Thermally conductive curable silicone composition and method for curing same

Abstract

To provide a thermally conductive curable silicone composition that does not need to be stored frozen or refrigerated and does not require a heating process for curing, despite being a curable heat dissipation grease, and a method for curing the composition.　The thermally conductive curable silicone composition contains (A) an organopolysiloxane having a kinematic viscosity at 25°C of 60 to 100,000 mm2 / s and having no alkoxysilyl groups or silanol groups, (B) gallium or an alloy containing gallium having a melting point of -20 to 100°C, and (C) a metal alkoxide and / or a (partial) hydrolysis condensate thereof.

Description

Thermally conductive curable silicone composition and curing method thereof

[0001] The present invention relates to a thermally conductive curable silicone composition and a method for curing the same.

[0002] A common challenge for electronic component packages and power modules is the heat generated during operation and the resulting performance degradation. Various heat dissipation technologies are used to address this issue. In particular, a common technique involves placing a cooling element near the heat-generating part, ensuring close contact between the two, and efficiently removing heat from the cooling element. However, if there is a gap between the heat-generating part and the cooling element, the poor thermal conductivity of air can interfere, reducing heat transfer and preventing the heat-generating part from cooling down sufficiently. To prevent this air interference and improve heat conduction, heat dissipation materials with good thermal conductivity and conformability to the surface of the material, such as thermal grease or thermal sheets, are used.

[0003] For actual thermal management of electronic component packages and power modules, a heat dissipation grease that is thin, compressible, and has excellent penetration into the gap between heat-generating parts and cooling materials is preferable from the viewpoint of heat dissipation performance. Furthermore, by compressing it to a desired thickness and then heat-curing it, it is possible to reduce the leakage of heat dissipation grease (pumping out) caused by expansion and contraction due to the repeated thermal history of heating and cooling of the heat-generating parts, thereby improving the reliability of electronic component packages and power modules. Many addition-curing type heat dissipation greases have been disclosed to date (for example, Patent Document 1). However, most of these have poor shelf life at room temperature and require freezing or refrigeration, which can make product management difficult. In addition, since heating for a certain period of time is required during curing, it leads to a decrease in production efficiency due to the complexity and length of the process, and is also undesirable from the viewpoint of environmental impact due to the heating process. In other words, there is a need for the development of a heat-conductive curable silicone composition that is less prone to heat dissipation grease leakage (pumping out) but does not require freezing or refrigeration or a heating process during curing.

[0004] Japanese Patent Publication No. 2016-053140

[0005] Therefore, the present invention aims to provide a heat-conductive, curable silicone composition that is a curable heat-dissipating grease but does not require freezing or refrigeration or a heating process during curing, as well as a method for curing the composition.

[0006] The inventors of the present invention conducted diligent research to achieve the above objectives and, as a result, discovered that the following thermally conductive curable silicone composition is a curable heat dissipation grease that does not require freezing or refrigeration or a heating process during curing, thus completing the present invention. That is, the present invention provides the following thermally conductive curable silicone composition and a method for curing the same.

[0007] [1] A thermally conductive, curable silicone composition comprising the following components (A), (B), and (C): (A) kinematic viscosity at 25°C is 60 to 100,000 mm² 2 (B) Organopolysiloxanes that are 1 / s and do not have either an alkoxysilyl group or a silanol group: an amount of 1.0 to 80% by mass of the whole composition (A) Gallium or gallium-containing alloys with a melting point of -20 to 100°C: an amount of 10 to 98% by mass of the whole composition (C) Metal alkoxides and / or their (partial) hydrolysis condensates represented by the following general formula (1): an amount of 0.01 to 10% by mass of the whole composition (In formula (1), M is titanium or zirconium, and R 1 R independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have substituents and does not have an aliphatic unsaturated bond, and each R 1 (These may be the same or different.) [2] The thermally conductive curable silicone composition according to [1], further comprising as component (D) at least one thermally conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides and allotropes of carbon, excluding component (C), in an amount of 1 to 20% by mass of the entire composition. [3] The thermally conductive curable silicone composition according to [1] or [2], further comprising as component (E) an organosilane represented by the following general formula (2) and / or a (partial) hydrolyzed condensate thereof, in an amount of 0.01 to 10% by mass of the entire composition. (In formula (2), R 2 R is an independent unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 3 (wherein a is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is a number from 1 to 3.) [4] A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface hardening reaction to proceed by exposing the thermally conductive curable silicone composition described in [1] to air at 0 to 50°C. [5] A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface hardening reaction to proceed by exposing the thermally conductive curable silicone composition described in [2] to air at 0 to 50°C. [6] A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface hardening reaction to proceed by exposing the thermally conductive curable silicone composition described in [3] to air at 0 to 50°C.

