JP5729882B2 - Thermally conductive silicone grease composition - Google Patents

Description

  The present invention relates to a thermally conductive silicone grease composition having excellent scratch resistance.

  Generally, electric and electronic parts generate heat during use. For this reason, heat removal is required to properly operate the electrical component, and various heat conductive materials for heat removal have been proposed. This heat conductive material is roughly classified into two types, and a sheet-like material (heat dissipating sheet) that is easy to handle and a paste material (heat dissipating grease) are known.

  The heat dissipation sheet is easy to handle and has the merit of excellent thermal stability, but the contact thermal resistance is increased in nature. Therefore, heat dissipation performance is generally superior to heat dissipation grease. Further, the heat dissipating grease has an advantage that it can be applied to mass production if a coating device or the like is used. Various grease-like silicone compositions based on silicone oil are known as the heat release grease. For example, Patent Document 1 describes a heat dissipating grease based on silicone oil and using zinc oxide or alumina powder as a thickener. Patent Document 2 describes a silicone grease composition having excellent thermal conductivity, containing two types of aluminum nitride powders having different average particle diameters. Patent Document 3 describes a thermally conductive silicone composition that can further reduce the thickness of the heat dissipation layer, has low thermal resistivity, and has excellent heat dissipation efficiency. Patent Document 4 describes a silicone grease composition having excellent thermal conductivity with a thermal conductivity of 5 W / mK or more and good workability. Patent Document 5 describes a thermally conductive silicone composition that is highly filled with a thermally conductive filler and has good fluidity and workability.

  However, since the heat dissipating grease is generally applied thinly on the heat generating element, it cannot absorb the stress received from the base material and may damage the heat generating element such as a silicon die. In particular, alumina powder, which is commonly used to improve the heat dissipation performance of thermally conductive silicone grease, and aluminum nitride powder, which has high thermal conductivity, are both hard and easily damage elements such as silicon dies. . Therefore, it is required to suppress damage due to the heat dissipating grease. However, all of the thermally conductive silicone compositions described in Patent Documents 1 to 5 are intended to improve heat dissipation performance, oil separation countermeasures, pump-out resistance, etc., and refer to scratch resistance. Absent.

  Patent Document 6 discloses that a thermally conductive composition that does not damage the silicon surface can be provided by combining a liquid organopolysiloxane and a metal aluminum powder formed by combining a fine powder and a coarse powder with a fixed particle size. It is described.

Japanese Patent No. 3195277 JP 2000-169873 A JP 2006-143978 A JP 2004-210856 A JP 2005-162975 A Japanese Patent No. 3948642

  However, although the composition described in Patent Document 6 has a scratch-preventing property, there is a problem in that the place where it can be used is limited because the aluminum powder is conductive. Therefore, in view of the above circumstances, an object of the present invention is to provide a heat conductive silicone composition that provides a heat dissipating grease that is insulating and has excellent scratch resistance.

  The present inventors diligently studied to achieve the above object, and focused on using a soft calcium carbonate powder as a heat conductive filler of a silicone grease composition. As a heat conductive filler, calcium carbonate powder was used. Or a silicone composition containing only a mixed powder of calcium carbonate powder and aluminum hydroxide powder is insulative, has a relatively high heat dissipation performance, and can provide a heat dissipating grease with excellent scratch resistance. The present invention has been found and the present invention has been made.

That is, the present invention
(A) A silicone composition comprising 100 parts by mass of an organopolysiloxane having a kinematic viscosity at 25 ° C. of 10 to 500,000 mm ² / s, and (B) 100 to 1300 parts by mass of a thermally conductive filler,
The thermally conductive filler is
(A) 100 to 1000 parts by weight of calcium carbonate powder having an average particle size 0.1 to 100 [mu] m, and (b) characterized in that it consists of from 100 to 1000 parts by weight of aluminum hydroxide powder having an average particle diameter of 0.1 to 100 [mu] m And a grease comprising the silicone composition.

  The silicone composition of the present invention can provide a thermally conductive silicone grease, particularly a heat-dissipating grease, which is insulative, has high heat dissipation performance, and has excellent scratch resistance.

