in the insulation properties of the composition. One type of amorphous alumina or a combination of two or more types can be used as the (Ci) component. Additionally, commercially available amorphous alumina products can be used.

[0096] The spherical alumina as the (C-ii) component improves the thermal conductivity of the composition and inhibits contact between amorphous alumina and the reactor and agitator blades, thereby providing a barrier effect to suppress equipment wear. The average particle size is preferably 30–85 μm, more preferably 40–80 μm. If the average particle size is 30 μm or more, a sufficient barrier effect can be obtained, reducing wear on the reactor and agitator blades caused by amorphous particles. On the other hand, if the average particle size is 85 μm or less, there is no situation where alumina precipitation occurs in the composition, thus preventing damage to the homogeneity of the composition. One or more spherical alumina components (C-ii) can be used. Furthermore, commercially available spherical alumina products can be used.

[0097] The insulating inorganic filler, as component (C-iii), also plays a role in improving the thermal conductivity of the composition. Its main functions are to adjust the viscosity of the composition, prevent sedimentation, improve smoothness, and improve filling properties. Furthermore, it also plays a role in coloring, improving flame retardancy, increasing strength, and improving compressive stress. To ensure the insulation properties of the composition, the filler preferably has insulating properties. The average particle size of component (C-iii) is preferably 0.1 to 6 μm, but 0.5 to 4 μm is more preferred due to the aforementioned characteristics. If the average particle size is 0.1 μm or more, the viscosity of the composition is sufficiently low, and the moldability becomes good. Furthermore, if the average particle size is 6 μm or less, the smoothness of the composition is not compromised, and rapid filler sedimentation does not occur, thus improving the thermal conductivity of the molded article and the moldability of the composition.

[0098] As insulating inorganic fillers of component (C-iii), for example, metal oxides such as alumina, silicon dioxide, magnesium oxide, red iron oxide, beryllium oxide, titanium dioxide, and zirconium oxide, other than components (Ci) and (C-ii) mentioned above; metal nitrides such as aluminum nitride, silicon nitride, and boron nitride; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; and synthetic diamond can be used. These insulating inorganic fillers can be spherical or amorphous, and one or more of these insulating inorganic fillers can be used. Furthermore, commercially available products can be used as insulating inorganic fillers.

[0099] The amount of component (Ci) is preferably 500 to 1500 parts by mass relative to 100 parts by mass of component (A), more preferably 700 to 1200 parts by mass. If the amount of component (Ci) is 500 parts by mass or more, the improvement in thermal conductivity becomes sufficient; if it is 1500 parts by mass or less, the flowability of the composition is not lost and the moldability is maintained. In addition, wear on the reactor and stirring blades is less likely to occur, and there is no concern about a decrease in the insulation of the composition.

[0100] The amount of component (C-ii) is preferably 150 to 4000 parts by mass relative to 100 parts by mass of component (A), more preferably 200 to 3000 parts by mass. If the amount of component (C-ii) is 150 parts by mass or more, the improvement in thermal conductivity becomes sufficient, and if it is 4000 parts by mass or less, the fluidity of the composition is not lost and the moldability is maintained.

[0101] The amount of component (C-iii) is preferably 500 to 2000 parts by mass relative to 100 parts by mass of component (A), more preferably 600 to 1800 parts by mass. If the amount of component (C-iii) is 500 parts by mass or more, the smoothness of the composition is not impaired, and filler deposition does not occur rapidly; therefore, the thermal conductivity of the molded article and the moldability of the composition become good. If it is 2000 parts by mass or less, the viscosity of the composition does not increase significantly, thus maintaining moldability.

[0102] Furthermore, relative to 100 parts by mass of component (A), the amount of component (C) (i.e., the total amount of components (Ci) to (C-iii) mentioned above) is preferably 1200 to 6500 parts by mass, more preferably 1500 to 5500 parts by mass. If the amount of this blending is 1200 parts by mass or more, the resulting composition has good thermal conductivity, the viscosity of the composition does not become too low, and the storage stability is sufficient. If it is 6500 parts by mass or less, the composition has sufficient ductility, and a molded article with sufficient hardness and strength can be formed.

