Thermally conductive silicone resin composition, method for manufacturing same, and thermally conductive sheet

Abstract

Provided is a thermally conductive silicone resin composition which has good thermal conductivity and in which a pumping-out phenomenon after extended use is prevented. This thermally conductive silicone resin composition contains component (A), component (B), and component (C), and contains X parts by mass of the component (A) (X = 50-99), (100−X) parts by mass of the component (B), and 50-3000 parts by mass of the component (C). The component (A) is a liquid silicone resin. The component (B) is a linear organopolysiloxane represented by formula (I). The component (C) is thermally conductive inorganic particles having a median diameter D50 of a cumulative particle size distribution by volume of 80 μm or more, the material of the thermally conductive inorganic particles having the D50 of 80 μm or more containing at least one selected from the group consisting of alumina and aluminum nitride. (In the formula, R1 to R5 are each independently a phenyl group or an alkyl group having 1 to 18 carbon atoms, R6 and R7 are each independently a phenyl group or an alkyl group having 1 to 18 carbon atoms, R8 and R10 are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, R9 is a phenyl group or an alkyl group having 1 to 3 carbon atoms, n is 4 to 2000, and m is 1 to 20. However, if there is a plurality of R4 and R5 above, the plurality of R4 and R5 may be the same or different.)

Description

Thermally conductive silicone resin composition, its manufacturing method, and thermally conductive sheet

[0001] The present invention relates to a thermally conductive silicone resin composition suitable for placement between a heat-generating portion of an electric or electronic component or the like and a heat sink, a method for producing the same, and a thermally conductive sheet.

[0002] In recent years, the performance of semiconductors such as CPUs has improved dramatically, resulting in enormous increases in the amount of heat generated. Heat sinks are therefore attached to heat-generating electronic components, and thermally conductive silicone resins are used to improve adhesion between heat sinks and heat-generating components such as semiconductors. However, when used over a long period of time, thermally conductive silicone resins can flow out of the heat sink due to the thermal shock of the semiconductor element, creating voids in the heat sink, resulting in the problem of "pumping out."

[0003] Japanese Patent Laid-Open Publication No. 2023-026788 proposes a thermally conductive silicone resin containing a specific cyclic organopolysiloxane and crosslinked. Japanese Patent Laid-Open Publication No. 2021-147591 proposes a thermally conductive silicone resin crosslinked using hydrosilylation catalyst fine particles having a microcapsule structure. Japanese Patent Laid-Open Publication No. 2021-098804 proposes a thermally conductive silicone resin crosslinked using an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule.

[0004] The present invention provides a thermally conductive silicone resin composition comprising the following components (A), (B), and (C): the thermally conductive silicone resin composition comprises X parts by mass (X=50 to 99) of the component (A), (100-X) parts by mass of the component (B), and 50 to 3,000 parts by mass of the component (C), wherein the component (A) is a liquid silicone resin, and the component (B) is a linear organopolysiloxane represented by the following chemical formula (I):

[0005]

[0006] (In the formula, R １ ~R ５ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ６ and R７ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ８ and R １０ are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms or a phenyl group, n is 4 to 2000, and m is 1 to 20. ４ and the R ５ When there are multiple R ４ and R ５ may be the same or different.) The component (C) is a thermally conductive silicone resin composition, wherein the component (C) is thermally conductive inorganic particles, and the component (C) contains thermally conductive inorganic particles having a median diameter D50 of 80 μm or more in a cumulative particle size distribution on a volume basis, and the material of the thermally conductive inorganic particles having a D50 of 80 μm or more contains at least one selected from the group consisting of alumina and aluminum nitride.

[0007] 1A-B are explanatory diagrams showing a method for measuring the thermal conductivity of a sample in one embodiment of the present invention. FIG. 2 is a photograph of the surface of a sample showing cracks or fissures in a pumping-out test in one embodiment of the present invention. FIG. 3 is a scanning electron microscope (SEM) photograph (magnification: 5000x) of surface-pretreated amorphous alumina (D50 = 0.3 μm) (C-1) used in one embodiment of the present invention. FIG. 4 is an SEM photograph (magnification: 3000x) of spherical alumina (D50 = 2.0 μm) (C-2) used in one embodiment of the present invention. FIG. 5 is an SEM photograph (magnification: 5000x) of crushed alumina (D50 = 2.0 μm) (C-3) used in one embodiment of the present invention. FIG. 6 is an SEM photograph (magnification: 10,000x) of spherical alumina (D50 = 4.0 μm) (C-4) used in one embodiment of the present invention. Figure 7 is an SEM photograph (magnification 1000x) of spherical alumina (D50 = 20 μm) (C-5) used in one embodiment of the present invention. Figure 8 is an SEM photograph (magnification 100x) of spherical alumina (D50 = 120 μm) (C-7) used in one embodiment of the present invention. Detailed Description of the Invention

[0008] However, the thermally conductive silicone compositions and thermally conductive sheets of the above-mentioned prior art suffer from the problem of being prone to pumping out when used for extended periods of time.

[0009] In order to solve the above-mentioned problems of the prior art, the present invention provides a thermally conductive silicone resin composition and a thermally conductive sheet that have good thermal conductivity and suppress the pumping-out phenomenon during long-term use.

[0010] One embodiment of the present invention is a thermally conductive silicone resin composition comprising the following components (A), (B), and (C): The thermally conductive silicone resin composition comprises X parts by mass (X=50 to 99) of the component (A), (100-X) parts by mass of the component (B), and 50 to 3,000 parts by mass of the component (C), wherein the component (A) is a liquid silicone resin, and the component (B) is a linear organopolysiloxane represented by the following chemical formula (I):

[0011]

[0012] (In the formula, R １ ~R ５ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ６ and R ７ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ８ and R １０ are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms or a phenyl group, n is 4 to 2000, and m is 1 to 20. ４ and the R ５ When there are multiple R ４ and R ５ may be the same or different.) The component (C) is a thermally conductive inorganic particle, and the component (C) contains thermally conductive inorganic particles having a median diameter D50 of a cumulative particle size distribution on a volume basis of 80 μm or more, and the material of the thermally conductive inorganic particles having a D50 of 80 μm or more contains at least one selected from the group consisting of alumina and aluminum nitride.

