Thermally conductive silicone composition

Abstract

To provide a thermally conductive silicone composition that can suppress the increase in hardness of an additive-curing silicone composition when its cured product is exposed to a high-temperature environment for a long period of time. [Solution] A thermally conductive silicone composition comprising (C) organopolysiloxane, (D) aluminum alloy powder, and (E) metal oxide powder, wherein (C) aluminum alloy powder contains 0.2 to 30.0% by mass of at least one metal element selected from silicon, copper, manganese, magnesium, chromium, and zinc, and is an aluminum alloy powder with a thermal conductivity of 10 W / m·K or higher.

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive silicone composition, and more particularly to an addition-curing type silicone composition that results in a cured product with excellent heat resistance. Specifically, the present invention relates to a thermally conductive silicone composition that results in a cured product that has better heat resistance when used in high-temperature environments than the cured products of general thermally conductive silicone compositions. [Background technology]

[0002] Many electronic components generate heat during use, and therefore, heat must be removed for them to function properly. In particular, integrated circuit elements such as CPUs and GPUs used in personal computers and smartphones continue to generate increasing heat due to higher operating frequencies and smaller packages, making heat management and design crucial issues. Furthermore, with the recent advancement of electric vehicles, many electronic components are used, and these components may be used under more severe conditions, such as high temperature and high humidity environments.

[0003] There are many methods for removing this heat. In particular, for electronic components that generate a lot of heat, a method is known in which a thermally conductive material such as thermally conductive grease or thermally conductive sheet is interposed between the electronic component and a heat sink or other material to dissipate the heat. Thermally conductive grease is particularly suitable because it has an amorphous shape and exhibits high thermal conductivity by adhering to the substrate after curing. As such a thermally conductive material, heat dissipation adhesives based on silicone and blended with zinc oxide, aluminum, or alumina powder are also known.

[0004] To create a highly thermally conductive material based on silicone, it is necessary to fill it with a high concentration of thermally conductive filler. However, simply attempting to fill it with a high concentration significantly reduces the fluidity of the thermally conductive material, resulting in poor workability such as application (dispensing, screen printing), and further, the inability to conform to the fine irregularities on the surface of electronic components and heat sinks. Therefore, to solve this problem, a method has been disclosed in which the thermally conductive filler is surface-treated with a wetter (dispersant) to disperse it in the silicone base polymer, thereby maintaining the fluidity of the thermally conductive material (Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-015717 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, electrification has progressed in the automotive industry, and it is anticipated that integrated circuit elements such as CPUs and GPUs, or electronic components that generate a lot of heat, will be exposed to high-temperature environments for extended periods. The aerospace industry also requires material stability in high-temperature environments. Therefore, there is a need for silicone compositions that produce cured products with even higher heat resistance than those of general thermally conductive silicone compositions, even when used in high-temperature environments. Previous research has shown that adding a single-ended modified organopolysiloxane as a thermally conductive filler wetter to an addition-curing silicone composition can suppress the hardness increase of the resulting cured product when exposed to high-temperature environments for extended periods, thus achieving the provision of a highly reliable heat dissipation material suitable for electronic component packages and power modules. While the use of single-ended modified organopolysiloxanes can suppress the hardness increase, challenges remain in terms of mass production.

[0007] In view of the above circumstances, the present invention aims to provide a thermally conductive silicone composition that can suppress the increase in hardness when the cured product of an addition-curing silicone composition is exposed to a high-temperature environment for a long period of time. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors of the present invention have discovered that using aluminum alloy powder containing metallic elements such as silicon, copper, manganese, magnesium, chromium, and zinc as a filler has the effect of suppressing the increase in hardness of cured products obtained from thermally conductive silicone compositions when exposed to high-temperature environments for extended periods, and have completed the present invention.

[0009] In other words, the present invention provides the following thermally conductive silicone composition.

