Thermally conductive composition and electronic device

Abstract

To provide a thermally conductive composition in which the generation of voids is suppressed during heat cycling, and an electronic device including such a thermally conductive composition.SOLUTION: A thermally conductive composition comprises an organopolysiloxane A and a thermally conductive filler B, where the content of anionic impurities is 10 ppm or less relative to the total mass of the thermally conductive filler B.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive composition and an electronic device. [Background technology]

[0002] As heat-generating electronic components, such as central processing units (CPUs) in personal computers, become smaller and more powerful, the amount of heat generated per unit area by these components has become extremely large. This amount of heat can reach approximately 20 times that of an iron. To prevent these heat-generating electronic components from breaking down over the long term, they must be cooled. Metal heat sinks and housings are used for cooling. However, when a heat-generating electronic component is placed directly in contact with a heat sink, microscopic air exists at the interface, which can impede heat conduction. Therefore, to efficiently transfer heat, a thermally conductive material is often placed between the heat-generating electronic component and the heat sink.

[0003] Thermally conductive materials include, for example, thermally conductive greases made by adding thermally conductive powder to room-temperature curing liquid silicone rubber. Room-temperature curing liquid silicone rubbers are primarily classified into one-component and two-component types, with the two-component type being further divided into condensation reaction and addition reaction types. Thermally conductive greases containing two-component liquid silicone rubbers are used as two-component curing composition sets containing two different compositions.

[0004] For example, Patent Document 1 describes that an addition reaction type silicone rubber composition containing an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane, a platinum catalyst, and an adhesion promoter is less susceptible to the effects of curing inhibitors and has excellent adhesion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-22284 Summary of the Invention [Problem to be solved by the invention]

[0006] It has been found that voids occur in the thermally conductive composition sandwiched between the heat-generating component and the heat-dissipating component during heat cycles, which increases the thermal resistance and makes the thermally conductive composition more susceptible to cracking and dripping.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a thermally conductive composition in which the generation of voids during heat cycles is suppressed, and an electronic device equipped with the thermally conductive composition. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to achieve the above object, and as a result have found that the above problem can be solved by keeping the amount of anionic impurities below a predetermined value in the coexistence of organopolysiloxane A and thermally conductive filler B, thereby completing the present invention.

[0009] That is, the present invention is as follows. [1] Organopolysiloxane A, A thermally conductive filler B, The content of anionic impurities is 10 ppm or less relative to the total mass of thermally conductive filler B. Thermally conductive compositions. [2] The thermally conductive filler B contains aluminum oxide. The thermally conductive composition according to [1]. [3] The total content of chloride ions, nitrate ions, and nitrite ions is 5.0 ppm or less based on the total mass of the thermally conductive composition. The thermally conductive composition according to [1] or [2]. [4] The thermally conductive filler B includes a thermally conductive filler B1 having an average particle size of 0.1 to 1.0 μm. The thermally conductive composition according to any one of [1] to [3]. [5] An electronic component, the thermally conductive composition according to any one of [1] to [4], and a heat sink, the electronic component and the heat sink are in contact with each other via the thermally conductive composition; electronic equipment. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thermally conductive composition in which the generation of voids during heat cycles is suppressed, and an electronic device including the thermally conductive composition. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes in detail an embodiment of the present invention (hereinafter referred to as "the present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0012] 1. Thermally conductive composition The thermally conductive composition of this embodiment contains organopolysiloxane A and thermally conductive filler B, and has an anionic impurity content of 10 ppm or less relative to the total mass of thermally conductive filler B. Furthermore, the thermally conductive composition may contain other components, such as a surfactant, a silane coupling agent, or an addition reaction catalyst, as necessary.

[0013] In investigating the mechanism by which voids are generated during heat cycles, the inventors evaluated the mass loss rate of each component in a high-temperature environment. As a result, it was found that no mass loss occurs when organopolysiloxane A alone or thermally conductive filler B alone is used in a high-temperature environment. However, it was also found that mass loss may occur when organopolysiloxane A and thermally conductive filler B coexist.