[0013] One embodiment of the method of the present invention relates to a method for producing the thermally conductive silicone resin composition, which comprises the step of mixing and stirring the component (A), the component (B), and the component (C).

[0014] One embodiment of the present invention is a thermally conductive sheet that contains a thermally conductive silicone resin composition, is formed into a sheet, and is cured.

[0015] The present invention provides a thermally conductive silicone resin composition and a thermally conductive sheet that have good thermal conductivity and suppress the pumping-out phenomenon during long-term use. The group at one end of the linear organopolysiloxane molecule of component (B) chemically reacts with the surface of the thermally conductive inorganic particles to form a covalent bond, while the group at the other end has high affinity with component (A) of the matrix resin. That is, component (B) acts as a coupling agent between the thermally conductive inorganic particles and component (A) of the matrix resin. Therefore, the pumping-out phenomenon, such as cracking or fissures, is suppressed even when the thermally conductive silicone resin composition of the present invention is used for a long period of time.

[0016] The present inventors investigated why pumping-out, such as cracking or fissures, occurs when conventional thermally conductive silicone resin compositions are used for extended periods. As a result, they came up with the idea that pumping-out, such as cracking or fissures, occurs because the matrix resin peels off at the interface between the thermally conductive inorganic particles. This phenomenon is particularly common when large thermally conductive inorganic particles are included to increase thermal conductivity.

[0017] By incorporating the linear organopolysiloxane (component (B)) described above together with the liquid silicone resin, the group at one end of the molecule chemically reacts with the surface of the thermally conductive inorganic particles to form a covalent bond, while the group at the other end has a high affinity with the matrix resin, thereby suppressing pumping-out phenomena such as cracks and fissures even after long-term use.

[0018] [Thermal Conductive Silicone Resin Composition] The thermally conductive silicone resin composition of the present invention contains component (A), component (B), and component (C).

[0019] <Component (A): Liquid Silicone Resin> The component (A) of the present invention is preferably at least one silicone selected from the group consisting of addition-curing silicone polymers and non-curing silicone oils. Silicones have high heat resistance and fluidity, making them suitable as thermally conductive materials (TIMs: Thermal Interface Materials). An example of the non-curing silicone oil is a silicone oil made of dimethylpolysiloxane. An example of the addition-curing silicone polymer includes a base polymer (A-1) made of an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms per molecule, a crosslinking component (A-2) made of an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms per molecule, and a catalyst component.

[0020] The addition-curable silicone polymer will be described below. <<Base Polymer Component (Component A-1)>> The base polymer component is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms per molecule. This organopolysiloxane contains two silicon-bonded alkenyl groups per molecule, such as vinyl or allyl groups, each having 2 to 8 carbon atoms, and preferably 2 to 6 carbon atoms. From the standpoint of workability and curability, a viscosity of 10 to 1,000,000 mPa·s at 25°C, and particularly 100 to 100,000 mPa·s, is desirable.

[0021] Specifically, an organopolysiloxane represented by the following general formula (II) is used, which contains two or more alkenyl groups bonded to silicon atoms at the molecular chain terminals per molecule. It is a linear organopolysiloxane whose side chains are blocked with alkyl groups. From the viewpoints of workability and curability, a viscosity of 10 to 1,000,000 mPa·s at 25°C is desirable. This linear organopolysiloxane may also contain a small amount of branched structures (trifunctional siloxane units) in the molecular chain.

[0022]

[0023] In the formula, R １ are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds, and R ２ is an alkenyl group, and k is 0 or a positive integer. １ Examples of unsubstituted or substituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds include those having 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms, and specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl, aryl groups such as phenyl, tolyl, xylyl, and naphthyl, aralkyl groups such as benzyl, phenylethyl, and phenylpropyl, and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, and chlorine, or with cyano groups, such as halogen-substituted alkyl groups such as chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl, and cyanoethyl groups. ２ The alkenyl group in formula (II) is, for example, preferably one having 2 to 6 carbon atoms, particularly preferably 2 to 3 carbon atoms, and specific examples thereof include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, hexenyl, and cyclohexenyl groups, with vinyl being preferred. In formula (II), k is generally 0 or a positive integer satisfying 0≦k≦10,000, preferably 5≦k≦2,000, and more preferably 10≦k≦1,200.

[0024] The organopolysiloxane of component (A-1) may be an organopolysiloxane having three or more, typically 3 to 30, and preferably about 3 to 20, alkenyl groups having 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms, such as vinyl groups or allyl groups, bonded to silicon atoms per molecule. The molecular structure may be linear, cyclic, branched, or three-dimensional network. Preferably, the organopolysiloxane has a main chain consisting of repeating diorganosiloxane units, both molecular chain terminals are capped with triorganosiloxy groups, and has a viscosity at 25°C of 10 to 1,000,000 mPa s, particularly 100 to 100,000 mPa s.

[0025] The alkenyl groups in the organopolysiloxane of component (A-1) may be bonded to any part of the molecule. For example, the alkenyl groups may be bonded to silicon atoms at the molecular chain terminals or non-terminal locations (in the middle of the molecular chain). Of these, linear organopolysiloxanes represented by the following general formula (III) have one to three alkenyl groups on each of the silicon atoms at both molecular chain terminals. However, if the total number of alkenyl groups bonded to the terminal silicon atoms at both molecular chain terminals is less than three, then linear organopolysiloxanes having at least one alkenyl group bonded to a non-terminal (in the middle of the molecular chain) silicon atom (for example, as a substituent in a diorganosiloxane unit) at the molecular chain, and as mentioned above, having a viscosity at 25°C of 10 to 1,000,000 mPa s, are preferred from the viewpoints of workability and curability. This linear organopolysiloxane may contain a small amount of branched structure (trifunctional siloxane unit) in the molecular chain.