[0010] [1] A thermally conductive silicone composition comprising (C) organopolysiloxane, (D) aluminum alloy powder, and (E) metal oxide powder, wherein (C) aluminum alloy powder contains 0.2 to 30.0% by mass of at least one metal element selected from silicon, copper, manganese, magnesium, chromium, and zinc, and is an aluminum alloy powder with a thermal conductivity of 10 W / m·K or higher. [2] (A) A molecule having at least two alkenyl groups bonded to silicon atoms, with a kinematic viscosity of 10 to 100,000 mmHg at 25°C. 2 / s organopolysiloxane: 100 parts by mass, (B) A hydrolyzable organopolysiloxane with one end trifunctionality represented by the following general formula (1): 10 to 300 parts by mass per 100 parts by mass of component (A), [ka] (In formula (1), R 1 (where is an alkyl group with 1 to 6 carbon atoms, and 'a' is a number between 5 and 100.) An aluminum alloy powder containing at least one metal element selected from silicon, copper, manganese, magnesium, chromium, and zinc in an amount of 0.2 to 30.0% by mass and having a thermal conductivity of 10 W / m·K or more: 280 to 1,680 parts by mass with respect to 100 parts by mass in total of component (A) and component (B), (D) Aluminum powder: 120 to 725 parts by mass with respect to 100 parts by mass in total of component (A) and component (B), (E) Metal oxide powder: 100 to 585 parts by mass with respect to 100 parts by mass in total of component (A) and component (B), (F) Organohydrogenpolysiloxane having hydrogen atoms directly bonded to at least two silicon atoms in one molecule: an amount such that {the number of Si-H groups in component (F)} / {the number of alkenyl groups in component (A)} is 0.5 to 1.5, and (G) A catalyst selected from the group consisting of platinum and platinum compounds: an effective amount with respect to the mass of component (A) as platinum atoms The thermally conductive silicone composition according to [1], which contains the above components. [3] The thermally conductive silicone composition according to [1] or [2], wherein the metal oxide powder of component (E) is zinc oxide powder. [4] Furthermore, the thermally conductive silicone composition according to any one of [1] to [3], which contains a controller selected from acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds in an amount of 0.1 to 5% by mass with respect to component (A). [Advantages of the Invention]

[0011] The thermally conductive silicone composition of the present invention can reduce the increase in hardness when the cured product is stored in a high-temperature environment for a long time by using an aluminum alloy powder containing a specific metal element as a filler. In addition, the thermally conductive silicone composition of the present invention can be suitably used as a thermal conduction material for a cooling member of a heat-generating element such as a semiconductor chip. [Embodiments for Carrying out the Invention]

[0012] The present invention will be described in more detail below. The present invention relates to a thermally conductive silicone composition containing organopolysiloxane, (C) aluminum alloy powder, (D) aluminum powder, and (E) metal oxide powder, wherein (C) aluminum alloy powder contains 0.2 to 30.0% by mass of at least one metal element selected from silicon, copper, manganese, magnesium, chromium, and zinc, and is an aluminum alloy powder with a thermal conductivity of 10 W / m·K or higher.

[0013] Organopolysiloxane The following components (A) and (B) are preferred as organopolysiloxanes.

[0014] Ingredient (A) Component (A) is an organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in one molecule, with a kinematic viscosity of 10 to 100,000 mmHg at 25°C. 2 / s organopolysiloxanes are preferred.

[0015] Alkenyl groups with 2 to 12 carbon atoms are preferred, and those with 2 to 6 carbon atoms are more preferred. Specifically, examples include vinyl groups, allyl groups, 1-butenyl groups, and 1-hexenyl groups, all of which have 2 to 6 carbon atoms, but vinyl groups are preferred in terms of ease of synthesis and cost.

[0016] Organic groups other than alkenyl groups bonded to silicon atoms are preferably unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, particularly 1 to 6 carbon atoms, that do not contain aliphatic unsaturated bonds. Specifically, examples include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups, aryl groups such as phenyl groups, and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups. Halogen-substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl groups are also given as examples. Of these, methyl groups are preferred in terms of ease of synthesis and cost.

[0017] The alkenyl group bonded to the silicon atom may be present at either the terminal or side chain of the organopolysiloxane molecular chain, but it is preferable that it be present at least at the terminal. The number of alkenyl groups in one molecule is at least two, preferably 2 to 10, more preferably 2 to 5, and the molecular structure of the organopolysiloxane may be linear or branched. It may also be a mixture of two or more different types.