[0008] The thermally conductive, curable silicone composition of the present invention is a curable heat-dissipating grease that does not require freezing or refrigeration, nor does it require a heating process for curing. As a result, product management is easy, production efficiency can be improved by simplifying and shortening the process, and it is also preferable from the viewpoint of environmental impact because it does not require a heating process. The thermally conductive, curable silicone composition of the present invention can be suitably used in electronic component packages and power modules, and can also accommodate expansion and contraction due to repeated heating and cooling of heat-generating parts over a long period of time.

[0009] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0010] [Component (A)] Component (A) has a kinematic viscosity of 60 to 100,000 mm at 25°C. 2It is an organopolysiloxane that has a viscosity of / s and has neither an alkoxysilyl group nor a silanol group. As the organic group bonded to the silicon atom of the organopolysiloxane, it is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms, excluding alkoxysilyl groups and silanol groups. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc.; aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, etc.; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, etc.; or those in which a part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, cyano group, hydroxyl group, etc., for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl group and other hindered phenol-containing groups. Particularly, a methyl group, a phenyl group, a decyl group, and a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl group are preferred.

[0011] The organopolysiloxane of component (A) has a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s, preferably 100 to 30,000 mm 2 / s. When the kinematic viscosity is less than 60 mm 2 / s, the physical properties of the thermally conductive curable silicone composition of the present invention deteriorate, and when it exceeds 100,000 mm 2 / s, the handleability of the silicone composition may be poor. In the present invention, the kinematic viscosity is the value at 25°C measured by an Ubbelohde type Ostwald viscometer (hereinafter the same).

[0012] The organopolysiloxane of component (A) is not particularly limited in its molecular structure as long as it has the above properties, and examples include a linear structure, a branched structure, a partially branched structure, or a linear structure having a cyclic structure. Particularly preferred is a linear structure in which the main chain consists of repeating diorganosiloxane units and both ends of the molecular chain are sealed with triorganosiloxy groups. An organopolysiloxane having a linear structure may also have a partially branched structure or a cyclic structure.

[0013] The amount of component (A) is 1.0 to 80% by mass of the total thermally conductive silicone composition of the present invention, preferably 1.7 to 20% by mass, and more preferably 1.8 to 10% by mass. When the amount of component (A) is in the range of 1.0 to 80% by mass, the thermally conductive curable silicone composition of the present invention will have sufficient thermal conductivity, appropriate viscosity, and excellent handling properties. The organopolysiloxane of component (A) can be used alone or in combination of two or more types.

[0014] [Component (B)] Component (B) is gallium or a gallium-containing alloy having a melting point of -20 to 100°C, with gallium or a gallium-containing alloy having a melting point of -20 to 50°C being particularly preferred. Components with a melting point below -20°C are undesirable because it is difficult to manufacture the alloy, and components with a melting point above 100°C do not melt quickly during the composition preparation process, resulting in poor workability and the possibility of precipitation and non-uniformity during manufacturing.

