Curable organopolysiloxane composition and semiconductor device

Abstract

Provided is a curable organopolysiloxane composition in which a necessary and sufficient amount of a material having excellent heat conduction characteristics is blended, and the material is uniformly dispersed in the form of fine particles in a matrix containing a resin component, thereby being capable of forming a cured product that does not produce cracks or voids during curing. A curable organopolysiloxane composition containing: (A) an organopolysiloxane which is liquid at 25 DEG C and has two or more alkenyl groups bonded to a silicon atom in one molecule; (B) an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom; (C) one or more elements selected from the group consisting of gallium and gallium alloys having a melting point of-20 to 70 DEG C; (D) a thermally conductive filler having an average particle diameter of 0.1-30 [mu] m; and (E) a platinum group metal catalyst, in which the freezing point of the gallium and / or the gallium alloy is-40 DEG C or less as a result of the gallium and / or the gallium alloy of (C) being dispersed in the form of particles in the organopolysiloxane.

Description

Technical Field

[0001] The present invention relates to a curable organopolysiloxane composition, a method for producing the same, a cured product thereof, use of the cured product as a heat conductive layer, a semiconductor device having the heat conductive layer, and a method for producing the semiconductor device. Background Art

[0002] Heat-generating electronic components mounted on a printed wiring board, such as an IC package like a CPU, sometimes cause performance degradation or breakage due to a temperature rise caused by heat generation during use. Therefore, conventionally, a heat conductive sheet having good heat conductivity is disposed between the IC package and a heat dissipating member having a heat sink, or a heat conductive grease is applied, so that heat generated from the IC package or the like is efficiently conducted to the heat dissipating member for heat dissipation. However, with the high performance of electronic components and the like, the amount of heat generated has a tendency to increase day by day, and it is necessary to develop materials and components having more excellent heat conductivity than before.

[0003] Conventional heat conductive sheets have advantages in terms of workability and processes such as being easily mountable and assemblable. In addition, in the case of a heat conductive grease, it has the advantage of being unaffected by surface irregularities of a CPU, a heat dissipating member, etc., being able to follow the irregularities without generating a gap between the two, making the two closely adhere, and having a small interfacial thermal resistance. However, both the heat conductive sheet and the heat conductive grease are obtained by blending a heat conductive filler to impart heat conductivity. In the case of a heat conductive sheet, in order not to interfere with workability and processability in its manufacturing process, and in the case of a heat conductive grease, in order not to cause trouble in workability when coating a heat-generating electronic component or the like using a syringe or the like, it is necessary to suppress the upper limit of its apparent viscosity within a certain limit. Therefore, in either case, the upper limit of the blending amount of the heat conductive filler is restricted, and there is a drawback that a sufficient heat conductive effect cannot be obtained.

[0004] Therefore, methods of incorporating low melting point metals into heat conductive pastes (Patent Document 1: Japanese Patent Laid-Open No. 7-207160, Patent Document 2: Japanese Patent Laid-Open No. 8-53664), granular materials that immobilize liquid metals in a three-phase composite to achieve a stabilizing effect (Patent Document 3: Japanese Patent Laid-Open No. 2002-121292), etc. have been proposed. However, heat conductive materials using these low melting point metals contaminate components other than the coating portion, and there are also problems such as leakage of oily substances when used for a long time. To solve these problems, a method of dispersing gallium and / or gallium alloys in curable silicone has been proposed (Patent Document 4: Japanese Patent No. 4551074), but when the thickness of the composition is large, due to its low thermal conductivity, it is not a heat conductive material that can sufficiently meet the requirements. In addition, methods for improving its thermal conductivity have also been proposed (Patent Document 5: Japanese Patent No. 4913874 and Patent Document 6: Japanese Patent No. 5640945), but cracks and voids are likely to occur during curing, and the performance cannot be fully exerted. Moreover, when exposed to an extremely low temperature environment of -40°C or lower, the reliability of heat-generating electronic components sometimes decreases. Prior Art Documents Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 7-207160 Patent Document 2: Japanese Patent Laid-Open No. 8-53664 Patent Document 3: Japanese Patent Laid-Open No. 2002-121292 Patent Document 4: Japanese Patent No. 4551074 Patent Document 5: Japanese Patent No. 4913874 Patent Document 6: Japanese Patent No. 5640945 Summary of the Invention Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to obtain a curable organopolysiloxane composition that incorporates a material with excellent heat conduction characteristics in a sufficient amount as required, and the material is uniformly dispersed in a matrix containing a resin component in a particulate state, so that the curable organopolysiloxane composition forms a cured product that does not generate cracks and voids during curing. Another object of the present invention is to provide a method for manufacturing the curable organopolysiloxane composition. In addition, an object of the present invention is also to provide a use in which, in the same manner as in conventional heat-conductive greases, the curable organopolysiloxane composition is disposed so as to be sandwiched between a heat-generating electronic component and a heat-dissipating member, follows the unevenness of the surface of the component or member without generating gaps, and serves as a heat-conductive layer composed of a cured product crosslinked by heat treatment. Further, an object of the present invention is to provide a semiconductor device having excellent heat dissipation performance obtained by bonding a heat-generating electronic component and a heat-dissipating member via the heat-conductive layer and a method for manufacturing the same. Means for solving the problems

[0007] The inventors of the present invention repeatedly conducted in-depth studies to solve the above problems, and as a result, found that by blending gallium and / or its alloy having a low melting point, a specific alkoxypolysiloxane, a specific organohydrogenpolysiloxane bonded to a silicon atom, and a heat-conductive filler, a composition in which the gallium and / or its alloy is uniformly dispersed in a fine particle state can be easily obtained, and by lowering the freezing point of the alloy fine particles to -40°C or lower, high reliability is exhibited even in an extremely low temperature environment of -40°C or lower. In addition, it was also found that the generation of cracks and voids is reduced in the step of heat-treating the composition to form a cured product. Further, it was also found that high reliability can be obtained by controlling the storage modulus of the cured product of the composition within a specific range.

[0008] Moreover, it was found that by disposing the cured product obtained as described above in a layer-like manner so as to be sandwiched between a heat-generating electronic component and a heat-dissipating member, it can be used as a heat-conductive layer having a low thermal resistance, and the heat generated when the heat-generating electronic component operates is rapidly conducted to the heat-dissipating member via the heat-conductive layer containing gallium and / or its alloy fixed and held in the above-described structure, thereby obtaining a semiconductor product having excellent heat dissipation characteristics. Based on these findings, the present invention has been completed. That is, the present invention is an invention for providing the following curable organopolysiloxane composition and a semiconductor device using the curable organopolysiloxane composition.