[0018] The kinematic viscosity of component (A) at 25°C, as measured by an Ostwald meter, was 10 to 100,000 mm². 2 Preferably in the range of / s, 100 to 50,000 mm 2 / s is preferable. Kinematic viscosity is 10 mm 2 If the value is 100,000 mm or more, the oil bleed of the composition is not significant and does not degrade reliability. 2 If the viscosity is less than or equal to / s, spreadability is ensured without increasing the viscosity of the composition. Component (A) may be used alone, or two or more components with different viscosities may be used in combination.

[0019] Examples of component (A) include dimethylpolysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane-methylvinylpolysiloxane copolymer in which one end of the molecular chain is sealed with a dimethylvinylsiloxy group and the other end of the molecular chain is sealed with a trimethylsiloxy group, dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups sealed at both ends of the molecular chain, methylvinylpolysiloxane with trimethylsiloxy groups sealed at both ends of the molecular chain, and dimethylsiloxane-methylvinylpolysiloxane copolymer with dimethylvinylsiloxy groups sealed at both ends of the molecular chain. However, it is not limited to these, and two or more of these may be used in mixture form.

[0020] The content of component (A) in the composition of the present invention is preferably 20.0 to 0.5% by mass, and more preferably 10.0 to 1.0% by mass.

[0021] Ingredient (B) Component (B) is an organopolysiloxane, and a hydrolyzable dimethylpolysiloxane having trifunctionality at one end represented by the following general formula (1) is preferred.

Chemical formula

[0022] R in formula (1) 1 is an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 5 carbon atoms is preferred. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Among these, a methyl group and an ethyl group are more preferred. In formula (1), a preferably ranges from 5 to 100, and more preferably from 10 to 60. If a is less than 5, oil bleeding of the composition becomes severe and the reliability deteriorates. On the other hand, if a is greater than 100, the wettability becomes insufficient.

[0023] The blending amount of this hydrolyzable dimethylpolysiloxane having trifunctionality at one end is preferably 10 to 300 parts by mass, and more preferably 20 to 280 parts by mass with respect to 100 parts by mass of component (A). If it is 10 parts by mass or more, sufficient wettability can be exhibited. If it is 300 parts by mass or less, there is no oil bleeding and the reliability is not deteriorated.

[0024] Component (C) Component (C) is an aluminum alloy powder having a thermal conductivity of 10 W / m·K or higher, preferably 15 W / m·K or higher, and the aluminum alloy powder contains 0.2 to 30.0% by mass of at least one metallic element selected from silicon, copper, manganese, magnesium, chromium, and zinc. The aluminum alloy powder contains at least one, preferably two or more, more preferably three or more, and particularly preferably four or more metallic elements selected from silicon, copper, manganese, magnesium, chromium, and zinc. The aluminum alloy powder contains a mixture doped with at least one metallic element selected from silicon, copper, manganese, magnesium, chromium, and zinc. If the thermal conductivity is less than 10 W / m·K, the thermal conductivity of the thermally conductive silicone composition itself will be reduced. Furthermore, the upper limit of the thermal conductivity of the aluminum alloy powder is 236 W / m·K, and aluminum alloy powder with a thermal conductivity of 236 W / m·K or less can be used.

[0025] The total content of metallic elements selected from silicon, copper, manganese, magnesium, chromium, and zinc in the aluminum alloy powder is in the range of 0.2 to 30%, preferably 0.4 to 25%, more preferably 0.6 to 20%, and particularly preferably 0.8 to 15%. Below 0.2%, it is ordinary aluminum powder, and the expected hardness increase suppression effect may not be obtained. Above 30%, the thermal conductivity of the aluminum alloy powder may decrease, and the thermal conductivity of the resulting composition may also decrease. The metallic elements contained in the aluminum alloy powder are silicon, copper, manganese, magnesium, chromium, and zinc, preferably silicon, copper, manganese, magnesium, and zinc, and more preferably silicon, copper, and magnesium.