[0015] The melting point of metallic gallium is 29.8°C. Representative gallium alloys having melting points within the above range include, for example, gallium-indium alloys; e.g., Ga-In (mass ratio = 75.4:24.6, melting point = 15.7°C), gallium-tin-zinc alloys; e.g., Ga-Sn-Zn (mass ratio = 82:12:6, melting point = 17°C), gallium-indium-tin alloys; e.g., Ga-In-Sn (mass ratio = 21.5:16.0:62.5, melting point = 10.7°C or mass ratio = 68.5:21.5:10, melting point = -19°C), and gallium-indium-bismuth-tin alloys; e.g., Ga-In-Bi-Sn (mass ratio = 9.4:47.3:24.7:18.6, melting point = 48.0°C).

[0016] This (B) component can be used alone or in combination of two or more types. The shape of the liquid or solid fine particles of gallium or its alloy present in the composition of the present invention is usually spherical, but amorphous particles may also be included. Furthermore, the average particle size is usually preferably 0.1 to 200 μm, and particularly preferably 10 to 100 μm. If the average particle size is 0.1 μm or more, the viscosity of the composition will not become too high, and it will have excellent spreadability, resulting in excellent coating workability. If it is 200 μm or less, the possibility of separation and sedimentation is low. Furthermore, the dispersion state of the fine particles, which is the shape and average particle size, is preferably maintained even when stored at room temperature because the composition of the present invention has an appropriate viscosity. The particle size of this (B) component can be measured by direct observation with an optical microscope, for example, with a VR-3200 microscope from Keyence Corporation. That is, the average particle size can be calculated by sandwiching the composition of the present invention between two glass slides and directly measuring the diameter of the particles with a microscope.

[0017] The amount of component (B) is 10 to 98% by mass of the total thermally conductive curable silicone composition of the present invention, preferably 40 to 95% by mass, more preferably 70 to 92% by mass, and even more preferably 75 to 90% by mass. If the amount is greater than 98% by mass, it becomes difficult to finish the silicone composition uniformly, and if it is less than 10% by mass, the thermal conductivity may be poor.

[0018] [Component (C)] Component (C) is a metal alkoxide and / or a (partial) hydrolysis condensate thereof, and is incorporated as a curing agent for a thermally conductive curable silicone composition. Component (C) is preferably a metal alkoxide and / or a (partial) hydrolysis condensate thereof represented by the following general formula (1). (In formula (1), M is titanium or zirconium, and R 1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and which does not have an aliphatic unsaturated bond, and 4 R 1 They may be the same or different.

[0019] In the above formula (1), R 1 This is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms (without an aliphatic unsaturated bond) which may have a hydrogen atom or substituents, preferably a monovalent saturated aliphatic hydrocarbon group which may have substituents, preferably a monovalent aromatic hydrocarbon group which may have substituents, and more preferably a monovalent saturated aliphatic hydrocarbon group which may have substituents.

[0020] Examples of monovalent saturated aliphatic hydrocarbon groups that may have substituents include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; branched alkyl groups such as isopropyl, isobutyl, tert-butyl, isopentyl, and neopentyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl groups; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, and 3-bromopropyl groups. The number of carbon atoms is 1 to 10, preferably 1 to 8, and more preferably 1 to 6.

[0021] Examples of monovalent aromatic hydrocarbon groups that may have substituents include aryl groups such as phenyl groups and tolyl groups, aralkyl groups such as benzyl groups and 2-phenylethyl groups, halogen-substituted aryl groups such as α,α,α-trifluorotolyl groups, and halogen-substituted aralkyl groups such as chlorobenzyl groups. The number of carbon atoms is preferably 6 to 10, more preferably 6 to 8, and even more preferably 6.

[0022] In the above formula (1), R 1 Among these, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, and octyl group are preferred, more preferably propyl group, isopropyl group, butyl group, and tert-butyl group, and particularly preferably isopropyl group and tert-butyl group.

[0023] The amount of component (C) is 0.01 to 10% by mass of the total thermally conductive curable silicone composition of the present invention, preferably 0.05 to 5% by mass, and more preferably 0.1 to 1% by mass. When the amount of component (C) is in the range of 0.01 to 10% by mass, the curing effect is sufficiently obtained and it is economical. Furthermore, it has sufficient storage properties at 25°C.

