Thermally conductive composition, thermally conductive sheet using same, and manufacturing method thereof

Abstract

The composition includes a matrix resin (component A) made of a thermosetting resin, a curing catalyst, and thermally conductive particles, the thermally conductive particles including the following components B and C: (1) component B: 220 to 500 parts by mass of alumina having a D50 (median diameter) of 0.01 μm or more and less than 1 μm in a cumulative particle size distribution based on volume, relative to 100 parts by mass of the matrix resin, and (2) component C: 1900 to 2500 parts by mass of aluminum nitride having a D50 (median diameter) of 0.01 μm or more and 150 μm or less, relative to 100 parts by mass of the matrix resin. This provides a thermally conductive composition having high thermal conductivity, low plasticity of the composition, and good moldability, and a thermally conductive sheet using the same and a method for producing the same.

Description

[Technical field]

[0001] The present invention relates to a thermally conductive composition suitable for being interposed between a heat generating portion of an electric or electronic component and a heat sink, a thermally conductive sheet using the same, and a method for producing the same. [Background technology]

[0002] In recent years, the performance of semiconductors such as CPUs has improved remarkably, and the amount of heat generated has also increased dramatically. For this reason, heat sinks are attached to electronic components that generate heat, and thermally conductive sheets are used to improve the adhesion between the semiconductor and the heat sink. As devices become smaller, more powerful, and more highly integrated, thermally conductive sheets are required to be soft and have high thermal conductivity. Conventionally, thermally conductive sheets have been proposed in Patent Documents 1 to 4. Furthermore, the applicant of the present invention has proposed a thermally conductive sheet with high thermal conductivity in Patent Document 5. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-518466 [Patent Document 2] Re-tabled publication No. 2020-137970 [Patent Document 3] Re-tabled publication No. 2018-088416 [Patent Document 4] JP 2016-216523 A [Patent Document 5] Patent No. 7061736 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional thermally conductive compositions and thermally conductive sheets using the same have a problem in that increasing the thermal conductivity increases the plasticity of the composition, resulting in poor moldability. This is because a large amount of thermally conductive particles must be added to increase the thermal conductivity, which increases the plasticity of the composition and deteriorates the moldability.

[0005] In order to solve the above-mentioned problems in the conventional art, the present invention provides a thermally conductive composition having high thermal conductivity, low plasticity of the composition and good moldability, a thermally conductive sheet using the same, and a method for producing the same. [Means for solving the problem]

[0006] The thermally conductive composition of the present invention is a thermally conductive composition containing a matrix resin (component A) made of a thermosetting resin, a curing catalyst, and thermally conductive particles, the thermally conductive particles containing the following components B and C: (1) Component B: Alumina having a volume-based cumulative particle size distribution D50 (median diameter) of 0.01 μm or more and less than 1 μm is contained in an amount of 220 to 500 parts by mass per 100 parts by mass of matrix resin, and the following components B-1 and B-2 are contained, B-1 component: D50 (median diameter) is 0.01 μm or more and less than 0.3 μm, BET specific surface area is 9 m 2 / g or more of alumina is 30 to 100 mass% relative to 100 mass% of component B, B-2 component: Alumina having a D50 (median diameter) of 0.3 μm or more and less than 1 μm is 0 to 70 mass% relative to 100 mass% of B component, (2) Component C: Contains 1,900 to 2,500 parts by mass of aluminum nitride having a D50 (median diameter) of 0.01 μm or more and 150 μm or less per 100 parts by mass of matrix resin, and contains the following components C-1 and C-2: C-1 component: D50 (median diameter) is 0.01 μm or more and less than 30 μm, C-2 component: D50 (median diameter) is 30 μm or more and 150 μm or less, It is characterized in that:

[0007] The thermally conductive sheet of the present invention is characterized in that the thermally conductive composition is formed into a sheet. In the method for producing a thermally conductive sheet of the present invention, the thermally conductive composition is vacuum degassed, rolled, formed into a sheet, and then cured by heating to produce a thermally conductive sheet. Effect of the Invention