[0026]

[0027] In the formula, R ３ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and at least one is an alkenyl group. ４ are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds, and R ５ is an alkenyl group, and l and m are 0 or positive integers. ３The monovalent hydrocarbon group preferably has 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and octenyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine, or with cyano groups, such as halogen-substituted alkyl groups such as chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl, and cyanoethyl groups.

[0028] Also, R ４ The monovalent hydrocarbon group of R preferably has 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms. １ Specific examples of R include the same as those of R, except that alkenyl groups are not included. ５ The alkenyl group of the formula (II) is preferably an alkenyl group having 2 to 6 carbon atoms, particularly preferably an alkenyl group having 2 to 3 carbon atoms. ２ Examples of l and m are the same as those shown in the above, and a vinyl group is preferred. l and m are generally 0 or a positive integer satisfying 0 < l + m ≦ 10,000, preferably 5 ≦ l + m ≦ 2,000, more preferably 10 ≦ l + m ≦ 1,200, and are integers satisfying 0 < l / (l + m) ≦ 0.2, preferably 0.0011 ≦ l / (l + m) ≦ 0.1.

[0029] <<Crosslinking Component (Component A-2)>> The organohydrogenpolysiloxane of component (A-2) of the present invention functions as a crosslinking agent, and a cured product is formed by addition reaction (hydrosilylation) of the SiH groups in this component with the alkenyl groups in component (A-1). Such organohydrogenpolysiloxanes may have two or more hydrogen atoms bonded to silicon atoms (i.e., SiH groups) per molecule, and the molecular structure of these organohydrogenpolysiloxanes may be linear, cyclic, branched, or a three-dimensional network structure. Organohydrogenpolysiloxanes having a number of silicon atoms per molecule (i.e., a degree of polymerization) of 2 to 1,000, preferably about 2 to 300, can be used.

[0030] In the organohydrogenpolysiloxane, the position of the silicon atom to which the hydrogen atom is bonded is not particularly limited, and it may be at the terminal or non-terminal position of the molecular chain (in the middle of the molecular chain). In addition, the group bonded to the silicon atom other than a hydrogen atom is, for example, R in the general formula (II). １ and unsubstituted or substituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds, similar to those shown above.

[0031] Examples of organohydrogenpolysiloxanes of component (A-2) include those with the following structures:

[0032]

[0033] In the above formula, R ６ are the same or different alkyl groups, phenyl groups, epoxy groups, acryloyl groups, methacryloyl groups, alkoxy groups, or hydrogen atoms, and at least two of them are hydrogen atoms. L is an integer of 0 to 1,000, particularly an integer of 0 to 300, and M is an integer of 1 to 200.

[0034] <<Catalyst Component>> The catalyst component can be a catalyst used in a hydrosilylation reaction. Examples of the catalyst component include platinum black, platinic chloride, chloroplatinic acid, a reaction product of chloroplatinic acid with a monohydric alcohol, a complex of chloroplatinic acid with an olefin or vinylsiloxane, a platinum-based catalyst such as platinum bisacetoacetate, a palladium-based catalyst, a rhodium-based catalyst, and other platinum-group metal catalysts. Two-component curing silicone polymers usually contain a platinum-group metal catalyst.

[0035] <Component (B): Linear Organopolysiloxane> The linear organopolysiloxane of component (B) is a linear organopolysiloxane represented by the following chemical formula (I).

[0036]

[0037] In the formula, R １ ~R ５ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ６ and R ７ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ８ and R １０ are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms or a phenyl group, n is 4 to 2000, and m is 1 to 20. ４ and the R ５ When there are multiple R ４ and R ５ may be the same or different from each other.

[0038] In the above formula, R １ ~R ５ are each independently an alkyl group having 1 to 5 carbon atoms, and R ６ and R ７ are each independently an alkyl group having 1 to 5 carbon atoms, and R ８ and R １０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９is preferably an alkyl group having 1 to 3 carbon atoms, n is preferably 5 to 1000, and m is preferably 1 to 10.

[0039] In the above formula, R １ ~R ５ are each independently a linear alkyl group having 1 to 5 carbon atoms, and R ６ and R ７ are each independently a linear alkyl group having 1 to 5 carbon atoms, and R ８ and R １０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９ is a linear alkyl group having 1 to 3 carbon atoms; n is 5 to 1000; and m is preferably 1 to 10.

[0040] In the above formula, R １ ~R ５ are each independently a linear alkyl group having 1 to 3 carbon atoms, and R ６ and R ７ are each independently a linear alkyl group having 1 to 3 carbon atoms, and R ８ and R １０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９ is a linear alkyl group having 1 to 3 carbon atoms; n is 5 to 1000; and m is preferably 1 to 5.

[0041] The linear organopolysiloxane of component (B) of the present invention is preferably a compound represented by the following chemical formula (I-1).

[0042]

[0043] In the compound of formula (I-1), the OH group at one end of the molecule chemically reacts with the surface of the thermally conductive inorganic particle to form a covalent bond, and the n-Bu group at the other end has high affinity with the matrix resin. Therefore, a thermally conductive silicone resin composition containing the compound of formula (I-1) as component B can suppress pumping-out phenomena such as cracks or fissures even when used for long periods of time.