[0009] <1> A curable organopolysiloxane composition comprising: (A) an organopolysiloxane which is liquid at 25°C and has two or more alkenyl groups bonded to silicon atoms in one molecule; (B) an organohydrogenpolysiloxane having hydrogen atoms bonded to silicon atoms; (C) one or more selected from the group consisting of gallium and gallium alloys having a melting point of -20 to 70°C; (D) a heat-conductive filler having an average particle diameter of 0.1 to 30 μm; and (E) a platinum group metal catalyst, wherein the freezing point of the gallium and / or gallium alloy becomes -40°C or lower by dispersing the gallium and / or gallium alloy of (C) in the organopolysiloxane in a particle state. It should be noted that the freezing point is defined as the temperature at the maximum peak position of the exothermic curve obtained when the curable organopolysiloxane composition is cooled from 25°C to -80°C at a cooling rate of 3°C / minute using a differential scanning calorimeter (DSC). <2> The curable organopolysiloxane composition as described in <1> contains the following (A) to (G-1): (A) Organopolysiloxane: 100 parts by mass, which is composed of the following (A-1) and (A-2), and the proportion of (A-1) is 10 to 90% by mass based on the total of (A-1) and (A-2); (A-1) Organopolysiloxane having a viscosity of 0.01 to 10 Pa·s at 25°C and having two or more alkenyl groups bonded to silicon atoms in one molecule; (A-2) Organopolysiloxane having a viscosity of 11 to 1000 Pa·s at 25°C and having two or more alkenyl groups bonded to silicon atoms in one molecule; (B) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, and the amount thereof is such that the number of hydrogen atoms bonded to silicon atoms in this component is 0.1 to 5.0 relative to one alkenyl group in the (A) component; (C) One or more selected from the group consisting of gallium and gallium alloys having a melting point of -20 to 70°C: 300 to 20000 parts by mass; (D) Thermally conductive filler: 10 to 1000 parts by mass, having an average particle diameter of 0.1 to 30 μm; (E) Platinum group metal catalyst: 0.1 to 500 ppm in terms of the mass of the platinum group metal relative to the mass of the (A) component; and (G-1) Organopolysiloxane represented by the following general formula (1): 10 to 500 parts by mass, [Chemical formula 1] (In formula (1), R 1 is an alkyl group of the same or different types, R 2 is an alkyl group, alkenyl group or acyl group, a is an integer of 5 to 100, and b is an integer of 1 to 3.) <3> The curable organopolysiloxane composition as described in <2> further contains: (G-2) An alkoxysilane compound represented by the following general formula (2), and 0.1 to 100 parts by mass relative to 100 parts by mass of the (A) component, R 3 c R 4d Si(OR 5 ) 4-c-d (2) (In formula (2), R 3 is independently an alkyl group having 6 to 16 carbon atoms, R 4 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R 5 is independently an alkyl group having 1 to 6 carbon atoms, c is an integer of 1 to 3, d is an integer of 0 to 2, and the sum of c + d is an integer of 1 to 3.) <4> The curable organopolysiloxane composition according to <2> or <3>, further comprising (G-3) trifluoropropyltrimethoxysilane: 0.1 to 100 parts by mass relative to 100 parts by mass of component (A). <5> The curable organopolysiloxane composition according to any one of <1> to <4>, wherein component (B) is an organohydrogenpolysiloxane having 5 or more hydrogen atoms bonded to silicon atoms in the molecular chain and satisfying the following formula (3), 0.1 < α / β (3) (In formula (3), α represents the number of hydrogen atoms bonded to silicon atoms in the non-terminal part of the molecular chain, and β represents the total number of silicon atoms in component (B).) <6> The curable organopolysiloxane composition according to any one of <1> to <5>, wherein component (C) is dispersed in the composition in the form of particles having a size of 1 to 200 μm. <7> A thermally conductive silicone grease composition comprising the curable organopolysiloxane composition according to any one of <1> to <6>. <8> A cured product which is a cured product of the curable organopolysiloxane composition according to any one of <1> to <6>. <9> The cured product of the curable organopolysiloxane composition according to <8>, which has a storage modulus of 3000 to 300000 Pa at 25°C. <10> Use of the cured product according to <8> as a thermally conductive layer disposed between a heat-generating electronic component and a heat sink. <11> A semiconductor device having a heat-generating electronic component, a heat sink, and a thermally conductive layer composed of the cured product according to <8>, Among them, the heat-generating electronic component and the heat dissipation member are joined via the heat-conductive layer. <12> A method for manufacturing a semiconductor device, which is the method for manufacturing the semiconductor device described in <11>, and includes the following steps: (a) Step: Coating the surface of the heat-generating electronic component with the curable organopolysiloxane composition described in any one of <1> to <6>, and forming a coating layer containing the above composition on the surface; (b) Step: Press-fitting and fixing the heat dissipation member to the coating layer; and (c) Step: Heating the structure obtained after step (b) at 80 to 180 °C to cure the coating layer to form a heat-conductive layer. Effects of the Invention

[0010] Regarding the curable organopolysiloxane composition of the present invention, by dispersing gallium and / or its alloy contained in the composition in an organopolysiloxane as a base oil, even when exposed to an extremely low temperature environment below -40 °C (such as a space environment), the low melting point metal exists in a liquid form, so the reliability under extremely low temperature environmental conditions is improved. In addition, the generation of cracks and voids during heat curing can be suppressed. Further, since the cured product of the curable organopolysiloxane composition of the present invention is suppressed to have a low storage modulus, it can sufficiently follow the warping of the substrate during thermal shock, and the reliability is improved. Since the curable organopolysiloxane composition of the present invention is in the form of a grease before curing, the workability during coating on heat-generating electronic components such as CPUs is good. Further, when the heat dissipation member is press-fitted, it can follow the unevenness of the surfaces of both the heat-generating electronic component and the heat dissipation member, and closely bond the two without generating a gap between them, so no interfacial thermal resistance is generated. In addition, during the heat treatment step for curing the resin component by an addition reaction, there is also little generation of cracks and voids. Regarding the gallium and / or its alloy contained in the composition of the present invention, in the three-dimensional crosslinked network formed by the curing of the resin component, the path-like structure is fixed and maintained, so the heat generated by the heat-generating electronic component can be quickly conducted to the heat dissipation member. Therefore, compared with conventional heat-conductive sheets or heat-conductive greases, a high heat dissipation effect can be reliably exerted. Moreover, the gallium and / or its alloy forming the path contained in the heat-conductive layer composed of the cured product of the composition of the present invention assembled in the semiconductor device is fixed and maintained in the three-dimensional crosslinked network of the cured resin, so there is no problem of contaminating other components or leaking oil over time as in the case of conventional heat-conductive greases. Therefore, the reliability of the semiconductor device can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. 1 is a schematic longitudinal sectional view showing an example of a semiconductor device to which the composition of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Curable Organopolysiloxane Composition] <(A) Organopolysiloxane> The component (A) of the composition of the present invention is an organopolysiloxane that is liquid at 25°C and has two or more alkenyl groups bonded to silicon atoms in one molecule, and is the main agent (base polymer) in the addition reaction curing system of the present invention. The component (A) preferably consists of the following (A-1) and (A-2).

[0013] (A-1) An organopolysiloxane having a viscosity of 0.01 to 10 Pa·s at 25°C and having two or more alkenyl groups bonded to silicon atoms in one molecule (A-2) An organopolysiloxane having a viscosity of 11 to 1000 Pa·s at 25°C and having two or more alkenyl groups bonded to silicon atoms in one molecule

[0014] The viscosity of (A-1) is preferably in the range of 0.1 to 5 Pa·s, more preferably 0.1 to 1 Pa·s. If the viscosity of (A-1) is less than 0.01 Pa·s, the cured product becomes brittle and cracks easily. If the viscosity of (A-1) is greater than 10 Pa·s, the cured product becomes soft and voids are likely to occur.

[0015] The viscosity of (A-2) is preferably in the range of 15 to 500 Pa·s, more preferably in the range of 20 to 100 Pa·s. If the viscosity of (A-2) is less than 11 Pa·s, no stirring shear is applied to the material during manufacturing, and the composition is difficult to become grease-like. If the viscosity of (A-2) is greater than 1000 Pa·s, the viscosity of the composition is too high, resulting in difficult handling.

[0016] It should be noted that in the present invention, the viscosity is the value measured at 25°C using a helical viscometer PC-ITL (manufactured by MALCOM Co., Ltd.).