[0008] The present invention provides a thermally conductive composition having high thermal conductivity, low plasticity, and good moldability by using the above composition, and a thermally conductive sheet using the same. That is, by specifying the type, particle size, and amount of conductive particles, a thermally conductive composition having high thermal conductivity, low plasticity, and good moldability can be obtained. Specifically, the plasticity of the thermally conductive composition after degassing before curing is preferably less than 100, and the preferred thermal conductivity is 14 W / m·K or more. In addition, the method for producing a thermally conductive sheet of the present invention allows continuous sheet molding because the composition has low plasticity and good moldability. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a method of using a thermally conductive sheet according to one embodiment of the present invention. [Diagram 2] 2A-B are schematic explanatory views showing a method for measuring the thermal conductivity of a sample in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention is a thermally conductive composition containing a matrix resin, a curing catalyst, and thermally conductive particles. The matrix resin is preferably a thermosetting resin such as silicone rubber, silicone gel, acrylic rubber, fluororubber, epoxy resin, phenolic resin, unsaturated polyester resin, melamine resin, acrylic resin, silicone resin, or fluororesin. Among these, silicone is preferred, and is elastomer, gel, putty, or grease. The silicone curing system may use any method such as peroxide, addition, or condensation. Silicone is preferred because of its high heat resistance. In addition, it is preferred to be an addition reaction type because it is not corrosive to the surroundings, there is little by-product released outside the system, and it is cured reliably to the depth.

[0011] The thermally conductive particles are as follows for 100 parts by mass of the matrix resin (component A). (1) Component B: Alumina having a volume-based cumulative particle size distribution D50 (median diameter) of 0.01 μm or more and less than 1 μm is added in an amount of 220 to 500 parts by mass per 100 parts by mass of the matrix resin. The amount added is preferably 230 to 480 parts by mass, and more preferably 240 to 440 parts by mass. In addition, component B includes components B-1 and B-2 below. B-1 component: D50 (median diameter) is 0.01 μm or more and less than 0.3 μm, BET specific surface area is 9 m 2 The alumina having a particle size of 30 to 100 mass % is 100 mass % of the B component. The preferred D50 (median diameter) is 0.1 μm or more and less than 0.3 μm. The preferred BET specific surface area is 9 to 20 m 2 / g, and more preferably 10 to 18 m 2 The BET specific surface area is measured according to the standard of JIS R 1626-1996. · Component B-2: Alumina having a D50 (median diameter) of 0.3 μm or more and less than 1 μm is 0 to 70 mass % relative to 100 mass % of component B. The preferred D50 (median diameter) is 0.3 μm or more and 1.0 μm or less. (2) Component C: Add 1,900 to 2,500 parts by mass of aluminum nitride with a D50 (median diameter) of 0.01 μm or more and 150 μm or less to 100 parts by mass of the matrix resin. The preferred D50 (median diameter) is 0.1 μm or more and 120 μm or less. Also, the preferred addition amount is 1,920 to 2,400 parts by mass, and the more preferred addition amount is 1,940 to 2,300 parts by mass. Further, Component C includes the following Component C-1 and Component C-2. · Component C-1: D50 (median diameter) is 0.01 μm or more and less than 30 μm · Component C-2: D50 (median diameter) is 30 μm or more and 150 μm or less.

[0012] In the present invention, the thermally conductive particles are a combination of multiple types of inorganic particles with different average particle diameters. By doing so, the thermally conductive inorganic particles with a small particle diameter are filled between the large particles, and it is possible to fill in a state close to the closest packing, resulting in a thermally conductive composition with high thermal conductivity, low plasticity of the composition, and good moldability.

[0013] The mass ratio of the presence of Component C-1 and Component C-2 is preferably Component C-2 ≤ Component C-1, and more preferably Component C-2 < Component C-1. Thereby, a thermally conductive composition with high thermal conductivity, low plasticity of the composition, and good moldability can be obtained. Also, the plasticity of the thermally conductive composition after vacuum degassing before curing is preferably less than 100, more preferably 10 to 99, even more preferably 20 to 99, and particularly preferably 30 to 99. Thereby, a thermally conductive composition with low plasticity of the composition and good moldability can be obtained. The plasticity is determined according to JIS K 6300-3, ISO 2007:1991, using a Wallace plastometer, at a measurement temperature of 25°C, and dividing the thickness (t) after compressing the sample between two metal plates with a constant load (100 N) for a constant time (15 seconds) by the thickness (t0) before compression, and the plasticity (P0 = t / t0 × 100). The smaller the P0 value, the softer it indicates. Note that a small numerical value of the plasticity (P0) and low plasticity are synonymous.