[0103] By using component (C) in the above blending ratio, the effects of the present invention can be achieved more advantageously and reliably.

[0104] [(D) Platinum group metal solidification catalysts]

[0105] Platinum group metal curing catalysts, which are components (D), are catalysts used to promote the addition reaction of alkenyl groups from component (A) with Si-H groups from component (B). Catalysts known as catalysts for hydrosilylation reactions can be listed.

[0106] Specific examples include platinum group metal monomers such as platinum (including platinum black), rhodium, and palladium; and platinum chlorides such as H₂PtCl₄·nH₂O, H₂PtCl₆·nH₂O, NaHPtCl₆·nH₂O, KaHPtCl₆·nH₂O, Na₂PtCl₆·nH₂O, K₂PtCl₄·nH₂O, PtCl₄·nH₂O, PtCl₂, and Na₂HPtCl₄·nH₂O (where n is an integer from 0 to 6, preferably 0 or 6). Chloroplatinic acid and chloroplatinate; alcohol-modified chloroplatinic acid (see US Patent No. 3,220,972), chloroplatinic acid and olefin complexes (see US Patent Nos. 3,159,601, 3,159,662, and 3,775,452); supported materials consisting of platinum group metals such as platinum black and palladium supported on alumina, silica, carbon, etc.; rhodium-olefin complexes, rhodium tri(triphenylphosphine)chloride (Wilkinson's catalyst); complexes of platinum chloride, chloroplatinic acid or chloroplatinate with vinylsiloxanes, especially vinylcyclic siloxanes, etc.

[0107] The amount of component (D) relative to component (A) is 0.1 to 2000 ppm, more preferably 50 to 1000 ppm, based on the mass conversion of platinum group metals.

[0108] [(E) Reaction Control Agent]

[0109] In the thermally conductive silicone composition of the present invention, an addition reaction control agent can be further used as component (E). The addition reaction control agent is not particularly limited, and known addition reaction control agents used in typical addition-curing silicone compositions can be used. Examples include acetylene compounds such as 1-ethynyl-1-hexanol, 3-butynyl-1-ol, and ethynylmethylene methanol, or various nitrides, organophosphorus compounds, oxime compounds, organochlorides, etc.

[0110] The amount of component (E) used as an admixture relative to 100 parts by mass of component (A) is preferably 0.01 to 1 part by mass, and more preferably about 0.1 to 0.8 parts by mass. If the admixture amount is less than 1 part by mass, the curing reaction can proceed well, and thus the molding efficiency is good.

[0111] [(F) Surface Treatment Agent]

[0112] Furthermore, component (C) is preferably hydrophobically treated with surface treatment agent (F). Hydrophobic treatment of component (C) improves its wettability with the organopolysiloxane (A), and allows the thermally conductive filler material (C) to be uniformly dispersed in the matrix composed of component (A). Component (F) is particularly preferably selected from one or more components in the group consisting of components (F-1) and (F-2) as shown below.

[0113] (F-1) is an alkoxysilane compound represented by the following general formula (1).

[0114] R 1 a R 2 b Si(OR 3 ) 4-a-b (1)

[0115] (In general formula (1), R) 1 Independently, it is an alkyl group having 6 to 15 carbon atoms, R 2 R is an independent monovalent hydrocarbon group having 1 to 12 carbon atoms. 3 Independently, it is an alkyl group having 1 to 6 carbon atoms, where a is an integer from 1 to 3, b is an integer from 0 to 2, and a+b is an integer from 1 to 3.

[0116] In the above general formula (1), as R 1 The alkyl group represented can be, for example, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, etc. If the condition R is satisfied... 1 If the number of carbon atoms in the alkyl group is in the range of 6 to 15, then the wettability of component (A) is sufficiently improved, the processability is good, and the low-temperature properties of the composition are good.