[0017] The proportion of (A-1) is 10 to 90% by mass, preferably 20 to 80% by mass, more preferably 30 to 70% by mass, based on the total of (A-1) and (A-2). If the proportion of (A-1) is less than 10% by mass, the cured product becomes soft and voids are likely to occur during curing. If the proportion of (A-1) is greater than 90% by mass, stirring shear is not applied to the material during production, and it is difficult for the composition to become grease-like.

[0018] The molecular structures of the organopolysiloxanes of (A-1) and (A-2) are not limited, and examples include, for example, linear, branched, and linear with partial branches, but linear is particularly preferred.

[0019] The number of alkenyl groups bonded to the silicon atom can be 2 or more, preferably 2 to 10, more preferably 2 to 5 in each of (A-1) and (A-2) per molecule. Examples of the alkenyl group bonded to the silicon atom include, for example, vinyl, allyl, 1-butenyl, 1-hexenyl, etc. Among them, vinyl with high versatility is preferred. This alkenyl group can be bonded to either the silicon atom at the end of the molecular chain or the silicon atom in the middle of the molecular chain, but in order to obtain a cured product with good softness, it is preferably present by bonding only to the silicon atom at the end of the molecular chain.

[0020] Examples of the group bonded to the silicon atom other than the alkenyl group include, for example, an unsubstituted or substituted monovalent hydrocarbon group, that is, an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, etc.; a cycloalkyl group such as cyclopentyl, cyclohexyl, etc.; an aryl group such as phenyl, tolyl, xylyl, naphthyl, etc.; an aralkyl group such as benzyl, 2-phenylethyl, 2-phenylpropyl, etc.; a halogenated alkyl group such as chloromethyl, 3,3,3-trifluoropropyl, 3-chloropropyl, etc. In addition, from the viewpoints of synthesis and economy, it is preferably 90% or more methyl.

[0021] Preferred specific examples of such organopolysiloxanes include polydimethylsiloxane capped at both ends of the molecular chain with dimethylethenylsiloxy, polydimethylsiloxane capped at both ends of the molecular chain with methyldivinylsiloxy, dimethylsiloxane-methylphenylsiloxane copolymer capped at both ends of the molecular chain with dimethylethenylsiloxy, etc.

[0022] <(B) Organohydrogenpolysiloxane> The component (B) of the composition of the present invention is an organohydrogenpolysiloxane having 2 or more hydrogen atoms bonded to the silicon atom (hereinafter referred to as "Si-H group") in 1 molecule, and is a component that functions as a crosslinking agent for the above-mentioned component (A). That is, the Si-H group in this component (B) undergoes an addition reaction with the alkenyl group in the component (A) through a hydrosilylation reaction by the action of the platinum-based catalyst of the following component (E), thereby producing a crosslinked cured product having a three-dimensional network structure with crosslinking bonds.

[0023] (B) The number of Si-H groups in the component is 2 or more per molecule, and from the viewpoint of suppressing voids during curing, it is preferably 5 or more, more preferably 10 or more. Further, component (B) is more preferably an organohydrogenpolysiloxane having 5 or more hydrogen atoms bonded to silicon atoms in the non-terminal portion of the molecular chain and satisfying the following formula (3). 0.1 < α / β (3) (In formula (3), α represents the number of hydrogen atoms bonded to silicon atoms in the non-terminal portion of the molecular chain, and β represents the total number of silicon atoms in component (B)) When the range of α / β is as low as 0.1 or less, voids are likely to be generated during curing. Therefore, 0.1 < α / β is also required. In this case, α / β is preferably 0.11 or more, particularly preferably 0.12 or more, and the upper limit is not particularly limited, preferably 0.95 or less, particularly preferably 0.90 or less.

[0024] (B) The molecular structure of the component is not particularly limited as long as it satisfies the above requirements, and it can also be any of the conventionally known ones, for example, linear, cyclic, branched, three-dimensional network (resin-like), etc. The number of silicon atoms (or degree of polymerization) per molecule is usually 3 to 1000, preferably 5 to 400, more preferably 10 to 300, further preferably 10 to 100, and particularly preferably 10 to 60.

[0025] (B) The kinematic viscosity of the organohydrogenpolysiloxane of the component is usually 1 to 10000 mm 2 / s, preferably 3 to 5000 mm 2 / s, more preferably 5 to 3000 mm 2 / s, and it is preferably liquid at room temperature (25 °C). It should be noted that this kinematic viscosity is the value measured by an Ostwald viscometer at 25 °C.

[0026] As the organohydrogenpolysiloxane satisfying the above requirements, preferably, for example, an organohydrogenpolysiloxane represented by the following average composition formula (4). R 6 e H f SiO (4-e-f) / 2 (4) (In formula (4), R 6 represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, e is a number from 0.7 to 2.2, f is a number from 0.001 to 0.5, provided that e + f is a number satisfying 0.8 to 2.5.)

[0027] In the above formula (4), R 6It is usually an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms and no aliphatic unsaturated bond. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and phenylpropyl; 3,3,3-trifluoropropyl in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine and chlorine, etc. Preferably, it is an alkyl group, an aryl group, or 3,3,3-trifluoropropyl, and more preferably methyl, phenyl, or 3,3,3-trifluoropropyl.

[0028] In the above formula (4), e, f, and e + f are as described above, but e is preferably a number from 0.9 to 2.1, f is a number from 0.002 to 0.2, particularly preferably a number from 0.005 to 0.1, and e + f is preferably a number satisfying 1.0 to 2.3, particularly preferably a number satisfying 1.5 to 2.2.

[0029] The molecular structure of the organohydrogenpolysiloxane represented by the above formula (4) is not particularly limited and can be any of linear, cyclic, branched, three-dimensional network (resin-like), etc. Among them, among the substances in which the number of silicon atoms and the kinematic viscosity in one molecule satisfy the above range, linear substances are particularly preferred.

[0030] Specific examples of the organohydrogenpolysiloxane represented by the above formula (4) include dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends of the molecular chain with dimethylhydrogensiloxy, methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer capped at both ends of the molecular chain with dimethylhydrogensiloxy, dimethylsiloxane-methylhydrogensiloxane copolymer capped at one end of the molecular chain with dimethylhydrogensiloxy and at the other end with trimethylsiloxy, methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer capped at one end of the molecular chain with dimethylhydrogensiloxy and at the other end with trimethylsiloxy, a copolymer containing (CH 3 ) 2 HSiO 1 / 2 units and (CH 3 ) 3 SiO 1 / 2 units and (CH 3 )HSiO 2 / 2 units and SiO 4 / 2 units, and a copolymer containing (CH 3 ) 2 HSiO 1 / 2 units and (CH 3 ) 3 SiO 1 / 2 units and (CH 3 )HSiO2 / 2 Unit and (CH 3 ) 2 SiO 2 / 2 Unit and SiO 4 / 2 Copolymer of units, containing (CH 3 ) 2 HSiO 1 / 2 Unit and (CH 3 )HSiO 2 / 2 Unit and (CH 3 ) 2 SiO 2 / 2 Unit and SiO 4 / 2 Copolymer of units, containing (CH 3 ) 2 HSiO 1 / 2 Unit and SiO 4 / 2 Unit and (CH 3 )HSiO 2 / 2 Unit and (CH 3 ) 2 SiO 2 / 2 Unit and (C 6 H 5 ) 3 SiO 1 / 2 Copolymer of units, containing (CH 3 ) 2 HSiO 1 / 2 Unit and (CH 3 ) 3 SiO 1 / 2 Unit and (C 6 H 5 ) 2 SiO 2 / 2 Unit and (CH 3 )HSiO 2 / 2 Unit and (CH 3 ) 2 SiO 2 / 2 Unit and SiO 4 / 2 Copolymer etc. of units.

