JP6884787B2 - Composition for heat conductive grease, heat conductive grease and heat dissipation member - Google Patents

Description

The present invention relates to a composition for thermally conductive grease, a thermally conductive grease, and a heat radiating member.

With the miniaturization and high output of heat-generating electronic components, the amount of heat generated from the electronic components per unit area has become extremely large. A metal heat sink, a housing, or the like is used as a cooling unit for cooling the electronic components, and a heat radiating material is used to efficiently transfer heat from the electronic components to the cooling unit. The reason for using this heat radiating material is that when the electronic component and the cooling unit are brought into contact with each other as they are, air is present at the interface microscopically, which hinders heat conduction. Therefore, heat can be efficiently transferred by having a heat radiating material exist between the electronic component and the cooling portion instead of the air existing at the interface.

Further, the heat radiating material continues to receive a large thermal shock every time the electronic component is used, such that the temperature becomes low at minus several tens of degrees Celsius depending on the usage environment before the operation of the electronic component and the temperature becomes high during the operation. In order to prevent the electronic components from failing for a long period of time, it is necessary to keep cooling the heat-generating electronic components, and it is necessary to sufficiently maintain the heat dissipation characteristics of the heat radiating material.

Conventionally, a silicone-based material has been used as a resin material interposed between an electronic component and another member (for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2014-162858 International Publication No. 2010/010841 Japanese Unexamined Patent Publication No. 2012-102177 Japanese Unexamined Patent Publication No. 2014-162886

As a heat radiating material having excellent heat radiating properties, for example, a fluid grease in which a heat conductive filler is added to a liquid silicone such as silicone oil or a low viscosity silicone such as a low molecular weight silicone is known. However, since grease has high thermal conductivity but is fluid, if it is used in a place where cold shock is repeated many times, it will crack (a phenomenon that causes defects in grease when exposed to high temperature) or pump out (base). Due to the thermal expansion and contraction of the material and the grease itself, the grease may flow out of the cooling part), and the thermal resistance may increase.

Pump-out is more likely to occur as the viscosity of grease at high temperature is lower, and it is extremely difficult to develop grease that suppresses both cracking and pump-out.

As a result of diligent studies, the inventors have confirmed that the grease cracking phenomenon in the thermal shock process is a phenomenon caused by the reaggregation of the filler. It was also found that it is effective to introduce a silane coupling agent that interacts with the filler surface into the silicone molecular chain in order to reduce the reaggregation of the filler. Furthermore, it was confirmed that structural control of the silicone crosslinked product is indispensable for the grease pump-out phenomenon. It was also found that a silicone having a specific molecular weight, a vinyl group number, and a certain number of average hydrosilyl groups in the molecule is indispensable for structural control of this silicone crosslinked product.

An object of the present invention is to provide a thermally conductive grease having excellent crack resistance and pump-out resistance in a thermal shock process in view of the above problems and actual conditions. Furthermore, an object of the present invention is to provide a composition for a heat conductive grease capable of forming the heat conductive grease, and a heat radiating member containing the heat conductive grease.

The present invention employs the following means in order to solve the above problems.
(1) (A) Silicone having a mass average molecular weight of 1000 to 800,000 containing vinyl groups at both ends, (B) No vinyl group in the molecule and an average of 5 to 10 hydrosilyl groups in the molecule Silicone with a mass average molecular weight of 2000 to 10000, (C) Silicone with a mass average molecular weight of 1000 to 40,000 containing vinyl groups at both ends and an average of 1 to 4 hydrosilyl groups in the molecule, (D) Reaction A composition for a heat conductive grease containing a silane coupling agent containing a sex double bond and (E) a heat conductive filler.
(2) The sum of the component (A), the component (B), the component (C) and the component (D) is 6 to 20% by mass based on the total amount of the composition for heat conductive grease. The composition for thermally conductive grease according to (1).
(3) Based on the total amount of the composition for heat conductive grease, the content of the component (A) is 2.5 to 15% by mass, and the content of the component (B) is 0.005 to 0.1% by mass. %, The content of the component (C) is 1 to 10% by mass, and the content of the component (D) is 0.01 to 0.6% by mass, according to (1) or (2). Composition for sex grease.
(4) The heat conduction according to any one of (1) to (3), wherein the component (E) contains at least one selected from the group consisting of silica, alumina, boron nitride, aluminum nitride and zinc oxide. Composition for sex grease.
(5) The component (E) includes a coarse powder having an average particle size of 15 to 100 μm, a medium particle powder having an average particle size of 2 to 11 μm, and a fine powder having an average particle size of 0.5 to 1 μm. The composition for thermally conductive grease according to any one of (1) to (4).
(6) A thermally conductive grease containing a cured product of the composition for thermally conductive grease according to any one of (1) to (5).
(7) A heat radiating member including a heat radiating material containing the heat conductive grease according to (6) and a cooling portion bonded to an electronic component via the heat radiating material.