[0117] As R 2 Examples of monovalent hydrocarbon groups include: alkyl groups with 1 to 5 carbon atoms, preferably alkyl groups with 1 to 3 carbon atoms; aryl groups with 6 to 15 carbon atoms, preferably aryl groups with 6 to 12 carbon atoms; and aralkyl groups with 7 to 15 carbon atoms, preferably aralkyl groups with 7 to 12 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, and neopentyl. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, and biphenyl. Examples of aralkyl groups include benzyl, phenethyl, phenylpropyl, and methylbenzyl. Among these, methyl, ethyl, propyl, and phenyl are preferred.

[0118] As R 3 Examples include methyl, ethyl, propyl, butyl, and hexyl.

[0119] (F-2) is a dimethyl polysiloxane whose molecular chain is capped with a trialkoxysilyl group at one end, as represented by the following general formula (2).

[0120] [Chemical Formula 3]

[0121]

[0122] (In general formula (2), R) 4 Independently, it is an alkyl group having 1 to 6 carbon atoms, where c is an integer from 5 to 100.

[0123] In general formula (2), as R 4 The alkyl group represented can be exemplified by R in the above general representation (1). 3 The alkyl group represents the same alkyl group. c is preferably an integer from 5 to 70, and particularly preferably an integer from 10 to 50.

[0124] The surface treatment agent used as component (F) can be either component (F-1) or component (F-2), or a combination of both.

[0125] The amount of component (F) as an admixture relative to 100 parts by mass of component (A) is preferably 0.01 to 300 parts by mass, and particularly preferably 0.1 to 200 parts by mass. If the proportion of this component is 300 parts by mass or less, oil separation will not be induced.

[0126] [(G) Organopolysiloxane]

[0127] With the aim of imparting properties such as viscosity adjustment to the thermally conductive silicone composition, it is possible to add a material with a kinematic viscosity of 10 to 100,000 mm at 23°C, represented by the following general formula (3), to the thermally conductive silicone composition used in the present invention. 2 / s of organopolysiloxane as component (G),

[0128] [Chemical Formula 4]

[0129]

[0130] (In general formula (3), R) 5 (Independently a monovalent hydrocarbon group with 1 to 12 carbon atoms and no aliphatic unsaturated bonds, d is an integer from 5 to 2000). (G) Components can be used alone or in combination of two or more.

[0131] In the above general formula (3), R 5 It is independently a monovalent hydrocarbon group with 1 to 12 carbon atoms and no aliphatic unsaturated bonds. As R 5Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups include cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups include phenyl, tolyl, xylyl, naphthyl, and biphenyl; and aralkyl groups include benzyl, phenethyl, phenylpropyl, and methylbenzyl. Representative groups are those with 1 to 10 carbon atoms, particularly those with 1 to 6 carbon atoms. Alkyl groups with 1 to 3 carbon atoms, such as methyl, ethyl, and propyl, and phenyl are preferred, with methyl and phenyl being especially preferred.

[0132] From the perspective of the required viscosity, the above-mentioned d is preferably an integer from 5 to 2000, and particularly preferably an integer from 10 to 1000.

[0133] Furthermore, the kinematic viscosity of the preferred (G) component at 23°C is 10–100,000 mm³. 2 / s, particularly preferably 100–10000 mm 2 / s. If the kinematic viscosity is 10 mm... 2 If the kinematic viscosity is above a certain value (e.g., 100,000 mM), the cured product of the resulting composition is less prone to oil seepage. 2 If the temperature is below a certain value, the flexibility of the resulting thermally conductive silicone composition can be fully maintained.

[0134] When component (G) is added to the thermally conductive silicone composition, the amount added is not particularly limited, as long as it is an amount that achieves the desired effect. The amount added is preferably 0.1 to 100 parts by weight relative to 100 parts by weight of component (A), more preferably 1 to 50 parts by weight. If the amount added is within this range, it is easy to maintain good flowability and workability of the thermally conductive silicone composition before curing, and it is also easy to fill the composition with the thermally conductive filler material as component (C).

[0135] [Installation method for heat-generating electronic components]

[0136] Furthermore, the present invention provides a method for mounting a heat-exothermic electronic component, which involves sliding the heat-exothermic electronic component on the insulating resin film of the thermally conductive composite sheet of the present invention and adjusting it to a target position, and then fixing the heat-exothermic electronic component.