[0031] (B) The compounding quantity of the component is such that, with respect to one alkenyl bonded to a silicon atom in the (A) component, the hydrogen atom bonded to a silicon atom in the (B) component becomes 0.1 to 5.0, preferably 0.3 to 3.0, more preferably 0.5 to 2.0. When the hydrogen atom bonded to a silicon atom is less than 0.1, the crosslinking density is too low, voids are likely to be generated during curing, and it is likely to flow out from a given part and the reliability deteriorates. If the hydrogen atom bonded to a silicon atom is more than 5.0, the obtained thermally conductive silicone composition becomes too hard and the reliability deteriorates. (B) component of organohydrogenpolysiloxane can be used alone or in combination of two or more kinds.

[0032] <(C) gallium and / or its alloy> The (C) component of the composition of the present invention is gallium and / or its alloy with a melting point of -20 to 70 °C. This (C) component is a component incorporated to impart good thermal conductivity to the cured product obtained from the composition of the present invention, and the incorporation of this component is a feature of the present invention.

[0033] As described above, the melting point of this (C) component needs to be in the range of -20 to 70 °C. For use in the present invention, substances below -20 °C can physically be used, but substances with a melting point below -20 °C are difficult to obtain and are not preferred from an economic perspective. On the contrary, if the melting point of this (C) component exceeds 70 °C, it cannot be rapidly melted during the composition preparation process, resulting in poor workability. Therefore, as described above, the range of -20 to 70 °C for the melting point of the (C) component is an appropriate range. In particular, the (C) component within the range of -19 to 50 °C is easy to prepare the composition of the present invention, and more preferably within the range of -18 to 40 °C.

[0034] The melting point of metallic gallium is 29.8 °C. In addition, as representative gallium alloys, for example, gallium-indium alloys can be cited; for example, Ga-In (mass ratio = 75.4:24.6, melting point = 15.7 °C), gallium-tin alloys, gallium-tin-zinc alloys; for example, Ga-Sn-Zn (mass ratio = 82:12:6, melting point = 17 °C), gallium-indium-tin alloys; for example, Ga-In-Sn (mass ratio = 68.5:21.5:10, melting point = -19 °C or mass ratio = 62:25:13, melting point = 5.0 °C or mass ratio = 21.5:16.0:62.5, melting point = 10.7 °C), gallium-indium-bismuth-tin alloys; for example, Ga-In-Bi-Sn (mass ratio = 9.4:47.3:24.7:18.6, melting point = 48.0 °C), etc.

[0035] This (C) component can be used alone or in combination of two or more kinds. The liquid or solid particles of gallium and / or its alloys present in the composition of the present invention in the uncured state are substantially spherical in shape, and may also contain amorphous ones. In addition, their average particle diameter is usually 1 to 200 μm, particularly preferably 5 to 150 μm, and more preferably 10 to 100 μm. If the average particle diameter is too small, the viscosity of the composition will become too high, resulting in a lack of ductility and problems in coating workability. On the contrary, if the average particle diameter is too large, the composition will become non-uniform, making it difficult to coat thin films such as heat-generating electronic components. It should be noted that, as described above, since the composition is rapidly stored at low temperature after preparation, the shape, average particle diameter, and thus the dispersion state in the composition can be maintained until the coating process for heat-generating electronic components and the like. It should also be noted that the average particle diameter is calculated by sandwiching the uncured composition between two glass slides and observing it with a VR-3000 manufactured by KEYENCE Co., Ltd. That is, from the images taken by this measuring instrument, 30 particles are randomly selected, the particle diameter of each is measured, and their average value is calculated.

[0036] The inventors of the present invention found that when the component (C) is dispersed in the component (A) with a particle diameter within the above range, the freezing point of the component (C) is lower than the freezing point of the whole (bulk). Electronic components are sometimes exposed to extremely low-temperature environments. From the viewpoint of reliability, the freezing point of the component (C) in the composition of the present invention is preferably -40°C or lower, more preferably -50°C or lower, and further preferably -60°C or lower. It should be noted that the freezing point is defined as the temperature at the maximum peak position of the exothermic curve obtained by cooling the curable organopolysiloxane composition from 25°C to -80°C at a cooling rate of 3°C / minute using a differential scanning calorimeter (DSC). This measurement can be carried out using a differential scanning calorimeter (DSC) model DSC7000X manufactured by Hitachi High-Tech Science Co., Ltd.

[0037] With respect to 100 parts by mass of the above component (A), the compounding amount of the component (C) is 300 to 20,000 parts by mass, particularly preferably 2,000 to 15,000 parts by mass, and further preferably 3,000 to 12,000. If the compounding amount is less than 300 parts by mass, the thermal conductivity becomes low, and in the case of a thick composition, sufficient heat dissipation performance cannot be obtained. If the compounding amount is more than 20,000 parts by mass, it is difficult to form a uniform composition, and in addition, since the viscosity of the composition becomes too high, a composition in the form of a ductile grease-like substance may sometimes not be obtained.

[0038] <(D) Thermal Conductive Filler> In the composition of the present invention, while the component (C) is incorporated, it is also necessary to incorporate a (D) heat conductive filler (excluding the component (C)) which is incorporated in conventionally known heat conductive sheets or heat conductive greases.

[0039] As the component (D), there is no particular limitation as long as it is a heat conductive filler having good thermal conductivity, and all conventionally known heat conductive fillers can be used. Examples thereof include aluminum powder, zinc oxide powder, alumina powder, boron nitride powder, aluminum nitride powder, silicon nitride powder, copper powder, diamond powder, nickel powder, zinc powder, stainless steel powder, carbon powder, etc. In addition, the component (D) can be used alone or in combination of two or more. Particularly, from the viewpoints of ease of availability and economy, zinc oxide powder and alumina powder are particularly preferred.

[0040] The average particle diameter of the component (D) is 0.1 to 30 μm, preferably 1 to 20 μm. If the average particle diameter is too small, the viscosity of the resulting composition becomes too high, resulting in a lack of ductility. On the contrary, if the average particle diameter is too large, it is difficult to obtain a uniform composition. It should be noted that this average particle diameter is the volume average diameter [MV] based on volume measured by MICROTRAC MT3300EX (manufactured by Nikkiso Co., Ltd.).

[0041] If the amount of the component (D) incorporated is less than 10 parts by mass relative to 100 parts by mass of the component (A), gallium and / or its alloy cannot be uniformly dispersed in the (A) or the mixture of the component (A) and the following component (G). If the amount of the component (D) incorporated is greater than 1000 parts by mass, there is a problem that the viscosity of the composition becomes high and a composition in the form of a ductile grease cannot be obtained. Therefore, it can be in the range of 10 to 1000 parts by mass, preferably in the range of 50 to 500 parts by mass.

[0042] <(E) Platinum group metal catalyst> The platinum group metal catalyst as the component (E) of the composition of the present invention is a component (curing catalyst) incorporated for promoting the addition reaction of the alkenyl group in the above-mentioned component (A) and the SiH group in the above-mentioned component (B) to form a three-dimensional network crosslinked cured product from the composition of the present invention.