[0026] The average particle size of component (C) is preferably in the range of 5.0 to 100 μm, more preferably in the range of 6.0 to 90 μm, even more preferably in the range of 6.0 to 80 μm, and particularly preferably in the range of 7.0 to 70 μm. If the average particle size is 5.0 μm or more, it is possible to include dissimilar metals in the aluminum alloy powder, and if it is 100 μm or less, it will not worsen the thermal resistance value of the heat dissipation grease and reduce its performance. In this invention, the average particle diameter is the volume-based volume average diameter measured by a particle size distribution analyzer (for example, Microtrac MT330OEX manufactured by Nikkiso Co., Ltd.). The shape of the thermally conductive fillers, such as component (C), component (D) and component (E) described later, may be any shape, including irregular, rounded, or spherical. Irregular shape refers to any shape that has not undergone intentional spheroidization treatment such as melting or granulation. Rounded and spherical refer to commercially available products that have undergone treatment such as melting or granulation. Rounded refers to a state in which the particles have few corners and are rounded and smooth, and does not include spherical shapes. Rounded shapes are clearly different from spherical shapes in that they have corners.

[0027] The amount of component (C) is preferably 280 to 1,680 parts by mass, more preferably 300 to 1,500 parts by mass, and particularly preferably 350 to 1,250 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). If the amount is 280 parts by mass or more, the thermal conductivity of the composition will not be too low, and if it is 1,680 parts by mass or less, the viscosity of the composition will not be too high, resulting in a spreadable material with good workability.

[0028] Ingredients (D) Component (D) is aluminum powder, preferably having a thermal conductivity of 10 W / m·°C or higher, and more preferably having a thermal conductivity of 15 W / m·°C or higher. If the thermal conductivity is 10 W / m·°C or higher, the thermal conductivity of the composition itself will not decrease, and close packing can be achieved. There is no upper limit to the thermal conductivity; for example, aluminum powder with a thermal conductivity of 236 W / m·K can be used.

[0029] The total content of metallic elements selected from silicon, copper, manganese, magnesium, chromium, and zinc in the aluminum powder is preferably less than 0.2%, and more preferably 0.1% or less. A content of less than 0.2% indicates a high-purity aluminum powder, and close packing can be expected when combined with the aluminum alloy powder of component (C).

[0030] The average particle size of component (D) is preferably in the range of 1.0 to 4.9 μm, and more preferably in the range of 1.1 to 4.5 μm. If the average particle size is 1.0 μm or more, the composition becomes grease-like and finishes as a spreadable material, and if it is 4.9 μm or less, the close packing density is not reduced. In this invention, the average particle diameter can be measured by a particle size distribution analyzer (for example, Microtrac MT330OEX manufactured by Nikkiso Co., Ltd.), and is the volume-based volume average diameter.

[0031] The amount of component (D) is preferably 120 to 725 parts by mass, more preferably 140 to 700 parts by mass, and particularly preferably 160 to 650 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). If the amount is 120 parts by mass or more, the thermal conductivity of the composition will not decrease, and if it is 725 parts by mass or less, the close packing will not decrease, nor will the thermal conductivity decrease.

[0032] Ingredient (E) Component (E) is a metal oxide powder. Preferably, the metal oxide is alumina, zinc oxide, and more preferably zinc oxide. A thermal conductivity of 10 W / m·K or higher is preferred, and 15 W / m·K or higher is more preferred. If the thermal conductivity of the metal oxide is 10 W / m·K or higher, the thermal conductivity of the thermally conductive silicone composition itself will not decrease. The upper limit of the thermal conductivity is 155 W / m·K, and metal oxides with a thermal conductivity of 155 W / m·K or less can be used.

[0033] The average particle size of component (E) is preferably in the range of 0.1 to 1.0 μm, and more preferably in the range of 0.2 to 0.8 μm. If the average particle size is 0.1 μm or more, the thermal conductivity of the composition will not decrease, and if it is 1.0 μm or less, the close packing will not decrease, nor will the thermal conductivity decrease. In this invention, the average particle size can be measured by a particle size distribution analyzer (for example, Microtrac MT330OEX manufactured by Nikkiso Co., Ltd.), and is the volume-based volume average diameter.

[0034] The amount of component (E) is preferably 100 to 585 parts by mass, and more preferably 120 to 500 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). If the amount is less than 100 parts by mass, the thermal conductivity of the composition will be low, and if it is 585 parts by mass or less, the thermal conductivity will not decrease without reducing the close packing density.