[0044] <Component (C): Thermally Conductive Inorganic Particles> The thermally conductive inorganic particles in the present invention are preferably at least one inorganic particle selected from the group consisting of aluminum oxide (alumina), zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silicon carbide. These inorganic particles have high thermal conductivity and are suitable as TIMs (Thermal Interface Materials). The D50 (median diameter) of the cumulative particle size distribution on a volume basis of the thermally conductive inorganic particles is preferably 0.01 to 150 μm, more preferably 0.05 to 130 μm, and even more preferably 0.1 to 120 μm. The thermally conductive inorganic particles are also referred to as thermally conductive fillers.

[0045] The thermally conductive inorganic particles can be in a variety of shapes, including spherical, scaly, and polyhedral. When using alumina, α-alumina with a purity of 99.5% by weight or higher is preferred. The average particle size of the thermally conductive inorganic particles is preferably in the range of 0.1 to 100 μm. The particle size is measured by measuring the median size using a laser diffraction light scattering method. An example of an instrument for this measurement is the LA-950S2 laser diffraction / scattering particle distribution analyzer manufactured by Horiba, Ltd.

[0046] The thermally conductive inorganic particles may be used in combination with at least two thermally conductive inorganic particles having different average particle sizes, because in this case the thermally conductive inorganic particles with smaller particle sizes are embedded between the larger particles, allowing for a near-close-packed state, thereby increasing the thermal conductivity of the thermally conductive silicone resin composition.

[0047] In the present invention, the proportion of thermally conductive inorganic particles having a median diameter D50 of 80 μm or more in the cumulative particle size distribution on a volume basis is preferably 40% by mass to 60% by mass, more preferably 43% by mass to 57% by mass, and even more preferably 45% by mass to 55% by mass, relative to 100% by mass of component (C). By using a relatively large amount of large particles as the thermally conductive inorganic particles, the thermal conductivity of the thermally conductive silicone resin composition can be increased.

[0048] The thermally conductive inorganic particles of the present invention preferably include thermally conductive inorganic particles having a D50 of 1 μm or less, thermally conductive inorganic particles having a size greater than 1 μm and less than 80 μm, and thermally conductive inorganic particles having a size of 80 μm or more and 200 μm or less. In this specification, D50 refers to the median diameter of the cumulative particle size distribution based on volume. Mixing large, medium, and small particles as the thermally conductive inorganic particles in this manner results in the medium and small particles filling the spaces between the large particles, thereby increasing the thermal conductivity of the thermally conductive silicone resin composition. The thermally conductive inorganic particles having a D50 of 1 μm or less, the thermally conductive inorganic particles having a size greater than 1 μm and less than 80 μm, and the thermally conductive inorganic particles having a size of 80 μm or more and 200 μm or less are preferably made of alumina, as alumina itself has high thermal conductivity.

[0049] It is preferable that the thermally conductive silicone resin composition contains, relative to 100 mass% of thermally conductive inorganic particles (component (C)), 5 to 20 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, 20 to 45 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 40 to 60 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, since this increases the thermal conductivity of the composition.

[0050] It is more preferable that the thermally conductive silicone resin composition contains, relative to 100 mass% of thermally conductive inorganic particles (component (C)), 7 to 18 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, 25 to 40 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 43 to 57 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, as this increases the thermal conductivity of the composition.

[0051] It is more preferable that the thermally conductive silicone resin composition contains, relative to 100 mass% of thermally conductive inorganic particles (component (C)), 10 to 15 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, 30 to 35 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 45 to 55 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, since this increases the thermal conductivity of the thermally conductive silicone resin composition.

[0052] The thermally conductive inorganic particles having a median diameter D50 of 1 μm or less are preferably surface-pretreated with a coupling agent. An example of the coupling agent is alkoxysilane, for example, a compound represented by the formula R(CH ３ ) ａ Si(OR') ４－ａ (R is an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1), or a partial hydrolyzate thereof. Examples of alkoxysilanes (hereinafter simply referred to as "silanes") of the above chemical formula include silane compounds such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane. The above silane compounds can be used alone or in combination.

[0053] In particular, if thermally conductive inorganic particles with a median diameter D = 50 of 1 μm or less are surface pretreated with a coupling agent in advance, they will have better mixability when compounded, improving workability, and will be less likely to adsorb the platinum catalyst during the compounding process, preventing the curing reaction from being inhibited.

[0054] <Thermal Conductive Silicone Resin Composition> The thermally conductive silicone resin composition comprises X parts by mass (X = 50 to 99) of the component (A), (100 - X) parts by mass of the component (B), and 50 to 3,000 parts by mass, preferably 100 to 2,800 parts by mass, and more preferably 200 to 2,500 parts by mass of the component (C). This amount of component added increases the thermal conductivity of the thermally conductive silicone resin composition, making it suitable as a thermally conductive material: TIM (Thermal Interface Material). X is preferably 55 to 98, more preferably 60 to 95. A thermally conductive silicone resin composition with such a composition ratio increases its thermal conductivity, making it suitable as a thermally conductive material: TIM (Thermal Interface Material).

[0055] The thermally conductive silicone resin composition preferably has a kinematic viscosity at 23°C, as measured with a rotational viscometer, in the range of 200 to 30,000 Pa·s, more preferably 300 to 2,000 Pa·s, and even more preferably 400 to 18,000 Pa·s. Due to this fluidity, the thermally conductive silicone resin composition of the present invention has the advantage of being excellent in workability and suitable for use as a TIM (thermal interface material).

[0056] The thermal conductivity of the thermally conductive silicone resin composition is preferably 1.0 W / m K or more and 30 W / m K or less, more preferably 2.0 to 30 W / m K, and even more preferably 3.0 to 30 W / m K. Such a thermally conductive silicone resin composition is suitable as a TIM (thermal interface material).