(B) Thermally conductive filler As described above, the present invention is such that (B) the thermally conductive filler is (a) only calcium carbonate powder, or (a) a mixed powder of calcium carbonate powder and (b) aluminum hydroxide powder. It is characterized by comprising. In particular, the silicone composition of the present invention is characterized by containing a specific amount of calcium carbonate powder having a specific particle size as a thermally conductive filler. The silicone composition of the present invention contains no thermally conductive filler other than calcium carbonate powder and aluminum hydroxide powder, such as aluminum powder, zinc oxide, alumina powder, boron nitride, and aluminum nitride powder. Thereby, it is possible to provide a thermally conductive silicone grease that is insulative, has a relatively high heat dissipation property, and has excellent scratch resistance. Hereinafter, (a) calcium carbonate powder and (b) aluminum hydroxide powder will be described in detail.

(A) Calcium carbonate powder In this invention, a calcium carbonate powder has an average particle diameter of 0.1-100 micrometers, Preferably it is 1.0-50 micrometers. If the average particle size of the calcium carbonate powder is smaller than the lower limit value, the resulting silicone composition has an excessively high viscosity, which makes the composition difficult to handle. If the average particle size of the calcium carbonate powder is larger than the above upper limit value, the resulting grease becomes non-uniform, which is not preferable. In the present invention, the average particle diameter is a volume average particle diameter, and can be measured with a laser diffraction / scattering particle size distribution measuring instrument Microtrac MT3300EX (hereinafter the same).

As the calcium carbonate powder, one having one kind of average particle diameter may be used alone, or ones having different average particle diameters may be mixed and used. In particular, when a fine calcium carbonate powder having a small average particle size (for example, an average particle size of 0.1 μm or more and less than 5 μm) is used, a coarse particle having a large average particle size (for example, an average particle size of 5 μm or more and 100 μm or less). It is preferable to combine with granular calcium carbonate powder. There is a possibility that a good grease cannot be obtained only with fine calcium carbonate powder. The mixing ratio of the fine calcium carbonate powder and the coarse calcium carbonate powder is not particularly limited, but the ratio of the mass of the coarse calcium carbonate powder to the mass of the fine calcium carbonate powder is 0.8 to 5, particularly 1 to 4. Is preferred.

  The compounding quantity of the calcium carbonate powder in a silicone composition is 100-1000 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 200-700 mass parts. If the blending amount of the calcium carbonate powder is smaller than the above lower limit value, it is not preferable because sufficient thermal conductivity cannot be obtained. Moreover, since the viscosity of a silicone composition will become high too much when the compounding quantity of a calcium carbonate powder is larger than the said upper limit, it is unpreferable.

  The calcium carbonate powder in this invention will not be restrict | limited especially if it has the said average particle diameter, What is necessary is just to be selected from well-known calcium carbonate powder. Examples thereof include dry pulverized (or heavy) calcium carbonate powder, precipitated (or light) calcium carbonate powder, and the like. Calcium carbonate powder may be used alone or in combination of two or more.

(B) Aluminum hydroxide powder The silicone composition of the present invention can contain an aluminum hydroxide powder in addition to the calcium carbonate powder as a thermally conductive filler. The aluminum hydroxide powder has an average particle size of 0.1 to 100 μm, preferably 1.0 to 50 μm. If the average particle diameter of the aluminum hydroxide powder is smaller than the lower limit, the viscosity of the resulting grease composition becomes too high, and the composition becomes difficult to handle. Moreover, when the average particle diameter of the aluminum hydroxide powder is larger than the above upper limit value, the obtained grease becomes ununiform, which is not preferable. The aluminum hydroxide powder in the present invention is not particularly limited as long as it has the above average particle diameter, and may be selected from known aluminum hydroxide powders. One kind of aluminum hydroxide powder may be used alone, or two or more kinds may be mixed and used.

  The compounding quantity of the aluminum hydroxide powder in a silicone composition is 0-1000 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 100-700 mass parts. If the blending amount of the aluminum hydroxide powder is larger than the above upper limit, the viscosity of the silicone composition becomes too high, which is not preferable.