[0014] A more detailed investigation into the cases in which mass loss occurs revealed that mass loss occurs in the coexistence of organopolysiloxane A and thermally conductive filler B, and when the amount of anionic impurities in the system is greater than a predetermined value. Furthermore, the inventors analyzed the volatile components of samples in which mass loss occurred, and detected siloxane compounds as volatile components.

[0015] Based on the above, it is presumed that when the amount of anionic impurities is greater than a predetermined value in the coexistence of organopolysiloxane A and thermally conductive filler B, partial decomposition of organopolysiloxane A occurs during heat cycles, which is the cause of voids.

[0016] Therefore, in this embodiment, the amount of anionic impurities in the thermally conductive composition containing organopolysiloxane A and thermally conductive filler B as described above is specified to be 10 ppm or less, thereby suppressing the generation of voids during heat cycles. The composition of the thermally conductive composition will be described in detail below.

[0017] 1.1. Anionic impurities Anionic impurities include those that are inevitably mixed into the composition due to components of the thermally conductive composition, such as, but not limited to, thermally conductive fillers.

[0018] Examples of anionic impurities include, but are not limited to, fluorine ions, chloride ions, bromide ions, nitrate ions, nitrite ions, sulfate ions, and phosphate ions. Among these, chloride ions, nitrate ions, and nitrite ions are particularly effective in causing voids.

[0019] The content of anionic impurities is 10 ppm or less, preferably 9.7 ppm or less, 9.5 ppm or less, 9.3 ppm or less, or 9.0 ppm or less, relative to the total mass of thermally conductive filler B. The lower limit of the content of anionic impurities may be below the detection limit, preferably 0 ppm or more, and may be 0.1 ppm or more from the viewpoint of the cost of adjusting the amount of impurities. By keeping the content of anionic impurities at 10 ppm or less, the generation of voids during heat cycles tends to be further suppressed.

[0020] The content of chloride ions is preferably 9.0 ppm or less, 7.5 ppm or less, 6.0 ppm or less, 4.5 ppm or less, 3.0 ppm or less, or 1.5 ppm or less, relative to the total mass of the thermally conductive filler B. The lower limit of the chloride ion content may be below the detection limit, preferably 0 ppm or more, and may be 0.1 ppm or more from the viewpoint of the cost of adjusting the amount of impurities. By keeping the chloride ion content at 9.0 ppm or less, the generation of voids during heat cycles tends to be further suppressed.

[0021] The total content of nitrate ions and nitrite ions is preferably 8.0 ppm or less, 6.0 ppm or less, 4.0 ppm or less, 2.0 ppm or less, 1.5 ppm or less, or 1.0 ppm or less, relative to the total mass of thermally conductive filler B. The lower limit of the total content of nitrate ions and nitrite ions may be below the detection limit, and is preferably 0 ppm or more, and may be 0.1 ppm or more from the perspective of the cost of adjusting the amount of impurities. When the total content of nitrate ions and nitrite ions is 8.0 ppm or less, the generation of voids during heat cycles tends to be further suppressed.

[0022] The total content of chloride ions, nitrate ions, and nitrite ions is preferably 9.0 ppm or less, 7.5 ppm or less, 5.0 ppm or less, 4.5 ppm or less, 3.0 ppm or less, or 2.0 ppm or less, relative to the total mass of thermally conductive filler B. The lower limit of the total content of chloride ions, nitrate ions, and nitrite ions may be below the detection limit, preferably 0 ppm or more, and may be 0.1 ppm or more from the perspective of the cost of adjusting the amount of impurities. When the total content of chloride ions, nitrate ions, and nitrite ions is 9.0 ppm or less, the generation of voids during heat cycles tends to be further suppressed.

[0023] The amount of anionic impurities in the thermally conductive composition is not particularly limited, but can be reduced by, for example, selecting and using a thermally conductive filler B with a low impurity content, using a thermally conductive filler B that has been purified to reduce the impurity content, or increasing the proportion of the thermally conductive filler B with a low impurity content used.