[0024] In addition to the above components (A) to (C), the thermally conductive curable silicone composition of the present invention may optionally contain the following further components.

[0025] [Component (D)] Component (D) is at least one thermally conductive filler other than gallium or a gallium-containing alloy of component (C), selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon. Examples include aluminum, silver, copper, metallic silicon, zinc oxide, magnesium oxide, aluminum oxide (alumina), silicon dioxide, cerium oxide, iron oxide, aluminum hydroxide, cerium hydroxide, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, carbon nanotubes, and graphene. These can be used individually or in appropriate combinations of two or more.

[0026] The average particle size of component (D) is preferably in the range of 0.01 to 300 μm, more preferably in the range of 0.05 to 100 μm, and even more preferably in the range of 0.1 to 50 μm. The average particle size can be determined, for example, as the volume-based average value (median diameter) in particle size distribution measurement by laser diffraction. The shape of component (D) is not particularly limited and can be spherical, irregularly shaped, needle-shaped, etc.

[0027] The amount of component (D) is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass, relative to the total thermally conductive curable silicone composition of the present invention.

[0028] [Component (E)] Component (E) is an organosilane and / or a (partial) hydrolysis condensate thereof represented by the following general formula (2). This component (E) is used to treat the surface of the thermally conductive filler and plays a role in assisting in the high-filling of component (D). (In formula (2), R 2 R is an independent unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 3 (where a is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is a number from 1 to 3.)

[0029] In the above general formula (2), R 2 Examples of such groups include monovalent hydrocarbon groups such as alkyl groups, cycloalkyl groups, and alkenyl groups. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl and allyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as 2-phenylethyl and 2-methyl-2-phenylethyl groups; and halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl, 2-(perfluorobutyl)ethyl, 2-(perfluorooctyl)ethyl, and p-chlorophenyl groups. a is 1, 2, or 3, but is particularly preferably 1. In the above general formula (2), R 3 Examples of such groups include hydrogen atoms or alkyl groups having 1 to 6 carbon atoms. Examples of such alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, etc., of which methyl group or ethyl group is preferred, and methyl group is more preferred.

[0030] The amount of component (E) is preferably 0.01 to 10% by mass, and more preferably 0.05 to 5% by mass, relative to the total composition. Within this range, the thermally conductive curable silicone composition can be made to an appropriate viscosity range. Component (E) may be used alone or in combination of two or more types.

[0031] [Other Components] The thermally conductive curable silicone composition of the present invention may contain non-reactive organo(poly)siloxanes such as methylpolysiloxane to adjust the strength and viscosity of the silicone composition. Furthermore, the thermally conductive curable silicone composition of the present invention may contain hydrolyzable organopolysiloxanes, various modified silicones, and hydrolyzable organosilanes for the purpose of imparting tackiness to the silicone composition. Furthermore, solvents may be added to adjust the viscosity of the silicone composition. Furthermore, conventionally known antioxidants such as 2,6-di-tert-butyl-4-methylphenol may be added as needed to prevent deterioration of the silicone composition. Furthermore, dyes, pigments, flame retardants, settling inhibitors, and thixotropic enhancers may be added as needed. The amount of the above other components added is preferably 0.1 to 10% by mass, and more preferably 1.0 to 5% by mass.