[0035] Ingredients (F) The organohydrogenpolysiloxane of component (F) has at least two, preferably 2 to 30, and more preferably 2 to 20, hydrogen atoms directly bonded to silicon atoms (Si-H groups) in one molecule. These Si-H groups may be located at the ends of the molecular chain, in the middle of the molecular chain, or in both locations.

[0036] Organic groups other than the Si-H group bonded to the silicon atom are preferably unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, particularly 1 to 6 carbon atoms, that do not contain aliphatic unsaturated bonds. Specifically, examples include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups; aryl groups such as phenyl groups; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups; halogen-substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl groups; and epoxy-substituted hydrocarbon groups such as 2-glycidoxyethyl, 3-glycidoxypropyl, and 4-glycidoxybutyl groups.

[0037] Such organohydrogenpolysiloxanes having Si-H groups may be linear, branched, or cyclic, or may be mixtures thereof. The number of silicon atoms in the organohydrogenpolysiloxane is preferably 10 to 250, and particularly preferably 10 to 200. These organohydrogenpolysiloxanes may be used individually or in combination of two or more types.

[0038] For example, component (F) could be (CH3)2HSiO 1 / 2 A copolymer consisting of units and (CH3)2SiO units, (CH3)2HSiO 1 / 2 Units and (CH3)3SiO 1 / 2 A copolymer consisting of units and (CH3)2SiO units, (CH3)3SiO 1 / 2 A copolymer consisting of units, (CH3)2SiO units, and (CH3)HSiO units, (CH3)2HSiO 1 / 2 Units and (CH3)3SiO 1 / 2 A copolymer consisting of units, (CH3)2SiO units, and (CH3)HSiO units, (CH3)3SiO 1 / 2 A copolymer consisting of units and (CH3)HSiO units, (CH3)2HSiO 1 / 2 A copolymer consisting of units, (CH3)2SiO units, and (CH3)HSiO units, (CH3)3SiO 1 / 2 Units and (CH3)2HSiO 1 / 2 Examples include, but are not limited to, copolymers consisting of units and (CH3)HSiO units, cyclic copolymers consisting of (CH3)HSiO units, and cyclic copolymers consisting of (CH3)HSiO units and (CH3)2SiO units.

[0039] The amount of component (F) is preferably such that the ratio of {number of Si-H groups in component (F)} / {number of alkenyl groups in component (A)} is 0.5 to 1.5, and more preferably 0.7 to 1.3. If it is 0.5 or higher, sufficient networking can be achieved without the grease being pumped out, and if it is 1.5 or lower, the crosslinking density will not become too high and peeling will not occur during reliability testing.

[0040] Ingredients (G) The catalyst selected from the group consisting of platinum and platinum compounds of component (G) is a catalyst that promotes the addition reaction between the alkenyl group in component (A) and the Si-H group in component (F). Examples of component (G) include elemental platinum, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum coordination compounds.

[0041] The amount of component (G) should be an effective amount as a catalyst, that is, an effective amount necessary to promote the addition reaction and cure the thermally conductive silicone composition of the present invention (effective amount of platinum atoms relative to the mass of component (A)). If the amount of platinum atoms is less than 0.1 ppm relative to the mass of component (A), there is no catalytic effect, and even if it exceeds 500 ppm, the effect does not increase and is uneconomical. Therefore, a range of 0.1 to 500 ppm is preferred, a range of 0.1 to 300 ppm is more preferred, and a range of 1 to 100 ppm is particularly preferred.

[0042] Ingredients (H) The thermally conductive silicone composition of the present invention may further contain a control agent as component (H) for the purpose of suppressing the catalytic activity of component (G). The control agent of component (H) suppresses the progress of the hydrosilylation reaction at room temperature and extends the shelf life and pot life. Known control agents can be used, such as acetylene compounds, nitrogen compounds, organophosphorus compounds, oxime compounds, and organochloro compounds.

[0043] The amount of component (H) is preferably 0.1 to 5% by mass, and more preferably 0.2 to 4% by mass, relative to component (A). If it is 0.1% by mass or more, sufficient shelf life and pot life can be obtained, and if it is 5% by mass or less, the curing rate will not decrease. These may be used diluted with a solvent such as toluene to improve dispersibility in the thermally conductive silicone composition.