[0024] 1.2. Organopolysiloxane A Organopolysiloxane A may be either a one-component or two-component organopolysiloxane. One-component organopolysiloxane A may be a non-reactive organopolysiloxane, while two-component organopolysiloxane A may be a reactive organopolysiloxane.

[0025] The one-component organopolysiloxane A does not need to be mixed with other agents before use, and the thermally conductive composition can be applied to an object as is.

[0026] Two-component organopolysiloxane A is mixed with other components before use. When mixed, the two organopolysiloxanes react with each other, causing the organopolysiloxanes in the two components to undergo addition reactions, condensation reactions, or peroxide curing reactions, resulting in hardening.

[0027] In the case of a two-component composition, the thermally conductive composition of the present embodiment may be either of the two components. For example, in the case of a two-component composition consisting of a component containing a vinyl-modified organopolysiloxane and a component containing a hydrosilyl-modified organopolysiloxane, at least one component may be the thermally conductive composition of the present embodiment, and both components may satisfy the configuration of the thermally conductive composition of the present embodiment. In other words, the present invention is implemented as long as at least one component of the two-component composition set is the thermally conductive composition of the present embodiment.

[0028] The one-component organopolysiloxane A1 and the two-component organopolysiloxane A2 will be described in detail below.

[0029] 1.2.1. One-component organopolysiloxane A1 The one-component organopolysiloxane A1 is not particularly limited, but examples thereof include non-crosslinked silicones such as linear silicones, branched silicones, and cyclic silicones; and crosslinked silicones with intramolecular three-dimensional crosslinking. Among these, non-crosslinked silicones are preferred, and linear silicones are more preferred. The use of such one-component organopolysiloxane A1 tends to reduce viscosity and further suppress dripping.

[0030] Generally, silicones are composed of monofunctional units (R 1 SiO 1 / 2 ), bifunctional units (R 2 SiO 2 / 2 ), trifunctional unit (R 3 SiO 3 / 2 ), and tetrafunctional units (SiO 4 / 2 For example, a linear silicone can be expressed as a monofunctional unit (R 1 SiO 1 / 2 ) and the bifunctional units (R 2 SiO 2 / 2 ) (n3, n4 = 0 in the formula below), and cyclic silicones have a bifunctional unit (RSiO 2 / 2) (n1, n3, n4 = 0 in the formula below). In addition, branched silicones and three-dimensionally crosslinked silicones have three functional units (R 3 SiO 3 / 2 ) and / or tetrafunctional units (SiO 4 / 2 ), and further, a monofunctional unit (R 1 SiO 1 / 2 ), and the bifunctional units (R 2 SiO 2 / 2 ) can be expressed as having

[0031] A composition formula using such units can be expressed as follows: In the following formula, n1 to n4 indicate the composition ratio of each unit, and can be expressed as a ratio such that the sum of n1 to n4 is 1. Whether or not these units are contained can be measured by a known method such as Si-NMR. 1 ~R 4 can each independently represent any group. (R 1 SiO 1 / 2 ) n1 (R 2 SiO 2 / 2 ) n2 (R 3 SiO 3 / 2 ) n3 (SiO 4 / 2 ) n4

[0032] The one-component organopolysiloxane A1 is not particularly limited, but examples thereof include non-curable silicones and curable silicones. The non-curable silicone resin is not particularly limited as long as it does not have the functional group that contributes to curing that the curable silicone resin has, or is not used in combination with a catalyst. The curable silicone is not particularly limited, but examples thereof include a combination of two types of silicones having functional groups that react with each other. Such curable silicones are not particularly limited, but examples thereof include addition-curable silicones, condensation-curable silicones, and peroxide-curable silicones.

[0033] Among these, organopolysiloxane A is preferably a non-curable silicone, as this tends to further improve handleability.

[0034] The one-component organopolysiloxane A1 is not particularly limited, but examples thereof include dimethylsilicone, diphenylsilicone, and methylphenylsilicone. These silicones may have organic groups introduced into their side chains and / or terminals. Examples of such silicones include, but are not particularly limited to, non-reactive silicones such as long-chain alkyl-modified silicones, polyether-modified silicones, aralkyl-modified silicones, fatty acid ester-modified silicones, and fatty acid amide-modified silicones; and reactive silicones such as amine-modified silicones, epoxy-modified silicones, mercapto-modified silicones, carboxyl-modified silicones, carbinol-modified silicones, and hydrogen-modified silicones.