  When the thermally conductive filler is a mixed powder of (a) calcium carbonate powder and (b) aluminum hydroxide powder, the mixing ratio of (a) calcium carbonate powder and (b) aluminum hydroxide powder is particularly limited However, the amount of each powder with respect to 100 parts by mass of component (A) satisfies the above-mentioned range, and the blending amount of the thermally conductive filler is preferably 100 to 1300 parts by mass with respect to 100 parts by mass of component (A), preferably Is blended in an amount of 200 to 1000 parts by mass, more preferably 300 to 900 parts by mass. If the blending amount of the heat conductive filler is less than the above lower limit value, it is not preferable because sufficient heat conductivity cannot be obtained. On the other hand, when the blending amount of the heat conductive filler exceeds the above upper limit, the viscosity of the silicone composition becomes too high, and there is a possibility that a good grease state cannot be obtained. In particular, when a fine powder having a small average particle diameter (for example, an average particle diameter of 0.1 μm or more and less than 5 μm) is used, a coarse powder having a large average particle diameter (for example, an average particle diameter of 5 μm or more and 100 μm or less) It is preferable to combine them. The mixing ratio of the fine powder and the coarse powder is not particularly limited, but the ratio of the mass of the coarse powder to the mass of the fine powder is preferably 0.8 to 5, particularly 1 to 4.

  The above (a) calcium carbonate powder and (b) aluminum hydroxide powder (hereinafter referred to as heat conductive filler) are hydrophobized with organosilane, organosilazane, organopolysiloxane, organic fluorine compound, etc. as necessary. It may be. In particular, it is preferable that it is hydrophobized with (C) organopolysiloxane described later. The conventionally known method may be used for the hydrophobizing treatment of the heat conductive filler. For example, a thermally conductive filler and the above compound are mixed with Trimix, Twinmix, Planetary Mixer (all registered trademarks of the mixer manufactured by Inoue Seisakusho Co., Ltd.), and registered trademark of the mixer manufactured by Mizuho Industry Co., Ltd. ), Hibis Disper Mix (registered trademark of a special mixer manufactured by Tokushu Kika Kogyo Co., Ltd.) and the like. You may perform the said mixing, heating at the temperature which exists in the range of 50-150 degreeC if necessary. For mixing, a solvent such as toluene, xylene, petroleum ether, mineral spirit, isoparaffin, isopropyl alcohol, or ethanol may be used. When using a solvent, it is preferable to remove the solvent using a vacuum apparatus or the like after mixing.

  Moreover, it is also possible to use (A) organopolysiloxane, which will be described later, as a diluent solvent for the surface hydrophobization treatment of the thermally conductive filler. For example, the above-mentioned compound for hydrophobizing treatment is mixed with (A) organopolysiloxane in advance, and the thermally conductive filler is added and mixed therewith, so that the hydrophobic treatment of the thermally conductive filler and this The inventive silicone composition can be prepared simultaneously. Compositions made by this method are also within the scope of the present invention.

(A) The liquid organopolysiloxane (A) component is an organopolysiloxane having a kinematic viscosity at 25 ° C. of 10 to 500,000 mm ² / s, preferably 30 to 10,000 mm ² / s. If the kinematic viscosity of the organopolysiloxane is lower than the lower limit, oil bleed tends to occur when grease is used. Moreover, since the extensibility of a silicone composition will become scarce when larger than the said upper limit, it is unpreferable. In the present invention, the kinematic viscosity of the organopolysiloxane is a value of 25 ° C. measured with an Ostwald viscometer.

  In the present invention, the (A) organopolysiloxane may have any of the above kinematic viscosities, and conventionally known liquid organopolysiloxanes can be used. The molecular structure of the organopolysiloxane is not particularly limited, and examples thereof include straight chain, branched chain, cyclic, and straight chain having a partially branched or cyclic structure. In particular, the main chain is preferably composed of a repeating diorganosiloxane unit and has a linear structure in which both ends of the molecular chain are blocked with a triorganosiloxy group. The organopolysiloxane may be used alone or in combination of two or more.

The organopolysiloxane can be represented, for example, by the following average composition formula (1).

R ¹ _a SiO _{(4-a) / 2} (1)

In the above formula (1), R ^{1 s} are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 14 carbon atoms, which may have an unsaturated bond. Examples of the monovalent hydrocarbon group include methyl groups, ethyl groups, propyl groups, hexyl groups, octyl groups, decyl groups, dodecyl groups, tetradecyl groups, hexadecyl groups, octadecyl groups and other alkyl groups, cyclopentyl groups, cyclohexyl groups, and the like. Cycloalkyl groups such as groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and tolyl groups, aralkyl groups such as 2-phenylethyl groups and 2-methyl-2-phenylethyl groups, Or, a part or all of hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, cyano groups, etc., for example, 3,3,3-trifluoropropyl group, 2- (perfluoro Butyl) ethyl group, 2- (perfluorooctyl) ethyl group, p-chlorophenyl group and the like.