[0137] If such a method is used to install heat-dissipating electronic components, then when installing heat-dissipating electronic components in electronic devices, the sliding properties of one side of the heat-conducting sheet are excellent, so the sheet will not peel or break. It is possible to slide the heat-dissipating electronic components in a way that existing heat-conducting sheets cannot achieve, thereby expanding the scope of application of the installation method.

[0138] Example

[0139] The present invention will be specifically described below with examples and comparative examples, but the present invention is not limited to the following examples. Furthermore, the values ​​of parameters such as hardness, initial tack, thermal conductivity, elastic modulus, kinematic viscosity, and particle size were measured by the methods described above.

[0140] The following shows the heat-conducting sheet and insulating resin film used in the embodiments and comparative examples.

[0141] [Thermal Conductive Sheet]

[0142] 1: TC-100CAD-10 (manufactured by Shin-Etsu Chemical Co., Ltd., thickness 1mm, 3.2W / mK, hardness measured by ASKER C type hardness tester is 10, initial tack is 85gf (0.834N))

[0143] 2: TC-100CAS-10 (manufactured by Shin-Etsu Chemical Co., Ltd., thickness 1mm, 1.8W / mK, hardness measured by ASKER C type hardness tester is 10, initial tack is 94gf (0.922N))

[0144] 3: TC-50CAD-10 (manufactured by Shin-Etsu Chemical Co., Ltd., thickness 0.5mm, 3.2W / mK, hardness measured by ASKER C type hardness tester is 10, initial tack is 90gf (0.883N))

[0145] 4: A 1mm thick thermally conductive sheet, which is obtained by curing the following composition using the forming method 2 of the thermally conductive composite sheet described below. The thermal conductivity is 3.2W / mK, the hardness measured by the ASKER C-type hardness tester is 10, and the initial tack is 90gf (0.883N).

[0146] 5: TC-80TA-1 (manufactured by Shin-Etsu Chemical Co., Ltd., thickness 0.8mm, 1W / mK, hardness measured by ASKERC type hardness tester is 90, initial tack is 10gf (0.098N))

[0147] The components (A) to (G) of the composition of the heat-conducting sheet 4 are shown below.

[0148] A composition comprising the following components:

[0149] A) The kinematic viscosity represented by the following general formula (5) is 600 mm. 2 / s of organopolysiloxane, which is 100 parts by mass.

[0150] [Chemical Formula 5]

[0151]

[0152] (In general formula (5), f represents the number of values ​​that satisfy the above kinematic viscosity);

[0153] B) The organohydrogen polysiloxane represented by the following general formula (6), in 11 parts by mass,

[0154] [Chemical Formula 6]

[0155]

[0156] C)

[0157] C-1) Amorphous alumina with an average particle size of 1 μm, comprising 230 parts by mass.

[0158] C-2) Amorphous alumina with an average particle size of 5 μm, comprising 470 parts by mass.

[0159] C-3) Amorphous alumina with an average particle size of 20 μm, comprising 800 parts by mass.

[0160] C-4) Spherical alumina with an average particle size of 45 μm, comprising 120 parts by weight.

[0161] C-5) Spherical alumina with an average particle size of 70 μm, comprising 120 parts by mass;

[0162] D) A 5% (w / w) solution of 2-ethylhexanol chloroplatinic acid, which is 1 part by weight;

[0163] E) Ethynylmethylene methanol: 0.4 parts by weight;

[0164] F) The organopolysiloxane represented by the following general formula (7), in 40 parts by mass,

[0165] [Chemical Formula 7]

[0166]

[0167] G) The organopolysiloxane represented by the following general formula (8), in 15 parts by mass,

[0168] [Chemical Formula 8]

[0169]

[0170] The physical properties of the heat-conducting sheet 4 obtained from the above composition are evaluated in the following manner.

[0171] [Evaluation Method]

[0172] Thermal conductivity: The obtained composition was cured into a sheet with a thickness of 6 mm. Using two sheets, the thermal conductivity of the sheet was measured using a thermal conductivity meter (TPA-501, trade name manufactured by KYOTO ELECTRONICS MANUFACTURING CO.,LTD.).