[0057] The thermally conductive silicone resin composition is placed between two plates with a thickness of 1.0 mm or 2.0 mm and a contact area with the plates of 300 mm ２In a pumping-out test, the test specimen is placed horizontally in a heat shock tester, compressed and clamped, and held at -40°C and 125°C for 30 minutes each, for 100 cycles. When the appearance is checked after 100 cycles, it is preferable that no cracks with a gap of 1 mm or more are present, or if present, there are no more than two. Furthermore, in the same pumping-out test, it is preferable that no cracks with a length of 10 mm or more are present, or if present, there are no more than two. With such a thermally conductive silicone resin composition, the pumping-out phenomenon caused by the occurrence of cracks or voids is suppressed even when used for long periods of time.

[0058] The thermally conductive silicone resin composition of the present invention can be used as a grease, putty, liquid, etc., but is preferably used as a thermally conductive grease. The thermally conductive grease is suitable for use as a thermal interface material (TIM) filled into a syringe and applied between heat-generating and heat-dissipating parts of electronic components, etc.

[0059] [Method for Producing a Thermally Conductive Silicone Resin Composition] The method for producing a thermally conductive silicone resin composition of the present invention includes a step of mixing and stirring the components (A), (B), and (C). The production method may further include a heating step after the mixing and stirring. The heating temperature is preferably less than 300°C, more preferably 100 to 150°C. The heating time is preferably 5 minutes to 48 hours. Upon heating, the diol group at one end of component (B) chemically reacts with the surface of the thermally conductive inorganic particles, generating low-molecular-weight substances such as water or methanol. However, these low-molecular-weight substances evaporate outside the composition and do not remain within the composition, thereby improving the heat resistance of the thermally conductive silicone resin composition. Furthermore, heating can accelerate the addition curing reaction.

[0060] The thermally conductive silicone resin composition of the present invention can contain other components as needed. For example, heat resistance improvers such as red iron oxide, titanium oxide, and cerium oxide, flame retardants, and flame retardant assistants may be added. Furthermore, organic or inorganic particle pigments may be added to the thermally conductive silicone resin composition for the purpose of coloring or toning. Alkoxy group-containing silicones may be added to the thermally conductive silicone resin composition as a material added for the purpose of surface treatment of thermally conductive inorganic particles.

[0061] The thermally conductive silicone resin composition of the present invention can be filled into various containers such as pails, syringes, and cartridges to produce finished products.

[0062] [Thermal Conductive Sheet] The thermal conductive sheet of the present invention comprises the thermally conductive silicone resin composition of the present invention, which is formed into a sheet and cured. The thermally conductive sheet can be produced by vacuum degassing the thermally conductive silicone resin composition, rolling it, forming it into a sheet, and then curing it. The vacuum degassing can be performed by reducing the pressure of the thermally conductive silicone resin composition (compound) to -0.08 to -0.1 Pa and leaving it for approximately 5 to 10 minutes to degas it. The rolling can be performed by roll rolling or press working, but roll rolling is preferred because it allows for continuous production. The resulting thermally conductive sheet is preferably a sheet with a substantially uniform composition from the inside to the outside. A sheet with a uniform composition is preferred because it exhibits uniform physical properties even after being mounted on an electrical or electronic component as a TIM. One example of the roll rolling process is to sandwich the compound between two synthetic resin films and then roll it with a roll. The curing is preferably carried out at a temperature of 90 to 120°C for a time of 5 to 180 minutes. In this specification, curing and crosslinking have the same meaning. When in sheet form, the thermally conductive silicone resin composition of the present invention is highly versatile and suitable as a TIM. The thickness of the thermally conductive sheet is preferably in the range of 0.2 to 10 mm.

[0063] The present invention includes the following aspects.

[0064] [Item 1] A thermally conductive silicone resin composition comprising the following components (A), (B), and (C): the thermally conductive silicone resin composition comprises X parts by mass of the component (A) (X=50 to 99, preferably 55 to 98, more preferably 60 to 95), (100-X) parts by mass of the component (B) (X=50 to 99, preferably 55 to 98, more preferably 60 to 95), and 50 to 3000 parts by mass, preferably 100 to 2800 parts by mass, more preferably 200 to 2500 parts by mass of the component (C), wherein the component (A) is a liquid silicone resin, and the component (B) is a linear organopolysiloxane represented by the following chemical formula (I):

[0065]

[0066] (In the formula, R １ ~R ５ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ６ and R ７ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ８ and R １０ are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms or a phenyl group, n is 4 to 2000, and m is 1 to 20. ４ and the R ５ When there are multiple R ４ and R ５ may be the same or different.) The component (C) is a thermally conductive silicone resin composition, wherein the component (C) is a thermally conductive inorganic particle, and the component (C) contains thermally conductive inorganic particles having a median diameter D50 of 80 μm or more in a cumulative particle size distribution on a volume basis, and the material of the thermally conductive inorganic particles having a D50 of 80 μm or more contains at least one selected from the group consisting of alumina and aluminum nitride.

[0067] [Item 2] The thermally conductive silicone resin composition according to Item 1, wherein the component (A) is at least one selected from the group consisting of an addition-curable silicone polymer and a non-curable silicone oil.

[0068] [Item 3] The thermally conductive silicone resin composition according to Item 2, wherein the non-curable silicone oil is a silicone oil made of dimethylpolysiloxane.

[0069] [Item 4] The thermally conductive silicone resin composition according to Item 2 or 3, wherein the addition-curable silicone polymer comprises a base polymer (A-1) made of an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule, a crosslinking component (A-2) made of an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms per molecule, and a catalyst component.