[0014] The thermal conductivity of the cured product of the thermally conductive composition is preferably 14 W / m K or more, more preferably 14 to 20 W / m K, and even more preferably 14.5 to 20 W / m K. This provides high thermal conductivity and makes the composition suitable for use as a heat dissipation sheet: TIM (Thermal Interface Material).

[0015] The SHORE 00 hardness of the cured product of the thermally conductive composition is preferably 75 or less, more preferably 10 to 75, and even more preferably 15 to 72. This provides good conformability to heat generating bodies and heat dissipating bodies (heat sinks).

[0016] The matrix resin is preferably at least one selected from an addition-curable silicone polymer, a peroxide-curable silicone polymer, and a condensation-curable silicone polymer.

[0017] It is preferable to further add 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, of a silane coupling agent to 100 parts by mass of the matrix resin. The silane coupling agent coats the surface of the thermally conductive particles (surface treatment), making them easier to fill into the matrix resin (plasticizer function), and also has the effect of preventing the curing catalyst from being adsorbed to the thermally conductive particles, preventing curing inhibition. This is useful for storage stability. The silane coupling agent is R(CH3) a Si(OR') 4-a (R is an unsubstituted or substituted organic 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. R(CH3) a Si(OR') 4-aExamples of alkoxysilane compounds (hereinafter simply referred to as "silane") represented by the formula (R is an unsubstituted or substituted organic group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) include 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 of two or more.

[0018] At least one component selected from the group consisting of alumina (aluminum oxide) as component B and aluminum nitride as component C is preferably in the form of irregularly pulverized particles. Irregularly pulverized particles are easily available. In the following description, the term "irregularly pulverized" is also simply referred to as "irregular shape."

[0019] The thermally conductive composition of the present invention is molded into a sheet to be a thermally conductive sheet, which 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.

[0020] In the method for producing a thermally conductive sheet of the present invention, the thermally conductive composition is vacuum degassed, rolled, formed into a sheet, and then heat cured to form a thermally conductive sheet. In the vacuum degassing, the thermally conductive composition (compound) is decompressed to a pressure of -0.08 to -0.1 Pa and left for about 5 to 10 minutes to degas. Rolling can be performed by roll rolling or press working, but roll rolling is preferred because it allows for continuous production.

[0021] The thermally conductive composition preferably has a breakdown voltage (JIS K6249) of 7 to 16 kV / mm, which makes it possible to provide a thermally conductive sheet with high electrical insulation properties.

[0022] The volume resistivity (JIS K6249) of the thermally conductive composition is 10 10 ~10 14 It is preferable that the resistance is Ω·cm, which allows the heat conductive sheet to have high electrical insulation properties.

[0023] As an example of the present invention, in the case of an addition reaction type silicone composition (uncured composition), a compound having the following composition is preferred. A Matrix resin The matrix resin contains the following (A1) and (A2). (A1) Base polymer component: a linear organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in each molecule. (A2) Crosslinking component: An organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in one molecule, in an amount of less than 1 mole per mole of silicon-bonded alkenyl groups in the above-mentioned component A. In addition to the components (A1) and (A2), the composition may contain an organopolysiloxane that does not have a reactive group, such as an unreacted silicone oil, for example dimethylpolysiloxane. In this specification, the base polymer component (A1), the crosslinking component (A2), the unreacted silicone oil, and the silane coupling agent and platinum-based metal catalysts The total amount of these components is 100 parts by mass. B. Thermally conductive particles: As described above. C. Platinum-based metal catalyst: 0.01 to 1000 ppm by mass relative to the matrix resin D. Other additives: silane coupling agents, hardening retarders, colorants, etc.; optional amounts