[0173] Hardness: The obtained composition was cured into a sheet with a thickness of 6 mm, and two sheets were overlapped and measured using an ASKER C hardness tester.

[0174] [Insulating Resin]

[0175] 1: Lumirror S10 (manufactured by Toray Industries, Inc., PET, thickness: 38μm, elastic modulus: 4.7GPa)

[0176] 2: Lumirror S10 (manufactured by Toray Industries, Inc., PET, thickness: 24μm, elastic modulus: 4.7GPa)

[0177] 3: APICAL (manufactured by KANEKA CORPORATION, PI, thickness: 24μm, elastic modulus: 3.2GPa)

[0178] 4: Kapton (manufactured by DU PONT-TORAY CO.,LTD., PI, thickness: 7.5μm, elastic modulus: 3.1GPa)

[0179] 5: TC-20TA-1 (manufactured by Shin-Etsu Chemical Co., Ltd., thermally conductive silicone rubber, thickness: 0.2mm, elastic modulus: 13MPa)

[0180] 6: Torayfan (manufactured by Toray Industries, Inc., polypropylene, thickness: 30μm, elastic modulus: 0.15GPa)

[0181] 7: Lumirror S10 (manufactured by Toray Industries, Inc., PET, thickness: 50μm, elastic modulus: 4.7GPa)

[0182] 8: Kapton (manufactured by DU PONT-TORAY CO.,LTD., PI, thickness: 12.5μm, elastic modulus: 3.1GPa)

[0183] 9: Lumirror S10 (manufactured by Toray Industries, Inc., PET, thickness: 75μm, elastic modulus: 4.7GPa)

[0184] [Examples 1 - 7, Comparative Examples 1 - 7]

[0185] Using the combination of laminated heat - conductive sheets and insulating resin films shown in Table 1 below, a heat - conductive composite sheet was formed. The forming method of the heat - conductive composite sheet is as follows.

[0186] [Forming Method 1 of Heat - Conductive Composite Sheet]

[0187] On one surface of the heat - conductive sheet, a rubber roller weighing 2 kg was moved from the end of the insulating resin film at a speed of 0.5 m / minute to seamlessly bond the heat - conductive sheet and the insulating resin film. This method is applicable to the examples using the above - mentioned heat - conductive sheets 1 - 3 and 5.

[0188] [Forming Method 2 of Heat - Conductive Composite Sheet]

[0189] A composition composed of an uncured silicone polymer and a heat - conductive filler was coated on the insulating resin film using a comma coater and cured under the conditions of 120°C for 20 minutes. This method is applicable to the example using the above - mentioned heat - conductive sheet 4.

[0190] The sliding property of the obtained film was evaluated, and the results were summarized in Table 1. The evaluation method is as follows.

[0191] [Evaluation Method]

[0192] Sliding property: Using a 2 - kg rubber roller, a heat - conductive composite sheet with dimensions of 200×500 mm was bonded to a sufficiently large aluminum plate at a speed of 0.5 m / minute. Then, a stainless - steel block with a width of 200 mm, a length of 40 mm, a height of 150 mm, and a weight of 2 kg was moved 500 mm on the insulating resin film at a speed of 1 m / minute, and it was confirmed whether the sheet cracked or peeled at this time. If the sheet did not crack or peel, it was considered qualified; when the sheet cracked or peeled, it was evaluated as unqualified.

[0193] Thermal resistance rise value: It is the difference between the thermal resistance of the heat - conductive sheet and the thermal resistance of the heat - conductive composite sheet laminated with the insulating resin film. The measurement method is based on ASTM D5470, and the measurement conditions are 50°C / 40 psi.

[0194] [Table 1]

[0195]

[0196] In Examples 1 - 7 using the heat - conductive composite sheet of the present invention, excellent sliding properties were exhibited, the sheet or film did not crack, and it was confirmed that the heat - conductive composite sheet of the present invention can be applied to the installation of exothermic electronic components.