[0070] [Item 5] In chemical formula (I), R １ ~R ５ are each independently an alkyl group having 1 to 5 carbon atoms, and R ６ and R ７ are each independently an alkyl group having 1 to 5 carbon atoms, and R ８ and R １０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms, n is 4 to 1000, and m is preferably 1 to 10, and in the above chemical formula (I), R １ ~R ５ are each independently a linear alkyl group having 1 to 5 carbon atoms, and R ６ and R ７ are each independently a linear alkyl group having 1 to 5 carbon atoms, and R ８ and R １０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９ is a linear alkyl group having 1 to 3 carbon atoms, n is 4 to 1000, and m is preferably 1 to 10, and in the above chemical formula (I), R １ ~R ５ are each independently a linear alkyl group having 1 to 3 carbon atoms, and R ６ and R ７ are each independently a linear alkyl group having 1 to 3 carbon atoms, and R ８ and R１０ are each independently an alkyl group having 1 to 2 carbon atoms substituted with OH, and R ９ Item 5. The thermally conductive silicone resin composition according to any one of Items 1 to 4, wherein: is a linear alkyl group having 1 to 3 carbon atoms; n is 5 to 1000; and m is preferably 1 to 5.

[0071] [Item 6] The thermally conductive silicone resin composition according to any one of Items 1 to 5, wherein the linear organopolysiloxane is a compound represented by the following chemical formula (I-1):

[0072]

[0073] (wherein Me is a methyl group, n-Bu is a normal butyl group, and n is 5 to 1000)

[0074] [Item 7] The thermally conductive silicone resin composition according to any one of Items 1 to 6, wherein the thermally conductive inorganic particles are at least one selected from the group consisting of aluminum oxide (alumina), zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silicon carbide.

[0075] [Item 8] The thermally conductive silicone resin composition according to any one of Items 1 to 7, wherein the proportion of the thermally conductive inorganic particles having a D50 of 80 μm or more is 40% by mass or more and 60% by mass or less, preferably 43% by mass or more and 57% by mass or less, and more preferably 45% by mass or more and 55% by mass or less, relative to 100% by mass of the component (C).

[0076] [Item 9] The thermally conductive silicone resin composition according to any one of Items 1 to 8, wherein the thermally conductive inorganic particles include thermally conductive inorganic particles having a D50 of 1 μm or less, thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, and the D50 is a median diameter of a cumulative particle size distribution on a volume basis.

[0077] [Item 10] The thermally conductive inorganic particles preferably contain, relative to 100 mass% of the thermally conductive inorganic particles (component (C)), 5 to 20 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, 20 to 45 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 40 to 60 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, 7 to 18 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, 25 to 40 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 43 to 57 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, because this increases the thermal conductivity of the thermally conductive silicone resin composition, and 10 to 15 mass% of thermally conductive inorganic particles having a D50 of 1 μm or less, Item 10. The thermally conductive silicone resin composition according to any one of Items 1 to 9, further preferably containing 30 to 35 mass% of thermally conductive inorganic particles having a D50 of more than 1 μm and less than 80 μm, and 45 to 55 mass% of thermally conductive inorganic particles having a D50 of 80 μm or more and 200 μm or less, because this increases the thermal conductivity of the thermally conductive silicone resin composition.

[0078] [Item 11] The thermally conductive inorganic particles having a D50 of 1 μm or less are alkylalkoxysilanes, preferably those having the formula R(CH ３ ) ａ Si(OR') ４－ａ Item 11. The thermally conductive silicone resin composition according to Item 9 or 10, wherein the composition is surface pretreated with an alkoxysilane represented by the formula: (R is an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1).

[0079] [Item 12] The thermally conductive silicone resin composition according to any one of Items 1 to 11, wherein the thermally conductive silicone resin composition has a kinematic viscosity at 23°C measured with a rotational viscometer in the range of 200 to 30,000 Pa s, preferably 300 to 2,000 Pa s, and more preferably 400 to 18,000 Pa s.

[0080] [Item 13] The thermally conductive silicone resin composition according to any one of Items 1 to 12, wherein the thermal conductivity of the thermally conductive silicone resin composition is 1.0 W / m K or more and 30 W / m K or less, preferably 2.0 to 30 W / m K, and more preferably 3.0 to 30 W / m K.

[0081] [Item 14] The thermally conductive silicone resin composition is placed between two plates with a thickness of 1.0 mm or 2.0 mm and a contact area with the plates of 300 mm ２ Item 14. The thermally conductive silicone resin composition according to any one of Items 1 to 13, wherein a test piece is placed horizontally in a heat shock tester, compressed and clamped, and held at −40°C and 125°C for 30 minutes each, for 100 cycles. In a pumping-out test, when the appearance is checked after 100 cycles, there are no cracks with gaps of 1 mm or more, or if cracks are present, there are no more than two cracks.

[0082] [Item 15] The thermally conductive silicone resin composition according to Item 14, wherein, when the appearance of the thermally conductive silicone resin composition is checked after 100 cycles in the pumping-out test, there are no cracks having a length of 10 mm or more, or if cracks are present, there are no more than two cracks.

[0083] [Item 16] A method for producing the thermally conductive silicone resin composition according to any one of Items 1 to 15, comprising mixing and stirring the component (A), the component (B), and the component (C).

[0084] [Item 17] The method for producing a thermally conductive silicone resin composition according to Item 16, further comprising the step of heating the mixture at a temperature of less than 300°C for 5 minutes to 48 hours after the mixing and stirring.

[0085] [Item 18] A thermally conductive sheet comprising the thermally conductive silicone resin composition according to any one of items 1 to 15, which is formed into a sheet and cured.

[0086] [Examples] The present invention will be described below using examples, but is not limited to these examples. Various parameters were measured by the following methods.