[0035] Among these, dimethyl silicone, diphenyl silicone, methylphenyl silicone, and non-reactive silicone are preferred, and dimethyl silicone is more preferred. Use of such one-component organopolysiloxane A1 tends to reduce viscosity and further suppress dripping.

[0036] The viscosity of the one-component organopolysiloxane A1 at 25°C is preferably 30 to 2000 mm 2 / s, 50 to 1000 mm 2 / s, and 70 to 500 mPa·s. When the viscosity of organopolysiloxane A21 is within the above range, the handling properties as a one-component agent tend to be improved.

[0037] The content of the one-component organopolysiloxane A1 is preferably 70 to 100 mass%, 80 to 100 mass%, 90 to 99 mass%, or may be 95 to 98 mass%, based on the total amount of the thermally conductive composition excluding the thermally conductive filler B.

[0038] 1.2.2. Two-component organopolysiloxane A2 The two-component organopolysiloxane A2 is not particularly limited, but examples thereof include addition reaction type organopolysiloxanes, condensation reaction type organopolysiloxanes, and peroxide curing type organopolysiloxanes.

[0039] The addition reaction type two-component organopolysiloxane A2 is not particularly limited, but examples include a combination of a vinyl-modified organopolysiloxane and a hydrosilyl-modified organopolysiloxane. The addition reaction between the vinyl group of the vinyl-modified organopolysiloxane and the hydrosilyl group of the hydrosilyl-modified organopolysiloxane can be promoted by an addition reaction catalyst.

[0040] The condensation reaction type two-component organopolysiloxane A2 is not particularly limited, but examples thereof include combinations of organopolysiloxanes having silanol groups and / or hydrolyzable groups. In these organopolysiloxanes, condensation reaction occurs between silanol groups or between silanol groups and hydrolyzable groups. The hydrolyzable groups are not particularly limited, but examples thereof include alkoxy groups, acetoxy groups, oxime groups, aminoxy groups, and propenoxy groups.

[0041] The peroxide-curable two-component organopolysiloxane A2 is not particularly limited, but examples include a combination of organopolysiloxanes having an unsaturated hydrocarbon group such as a vinyl group. The reaction can be accelerated by the use of an alkyl-based organic peroxide or an acyl-based organic peroxide.

[0042] In the two-component organopolysiloxane A2, the organopolysiloxane to be reacted may be contained in a separate agent, or the addition reaction catalyst and organic peroxide may be contained in a separate agent from the organopolysiloxane.

[0043] Among the above, vinyl-modified organopolysiloxane A21 (hereinafter simply referred to as "organopolysiloxane A21") is an organopolysiloxane having at least one vinyl group. Organopolysiloxane A21 may have a vinyl group on a side chain and / or at a terminal. Such organopolysiloxane has a structural unit represented by the following formula (b1-1) or a terminal structure represented by formula (b1-2). Organopolysiloxane A21 may have, for example, at least one of the structural unit represented by formula (b1-1) and the terminal structure represented by formula (b1-2), and a structural unit represented by formula (b1-3).

[0044] [ka]

[0045] In formulas (b1-1), (b1-2), and (b1-3), R represents any monovalent hydrocarbon group which may have a substituent. That is, in organopolysiloxane A21, any monovalent hydrocarbon group which may have a substituent is bonded to a side chain of the siloxane skeleton.

[0046] Such monovalent hydrocarbon groups are not particularly limited, and examples thereof include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 2-phenylpropyl; and groups having a substituent in these groups. Examples of the substituent in the monovalent hydrocarbon group include a halogen atom, particularly a fluorine atom or a chlorine atom.

[0047] The number of vinyl groups per molecule of organopolysiloxane A21 is preferably 2.0 or more, 2.5 or more, or 3.0 or more, so that when reacted with organopolysiloxane A22, a network structure is formed, and a cured product having superior mechanical strength can be obtained.