[0044] Furthermore, in addition to the above-mentioned components (A) to (H), the thermally conductive silicone composition of the present invention may contain other optional components such as antioxidants to prevent degradation, as needed. The amount of these components is preferably 0.1 to 5% by mass, and more preferably 0.2 to 4% by mass, relative to the total composition.

[0045] The thermally conductive silicone composition of the present invention can be manufactured by mixing components (A) to (G), and optionally component (H) and / or other optional components using a mixer such as Trimix, Twinmix, Planetary Mixer (all registered trademarks of mixers manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (registered trademark of mixers manufactured by Mizuho Kogyo Co., Ltd.), or Hibiscus Disper Mix (registered trademark of mixers manufactured by Tokushu Kika Kogyo Co., Ltd.).

[0046] The absolute viscosity of the obtained thermally conductive silicone composition at 25°C, as measured by a rotational viscometer, is preferably 5 to 2,000 Pa·s, and more preferably 10 to 900 Pa·s.

[0047] Furthermore, the obtained thermally conductive silicone composition can be cured by heating it at 80-180°C, particularly 90-170°C, for 30-150 minutes, especially 40-140 minutes.

[0048] The cured product of the thermally conductive silicone composition of the present invention can reduce the increase in hardness during high-temperature aging, and therefore can be suitably used as a thermal conductive material for cooling elements of heat-generating devices such as semiconductor chips. [Examples]

[0049] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The following components were prepared to create the thermally conductive silicone composition of the present invention. The tests concerning the effects of the present invention were conducted as follows.

[0050] Ingredient (A) A-1: Both ends are sealed with dimethylvinylsilyl groups, and the kinematic viscosity at 25°C is 30,000 mmHg. 2 / s Dimethylpolysiloxane (Vi value: 0.0038 mol / 100g) A-2: Both ends are sealed with dimethylvinylsilyl groups, and the kinematic viscosity at 25°C is 600 mmHg. 2 / s Dimethylpolysiloxane (Vi value: 0.014 mol / 100g)

[0051] Ingredient (B) B-1: Dimethylpolysiloxane with one-terminated trialkoxysilyl group sealed off, represented by the following formula [ka]

[0052] Ingredients (C) Components (C-1~13): Aluminum alloy powder with an average particle size of 20 μm (thermal conductivity: 50~200 W / m·℃), containing the dissimilar metals listed in Table 1 below. Components (CN): Aluminum powder with an average particle size of 20 μm (thermal conductivity: 236 W / m·K) - (For comparative example): Ordinary aluminum powder that does not intentionally contain dissimilar metals.

[0053] [Table 1]

[0054] Ingredients (D) Aluminum powder with an average particle size of 2 μm (thermal conductivity: 236 W / m·K)

[0055] Ingredient (E) Zinc oxide powder with an average particle size of 0.6 μm (thermal conductivity: 25 W / m·K)

[0056] Ingredients (F) F-1: Organohydrogenpolysiloxane represented by the following formula (H value: 0.00095 mol / g) [ka] F-2: Organohydrogenpolysiloxane represented by the following formula (H value: 0.00142 mol / 1g) [ka]

[0057] Ingredients (G) G-1: Solution of platinum-divinyltetramethyldisiloxane complex (containing 1% by mass as platinum atoms)

[0058] Ingredients (H) H-1:1-Ethynyl-1-cyclohexanol

[0059] Components (A) to (H) were mixed as follows to obtain the thermally conductive silicone compositions of Examples 1 to 15 and Comparative Examples 1 to 5.

[0060] First, components (C) ((C-1) to (C-13)), (D), and (E) were mixed at room temperature for 15 minutes using a mixer (5-liter planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.)) in the mixing ratios shown in Table 2 below to obtain X-1 to X-13. In addition, Y-1 was obtained by similarly mixing aluminum powder (CN) with an average particle size of 20 μm that does not contain dissimilar metals, instead of aluminum alloy powder (C).

[0061] [Table 2] The percentage of dissimilar metals in the aluminum alloy powder is as shown in Table 1 above.