[0087] <Thermal Conductivity> The thermal conductivity of the thermally conductive silicone resin composition was measured using a hot disk (in accordance with ISO 22007-2:2008). As shown in FIG. 1A, this thermal conductivity measuring device 1 sandwiches a polyimide film sensor 2 between two samples 3a and 3b. A constant power is applied to the sensor 2 to generate a constant amount of heat, and the thermal characteristics are analyzed from the temperature rise of the sensor 2. The sensor 2 has a 7 mm diameter tip 4 and, as shown in FIG. 1B, has a double spiral electrode structure, with an applied current electrode 5 and a resistance value electrode (temperature measurement electrode) 6 located at the bottom. The measurement sample can be obtained by rolling a degassed thermally conductive silicone resin composition to a thickness of 7 mm or more. The thermal conductivity is calculated using the following equation (Equation 1):

[0088]

[0089] <Pumping-out test> The pumping-out test of the thermally conductive silicone resin composition was carried out by applying the thermally conductive silicone resin composition between an aluminum plate measuring 40 mm in length, 100 mm in width, and 5 mm in thickness and a glass plate measuring 40 mm in length, 100 mm in width, and 5 mm in thickness, and then placing a spacer between the two plates so that the area of ​​the thermally conductive silicone resin composition (sample) was 300 mm. ２ The samples were arranged so that the sample thickness was 2.0 mm for Examples 1 to 4 and Comparative Examples 1 to 3, and 1.0 mm for Examples 5 to 6 and Comparative Examples 4 to 6. Next, the aluminum plate and the glass plate were placed in a heat cycle tester so that their main surfaces were parallel to the ground. In this state, a heat cycle test was performed in which the sample was held at -40°C for 30 minutes, then heated to 125°C, and then held at 1125°C for 30 minutes before being cooled to -40°C. This cycle was repeated 100 times. After 100 cycles, the test pieces of the thermally conductive silicone resin composition were removed, and the surfaces of the thermally conductive silicone resin compositions were observed. The temperature transition times from -40°C to 125°C and from 125°C to -40°C were each within 10 minutes. The samples were heated in an electric furnace at 100°C for 24 hours before being sandwiched between the plates.

[0090] Evaluation criteria: presence or absence of cracks OK: When visually inspected, no cracks with a gap of 1 mm or more are present on the test piece, or if present, no more than two are observed. Also, no cracks with a length of 10 mm or more are present, or if present, no more than two are observed. In other words, this includes cases where no cracks are observed. NG: When visually inspected, cracks with a gap of 1 mm or more are observed in three or more places on the test piece, or cracks with a length of 10 mm or more are observed in three or more places.

[0091] <Kinematic Viscosity> The kinematic viscosity of the thermally conductive silicone resin composition was measured at a temperature of 25°C, a measurement thickness of 0.5 mm, and a rotation speed of 1.0 (1 / s) using a MARSIII viscosity and viscoelasticity measuring device manufactured by HAAKE Co., Ltd. The average value measured from 30 seconds to 1 minute after the start of rotation was recorded as the viscosity.

[0092] <Hardness of Cured Sheet> The hardness of the cured sheet was measured in accordance with ASKER-C (JIS K7312) and SHORE-OO (ASTM D2240).

[0093] (Examples 1 to 6, Comparative Examples 1 to 6) 1. Raw Material Components (1) Component (A) Component (A-1) was a non-curable base polymer, dimethyl silicone oil (liquid dimethylpolysiloxane, manufactured by Momentive Performance Materials Japan, product number TSF458-100, having a kinematic viscosity of 100 mm at 23°C measured with a rotational viscometer). ２ / s range) was used. An addition-cure reaction-type silicone polymer (trade name "CF5036" manufactured by Dow Toray Industries, Inc.) was used as components (A-2, A-3). This silicone polymer was divided into liquid A and liquid B, with liquid A being used as component (A-2) and liquid B being used as component (A-3). Liquid A contains a base polymer made of organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms per molecule, and a platinum catalyst. Liquid B contains a crosslinking component made of organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms per molecule. The viscosity of liquid A at 23°C is 450 cs.

[0094] (2) Component (B) The linear organopolysiloxane (Mn=5000) having a diol group at one end, shown as (I-1) above, was used as component (B).

[0095] (3) Component (C) As component (C-1), amorphous alumina (D50=0.3 μm) pretreated with octyltrimethoxysilane as shown in Figure 3 was used. As component (C-2), spherical alumina (D50=2.0 μm, 75 μm top cut product) as shown in Figure 4 was used. As the (C-3) component, crushed alumina (D50 = 2.0 μm) shown in FIG. 5 was used. As the (C-4) component, spherical alumina (D50 = 4.0 μm, 75 μm top cut product) shown in FIG. 6 was used. As the (C-5) component, spherical alumina (D50 = 20 μm, 55 μm top cut product) shown in FIG. 7 was used. As the (C-6) component, spherical alumina (D50 = 90 μm) was used. As the (C-7) component, spherical alumina (D50 = 120 μm) shown in FIG. 8 was used. As the (C-8) component, spherical alumina (D50 = 150 μm) was used. Top cut refers to passing the powder through a sieve of a specific size, for example, a 75 μm top cut means passing the powder through a sieve with a mesh size of 75 μm. However, even a 75 μm top cut product still contains a certain amount of powder with a particle size of 75 μm or more.

[0096] <Thermal conductive silicone resin composition (non-curable liquid composition)> Examples 1 to 3, Comparative Examples 1 to 3 Procedure: Using a 1 L planetary mixer, component (A), component (B), and component (C) shown in Table 1 were kneaded and degassed to obtain a thermal conductive silicone resin composition.

[0097] <Thermal conductive silicone resin composition (liquid composition containing cured components)> Example 4, Comparative Example 4 Procedure 1: Using a 1 L planetary mixer, the component (A) shown in Table 2 was kneaded and degassed. Procedure 2: The kneaded component (A) obtained in procedure 1 was placed in an electric furnace and heated at a heating temperature of 100°C for 30 minutes to completely cure. Procedure 3: Using a 1 L planetary mixer, the component (A) obtained in procedure 2 was kneaded with the components (B) and (C) shown in Table 2, and degassed to obtain a thermal conductive silicone resin composition.