[0024] Each component will be described below. (1) Base polymer component (A1 component) The base polymer component is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule, and the organopolysiloxane containing two or more alkenyl groups is the main component (base polymer component) in the silicone rubber composition of the present invention. This organopolysiloxane has two alkenyl groups bonded to silicon atoms in one molecule, such as vinyl groups and allyl groups, having 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms. The viscosity at 25°C is preferably 10 to 1,000,000 mPa·s, particularly 100 to 100,000 mPa·s, in terms of workability, curability, etc. Specifically, an organopolysiloxane containing two or more alkenyl groups in one molecule, which are bonded to silicon atoms at the molecular chain ends, and which is represented by the following general formula (Chemical Formula 1), is used. The side chains are linear organopolysiloxanes blocked with alkyl groups. From the viewpoints of workability, curability, etc., a viscosity of 10 to 1,000,000 mPa·s at 25°C is desirable. Note that this linear organopolysiloxane may contain a small amount of a branched structure (trifunctional siloxane unit) in the molecular chain.

[0025] [ka]

[0026] In the formula, R 1 are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and R 2 is an alkenyl group, and k is 0 or a positive integer. 1Examples of unsubstituted or substituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds include alkyl groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl groups; 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 a cyano group, such as a halogen-substituted alkyl group such as a chloromethyl group, a chloropropyl group, a bromoethyl group, or a trifluoropropyl group; and a cyanoethyl group. 2 The alkenyl group preferably has 2 to 6 carbon atoms, particularly 2 to 3 carbon atoms, and specifically includes vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, hexenyl, and cyclohexenyl groups, and is preferably vinyl. In the general formula (1), k is generally 0 or a positive integer satisfying 0≦k≦10000, preferably 5≦k≦2000, and more preferably 10≦k≦1200. The organopolysiloxane of component A1 may be an organopolysiloxane having at least 3, usually 3 to 30, and preferably about 3 to 20 alkenyl groups, such as vinyl groups and allyl groups, bonded to silicon atoms having 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms, in one molecule. The molecular structure may be any of linear, cyclic, branched, and three-dimensional network molecular structures. A preferred organopolysiloxane is a linear organopolysiloxane whose main chain is made of repeated diorganosiloxane units and whose both molecular chain terminals are blocked with triorganosiloxy groups, and whose viscosity at 25°C is 10 to 1,000,000 mPa·s, particularly 100 to 100,000 mPa·s.

[0027] The alkenyl group may be bonded to any part of the molecule. For example, it may include those bonded to silicon atoms at the molecular chain terminals or non-terminals (in the middle of the molecular chain). Among them, a linear organopolysiloxane having 1 to 3 alkenyl groups on each of the silicon atoms at both ends of the molecular chain represented by the following general formula (Chemical Formula 2), and having at least one alkenyl group bonded to a silicon atom at a non-terminal (in the middle of the molecular chain) of the molecular chain (for example, as a substituent in a diorganosiloxane unit) when the total number of alkenyl groups bonded to the silicon atoms at the molecular chain terminals is less than 3, and having a viscosity of 10 to 1,000,000 mPa·s at 25°C as described above is desirable in terms of workability, curability, etc. Note that this linear organopolysiloxane may contain a small amount of a branched structure (trifunctional siloxane unit) in the molecular chain.

[0028] [ka]

[0029] In the formula, R 3 are the same or different unsubstituted or substituted monovalent hydrocarbon groups, at least one of which is an alkenyl group. 4 are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and R 5 is an alkenyl group, and l and m are 0 or positive integers. 3As the monovalent hydrocarbon group, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, are preferred. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group, and those in which a part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, cyano group, etc., for example, halogen-substituted alkyl groups such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, and cyanoethyl group, etc. can be mentioned. Also, R 4 As the monovalent hydrocarbon group of, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, are preferred, and the same ones as the specific examples of the above R 1 can be exemplified, provided that alkenyl groups are not included. As the alkenyl group of R 5 , those having 2 to 6 carbon atoms, particularly 2 to 3 carbon atoms, are preferred. Specifically, the same ones as R 2 in the above formula (Chemical Formula 1) are exemplified, and preferably it is a vinyl group. l and m are generally 0 or positive integers that satisfy 0 < l + m ≤ 10000, preferably 5 ≤ l + m ≤ 2000, more preferably 10 ≤ l + m ≤ 1200, and are integers that satisfy 0 < l / (l + m) ≤ 0.2, preferably 0.0011 ≤ l / (l + m) ≤ 0.1.