[0062] Next, 100 parts by mass of component (A) were placed in a 5-liter planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.), and components (B) and (X) or (Y) were added in the proportions shown in Tables 3 to 5. The mixture was then mixed at 170°C for 1 hour. After cooling to room temperature, components (F), (G), and (H) were added in the proportions shown in Tables 3 to 5 and mixed until uniform to obtain each thermally conductive silicone composition.

[0063] 〔viscosity〕 The absolute viscosity of the thermally conductive silicone composition was measured at 25°C using a viscometer (Type PC-1TL) manufactured by Malcolm Corporation.

[0064] [Thermal conductivity] A thermally conductive silicone composition was poured into a 3cm thick mold, covered with kitchen wrap, and measured using a Model QTM-500 manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0065] [Hardness increase evaluation] A sheet-like sample was prepared by pouring a thermally conductive silicone composition into a 6cm x 6cm x 6mm thick mold and heating it at 150°C for 90 minutes. Two of these sheets were stacked together, and their hardness was measured using an Asker C hardness tester to determine the initial hardness. Subsequently, the sample was aged at 150°C for 500 hours, and its hardness was measured again. As a hardness change rate, if the value calculated from the hardness after aging / initial hardness is 2 or more, it is evaluated as unsuitable because it tends to increase in hardness from the initial hardness. If it is 2 or less, it is evaluated as having a hardness increase suppression effect and sufficient heat resistance.

[0066] [Thermal resistance measurement] A thermally conductive silicone composition was sandwiched between a 15mm x 15mm x 1mm thick Si chip and a 15mm x 15mm x 1mm thick Ni plate to a thickness of 80 μm. After compressing at 0.7 MPa for 15 minutes, the thermally conductive silicone composition was heated and cured in a 150°C oven for 90 minutes while the load was still applied. A test specimen for thermal resistance measurement was then prepared, and the thermal resistance was measured. This thermal resistance measurement was performed using NanoFlash (LFA447, manufactured by Nitche Co., Ltd.).

[0067] [Table 3]

[0068] [Table 4]

[0069] Table 5

Claims

1. A thermally conductive silicone composition comprising (C) organopolysiloxane, (D) aluminum alloy powder, and (E) metal oxide powder, wherein (C) aluminum alloy powder contains 0.2 to 30.0% by mass of at least one metal element selected from silicon, copper, manganese, magnesium, chromium, and zinc, and is an aluminum alloy powder with a thermal conductivity of 10 W / m·K or higher.

2. (A) A molecule having at least two alkenyl groups bonded to a silicon atom, with a kinematic viscosity of 10 to 100,000 mm at 25°C. 2 / s organopolysiloxane: 100 parts by mass, (B) A hydrolyzable organopolysiloxane with one end trifunctionality represented by the following general formula (1): 10 to 300 parts by mass per 100 parts by mass of component (A), 【Chemistry 1】 (In formula (1), R 1 (where a is an alkyl group having 1 to 6 carbon atoms, and a is a number from 5 to 100.) (C) Aluminum alloy powder containing 0.2 to 30.0% by mass of at least one metallic element selected from silicon, copper, manganese, magnesium, chromium, and zinc, and having a thermal conductivity of 10 W / m·K or more: 280 to 1,680 parts by mass per 100 parts by mass of the total of component (A) and component (B), (D) Aluminum powder: 120 to 725 parts by mass per 100 parts by mass of the total of components (A) and (B), (E) Metal oxide powder: 100 to 585 parts by mass per 100 parts by mass of the total of components (A) and (B), (F) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule: an amount such that {number of Si-H groups in component (F)} / {number of alkenyl groups in component (A)} is 0.5 to 1.5, and (G) Catalyst selected from the group consisting of platinum and platinum compounds: effective amount of platinum atoms relative to the mass of component (A) A thermally conductive silicone composition according to claim 1, containing the following.

3. The thermally conductive silicone composition according to claim 2, wherein the metal oxide powder of component (E) is zinc oxide powder.

4. Furthermore, the thermally conductive silicone composition according to claim 2, comprising 0.1 to 5% by mass of a control agent selected from (H) acetylene compounds, nitrogen compounds, organophosphorus compounds, oxime compounds, and organochloro compounds relative to component (A).

Images