[0048] The organopolysiloxane A21 preferably contains at least an organopolysiloxane having vinyl groups at both ends. The use of such an organopolysiloxane tends to make it easier to adjust the crosslink density of the resulting cured product. From the same perspective, the organopolysiloxane A21 preferably contains at least a polydimethylsiloxane having vinyl groups at both ends.

[0049] The viscosity of organopolysiloxane A21 at 25° C. is preferably 30 to 1000 mPa·s, 60 to 700 mPa·s, or 70 to 500 mPa·s. When the viscosity of organopolysiloxane A21 is within the above range, it tends to have excellent handleability.

[0050] The content of the vinyl-modified organopolysiloxane A21 relative to the total amount of the thermally conductive composition excluding the thermally conductive filler B is preferably 50 to 99 wt %, 55 to 98 wt %, or 60 to 95 wt %.

[0051] Furthermore, hydrosilyl-modified organopolysiloxane A22 (hereinafter also referred to simply as "organopolysiloxane A22") is an organopolysiloxane having at least one hydrosilyl group. Organopolysiloxane A22 may have a hydrosilyl group on a side chain and / or at a terminal. Such organopolysiloxane has a structural unit represented by the following formula (e2-1) or a terminal structure represented by formula (e2-2). Organopolysiloxane A22 may have, for example, at least one of the structural unit represented by formula (e2-1) and the terminal structure represented by formula (e2-2), and a structural unit represented by formula (e2-3). [ka]

[0052] In formulae (e2-1), (e2-2), and (e2-3), R represents any monovalent hydrocarbon group which may have a substituent. That is, in organopolysiloxane A22, any monovalent hydrocarbon group which may have a substituent is bonded to a side chain of the siloxane skeleton.

[0053] Such monovalent hydrocarbon groups include the same monovalent hydrocarbon groups that may be contained in the vinyl-modified organopolysiloxane A21.

[0054] The number of hydrosilyl groups per molecule of organopolysiloxane A22 is preferably 2.0 or more, 2.5 or more, or 3.0 or more, so that when reacted with organopolysiloxane A21, a network structure is formed, and a cured product having excellent mechanical strength can be obtained.

[0055] The viscosity of organopolysiloxane A22 at 25° C. is preferably 1 to 300 mPa·s, 2 to 200 mPa·s, or 3 to 100 mPa·s. When the viscosity of organopolysiloxane A22 is within the above range, it tends to have excellent handleability.

[0056] The content of organopolysiloxane A22 relative to the total amount of the thermally conductive composition excluding thermally conductive filler B is preferably 1 to 50 wt %, 2 to 45 wt %, or 5 to 40 wt %.

[0057] 1.3.Thermal Conductive Filler B The thermally conductive filler B is not particularly limited, but examples thereof include aluminum oxide, aluminum nitride, boron nitride, silicon nitride, zinc oxide, aluminum hydroxide, metallic aluminum, magnesium oxide, diamond, carbon, indium, gallium, copper, silver, iron, nickel, gold, tin, metallic silicon, etc. These fillers may be used alone or in combination of two or more.

[0058] Among these, it is preferable to include at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, zinc oxide, aluminum hydroxide, metallic aluminum, magnesium oxide, copper, silver, and diamond, with aluminum oxide and magnesium oxide being more preferred, and aluminum oxide being even more preferred. By using such a thermally conductive filler B, the thermal conductivity tends to be further improved. Furthermore, since the use of aluminum oxide tends to make voids more likely to occur during heat cycles, the present invention, which aims to suppress voids, becomes more useful.

[0059] The average particle size of the thermally conductive filler B is preferably 0.1 to 200 μm, more preferably 0.1 to 100 μm. When the average particle size of the thermally conductive filler B is within the above range, the fluidity of the thermally conductive composition and the dispersibility and filling properties of the thermally conductive filler B tend to be further improved. In this specification, the average particle size refers to D50 (median diameter).