  In the above formula (1), a is a positive number in the range of 1.8 to 2.2, particularly in the range of 1.9 to 2.1. When a is in the above range, the resulting silicone composition can have a good consistency required as a grease.

上記式において、Ｒ^１は、互いに独立に、炭素数１〜１８、好ましくは１〜１４の、不飽和結合を有してよい、非置換または置換の一価炭化水素基であり、上述した基が挙げられる。中でも、両末端のＲ^１は全てメチル基であることが好ましい。ｍは該オルガノポリシロキサンの２５℃での動粘度が１０〜５００，０００ｍｍ^２／ｓ、好ましくは３０〜１０，０００ｍｍ^２／ｓとなる数である。 As said organopolysiloxane, what is represented by a following formula is preferable.

In the above formula, R ¹ , independently of each other, is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 14 which may have an unsaturated bond, and the group described above Is mentioned. Especially, it is preferable that all R < ¹ > of both ends is a methyl group. m is a number such that the kinematic viscosity of the organopolysiloxane at 25 ° C. is 10 to 500,000 mm ² / s, preferably 30 to 10,000 mm ² / s.

（式中、Ｒ^２は炭素数１〜６のアルキル基であり、Ｒ^３は、互いに独立に、炭素数１〜１８の、不飽和結合を有してよい、非置換または置換の一価炭化水素基であり、ｂは５〜１２０の整数である） Component (C) The silicone composition of the present invention can further contain a hydrolyzable organopolysiloxane represented by the following general formula (2).

(In the formula, R ² is an alkyl group having 1 to 6 carbon atoms, and R ³ , independently of each other, may have an unsaturated bond, unsubstituted or substituted monovalent carbonization having 1 to 18 carbon atoms. A hydrogen group, and b is an integer of 5 to 120)

  The organopolysiloxane functions to help highly fill the thermally conductive filler in the silicone composition. Moreover, when the silicone composition contains the organopolysiloxane, the surface of the powder is covered with the organopolysiloxane, and the effect that the powders hardly aggregate is also obtained. Since this effect can be maintained even at high temperatures, the heat resistance of the silicone composition is improved. Further, as described above, the surface of the thermally conductive filler can be hydrophobized with the organopolysiloxane.

In the above formula (2), ^{R 2} is an alkyl group having 1 to 6 carbon atoms. Examples thereof include alkyl groups having 1 to 6 carbon atoms such as a methyl group, an ethyl group, and a propyl group, and a methyl group and an ethyl group are particularly preferable. R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and optionally having an unsaturated bond. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, and octadecyl group, cyclopentyl group, and the like. Aralkyl groups such as cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and tolyl groups, 2-phenylethyl groups, and 2-methyl-2-phenylethyl groups Or a group in which some or all of the hydrogen atoms in these groups are substituted with a halogen atom such as fluorine, bromine or chlorine, a cyano group, for example, 3,3,3-trifluoropropyl group, 2- (par A fluorobutyl) ethyl group, a 2- (perfluorooctyl) ethyl group, a p-chlorophenyl group, and the like. A methyl group is particularly preferable. In said formula (2), b is an integer of 5-120, Preferably it is an integer of 10-90.

  The amount of the component (C) in the silicone composition is preferably such that the amount of the component (C) is in the range of 1 to 30% by mass, more preferably in the range of 3 to 20% by mass relative to the total mass of the silicone composition. This is the amount. When the amount of component (C) exceeds the above range, the resulting silicone composition may easily cause oil bleeding.

Component (D) The silicone composition of the present invention can further contain an organosilane represented by the following general formula (3) and / or a partial hydrolysis condensate of the organosilane.
R ⁴ _c SiY _4-c (3)
(Wherein R ⁴ are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms and optionally having an unsaturated bond, and Y is independently of each other a hydroxyl group or A hydrolyzable group, and c is an integer of 1 to 3)

  The organosilane and the partially hydrolyzed condensate of the organosilane function to help highly fill the thermally conductive filler in the silicone composition. In addition, when the silicone composition contains the compound, the surface of the powder is covered with the organosilane, and the effect that the powder hardly aggregates is also obtained. Since this effect can be maintained even at high temperatures, the heat resistance of the silicone composition is improved. Further, the surface of the thermally conductive filler can be subjected to a hydrophobic treatment with the organosilane.