[0043] As the component (E), all known platinum group metal catalysts used in ordinary hydrosilylation reactions can be used. For example, platinum metal (platinum black), chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound, etc. can be cited. The compounding amount of the component (E) only needs to be an effective amount required for curing the composition of the present invention, and there is no particular limitation. For example, based on the mass of the component (A), it is generally preferably about 0.1 to 500 ppm in terms of platinum atoms.

[0044] <(G-1) surface treatment agent> Preferably, for the following purposes, a polysiloxane represented by the following general formula (1) is compounded as the (G-1) surface treatment agent in the composition of the present invention: to hydrophobize the gallium and / or its alloy of the component (C) during the preparation of the composition, and to improve the wettability of the component (C) and the organopolysiloxane of the component (A), and to make the component (C) into fine particles and uniformly disperse them in the matrix containing the component (A).

[0045] In addition, the (G-1) component also has the effect of improving the surface wettability of the heat conductive filler of the component (D) and making its uniform dispersibility good.

[0046] As the (G-1) component, it is a polysiloxane whose single terminal of the molecular chain is capped with a hydrolyzable group, which is represented by the following general formula (1), and its kinematic viscosity at 25 °C is 10 to 10000 mm 2 / s. It should be noted that this kinematic viscosity is the value measured by an Ostwald viscometer at 25 °C. [Chemical formula 2] (In the formula (1), R 1 is an alkyl group of the same or different types, R 2 is an alkyl group, alkenyl group or acyl group, a is an integer of 5 to 100, and b is an integer of 1 to 3.)

[0047] If the compounding amount of the (G-1) component is 10 parts by mass or more relative to 100 parts by mass of the (A) component, the (C) component and the (D) component will be sufficiently dispersed and become a uniform grease composition. Therefore, it is preferred. However, if it is more than 500 parts by mass, the (A) component will relatively decrease, and thus there will be a problem that the resulting composition is difficult to cure. If it is not cured, it is possible that the grease will shift after being applied to devices such as CPUs, resulting in a significant decrease in performance. Therefore, the compounding amount of the (G-1) component is in the range of 10 to 500 parts by mass, preferably 50 to 300 parts by mass.

[0048] <Other components> In addition to the above components, the following components can also be incorporated into the curable organopolysiloxane composition of the present invention as needed. <(F) Addition reaction controller> The addition reaction controller of the (F) component in the composition of the present invention is an optionally incorporated component. Incorporating this component suppresses the hydrosilylation reaction by the action of the above-mentioned platinum-based catalyst under room temperature conditions, ensuring the pot life (storage period, working life) of the composition of the present invention, so as not to hinder the coating operation on heat-generating electronic components, etc.

[0049] As the (F) component, all known addition reaction controllers used in conventional addition reaction curable silicone compositions can be used. Examples include, for example, acetylene compounds such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol; various nitrogen compounds; organophosphorus compounds; oxime compounds; organic chlorine compounds, etc.

[0050] The blending amount of the (F) component varies depending on the amount of the (E) component used and cannot be generalized. As long as it is an effective amount capable of suppressing the progress of the hydrosilylation reaction, there is no particular limitation. For example, relative to 100 parts by mass of the (A) component, the blending amount of the (F) component can usually be set to about 0.001 to 5 parts by mass. If the blending amount of the (F) component is too small, sufficient pot life cannot be ensured. On the other hand, if the blending amount of the (F) component is too large, the curability of the composition of the present invention decreases. It should be noted that in order to improve the dispersibility of the (F) component in the composition, the (F) component can be diluted with an organic solvent such as toluene, xylene, or isopropyl alcohol and then used as needed.

[0051] In addition, the following alkoxysilanes can be incorporated as the (G-2) component in the composition of the present invention. (G-2) is represented by the following general formula (2): R 3 c R 4 d Si(OR 5 ) 4-c-d (2) (In formula (2), R 3 is independently an alkyl group having 6 to 16 carbon atoms, R 4 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R 5 is independently an alkyl group having 1 to 6 carbon atoms, c is an integer from 1 to 3, d is an integer from 0 to 2, and the sum of c + d is an integer from 1 to 3.)

[0052] As R 3, examples include, for example, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, etc. If the number of carbon atoms is less than 6, the wettability of the above components (C) and (D) cannot be sufficiently improved. If the number of carbon atoms exceeds 16, the silane of this (G-2) component will solidify under normal temperature conditions, so the treatment is inconvenient and the low-temperature characteristics of the obtained composition are reduced.

[0053] In addition, as R in the above general formula (2) 4 , examples include, for example, alkyl groups such as methyl, ethyl, propyl, hexyl, octyl; cycloalkyl groups such as cyclopentyl, cyclohexyl; alkenyl groups such as vinyl, allyl; aryl groups such as phenyl, tolyl; aralkyl groups such as 2-phenylethyl, 2-methyl-2-phenylethyl; halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, 2-(heptadecafluorooctyl)ethyl, p-chlorophenyl. Among them, methyl and ethyl are particularly preferred.

[0054] In addition, as R in the above general formula (2) 5 , examples include, for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl. Among them, methyl and ethyl are particularly preferred.

[0055] Preferred specific examples of this (G-2) component include the following components. C 6 H 13 Si(OCH 3 ) 3 C 10 H 21 Si(OCH 3 ) 3 C 12 H 25 Si(OCH 3 ) 3 C 12 H 25 Si(OC 2 H 5 ) 3 C 10 H 21 (CH 3 )Si(OCH 3 ) 2 C 10 H 21 (C 6 H 5 )Si(OCH 3 ) 2 C 10H 21 (CH 3 )Si(OC 2 H 5 ) 2 C 10 H 21 (CH=CH 2 )Si(OCH 3 ) 2

[0056] It should be noted that the component (G-2) can be used alone as one kind, or two or more kinds can be used in combination. In addition, with respect to 100 parts by mass of the component (A), if the blending amount of the component (G-2) is 0.1 part by mass or more, the viscosity of the composition is likely to be in the desired range. If the blending amount of the component (G-2) is more than 100 parts by mass, the wetting effect will not increase and it is uneconomical. Therefore, it is preferably in the range of 0.1 to 100 parts by mass, and more preferably in the range of 1 to 50 parts by mass.

[0057] In addition, depending on the situation, trifluoropropyltrimethoxysilane as the component (G-3) can be further blended in the composition of the present invention. In addition, with respect to 100 parts by mass of the component (A), if the blending amount of the component (G-3) is 0.1 part by mass or more, the viscosity of the composition is likely to be in the desired range. If the blending amount of the component (G-3) is more than 100 parts by mass, the wetting effect will not increase and it is uneconomical. Therefore, it is preferably in the range of 0.1 to 100 parts by mass, and more preferably in the range of 1 to 50 parts by mass. It should be noted that the component (G-1), the component (G-2), and the component (G-3) can be used alone or in combination.

[0058] <Any component other than the above> Within the range that does not impair the object and effect of the present invention, an organopolysiloxane represented by the following average composition formula (5) can also be blended in the composition of the present invention.

[0059] An organopolysiloxane having a kinematic viscosity of 10 to 100,000 mm 2 / s at 25°C represented by the average composition formula (5), which can be used alone as one kind or two or more kinds can be used in combination. R 7 g SiO (4-g) / 2 (5) (In formula (5), R 7 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms without an aliphatic unsaturated bond, and g is a number from 1.8 to 2.2.)

[0060] The above-mentioned R 7 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms. As R 7 , for example, alkyl groups such as methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl; cyclohexyl groups such as cyclopentyl, cyclohexyl; alkenyl groups such as vinyl, allyl; aryl groups such as phenyl, tolyl; aralkyl groups such as 2-phenylethyl, 2-methyl-2-phenylethyl; halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl, 2-(perfluorobutyl)ethyl, 2-(perfluorooctyl)ethyl, p-chlorophenyl, etc. can be cited.