[0030] (2) Crosslinking component (A2 component) The organohydrogenpolysiloxane of component A2 of the present invention acts as a crosslinking agent, and forms a cured product by addition reaction (hydrosilylation) between the SiH groups in this component and the alkenyl groups in component A. Any organohydrogenpolysiloxane may be used as long as it has two or more hydrogen atoms (i.e., SiH groups) bonded to silicon atoms in one molecule, and the molecular structure of this organohydrogenpolysiloxane may be any of linear, cyclic, branched, and three-dimensional network structures, but the number of silicon atoms in one molecule (i.e., degree of polymerization) is 2 to 1000, and particularly about 2 to 300.

[0031] The position of the silicon atom to which the hydrogen atom is bonded is not particularly limited, and may be at the end of the molecular chain or at a non-end of the molecular chain (in the middle of the molecular chain). In addition, examples of organic groups bonded to silicon atoms other than hydrogen atoms include R 1 and the like. Examples of the substituted or unsubstituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds include those shown below.

[0032] The organohydrogenpolysiloxane of component A2 may, for example, be one having the structure shown below. [ka]

[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] (3) Catalyst component (C component) The catalyst component of component C can be a catalyst used in hydrosilylation reactions. Examples include platinum black, platinum (II) chloride, chloroplatinic acid, reactants of chloroplatinic acid with monohydric alcohols, complexes of chloroplatinic acid with olefins or vinylsiloxanes, platinum-based catalysts such as platinum bisacetoacetate, palladium-based catalysts, and rhodium-based catalysts. Two-part room-temperature curing silicone polymers contain a platinum-based metal catalyst, but the reason for using an additional platinum-based metal catalyst is to control the curing speed.

[0035] (4) Thermally conductive particles (components B and C) In the present invention, it is preferable to use three or more types of inorganic particles with different average particle sizes as the thermally conductive particles. In the case of three types, the B-1 component, C-1 component, and C-2 component are used, and in the case of four types, the B-2 component is added to the above. In this way, the thermally conductive inorganic particles with smaller particle sizes are filled between the larger particles, allowing them to be packed in a state close to close packing, thereby increasing the thermal conductivity.

[0036] (5) Other additives The composition of the present invention may contain other components as necessary. For example, heat resistance improvers such as red iron oxide, titanium oxide, and cerium oxide, flame retardant assistants, and hardening retarders may be added. For the purpose of coloring and color matching, organic or inorganic pigments may be added. The above-mentioned silane coupling agent may be added.

[0037] The following description will be given with reference to the drawings. In the following drawings, the same reference numerals indicate the same objects. FIG. 1 is a schematic cross-sectional view of a heat dissipation structure 10 incorporating a heat conductive sheet according to an embodiment of the present invention. The heat conductive sheet 11b dissipates heat generated by an electronic component 13 such as a semiconductor element, and is fixed to a main surface 12a of the heat spreader 12 facing the electronic component 13, and is sandwiched between the electronic component 13 and the heat spreader 2. The heat conductive sheet 11a is sandwiched between the heat spreader 12 and a heat sink 15. The heat conductive sheets 11a and 11b, together with the heat spreader 2, constitute a heat dissipation member that dissipates heat from the electronic component 13. The heat spreader 12 is formed, for example, in a rectangular plate shape, and has a main surface 12a facing the electronic component 13 and a side wall 12b erected along the outer periphery of the main surface 12a. The heat spreader 2 has a thermally conductive sheet 11b provided on a main surface 12a surrounded by side walls 12b, and a heat sink 15 provided on another surface 12c opposite to the main surface 12a with the thermally conductive sheet 11a interposed therebetween. The electronic component 13 is, for example, a semiconductor element such as a BGA, and is mounted on a wiring board 14. EXAMPLES

[0038] The present invention will be described below with reference to examples, but is not limited to these examples. Various parameters were measured by the methods described below.