[0098] <Thermal Conductive Sheet> Examples 5-6, Comparative Examples 5-6 Procedure 1: Using a 1 L planetary mixer, the components (A), (B), and (C) shown in Table 2 were kneaded and degassed. Procedure 2: The mixture obtained in Procedure 1 was rolled into a sheet. Procedure 3: The rolled product obtained in Procedure 2 was heated and cured in an electric furnace at a heating temperature of 100°C for a heating time of 15 minutes to obtain a thermally conductive sheet. The thickness of the obtained thermally conductive sheet was 2 mm.

[0099] The thermally conductive silicone resin compositions and thermally conductive sheets obtained as described above were evaluated. The conditions and results are summarized in Tables 1 and 2 below.

[0100]

[0101]

[0102] The above results reveal the following: (1) It was confirmed that in Examples 1 to 6, cracking was suppressed in the pumping-out test due to the effect of adding component (B). It was also confirmed that Examples 5 and 6 had appropriate hardness for thermally conductive sheets. (2) Since Comparative Examples 1 to 6 did not contain component (B), cracks occurred in the pumping-out test. An example of cracks that occurred in the thermally conductive silicone resin composition of Comparative Example 1 is shown in Figure 2. Figure 2 shows a thermally conductive silicone resin composition containing cracks.

[0103] The thermally conductive silicone resin composition and thermally conductive sheet of the present invention are suitable as a thermally conductive material (TIM) to be interposed between a heat-generating portion of an electric or electronic component and a heat sink.

[0104] [Explanation of symbols] 1 Thermal conductivity measuring device 2 Sensor 3a, 3b Sample 4 Sensor tip 5 Applied current electrode 6 Resistance value electrode (temperature measurement electrode)

Claims

1. A thermally conductive silicone resin composition comprising the following components (A), (B), and (C): the thermally conductive silicone resin composition comprises X parts by mass (X=50 to 99) of the component (A), (100-X) parts by mass of the component (B), and 50 to 3,000 parts by mass of the component (C), wherein the component (A) is a liquid silicone resin, and the component (B) is a linear organopolysiloxane represented by the following chemical formula (I): (In the formula, R １ ~R ５ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ６ and R ７ are each independently an alkyl group having 1 to 18 carbon atoms or a phenyl group, and R ８ and R １０ are each independently an alkyl group having 1 to 5 carbon atoms substituted with OH, and R ９ is an alkyl group having 1 to 3 carbon atoms or a phenyl group, n is 4 to 2000, and m is 1 to 20. ４ and the R ５ When there are multiple R ４ and R ５ may be the same or different.) The component (C) is a thermally conductive inorganic particle, and the component (C) contains thermally conductive inorganic particles having a median diameter D50 of 80 μm or more in a cumulative particle size distribution on a volume basis, and the material of the thermally conductive inorganic particles having a D50 of 80 μm or more contains at least one selected from the group consisting of alumina and aluminum nitride.

2. The thermally conductive silicone resin composition according to claim 1, wherein component (A) is at least one selected from the group consisting of addition-curing silicone polymers and non-curing silicone oils.

3. A thermally conductive silicone resin composition according to claim 1 or 2, wherein the proportion of the thermally conductive inorganic particles having a D50 of 80 μm or more is 40% by mass or more and 60% by mass or less relative to 100% by mass of component (C).

4. The thermally conductive silicone resin composition according to any one of claims 1 to 3, wherein the thermally conductive silicone resin composition has a kinematic viscosity at 23°C measured with a rotational viscometer in the range of 200 to 30,000 Pa·s.

5. The thermally conductive silicone resin composition according to any one of claims 1 to 4, wherein the thermal conductivity of the thermally conductive silicone resin composition is 1.0 W / m·K or more and 30 W / m·K or less.

6. The thermally conductive silicone resin composition is placed between two plates with a thickness of 1.0 mm or 2.0 mm and a contact area with the plates of 300 mm ２ The thermally conductive silicone resin composition according to any one of claims 1 to 5, wherein a test piece is placed horizontally in a heat shock testing machine, compressed and clamped, and held at -40°C and 125°C for 30 minutes each, for 100 cycles. When the appearance of the composition is checked after 100 cycles, no cracks with gaps of 1 mm or more are present, or if cracks are present, they are in two or fewer locations.

7. The thermally conductive silicone resin composition according to claim 6, wherein, when the appearance of the thermally conductive silicone resin composition is checked after 100 cycles in the pumping-out test, there are no cracks of 10 mm or more in length, or if cracks are present, there are two or fewer cracks.

8. A thermally conductive silicone resin composition according to any one of claims 1 to 7, wherein the thermally conductive inorganic particles are at least one selected from the group consisting of aluminum oxide (alumina), zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silicon carbide.

9. The thermally conductive silicone resin composition according to any one of claims 1 to 8, wherein the thermally conductive inorganic particles comprise particles having a D50 of 1 μm or less, particles having a D50 of more than 1 μm and less than 80 μm, and particles having a D50 of 80 μm or more and 200 μm or less, wherein the D50 is the median diameter of a cumulative particle size distribution on a volume basis.

10. The thermally conductive silicone resin composition according to claim 9, wherein the thermally conductive inorganic particles having a D50 of 1 μm or less have been surface pretreated with an alkylalkoxysilane.

11. A thermally conductive silicone resin composition according to any one of claims 1 to 10, wherein the linear organopolysiloxane is a compound represented by the following chemical formula (I-1):

12. A method for producing the thermally conductive silicone resin composition according to any one of claims 1 to 11, comprising the step of mixing and stirring the component (A), the component (B), and the component (C).

13. The method for producing a thermally conductive silicone resin composition according to claim 12, further comprising the step of heating the mixture at a temperature of less than 300°C for 5 minutes to 48 hours after the mixing and stirring.

14. A thermally conductive sheet comprising the thermally conductive silicone resin composition according to any one of claims 1 to 11, which is formed into a sheet and cured.

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