[0060] Furthermore, fillers with different average particle sizes may be mixed and used as the thermally conductive filler B. For example, the thermally conductive filler B may be one or more of thermally conductive filler B1 having an average particle size of 0.1 to 1.0 μm, thermally conductive filler B2 having an average particle size of 1.2 to 20 μm, and thermally conductive filler B3 having an average particle size of 22 to 200 μm.

[0061] The content of the thermally conductive filler B1 is preferably 0 to 20 mass%, or may be 0.5 to 15 mass%, 1.0 to 10 mass%, or 1.5 to 5.0 mass%, relative to the total amount of the thermally conductive filler components. When the content of the thermally conductive filler B1 is 0.1 mass% or more, thermal conductivity tends to be further improved. Furthermore, when the content of the thermally conductive filler B1 is 20 mass% or less, voids during heat cycles tend to be further suppressed. The thermally conductive filler B1 may not be included.

[0062] The content of the thermally conductive filler B2 may be preferably 20 to 60 mass%, 25 to 55 mass%, 30 to 50 mass%, or 35 to 45 mass% relative to the total amount of the thermally conductive filler B. When the content of the thermally conductive filler B2 is within the above range, the thermal conductivity tends to be further improved, the viscosity tends to be further reduced, and changes in hardness and bleeding tend to be further suppressed.

[0063] The content of thermally conductive filler B3 is preferably 40 to 70 mass%, or may be 45 to 65 mass%, or 50 to 60 mass%, relative to the total amount of thermally conductive filler B. When the content of thermally conductive filler B3 is within the above range, thermal conductivity tends to be further improved and viscosity tends to be further reduced.

[0064] The total content of the thermally conductive filler B may be preferably 1200 to 2000 parts by mass, 1300 to 1900 parts by mass, 1400 to 1800 parts by mass, or 1500 to 1700 parts by mass per 100 parts by mass of the organopolysiloxane A. When the content of the thermally conductive filler B is within the above range, the generation of voids during heat cycles is further suppressed, and the thermal conductivity is further improved, the viscosity is further reduced, and changes in hardness and bleeding are further suppressed.

[0065] Each filler component may be surface-treated with a surface treatment agent by a known wet or dry treatment method. The surface treatment agent is not particularly limited, but may be, for example, the above-mentioned silane coupling agent, but the silane coupling agent may be added separately regardless of this surface treatment.

[0066] 1.4.Other Ingredients Other components include, as required, a surfactant, a silane coupling agent, and an addition reaction catalyst.

[0067] Surfactants The thermally conductive composition may contain a surfactant to improve the dispersibility of the thermally conductive filler. The surfactant is not particularly limited, but examples thereof include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. These surfactants may be used alone or in combination of two or more.

[0068] 1.4.2.Silane coupling agents The thermally conductive composition may further contain a silane coupling agent. By including a silane coupling agent, the viscosity tends to be further reduced, and changes in hardness and bleeding tend to be further suppressed. In addition, dripping tends to be further suppressed.

[0069] The silane coupling agent is not particularly limited, but examples thereof include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino silanes such as aminopropyltriethoxysilane, ureidopropyltriethoxysilane and N-phenylaminopropyltrimethoxysilane; and hydrophobic silane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, octadecyltrimethoxysilane and n-decyltrimethoxysilane.

[0070] Among these, hydrophobic silane compounds are more preferred. By using such a silane coupling agent, the viscosity tends to be further reduced, the hardness change tends to be further suppressed, and dripping tends to be further suppressed.

[0071] The content of the silane coupling agent is preferably 0.1 to 5 mass %, or may be 0.2 to 2 mass %, based on the total amount of the thermally conductive filler. When the content of the silane coupling agent is within the above range, the viscosity tends to be further reduced, and changes in hardness and bleeding tend to be further suppressed.

[0072] 1.4.2. Addition reaction catalysts The addition reaction catalyst is not particularly limited as long as it catalyzes the addition reaction between the vinyl-modified organopolysiloxane A21 and the hydrosilyl-modified organopolysiloxane A22. Examples of the addition reaction catalyst include platinum compound catalysts, rhodium compound catalysts, and palladium compound catalysts. Among these, platinum compound catalysts are preferred. Use of such an addition reaction catalyst tends to allow the curing rate of the addition reaction to fall within a suitable range.