[0061] In the composition of the present invention, heat resistance improvers such as iron oxide, cerium oxide, etc.; viscosity regulators such as silica; colorants, etc. can also be incorporated.

[0062] <Viscosity of the composition> As described later, when the composition of the present invention is applied to the surface of a heat-generating electronic component and a heat dissipation member is press-fitted thereto, it is cured by heat treatment to form a heat conductive layer. At this time, in order to have good workability, the composition of the present invention needs to be in the form of a grease.

[0063] For example, the composition of the present invention is stored in a syringe and coated on the surface of a heat-generating electronic component such as a CPU from the syringe to form a coating layer, and a heat dissipation member is press-fitted to the coating layer. Therefore, the viscosity of the composition of the present invention is usually preferably 10 to 1000 Pa·s, particularly preferably 30 to 400 Pa·s. If the viscosity is too low, dripping will occur during the coating, which may sometimes cause problems in the operation. On the contrary, if the viscosity is too high, the composition is difficult to be extruded from the syringe, so the efficiency of the coating operation may sometimes deteriorate. It should be noted that this viscosity is a value measured by a helical viscometer PC-ITL (manufactured by MALCOM Co., Ltd.) under the condition of 25°C.

[0064] [Preparation of the composition] The curable organopolysiloxane composition of the present invention can be obtained by a manufacturing method having the following steps, but is not limited to this description: (i) Step, at a temperature in the range of 20 to 120°C and at a temperature above the melting point of the (C) component, knead the (A) component, the (C) component, the (D) component, the (G-1) component as required, and the (G-2) component and (G-3) component when contained, to obtain a uniform mixture (i); (ii) Step, stop kneading the mixture (i), and cool the temperature of the mixture (i) to below the melting point of the (C) component to obtain a mixture (ii); and (iii) A process of adding the component (B), the component (E), the component (F) if any, and other components as appropriate to the mixture (ii), and kneading at a temperature below the melting point of the component (C) to obtain a homogeneous mixture (iii).

[0065] In the manufacturing method, a stirring / kneading machine such as a conditioning mixer or a planetary mixer having a heating unit and a cooling unit as required is used.

[0066] In the step (i), the liquid of gallium and / or its alloy of the component (C) and the heat-conductive filler of the component (D) are uniformly dispersed in a mixed liquid composed of any one or a combination of two or more of the components (A), (G-1), (G-2), and (G-3).

[0067] The temperature reduction operation or the cooling operation in the step (ii) is preferably carried out rapidly. In this step (ii), the component (C) in a liquid particle state or a solid particle state, which is uniformly dispersed in a matrix containing a mixed liquid composed of any one or a combination of two or more of the components (A), (G-1), and (G-2) and (G-3), maintains its average particle size and the dispersed state.

[0068] The step (iii) is also preferably completed in as short a time as possible. At the end time point of this step (iii), the dispersed state of the particles of the component (C) is basically unchanged. Then, after the completion of this step (iii), the generated composition can be housed in a container and rapidly stored in a freezer, a freezing chamber, etc. at a temperature of about -30 to -10 °C, preferably -25 to -15 °C. In addition, a vehicle equipped with a refrigeration device can also be used during its transportation, etc. By storing and transporting under such low-temperature conditions, for example, even after long-term storage, the composition and the dispersed state of the composition of the present invention can be stably maintained.

[0069] [Application in semiconductor devices] When the composition of the present invention is cured, it can be carried out by maintaining at a temperature of 80 to 180 °C for about 30 to 240 minutes. The cured product of the composition of the present invention can be used as a thermally conductive cured product for forming a thermally conductive layer between an exothermic electronic component and a heat dissipation member. In this case, it is a semiconductor device with excellent heat dissipation characteristics when using the composition of the present invention, that is, a semiconductor device having a heat-generating electronic component, a heat dissipation member, and a heat-conductive layer containing a cured product of the composition of the present invention, and a semiconductor device in which the heat-generating electronic component and the heat dissipation member are joined via the heat-conductive layer can be obtained. The storage modulus of the cured product of the composition of the present invention at 25°C is preferably 3000 to 300000 Pa, more preferably 5000 to 200000 Pa, and still more preferably 10000 to 150000 Pa. If the storage modulus is less than 3000 Pa, voids are sometimes likely to occur in the cured product of the composition, and it is likely to flow out from a given part, resulting in poor reliability. In addition, if the storage modulus is greater than 300000 Pa, the cured product of the composition sometimes cannot follow the warping generated when a heat-generating component such as a CPU operates, resulting in failure to obtain the desired heat dissipation characteristics.

[0070] The semiconductor device can be obtained by a manufacturing method having the following steps: (a) Step of coating the surface of the heat-generating electronic component with the composition of the present invention to form a coating layer containing the composition on the surface; (b) Step of press-fitting and fixing the heat dissipation member to the coating layer; and (c) Step of heating the structure obtained after step (b) at 80 to 180°C to cure the coating layer, thereby forming a heat-conductive layer. Refer to Figure 1 , and the semiconductor device and its manufacturing method will be described. It should be noted that the device described in Figure 1 only represents an example of the application of the composition of the present invention in a semiconductor device, and is not intended to limit the semiconductor device related to the present invention to the device described in Figure 1 .

[0071] First, the composition of the present invention in a cryopreserved state is placed at room temperature and thawed naturally to form a grease-like state. Then, the liquid composition of the present invention is stored in a coating tool such as a syringe.

[0072] The composition of the present invention is coated (dispensed) from a syringe, etc. onto a heat-generating electronic component, for example, on the surface of a heat-generating electronic component such as a CPU 2 mounted on the substrate 3 described in Figure 1 to form a curable composition layer (coating layer) 1. In addition, at the same time, in order to fix the heat dissipation member 4, an adhesive 5 is also coated, and on it, the heat dissipation member 4 is press-fitted and fixed to the CPU 2 via the coating layer 1.

[0073] At this time, the thickness of the coating layer 1 sandwiched between the CPU 2 and the heat dissipation member 4 can usually be adjusted to 5 to 100 μm, and particularly preferably to 10 to 70 μm. If the thickness of the coating layer 1 is too thin, peeling is likely to occur and the reliability deteriorates. On the contrary, if the thickness of the coating layer 1 is too thick, the thermal resistance becomes large, and thus a sufficient heat dissipation effect cannot be obtained.

[0074] Next, the device configured as described above is placed in a heating device to cure the coating layer 1 containing the composition of the present invention, thereby forming the heat conductive layer 1. The temperature conditions required for this curing are 80 to 180 °C, and particularly preferably 100 to 150 °C. If the temperature is lower than 80 °C, the curing is insufficient. On the contrary, at a high temperature exceeding 180 °C, the electronic components and the base material may deteriorate.

[0075] During the process of heating up to the temperature conditions for the curing, the liquid particles of gallium and / or its alloy of the component (C) in the composition of the present invention are connected to the above-mentioned component (D), thereby forming a kind of connecting path.

[0076] Furthermore, the liquid particles of the component (C) are also welded to the surfaces of the adjacent CPU 2 and the heat dissipation member 4. Therefore, the CPU 2 and the heat dissipation member 4 are basically made to have an overall continuous heat conductivity via a kind of path connected by the heat conductive filler connecting the liquid particles of the component (C) and the component (D). In addition, the path-like structure is fixed and held in the three-dimensional crosslinked network formed by the addition reaction of the component (A) and the component (B).