[0197] Furthermore, as shown in Comparative Example 1, if the insulating resin film was not laminated, the sheet remained sticky and cracked, resulting in unsatisfactory sliding performance. In Comparative Example 2, the insulating resin film was too thin, causing it to crack. In Comparative Example 3, the elastic modulus of the silicone rubber was insufficient, leading to the cracking of TC-20TA-1. In Comparative Example 4, the polypropylene film with a low elastic modulus cracked after elongation, resulting in unsatisfactory sliding performance. In Comparative Example 5, the heat-conducting sheet had high hardness and insufficient initial adhesion, causing the insulating resin film to peel off. In Comparative Example 6, although an insulating resin film was laminated on both sides of the heat-conducting sheet, it still could not adhere to the aluminum plate, making a sliding performance evaluation impossible. In Comparative Example 7, although the sliding performance test was satisfactory due to the use of a thicker insulating resin film, the result was a significant increase in thermal resistance.

[0198] Furthermore, this invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any solutions that have substantially the same composition and achieve the same effect as the technical concept described in the claims of this invention are included within the technical scope of this invention.

Claims

1. A thermally conductive composite sheet, characterized in that, It is formed by stacking a thermally conductive sheet and an insulating resin film on one side of the thermally conductive sheet. The thermally conductive sheet has a hardness of 30 or less, an initial tack of 0.294 N or more, a thickness of 0.3 mm or more, and a thermal conductivity of 0.8 W / mK or more, as measured by an ASKER C-type hardness tester. The thermally conductive sheet contains an organopolysiloxane elastomer and a thermally conductive filler material. The insulating resin film has a thickness of 10 μm or more and 50 μm or less, and an elastic modulus of 1 GPa or more. Using a 2kg rubber roller at a speed of 0.5m / min, a thermally conductive composite sheet measuring 200×500mm was bonded to an aluminum plate. Then, a stainless steel block measuring 200mm in width, 40mm in length, 150mm in height, and weighing 2kg was moved 500mm across an insulating resin film at a speed of 1m / min. The sheet did not crack or peel.

2. The thermally conductive composite sheet according to claim 1, characterized in that, The insulating resin film is a polyester resin film.

3. The thermally conductive composite sheet according to claim 1, characterized in that, The thermal conductivity of the heat-conducting sheet is above 3.0 W / mK.

4. The thermally conductive composite sheet according to claim 2, characterized in that, The thermal conductivity of the heat-conducting sheet is above 3.0 W / mK.

5. The thermally conductive composite sheet according to claim 1, characterized in that, The thermally conductive sheet is a cured product of a thermally conductive silicone composition containing the following components (A) to (D): (A) An organopolysiloxane having two or more alkenyl groups in one molecule, in 100 parts by mass; (B) An organohydrogen polysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, wherein the number of moles of the hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups from component (A); (C) A thermally conductive filler material, comprising 1200–6500 parts by weight; and (D) Platinum group metal solidification catalyst, with a mass conversion of platinum group metal elements, relative to component (A) of 0.1 to 2000 ppm.

6. The thermally conductive composite sheet according to claim 2, characterized in that, The thermally conductive sheet is a cured product of a thermally conductive silicone composition containing the following components (A) to (D): (A) An organopolysiloxane having two or more alkenyl groups in one molecule, in 100 parts by mass; (B) An organohydrogen polysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, wherein the number of moles of the hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups from component (A); (C) A thermally conductive filler material, comprising 1200–6500 parts by weight; and (D) Platinum group metal solidification catalyst, which, based on the mass conversion of platinum group metal elements, is 0.1 to 2000 ppm relative to the component (A).

7. The thermally conductive composite sheet according to claim 3, characterized in that, The thermally conductive sheet is a cured product of a thermally conductive silicone composition containing the following components (A) to (D): (A) An organopolysiloxane having two or more alkenyl groups in one molecule, in 100 parts by mass; (B) An organohydrogen polysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, wherein the number of moles of the hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups from component (A); (C) A thermally conductive filler material, comprising 1200–6500 parts by weight; and (D) Platinum group metal solidification catalyst, which, based on the mass conversion of platinum group metal elements, is 0.1 to 2000 ppm relative to the component (A).