[0032] [Process for Producing Thermally Conductive Curable Silicone Composition] The method for producing the thermally conductive curable silicone composition in the present invention will be described. The method for producing the thermally conductive curable silicone composition in the present invention is not particularly limited, but the above components (A) to (C), and, if necessary, in addition thereto, component (D), component (E), and / or other components can be mixed to produce a thermally conductive curable silicone composition. Specifically, the above components (A) to (C), and, if necessary, in addition thereto, component (D), component (E), and / or other components can be mixed, for example, using a mixer such as a trimix, a twin mix, a planetary mixer (all are registered trademarks of mixers manufactured by Inoue Manufacturing Co., Ltd.), an ultra mixer (a registered trademark of a mixer manufactured by Mizuho Industries Co., Ltd.), a high vis mixer (a registered trademark of a mixer manufactured by Primix Corporation), etc., at 25°C for usually 3 minutes to 24 hours, preferably 5 minutes to 12 hours, more preferably 10 minutes to 6 hours. Further, degassing may be performed during mixing, or mixing may be performed while heating in the range of 40 to 200°C. In the present invention, it is preferable from the viewpoint that the thermally conductive curable silicone composition exhibits good thermal conductivity and appropriate viscosity to mix components (A) and (B) in advance at 25 to 200°C and then mix component (C) at 25°C.

[0033] The thermally conductive curable silicone composition of the present invention preferably has a viscosity measured at 25°C of 10 to 1,000 Pa·s, more preferably 20 to 500 Pa·s, and even more preferably 50 to 300 Pa·s. If the viscosity is in the range of 10 to 1,000 Pa·s, the thermally conductive curable silicone composition of the present invention is easy to maintain its shape, the thermally conductive filler becomes uniform in the silicone composition, and discharge and coating are also easy, resulting in excellent workability. The viscosity can be obtained by adjusting the blending amounts of the above-described respective components. In the present invention, the viscosity is a value measured at 25°C using a Malcolm viscometer (type PC-1T) for the absolute viscosity of the thermally conductive curable silicone composition (10 rpm with rotor A, shear rate 6 [1 / s]).

[0034] The curing method of the thermally conductive curable silicone composition of the present invention is not particularly limited, but the curing temperature is 0 to 100 ° C, preferably 0 to 50 ° C, and the curing time is 4 to 300 hours, preferably 24 to 200 hours.

[0035] In addition, the thermally conductive curable silicone composition of the present invention usually has a thermal conductivity of 0.5 to 100 W / m·K, but in order to exhibit excellent heat dissipation performance when mounted on an electronic component package or a power module, it preferably has a thermal conductivity of 2.5 W / m·K or more. In the present invention, the thermal conductivity is a value measured by wrapping each thermally conductive curable silicone composition with kitchen wrap and using a TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd.

[0036] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto. The kinematic viscosity is the value at 25 ° C measured by an Ubbelohde-type Ostwald viscometer.

[0037] [Component (A)] A-1: Dimethylpolysiloxane blocked at both ends with trimethylsilyl groups and having a kinematic viscosity at 25 ° C of 1,000 mm 2 / s A-2: Dimethylpolysiloxane blocked at both ends with trimethylsilyl groups and having a kinematic viscosity at 25 ° C of 2,000 mm 2 / s A-3: Polysiloxane represented by the following formula (3) and having a kinematic viscosity at 25 ° C of 500 mm 2 / s

[0038] [Component (B)] B-1: Metal gallium (melting point = 29.8 ° C) B-2: Ga-In-Sn (mass ratio = 68.5:21.5:10, melting point = -19 ° C)

[0039] [Component (C)] C-1: Tetra tert-butyl titanate represented by the following formula (4) C-2: Tetraisopropyl titanate represented by the following formula (5) C-3: Normal propyl zirconate represented by the following formula (6)

[0040] [Component (D)] D-1: Irregularly shaped zinc oxide powder with an average particle size of 0.4 μm

[0041] [Component (E)] E-1: Organosilane represented by the following formula (7) E-2: Organosilane represented by the following formula (8)

[0042] [Examples 1-8, Comparative Examples 1-5] <Preparation of Thermally Conductive Curable Silicone Compositions> Thermally conductive curable silicone compositions were prepared by combining components (A) to (E) in the amounts shown in Tables 1 and 2 below, using the method described below. Components (A), (B), (D), and (E) were added to Hibismix 2P-03 (manufactured by Primix Corporation) and mixed at 40°C for 1.5 hours. After mixing, the mixture was cooled to below 30°C, and component (C) was added and mixed until uniform to prepare a thermally conductive curable silicone composition.