[0077] In addition, when operating and using the semiconductor device obtained as described above, in the case of heat-generating electronic components such as the CPU, the surface temperature is usually as high as about 60 to 120 °C. For this heat generation, as described above, the heat conductive layer composed of the cured product of the composition of the present invention exhibits high heat conductivity and plays a significantly excellent role and effect of more excellent heat dissipation characteristics compared with conventional heat conductive sheets and heat conductive greases. Moreover, even if the semiconductor device is continuously operated and used for a long time, since the gallium and / or its alloy of the component (C) forming the path contained in the heat conductive layer is fixed and held in the three-dimensional crosslinked network of the cured product, it does not leak from the heat conductive layer.

[0078] Moreover, the heat conductive layer has adhesiveness and has stable flexibility even when the heat dissipation member is displaced or even during long-term use, and does not peel off from the heat-generating electronic component and the heat dissipation member.

[0079] It should be noted that even if a sheet-like cured product with a desired thickness is prepared in advance from the composition of the present invention and interposed between a heat-generating electronic component and a heat-dissipating member in the same manner as a conventional heat-conductive sheet, the same effect can be obtained. In addition, as components of other devices and the like that require heat conductivity and heat resistance, sheets of the cured product of the composition of the present invention can also be appropriately used. [Examples]

[0080] Hereinafter, examples are given to explain the present invention in more detail, but the present invention is not limited thereto. The components (A) to (G) used in the following examples and comparative examples are shown below. It should be noted that the viscosity is the value measured using a helical viscometer PC-ITL (manufactured by MALCOM Co., Ltd.) at 25 °C, and the kinematic viscosity is the value measured using an Ostwald viscometer at 25 °C.

[0081] (Component (A)): Dimethylpolysiloxane capped with dimethylvinylsilyl groups at both ends having the following viscosity at 25 °C: (A-1-1) Viscosity: 0.1 Pa·s (A-1-2) Viscosity: 1.0 Pa·s (A-2-1) Viscosity: 30 Pa·s (A-2-2) Viscosity: 100 Pa·s

[0082] (Component (B)): (B-1) Organohydrogenpolysiloxane represented by the following structural formula (α / β = 0.35, kinematic viscosity at 25 °C is 113 mm 2 / s) [Chemical formula 3] (In the formula, the arrangement order of the siloxane units in the parentheses is arbitrary.) (B-2) Organohydrogenpolysiloxane represented by the following structural formula (α / β = 0.29, kinematic viscosity at 25 °C is 27 mm 2 / s) [Chemical formula 4] (In the formula, the arrangement order of the siloxane units in the parentheses is arbitrary.)

[0083] (Component (C)): (C-1) Gallium metal [melting point = 29.8 °C] (C-2) Ga-In alloy [mass ratio = 75.4:24.6, melting point = 15.7 °C] (C-3) Ga-In-Sn alloy [mass ratio = 68.5:21.5:10, melting point = -19 °C] (C-4) Ga-In-Sn alloy [mass ratio = 62:25:13, melting point = 5.0 °C]

[0084] (D) Composition: (D-1): Alumina powder [average particle size: 8.2 μm] (D-2): Zinc oxide powder [average particle size: 1.0 μm]

[0085] (E) Composition: (E-1): Solution of platinum-divinyltetramethyldisiloxane complex in dimethylpolysiloxane (both ends capped with dimethylvinylsilyl group, viscosity: 0.6 Pa·s) [platinum atom content: 1 mass%]

[0086] (F) Composition: (F-1): 1-Ethynyl-1-cyclohexanol

[0087] (G) Composition (G-1): Dimethylpolysiloxane with a kinematic viscosity of 32 mm 2 / s and a single end capped with trimethoxysilyl group [Chemical formula 5] (G-2): Organosilane represented by the structural formula C 10 H 21 Si(OCH 3 ) 3 Indicated (G-3): Trifluoropropyltrimethoxysilane It should be noted that in the process of preparing the composition, the so-called "(G) composition" refers to the composition obtained by aggregating (G-1), (G-2) and (G-3) used in each example described in Table 1.

[0088] [Examples 1 to 6, Comparative Examples 1 to 5] [Preparation of Composition] Each component was taken in the composition ratio described in Table 1, and the composition was prepared as follows. The components (A), (C), (D) and (G) were added to a container of a conditioning mixer (manufactured by Thinky Corporation, trade name: Awatori Rentaro) with an internal volume of 250 ml, and the temperature was raised to 70 °C. This temperature was maintained and kneading was carried out for 5 minutes. Then, the kneading was stopped and it was cooled to 15 °C. Next, the components (B), (E) and (F) were added to the mixture of the components (A), (C), (D) and (G), and kneading was carried out at 25 °C until uniform, thereby preparing each composition.

[0089] <Measurement of Viscosity> The absolute viscosity of the composition was measured using a PC-1TL (10 rpm) manufactured by MALCOM Co., Ltd. at 25 °C.

[0090] <Measurement of Particle Size of Component (C)> Two glass slides were used to hold each of the above-obtained compositions, and 30 particles were randomly selected from the images taken by VR-3000 manufactured by Keyence Co., Ltd., and the particle size of each was measured, and the average value thereof was calculated therefrom.

[0091] <Measurement of Freezing Point of Component (C)> Using a differential scanning calorimeter (DSC) model DSC7000X manufactured by Hitachi High-Tech Science Corporation, each of the above-obtained compositions was measured. The freezing point was defined as the temperature at the maximum peak position of the exothermic curve obtained when cooling from 25 °C to -80 °C at 3 °C / minute.

[0092] <Preparation of Solidified Product> Each of the above-obtained compositions was coated on the entire surface of an aluminum plate with a diameter of 1.26 mm and a thickness of 1 mm (hereinafter referred to as "standard aluminum plate"), and another standard aluminum plate was overlapped, and a pressure of about 175.5 kPa (1.80 kgf / cm 2 ) was applied to obtain a three-layer structure. Next, the three-layer structure was heated to 150 °C in an electric furnace and this temperature was maintained for 1 hour to cure each composition, and then it was left to cool to room temperature to prepare a sample for thermal resistance measurement. The thickness of each obtained sample was measured, and the thickness of each cured composition was calculated by subtracting the known thickness of the standard aluminum plate. It should be noted that when measuring the thickness of the above-mentioned samples, a micrometer (Mitutoyo Co., Ltd., model: M820-25VA) was used. The thickness of each cured composition is shown in Table 1.

[0093] <Measurement of Initial Thermal Resistance> Using the above-mentioned samples and a thermal resistance measuring device (manufactured by NETZSCH, model: LFA447), the thermal resistance (mm 2 ·K / W) of each cured composition was measured. The initial measurement results are shown in Tables 1-3. <Measurement of Thermal Resistance after Thermal Shock Test> After measuring the initial thermal resistance, the above-mentioned samples were put into a rapid temperature change type low-temperature thermostat (model SP-61NX-A) manufactured by Kato Co., Ltd., and the conditions of -55°C / 30 minutes and 125°C / 30 minutes were taken as one cycle, and the thermal resistance after 1000 cycles was measured. The measurement results are shown in Table 1.