[0073] The platinum compound catalyst is not particularly limited, but examples thereof include simple platinum, platinum compounds, and platinum-supported inorganic powders. The platinum compound is not particularly limited, but examples thereof include chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum coordination compounds, etc. The platinum-supported inorganic powder is not particularly limited, but examples thereof include platinum-supported aluminum oxide powder, platinum-supported silica powder, and platinum-supported carbon powder.

[0074] The addition reaction catalyst may be used alone or in combination of two or more. Furthermore, when preparing the thermally conductive composition, the addition reaction catalyst may be blended alone or in a premixed state with other components, such as the vinyl-modified organopolysiloxane A21 or other organopolysiloxanes.

[0075] The content of the addition reaction catalyst is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, and even more preferably 0.5 to 2 parts by weight, per 100 parts by weight of the total content of the vinyl-modified organopolysiloxane A21 and the hydrosilyl-modified organopolysiloxane A22. When the content of the addition reaction catalyst is within the above range, the curing rate of the addition reaction tends to be within a suitable range.

[0076] 1.5.Applications The thermally conductive composition of this embodiment can be suitably used as a thermally conductive and heat-dissipating material such as thermally conductive grease.

[0077] 2.Cured product The cured product of this embodiment is a cured product of the thermally conductive composition described above. More specifically, the cured product (crosslinked cured product) is obtained by reacting a two-component organopolysiloxane through an addition reaction, a condensation reaction, or a peroxide reaction.

[0078] To mix the thermally conductive composition, a mixer such as a roll mill, kneader, Banbury mixer, or line mixer is used. More specifically, examples include kneading methods using a universal mixer, hybrid mixer, Trimix (manufactured by Inoue Seisakusho), or static mixer. The preferred molding method is the doctor blade method, but depending on the viscosity of the resin, extrusion, pressing, or calendar roll methods may also be used. The reaction conditions for the addition reaction are not particularly limited, but are usually carried out at room temperature (e.g., 25°C) to 150°C for 0.1 to 24 hours.

[0079] 2.Electronic equipment The electronic device of this embodiment includes an electronic component, a heat sink, and the thermally conductive composition, and the electronic component and the heat sink are in contact with each other via the thermally conductive composition. In this electronic device, the electronic component and the heat sink are thermally coupled via the thermally conductive composition.

[0080] Here, the electronic component is not particularly limited, but examples thereof include heat-generating electronic components such as motors, battery packs, circuit boards used in on-board power supply systems, power transistors, microprocessors, etc. Among these, electronic components used in on-board power supply systems for vehicles are preferred. Furthermore, the heat sink is not particularly limited as long as it is a component configured for the purpose of heat dissipation or heat absorption.

[0081] The method for bonding an electronic component to a heat sink via the thermally conductive composition is not particularly limited. For example, an electronic device may be obtained by bonding an electronic component to a heat sink using the thermally conductive composition. [Example]

[0082] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples. Unless otherwise specified, all operations were carried out at room temperature (25°C).

[0083] 1. Preparation of One-Component Thermally Conductive Compositions (Examples 1 to 6 and Comparative Examples 1 and 2) A thermally conductive composition was prepared by mixing organopolysiloxane A and thermally conductive filler B according to the composition shown in Table 1. In Table 1, the composition of each component is shown so that organopolysiloxane A is 100 parts by weight.