In the present invention, a composition for a thermally conductive grease containing a specific silicone, a silane coupling agent and a thermally conductive filler maintains the properties as a grease even after a thermal shock process, and has crack resistance and pump-out resistance. We have found that it is possible to form a thermally conductive grease that has both properties.

It is a test piece after the pump-out resistance evaluation test of Example 2. It is a test piece after the pump-out resistance evaluation test of Comparative Example 3. It is a test piece after the crack resistance evaluation test of Example 2. It is a test piece after the crack resistance evaluation test of Comparative Example 2. It is a binarized image of the test piece after the crack resistance evaluation test of Comparative Example 2. It is a schematic cross-sectional view which shows one Embodiment of a heat radiating member.

Hereinafter, preferred embodiments of the present invention will be described.

The composition for heat conductive grease of the present embodiment contains (A) a silicone (component (A)) having a mass average molecular weight of 1000 to 800,000 containing vinyl groups at both ends, and (B) containing a vinyl group in the molecule. Silicone (component (B)) having a mass average molecular weight of 2000 to 10000 containing an average of 5 to 10 hydrosilyl groups in the molecule, and (C) containing vinyl groups at both ends and an average of 1 in the molecule. Silicone (component (C)) having a mass average molecular weight of 1000 to 40,000 containing up to 4 hydrosilyl groups, (D) a silane coupling agent containing a reactive double bond (component (D)), and (E). Contains a thermally conductive filler (component (E)).

The composition for thermally conductive grease is crosslinked by an addition reaction (crosslinking reaction) of silicone, and a fluid thermally conductive grease can be obtained by optimizing the degree of crosslinking. In the present specification, advancing the cross-linking reaction of the composition for thermally conductive grease is referred to as curing, and the cross-linking reaction is also referred to as a curing reaction in some cases. Examples of the curing method include a method of adding an addition reaction catalyst to the composition for thermally conductive grease and heating the composition. Further, a method can also be adopted in which the composition for thermally conductive grease is divided into two agents, an addition reaction catalyst is added to one of them, and the composition is cured at room temperature. That is, the composition for thermally conductive grease may further contain an addition reaction catalyst. The addition reaction catalyst may be, for example, a platinum-based catalyst.

(A) Silicone containing vinyl groups at both ends preferably has a mass average molecular weight of 1000 to 800,000, and more preferably a mass average molecular weight of 1000 to 40,000. By setting the mass average molecular weight to 10,000 or more, the pump-out resistance becomes good. Further, by setting the mass average molecular weight to 800,000 or less, the crack resistance becomes good. As these commercially available products, for example, SE1885 / A agent manufactured by Toray Dow Corning Co., Ltd. can be used.

The component (A) may be a silicone having an average of less than one hydrosilyl group in the molecule, and is preferably a silicone containing no hydroxyl group.

The amount of the component (A) added to the composition for heat conductive grease is preferably 2.5 to 15% by mass, more preferably 3 to 5% by mass, based on the total amount of the composition for heat conductive grease. When it is 2.5% by mass or more, the crack resistance becomes better. Further, when the content is 15% by mass or less, the pump-out resistance becomes better.

The component (B) is for adjusting the degree of cross-linking of the cured product of the composition for heat conductive grease. The average number of hydrosilyl groups in the molecule is 5 to 10, with an average of 5 to 7 being more preferred. By setting the average number of hydrosilyl groups to 5 or more, the pump-out resistance is improved. Further, when the average number is 10 or less, the crack resistance is improved. Examples of commercially available products of the component (B) include Toray Dow Corning Silicone Co., Ltd. and the trade name "RD-1".