In the above formula (3), R ⁴ , independently of each other, is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, which may have an unsaturated bond. It is. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, and octadecyl group, cyclopentyl group, and the like. Aralkyl groups such as cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and tolyl groups, 2-phenylethyl groups, and 2-methyl-2-phenylethyl groups Or a group in which some or all of the hydrogen atoms in these groups are substituted with a halogen atom such as fluorine, bromine or chlorine, a cyano group, for example, 3,3,3-trifluoropropyl group, 2- (par A fluorobutyl) ethyl group, a 2- (perfluorooctyl) ethyl group, a p-chlorophenyl group, and the like. In the above formula (3), c is 1, 2 or 3, particularly preferably 1.

  In said formula (3), Y is a hydroxyl group or a hydrolysable group mutually independently. The hydrolyzable group is preferably a group having 1 to 6 carbon atoms, and examples thereof include an alkoxy group, an acyloxy group, and an alkenyloxy group. More specifically, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an acetoxy group, a propenoxy group, etc. are mentioned. Of these, a hydroxyl group and an alkoxy group are preferable. In the present invention, the partially hydrolyzed condensate of organosilane means a compound obtained by partially hydrolyzing and condensing the group represented by Y in the above formula (3).

  The amount of the component (D) in the silicone composition is preferably such that the amount of the component (D) is in the range of 0.1 to 10% by mass relative to the total mass of the silicone composition, more preferably 0.8. The amount is in the range of 1 to 5% by mass. When the amount of component (D) exceeds the above range, the resulting silicone composition may easily cause oil bleeding.

  In addition, the silicone composition of the present invention may contain, as necessary, conventionally known antioxidants, dyes, pigments, flame retardants, antisettling agents, thixotropic agents, and the like as long as the object of the present invention is not impaired. Can be blended.

  The method for producing the silicone composition of the present invention is not particularly limited and may follow a conventionally known method for producing a silicone grease composition. For example, the above components (A) to (D), and other components as necessary, are mixed with Trimix, Twinwin, Planetary Mixer (all are registered trademarks of a mixer manufactured by Inoue Seisakusho Co., Ltd.), Ultramixer (Mizuho) It can be produced by mixing for 30 minutes to 4 hours in a mixer such as Kogyo Co., Ltd. (mixed trademark), Hibis Disper Mix (registered trademark of Koki Kogyo Co., Ltd.). . Moreover, you may mix, heating as needed at the temperature of the range of 50-150 degreeC.

  The silicone composition of the present invention preferably has a viscosity of 10 to 500 Pa · s, more preferably 50 to 300 Pa · s measured at 25 ° C. If the viscosity is higher than the upper limit, workability is deteriorated, which is not preferable. On the other hand, if the viscosity is smaller than the lower limit, the composition will flow out after coating on various substrates, which is not preferable. The viscosity can be obtained by adjusting the blending of each component described above. In the present invention, the viscosity of the silicone composition is a value measured at 25 ° C. using model number PC-1TL (10 rpm) manufactured by Malcolm Corporation.

  The silicone composition of the present invention preferably has a thermal conductivity of 0.3 W / mK or more, more preferably 0.5 W / mK or more. When the thermal conductivity is within the above range, a sufficient heat dissipation effect can be obtained.

  The silicone composition of the present invention can be used as a grease. The embodiment in which the silicone composition of the present invention is used as a grease is not particularly limited, and may be used in the same manner as a conventional heat conductive silicone grease. For example, in a mode in which the grease is sandwiched between an electrical / electronic component such as LSI or other heat generating member and a cooling member or a heat radiating member, and heat from the heat generating member is transferred to the cooling member or heat radiating member It can be used suitably. Since the silicone composition of the present invention is insulative, has high thermal conductivity, and has good scratch resistance, it can be particularly suitably used as a heat radiation grease for high-quality semiconductor devices and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example. In the following, the average particle diameter of the powder is a volume-based cumulative average diameter measured using Microtrac MT3300EX, a particle size analyzer manufactured by Nikkiso Co., Ltd.

Each component used in the examples and comparative examples is described below.