[0039] <Thermal conductivity> The thermal conductivity of the thermally conductive silicone rubber sheet was measured using a hot disk (compliant with ISO 22007-2:2008). As shown in Figure 2A, this thermal conductivity measuring device 1 sandwiches a polyimide film sensor 2 between two samples 3a and 3b, applies a constant power to the sensor 2, and generates a constant amount of heat, analyzing the thermal characteristics from the temperature rise of the sensor 2. The sensor 2 has a tip 4 with a diameter of 7 mm, and as shown in Figure 2B, it has a double spiral electrode structure, with an electrode 5 for applied current and an electrode 6 for resistance (electrode for temperature measurement) located at the bottom. The thermal conductivity is calculated using the following formula (Equation 1).

number

[0040] (Examples 1 to 5, Comparative Examples 1 to 5) 1. Material components (1) Polyorganosiloxane (Component A) A two-component room-temperature-curing silicone polymer (silicone component) containing a commercially available polyorganosiloxane was used. One liquid (Liquid A) contains a base polymer component (Component A1 of Component A) and a platinum-group metal catalyst, and the other liquid (Liquid B) contains a base polymer component (Component A1 of Component A) and an organohydrogenpolysiloxane as a cross-linking agent component (Component A2 of Component A). The ratio of Liquid A to Liquid B is A:B = 100:100 by mass. (2) Thermally conductive particles (Component B) The thermally conductive particles used were those shown in Table 1. The average particle size is the D50 (median size) of the cumulative particle size distribution based on volume in particle size distribution measurement by laser diffraction light scattering method. An example of the measuring device is the LA-950S2 laser diffraction / scattering type particle distribution measuring device manufactured by Horiba, Ltd. The number before μm in the table is the average particle size of each particle. (3) Thermally conductive particles (component C) The thermally conductive particles used were those listed in Table 1. The average particle size is the D50 (median size) of the cumulative particle size distribution based on volume in particle size distribution measurement using a laser diffraction light scattering method. An example of an instrument for this purpose is the LA-950S2 laser diffraction / scattering particle distribution measuring instrument manufactured by Horiba, Ltd. The numbers before μm in the table are the average particle size of each particle. Additionally, AlN in the table is an abbreviation for aluminum nitride. (4) Platinum group metal catalyst (C component) As the additional platinum group metal catalyst, platinum-vinyldisiloxane complex is used. As mentioned above, the two-part room temperature curing silicone polymer (silicone component) contains a platinum group metal catalyst. When preparing the silicone composition of each example, an additional platinum group metal catalyst is added so that polyorganosiloxane is sufficiently cured. (5) Additive 1 Dimethylpolysiloxane was used as the unreacted silicone oil (viscosity at 25°C: 100 mm using a Brooklyn Field type rotational viscometer SP No. 2). 2 / s) was used. (6) Additive 2 Decyltrimethoxysilane was used as the silane coupling agent.

[0041] 2. Compound The amounts of each material shown in Table 1 were weighed out and put into a mixer to form a compound. The amount of additive is 100g in total of two-liquid curing silicone polymer, unreacted oil, silane coupling agent, and platinum catalyst. The amount ( g The compound was degassed for 5 minutes under reduced pressure of -0.1 Pa.

[0042] 3.Sheet forming process The compound was sandwiched between release-treated polyethylene terephthalate (PET) films and rolled into a 2.0 mm thick sheet using a constant speed roll at 23°C and a roll speed of 0.5 m / min, followed by heat curing at 100°C for 15 minutes to obtain a thermally conductive silicone rubber sheet. Moldability was judged as "possible" if molding was possible under the above conditions, and "NG" if not. The above conditions and results are shown in Tables 1 and 2. In Tables 1 and 2, The total weight of two-component curing silicone polymer [base polymer component (A1) and crosslinking component (A2)], unreacted oil, silane coupling agent, and platinum metal catalyst is 100g. The amount of each component added when (g) Shows.