[0084] 1.1. Raw materials (One-component organopolysiloxane A) Aa: Organopolysiloxane, manufactured by Shin-Etsu Silicone Co., Ltd., KF-96-100CS (Thermal conductive filler B) Ba: Aluminum oxide: Denka Co., Ltd., DAW45S, average particle size: 46 μm Bb: Aluminum oxide: DAW05 manufactured by Denka Co., Ltd., average particle size: 6.4 μm Bc: Aluminum oxide: DAW01 manufactured by Denka Co., Ltd., average particle size: 1.9 μm Bd: Aluminum oxide: AEAS12 manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.5 μm Be: Aluminum oxide: AKP-20 manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.4 μm Bf: Aluminum oxide: Sumitomo Chemical Co., Ltd., NXA-150, average particle size: 0.2 μm Bg: Aluminum oxide: AA05N manufactured by Sumitomo Chemical Co., Ltd., average particle size: 0.6 μm Bh: Aluminum oxide: Sumitomo Chemical Co., Ltd., AA05, average particle size: 0.6 μm Bi: Aluminum oxide: Denka Co., Ltd., ASFP40, average particle size: 0.4 μm

[0085] The average particle size of each filler component was measured using a Shimadzu SALD-20 laser diffraction particle size distribution analyzer. The evaluation sample was prepared by adding 50 ml of pure water and 5 g of each filler component to be measured to a glass beaker, stirring with a spatula, and then dispersing in an ultrasonic cleaner for 10 minutes. The dispersion of each dispersed filler component was added drop by drop to the sampler section of the analyzer using a dropper, and measurements were taken once the absorbance had stabilized. The average particle size was measured as D50 (median diameter).

[0086] 1.2. Weight loss rate Each thermally conductive composition obtained as described above was measured for its weight loss rate when held at 150°C for 500 hours. The weight loss rate was calculated using the following formula based on the weight of the thermally conductive composition before heating (W0) and the weight of the thermally conductive composition after heating at 150°C for 500 hours (W1). Weight reduction rate=(W0-W1) / W0×100

[0087] [Table 1]

[0088] 2. Preparation of Cured Products from Two-Component Thermally Conductive Compositions (Examples 7-8 and Comparative Examples 3-4) A two-component thermally conductive composition cured product was prepared by mixing the following two-component organopolysiloxane A and thermally conductive filler B according to the formulation shown in Table 2. In Table 2, the composition of each component is shown so that organopolysiloxane A is 100 parts by weight. The DOWSIL SE 1885 series contains a platinum catalyst.

[0089] The weight loss rate of the resulting cured product was measured in the same manner as above, and the results are shown in Table 2.

[0090] 2.1. Raw materials (Two-component organopolysiloxane A) Ab: Organopolysiloxane: DOWSIL SE 1885A manufactured by Dow Toray Co., Ltd. Ac: Organopolysiloxane: DOWSIL SE 1885B, manufactured by Dow Toray Co., Ltd.

[0091] [Table 2]

[0092] In addition, it was confirmed that there was substantially no mass loss when only the organopolysiloxane A or only the thermally conductive filler B shown in Tables 1 and 2 was used for 500 hours at 150°C. Comparison of the Examples and Comparative Examples showed that in the coexistence of organopolysiloxane A and thermally conductive filler B, the presence of a certain amount of anionic impurities causes a weight loss, which becomes a cause of voids during heat cycling.

[0093] Furthermore, a comparison between Examples 5 and 6 reveals that the less the thermally conductive filler with a smaller average particle size is used, the lower the weight loss rate is. [Industrial Applicability]

[0094] The thermally conductive composition of the present invention has industrial applicability as a thermally conductive grease used to thermally bond a heating element to a metal housing, or as other thermally conductive materials.

Claims

1. Organopolysiloxane A, A thermally conductive filler B, The content of anionic impurities is 10 ppm or less relative to the total mass of the thermally conductive filler B. Thermally conductive compositions.

2. The thermally conductive filler B contains aluminum oxide. The thermally conductive composition of claim 1 .

3. The total content of chloride ions, nitrate ions, and nitrite ions is 5.0 ppm or less based on the total mass of the thermally conductive composition. The thermally conductive composition of claim 1 .

4. The thermally conductive filler B includes a thermally conductive filler B1 having an average particle size of 0.1 to 1.0 μm. The thermally conductive composition of claim 1 .

5. An electronic component, the thermally conductive composition according to any one of claims 1 to 4, and a heat sink, the electronic component and the heat sink are in contact with each other via the thermally conductive composition; electronic equipment.

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