（Ａ−２）

(A) Component (A-1)

(A-2)

(B) Component: Thermally conductive filler (a) Calcium carbonate powder (a-1) Average particle size 1.0 μm
(A-2) Average particle size 20.5 μm
In Comparative Example 3, the following calcium carbonate powder was used.
(A-3) Average particle size of 130 μm
(B) Aluminum hydroxide powder (b-1) Average particle size 2.5 μm
(B-2) Average particle diameter of 14.5 μm

(C) Component (C-1)

(D) Component (D-1)
C ₁₀ H ₂₁ Si (OCH ₃ ) ₃

In Comparative Examples 4 to 7, the following thermally conductive fillers were used.
(E-1) Aluminum powder (average particle size: 30 μm)
(E-2) Zinc oxide powder (average particle size: 1.0 μm)
(E-3) Alumina powder (average particle size: 8.9 μm)
(E-4) Boron nitride powder (average particle size: 2.0 μm)
(E-5) Aluminum nitride powder (average particle size: 6.8 μm)

[Examples 1 to 5 and Comparative Examples 1 to 8 ]
Preparation of silicone composition According to the blending amounts shown in Tables 1 and 2, the above components were put into a 5 liter planetary mixer (registered trademark of a mixer manufactured by Inoue Seisakusho Co., Ltd.) and stirred at 150 ° C for 1 hour. Thus, a silicone composition was produced.

  About each composition obtained by the said method, according to the following method, the viscosity, the heat conductivity, the test with a damage | wound, and the volume resistance value were measured. The results are shown in Tables 1 and 2.

[viscosity]
The absolute viscosity of each composition was measured at 25 ° C. using model number PC-1TL (10 rpm) manufactured by Malcolm Corporation.

[Thermal conductivity]
The thermal conductivity of each composition was measured at 25 ° C. using TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

[Scratched test]
Grease made of the above silicone composition was sandwiched between two 10 mm × 10 mm silicone wafers and reciprocated 30 times with fingers. The grease was then wiped clean with a solvent, and the surface of the silicone wafer was observed with a microscope. The damaged state of the silicone wafer surface was evaluated as follows.
○: No scratch is observed.
X: Scratches were observed on the surface.

[Measurement of volume resistivity]
The volume resistance value was measured at 25 ° C. using a liquid electrode manufactured by Soken Denki Co., Ltd .: Model DAC-OBE-2 (conforming to JIS C2101).

  As shown in Table 2, the silicone composition containing zinc oxide powder and alumina powder or aluminum nitride powder as the thermally conductive filler is inferior in scratch resistance. The silicone composition containing the boron nitride powder did not become greasy. Also, silicone compositions having aluminum powder are not insulating. On the other hand, as shown in Table 1, the silicone composition of the present invention is insulative, has high thermal conductivity, and good scratch resistance.

  Since the silicone composition of the present invention is insulative, has high thermal conductivity, and has good scratch resistance, it can be particularly suitably used as a heat dissipating grease for high-quality semiconductor devices and the like. it can.

Claims (6)

(A) A silicone composition comprising 100 parts by mass of an organopolysiloxane having a kinematic viscosity at 25 ° C. of 10 to 500,000 mm ² / s, and (B) 100 to 1300 parts by mass of a thermally conductive filler,
The thermally conductive filler is
(A) 100 to 1000 parts by weight of calcium carbonate powder having an average particle size 0.1 to 100 [mu] m, and (b) characterized in that it consists of from 100 to 1000 parts by weight of aluminum hydroxide powder having an average particle diameter of 0.1 to 100 [mu] m A silicone composition. (A) Organopolysiloxane has the following average composition formula (1)
R ¹ _a SiO _{(4-a) / 2} (1)
(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms and optionally having an unsaturated bond, and a is 1.8 ≦ a ≦ 2. .2 is a positive number satisfying 2)
The silicone composition of Claim 1 represented by these. (C) The following general formula (2)

(In the formula, R ² is an alkyl group having 1 to 6 carbon atoms, and R ³ , independently of each other, may have an unsaturated bond, unsubstituted or substituted monovalent carbonization having 1 to 18 carbon atoms. A hydrogen group, and b is an integer of 5 to 120)
The silicone composition of Claim 1 or 2 which further contains the hydrolyzable organopolysiloxane represented by these in the quantity used as 1-30 mass% in a silicone composition. (D) The following general formula (3)
R ⁴ _c SiY _4-c (3)
(Wherein R ⁴ are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms and optionally having an unsaturated bond, and Y is independently of each other a hydroxyl group or A hydrolyzable group, and c is an integer of 1 to 3)
The organosilane represented by the above and / or the partially hydrolyzed condensate of the organosilane is further contained in an amount of 0.1 to 10% by mass in the silicone composition. The silicone composition described.   The silicone composition according to any one of claims 1 to 4, which has a thermal conductivity of 0.3 W / mk or more.   The grease which consists of a silicone composition of any one of Claims 1-5.