[0043] [Table 1]

[0044] [Table 2]

[0045] As shown in Tables 1 and 2, it was confirmed that Examples 1 to 5 had high thermal conductivity and low plasticity after degassing of the composition (plasticity before curing). In contrast, in Comparative Example 1, the absence of B-1 component caused an increase in plasticity, and the molding processability was NG. In Comparative Example 2, the absence of B-1 component caused an increase in plasticity even though the BET specific surface area was large, and the molding processability was NG. In Comparative Example 3, the B component was below the lower limit, the plasticity was increased, and the molding processability was NG. In Comparative Example 4, the B component exceeded the upper limit, and the thermal conductivity decreased. In Comparative Example 5, the C component was below the lower limit, and the thermal conductivity decreased. [Industrial Applicability]

[0046] The thermally conductive composition and thermally conductive sheet of the present invention are suitable as a thermal interface material (TIM) that is a heat dissipation sheet to be interposed between a heat generating portion of an electric or electronic part and a heat sink. [Explanation of symbols]

[0047] 1. Thermal conductivity measuring device 2 Sensors 3a,3b Sample 4 Sensor tip 5 Electrode for applied current 6 Resistance electrodes (temperature measurement electrodes) 10 Heat dissipation structure 11a, 11b Thermally conductive sheet 12 Heat spreader 13. Electronic Components 14 Wiring board 15 Heat sink

Claims

1. A thermally conductive composition comprising a matrix resin (component A) made of a thermosetting resin, a curing catalyst, and thermally conductive particles, The thermally conductive particles contain the following components B and C: (1) Component B: Alumina having a volume-based cumulative particle size distribution D50 (median diameter) of 0.01 μm or more and less than 1 μm is contained in an amount of 220 to 500 parts by mass per 100 parts by mass of matrix resin, and the following Component B-1 and Component B-2 are contained, B-1 component: D50 (median diameter) is 0.01 μm or more and less than 0.3 μm, BET specific surface area is 9 m 2 / g or more of alumina is 30 to 100 mass% relative to 100 mass% of the B component, B-2 component: 0 to 70% by mass of alumina having a D50 (median diameter) of 0.3 μm or more and less than 1 μm, based on 100% by mass of B component; (2) Component C: Contains 1,900 to 2,500 parts by mass of aluminum nitride having a D50 (median diameter) of 0.01 μm or more and 150 μm or less, relative to 100 parts by mass of matrix resin, and contains the following components C-1 and C-2: C-1 component: D50 (median diameter) is 0.01 μm or more and less than 30 μm, C-2 component: D50 (median diameter) is 30 μm or more and 150 μm or less, A thermally conductive composition comprising:

2. 2. The thermally conductive composition according to claim 1, wherein the mass ratio of the C-1 component and the C-2 component is such that the C-2 component is less than or equal to the C-1 component.

3. 2. The thermally conductive composition according to claim 1, wherein the thermal conductivity of the cured product of the thermally conductive composition is 14 W / m·K or more.

4. 2. The thermally conductive composition according to claim 1, wherein the cured product of the thermally conductive composition has a SHORE 00 hardness of 75 or less.

5. 2. The thermally conductive composition according to claim 1, wherein the matrix resin is at least one selected from the group consisting of an addition-curable silicone polymer, a peroxide-curable silicone polymer, and a condensation-curable silicone polymer.

6. 2. The thermally conductive composition according to claim 1, further comprising 0.1 to 10 parts by mass of a silane coupling agent relative to 100 parts by mass of the matrix resin.

7. 2. The thermally conductive composition according to claim 1, wherein at least one component selected from the group consisting of alumina as component B and aluminum nitride as component C is in the form of irregularly pulverized particles.

8. A thermally conductive sheet, comprising the thermally conductive composition according to any one of claims 1 to 7 formed into a sheet.

9. The thermally conductive sheet according to claim 8, wherein the thermally conductive sheet has a thickness in the range of 0.2 to 10 mm.

10. A method for producing a thermally conductive sheet, comprising vacuum degassing the thermally conductive composition according to any one of claims 1 to 7, rolling it, forming it into a sheet, and then heat curing it to produce a thermally conductive sheet.

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