[0043] For each thermally conductive curable silicone composition obtained by the above method, viscosity and thermal conductivity were measured according to the following method, and pumping-out resistance was evaluated. The results are shown in Tables 1 and 2.

[0044] [Viscosity] The absolute viscosity of each thermally conductive curable silicone composition was measured at 25°C using a Malcolm viscometer (Type PC-1T) (rotor A at 10 rpm, shear rate 6 [1 / s]).

[0045] [Thermal Conductivity] Each thermally conductive curable silicone composition was wrapped in kitchen wrap, and its thermal conductivity was measured using a TPS-2500S manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0046] [Pumping-out Resistance] 0.1 ml of each composition was sandwiched between two glass plates with a 0.1 mm spacer in between, compressed using two 1.8 kgf (17.65 N) clips, and cured at 25°C / 50 RH% for one week. This was then placed horizontally in a thermal shock tester that repeatedly cycled between -40°C / 30 min and 125°C / 30 min, and removed after 1,000 cycles. This thermal history caused the composition to repeatedly expand and contract. The presence or absence of flow out of the silicone composition from its initial position, i.e., pumping-out, resulting from this was evaluated.

[0047]

[0048]

[0049] From the evaluation results in Tables 1 and 2, it was found that the thermally conductive curable silicone compositions of Examples 1 to 8 yield cured products of highly thermally conductive silicone compositions with excellent resistance to pumping out. On the other hand, the silicone compositions of Comparative Examples 1 to 2, which do not contain component (C), were found to have poor resistance to pumping out. Furthermore, the silicone compositions of Comparative Examples 3 to 5, which contain a small amount of component (C), were also found to have poor resistance to pumping out. Therefore, the thermally conductive curable silicone compositions of the present invention do not require freezing or refrigeration for storage or a heating process during curing. As a result, product management is easy, production efficiency can be improved by simplifying and shortening the process, and the environmental impact is also small because no heating process is required. As a result, it can be suitably used for electronic component packages and power modules with large warping, and can also follow the expansion and contraction caused by the thermal history of repeated heating and cooling of the heating part over a long period of time.

Claims

1. A thermally conductive, curable silicone composition comprising the following components (A), (B), and (C): (A) kinematic viscosity at 25°C is 60 to 100,000 mm². 2 (B) Organopolysiloxanes that are 1 / s and do not have either an alkoxysilyl group or a silanol group: an amount of 1.0 to 80% by mass of the whole composition (A) Gallium or gallium-containing alloys with a melting point of -20 to 100°C: an amount of 10 to 98% by mass of the whole composition (C) Metal alkoxides and / or their (partial) hydrolysis condensates represented by the following general formula (1): an amount of 0.01 to 10% by mass of the whole composition (In formula (1), M is titanium or zirconium, and R 1 R independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have substituents and does not have an aliphatic unsaturated bond, and each R 1 They may be the same or different.

2. The thermally conductive curable silicone composition according to claim 1, further comprising, as component (D), at least one thermally conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon, excluding component (C), in an amount of 1 to 20% by mass relative to the entire composition.

3. Furthermore, the thermally conductive curable silicone composition according to claim 1 or claim 2, comprising as component (E), an organosilane and / or a (partial) hydrolyzed condensate thereof represented by the following general formula (2): in an amount of 0.01 to 10% by mass relative to the whole composition. (In formula (2), R 2 R is an independent unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 3 (where a is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is a number from 1 to 3.) 4. A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface curing reaction to proceed by exposing the thermally conductive curable silicone composition described in claim 1 to air at 0 to 50°C.

5. A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface curing reaction to proceed by exposing the thermally conductive curable silicone composition described in claim 2 to air at 0 to 50°C.

6. A method for curing a thermally conductive curable silicone composition, comprising the step of allowing a surface curing reaction to proceed by exposing the thermally conductive curable silicone composition described in claim 3 to air at 0 to 50°C.

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