[0094] <Void Test> 0.2 g of each composition was sandwiched between two glass slides of 5×7 cm, a 1 kg weight was placed on it, and it was left at room temperature for 15 minutes. Then, this weight was removed, and this test piece was taken out after being placed in an oven at 150°C for 1 hour. The cured product sandwiched between the glass slides was observed visually and with a microscope (manufactured by Keyence Co., Ltd., model VR-3200). [Evaluation] · Cracks observed visually: × · Using a microscope, one or more circular voids with a diameter of 1.0 mm or more were observed: × · Through visual observation and microscopic observation, no cracks and circular voids with a diameter of 1.0 mm or more were observed at all: ○

[0095] <Measurement of Storage Modulus> A viscoelasticity measuring device (manufactured by T.A. Instrument Co., Ltd., model ARES-G2) was used, and two parallel plates with a diameter of 2.5 cm were used (the thickness of the curable organopolysiloxane composition was set to 2 mm). For the measurement, first, the temperature was raised from room temperature to 125°C at a rate of 10°C / min, then from 125°C to 150°C at a rate of 2°C / min. After reaching 150°C, the temperature was maintained for 2 hours to completely cure the composition. Then it was cooled to 25°C, and the storage modulus of the cured product of the composition was measured (set frequency: 1.0 Rad / sec, strain (displacement): 1%).

[0096] <Measurement of Thermal Conductivity> Using TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd., the thermal conductivities of the above samples were measured at 25°C.

[0097] <Measurement of Particle Size of Component (D)> The measured particle size of the thermal conductive filler is the cumulative average diameter of volume standard measured by the particle size analyzer MICROTRAC MT3300EX manufactured by Nikkiso Co., Ltd.

[0098] <Application in Semiconductor Devices> 0.2 g of the composition obtained in each of the above Examples 1 to 6 was coated on the surface of a 2 cm × 2 cm CPU to form a coating layer. A heat dissipation member was overlapped on the coating layer and cured, thereby obtaining a semiconductor device in which the CPU and the heat dissipation member were joined via a 10 - 70 μm thick thermal conductive layer. When these devices were assembled into a mainframe computer, a personal computer, etc. and operated, the heating temperature of the CPU was about 100°C, and in any case of the devices, heat conduction and heat dissipation could be stably performed for a long time, and it was possible to prevent performance degradation, breakage, etc. of the CPU caused by overheat accumulation. Therefore, it was confirmed that by using the cured product of the composition of the present invention, the reliability of the semiconductor device could be improved.

[0099] Table 1 * The ratio of the number of hydrogen atoms bonded to silicon atoms in component (B) to one vinyl group bonded to silicon atoms in component (A) is denoted as SiH / Vi.

[0100] It was clear that if the freezing point of component (C) was higher than the desired temperature, it could not withstand the thermal shock test and the thermal resistance deteriorated. Explanation of Reference Numerals

[0101] 1 - Curing Composition Layer (Coating Layer) (Thermal Conductive Layer) 2 - CPU (Central Processing Unit) 3 - Substrate 4 - Heat Dissipation Member 5 - Adhesive

Claims

1. A curable organopolysiloxane composition comprising: (A) An organopolysiloxane which is liquid at 25 °C and has two or more alkenyl groups bonded to silicon atoms in one molecule; (B) An organohydrogenpolysiloxane having hydrogen atoms bonded to silicon atoms; (C) One or more selected from the group consisting of gallium and gallium alloys having a melting point of -20 to 70 °C; (D) A thermally conductive filler having an average particle diameter of 0.1 to 30 μm; and (E) A platinum group metal catalyst, wherein the gallium and / or gallium alloy of (C) is dispersed in the organopolysiloxane in particulate form, whereby the freezing point of the gallium and / or gallium alloy becomes -40 °C or lower.

2. The curable organopolysiloxane composition according to claim 1, comprising the following (A) to (G-1): (A) Organopolysiloxane: 100 parts by mass, which is composed of the following (A-1) and (A-2), and the proportion of (A-1) is 10 to 90% by mass relative to the total of (A-1) and (A-2); (A-1) An organopolysiloxane having a viscosity of 0.01 to 10 Pa·s at 25 °C and having two or more alkenyl groups bonded to silicon atoms in one molecule; (A-2) An organopolysiloxane having a viscosity of 11 to 1000 Pa·s at 25 °C and having two or more alkenyl groups bonded to silicon atoms in one molecule; (B) An organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, and the amount thereof is such that the number of hydrogen atoms bonded to silicon atoms in this component is 0.1 to 5.0 relative to one alkenyl group in the component (A); (C) One or more selected from the group consisting of gallium and gallium alloys having a melting point of -20 to 70 °C: 300 to 20000 parts by mass; (D) Thermally conductive filler: 10 to 1000 parts by mass, having an average particle diameter of 0.1 to 30 μm; (E) Platinum group metal catalyst: 0.1 to 500 ppm in terms of the mass of the platinum group metal relative to the mass of the component (A); and (G-1) An organopolysiloxane represented by the following general formula (1): 10 to 500 parts by mass, [Chemical formula 1] In formula (1), R 1 is an alkyl group of the same or different types, R 2 is an alkyl group, alkenyl group or acyl group, a is an integer from 5 to 100, and b is an integer from 1 to 3.

3. The curable organopolysiloxane composition according to claim 2, further comprising: (G-2) An alkoxysilane compound represented by the following general formula (2) and 0.1 to 100 parts by mass relative to 100 parts by mass of the component (A), R 3 c R 4 d Si(OR 5 ) 4-c-d (2) In formula (2), R 3 is independently an alkyl group having 6 to 16 carbon atoms, R 4 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R 5 is independently an alkyl group having 1 to 6 carbon atoms, c is an integer of 1 to 3, d is an integer of 0 to 2, and the sum of c + d is an integer of 1 to 3.

4. The curable organopolysiloxane composition according to claim 2 or claim 3, which further comprises (G-3) trifluoropropyltrimethoxysilane in an amount of 0.1 to 100 parts by mass relative to 100 parts by mass of the component (A).

5. The curable organopolysiloxane composition according to claim 1, wherein (B) is an organohydrogenpolysiloxane having five or more hydrogen atoms bonded to silicon atoms in the non-terminal part of the molecular chain in one molecule and satisfying the following formula (3), 0.1<α / β (3) in formula (3), α represents the number of hydrogen atoms bonded to silicon atoms in the non-terminal part of the molecular chain, and β represents the total number of silicon atoms in the component (B).

6. The curable organopolysiloxane composition according to claim 1, wherein, component (C) is dispersed in the composition in the form of particles having a particle size of 1 to 200 μm.

7. A thermally conductive silicone grease composition, which comprises the curable organopolysiloxane composition according to claim 1.

8. A cured product, which is a cured product of the curable organopolysiloxane composition according to claim 1.

9. The cured product of the curable organopolysiloxane composition according to claim 8, having a storage modulus of 3000 to 300000 Pa at 25°C.

10. Use of the cured product according to claim 8 as a thermally conductive layer disposed between a heat-generating electronic component and a heat dissipating member.

11. A semiconductor device, which is a semiconductor device having a heat-generating electronic component, a heat dissipating member, and a thermally conductive layer composed of the cured product according to claim 8, wherein, the heat-generating electronic component and the heat dissipating member are joined via the thermally conductive layer.

12. A method for manufacturing a semiconductor device, which is a method for manufacturing the semiconductor device according to claim 11, wherein, it has the following steps: (a) step: coating the surface of the heat-generating electronic component with the curable organopolysiloxane composition according to claim 1 to form a coating layer containing the above composition on the surface; (b) step: press-fixing the heat dissipating member to the coating layer; and (c) step: heating the structure obtained after step (b) at 80 to 180°C to cure the coating layer to form a thermally conductive layer.

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