8. The thermally conductive composite sheet according to claim 4, characterized in that, The thermally conductive sheet is a cured product of a thermally conductive silicone composition containing the following components (A) to (D): (A) An organopolysiloxane having two or more alkenyl groups in one molecule, in 100 parts by mass; (B) An organohydrogen polysiloxane having two or more hydrogen atoms directly bonded to silicon atoms, wherein the number of moles of the hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups from component (A); (C) A thermally conductive filler material, comprising 1200–6500 parts by weight; and (D) Platinum group metal solidification catalyst, which, based on the mass conversion of platinum group metal elements, is 0.1 to 2000 ppm relative to the component (A).

9. The thermally conductive composite sheet according to any one of claims 5 to 8, characterized in that, The thermally conductive filler material of component (C) consists of the following three components: (Ci) Amorphous alumina with an average particle size of 10-30 μm, in quantities of 500-1500 parts by mass; (C-ii) Spherical alumina with an average particle size of 30–85 μm, in quantities of 150–4000 parts by mass; and (C-iii) Insulating inorganic fillers with an average particle size of 0.1 to 6 μm, in quantities of 500 to 2000 parts by mass.

10. The thermally conductive composite sheet according to any one of claims 5 to 8, characterized in that, Component (C) has been treated with surface treatment agent (F), which is one or more selected from the group consisting of alkoxysilane compounds represented by general formula (1) below (F-1) and dimethyl polysiloxanes with single ends of trialkoxysilyl groups represented by general formula (2) below (F-2). R 1 a R 2 b Si(OR 3 ) 4-a-b (1) In general formula (1), R 1 Independently, it is an alkyl group having 6 to 15 carbon atoms, R 2 R is an independent monovalent hydrocarbon group having 1 to 12 carbon atoms. 3 Independently, it is an alkyl group having 1 to 6 carbon atoms, where a is an integer from 1 to 3, b is an integer from 0 to 2, and a+b is an integer from 1 to 3; In general formula (2), R 4 Independently, it is an alkyl group having 1 to 6 carbon atoms, where c is an integer from 5 to 100.

11. The thermally conductive composite sheet according to claim 9, characterized in that, Component (C) has been treated with surface treatment agent (F), which is one or more selected from the group consisting of alkoxysilane compounds represented by general formula (1) below (F-1) and dimethyl polysiloxanes with single ends of trialkoxysilyl groups represented by general formula (2) below (F-2). R 1 a R 2 b Si(OR 3 ) 4-a-b (1) In general formula (1), R 1 Independently, it is an alkyl group having 6 to 15 carbon atoms, R 2 R is an independent monovalent hydrocarbon group having 1 to 12 carbon atoms. 3 Independently, it is an alkyl group having 1 to 6 carbon atoms, where a is an integer from 1 to 3, b is an integer from 0 to 2, and a+b is an integer from 1 to 3; In general formula (2), R 4 Independently, it is an alkyl group having 1 to 6 carbon atoms, where c is an integer from 5 to 100.

12. The thermally conductive composite sheet according to claim 10, characterized in that, The amount of component (F) is 0.01 to 300 parts by mass relative to 100 parts by mass of component (A).

13. The thermally conductive composite sheet according to claim 11, characterized in that, The amount of component (F) is 0.01 to 300 parts by mass relative to 100 parts by mass of component (A).

14. A method for mounting a heat-exothermic electronic component, characterized in that, After sliding the exothermic electronic component on the insulating resin film of the thermally conductive composite sheet and adjusting it to the target position, the exothermic electronic component is fixed. The thermally conductive composite sheet is formed by stacking a thermally conductive sheet and an insulating resin film on one side of the thermally conductive sheet. The thermally conductive sheet has a hardness of less than 30, an initial surface tack of more than 0.294 N, a thickness of more than 0.3 mm, and a thermal conductivity of more than 0.8 W / mK, as measured by an ASKER C-type hardness tester. The thermally conductive sheet contains an organopolysiloxane elastomer and a thermally conductive filler material. The insulating resin film has a thickness of more than 10 μm and less than 50 μm and an elastic modulus of more than 1 GPa.

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