The amount of the component (B) added to the composition for heat conductive grease is preferably 0.005 to 0.1% by mass, preferably 0.005 to 0.04% by mass, based on the total amount of the composition for heat conductive grease. % Is more preferable. When the content is 0.005% by mass or more, the pump-out resistance becomes better. Further, when the content is 0.1% by mass or less, the crack resistance becomes better.

The component (C) is for adjusting the degree of cross-linking of the cured product of the composition for heat conductive grease. The number of hydrosilyl groups in the molecule is 1 to 4 on average, more preferably 1 to 2 on average. By setting the number of hydrosilyl groups to 1 or more on average, the crack resistance is improved. Further, when the average number is 4 or less, the pump-out resistance is improved.

The mass average molecular weight of the component (C) is 1000 to 40,000, more preferably 1000 to 25000. By setting the mass average molecular weight to 10,000 or more, the pump-out resistance becomes good. Further, when the content is 40,000 or less, the crack resistance is improved.

The amount of the component (C) added to the composition for heat conductive grease is preferably 1 to 10% by mass, more preferably 2.5 to 5% by mass, based on the total amount of the composition for heat conductive grease. When the content is 1% by mass or more, the pump-out resistance becomes better. Further, when the content is 10% by mass or less, the crack resistance becomes better.

The component (D) is used to introduce a silane coupling agent that interacts with the filler surface into the silicone molecular chain in order to reduce the reaggregation of the filler. Since the silane coupling agent is introduced into the silicone molecular chain, the silane coupling agent has a reactive double bond. Examples of the reactive double bond include a vinyl group and an allyl group. The component (D) includes allyltriethoxysilane, allylchlorodimethylsilane, allyltrimethoxysilane, allyltrichlorosilane, chlorodimethylvinylsilane, diethoxymethylvinylsilane, dimethoxymethylvinylsilane, trichlorovinylsilane, vinyltrimethoxysilane, and dimethylethoxyvinylsilane. , Vinyltris (2-methoxyethoxy)silane and the like. Examples of commercially available products of the component (D) include trade names "Z6300", "Z6519", and "Z6075" manufactured by Toray Dow Corning Silicone Co., Ltd. Among these, Z6519 (allyltriethoxysilane) is preferable in terms of reactivity with the filler and generation of less harmful ethanol as a by-product after the dehydration condensation reaction with the filler.

The amount of the component (D) added to the composition for heat conductive grease is preferably 0.01 to 0.6% by mass, preferably 0.02 to 0.3% by mass, based on the total amount of the composition for heat conductive grease. % Is more preferable. When it is 0.01% by mass or more, the crack resistance becomes better. Further, when the content is 0.60% by mass or less, the pump-out resistance becomes better.

The sum of the components (A), (B), (C) and (D) in the composition for thermally conductive grease is 6 to 20% by mass based on the total amount of the composition for thermally conductive grease. It is preferable, and 6 to 10% by mass is more preferable. When it is 6% by mass or more, the thermal conductivity becomes better. Further, when the content is 20% by mass or less, the viscosity at the time of coating becomes better.

When the composition for heat conductive grease of the present embodiment is divided into two agents and used, the first agent is the component (A), the component (D) and the addition reaction catalyst, and the second agent is the component (B). It is preferable to contain the component (C). As a result, the storage stability of the two agents can be improved even in the presence of the addition reaction catalyst.

The component (E) is preferably one or more selected from the group consisting of silica, alumina, boron nitride, aluminum nitride and zinc oxide. As the component (E), alumina is preferable in terms of filling property, and alumina and aluminum nitride are preferable in terms of thermal conductivity.

The component (E) is preferably composed of a coarse powder having an average particle size of 15 to 100 μm, a medium particle powder having an average particle size of 2 to 11 μm, and a fine powder having an average particle size of 0.5 to 1 μm. By setting the average particle size of the coarse powder to 15 μm or more, the thermal conductivity and pump-out resistance become better. Further, by setting the average particle size of the coarse powder to 100 μm or less, the insulating property and the crack resistance become better. Further, by setting the average particle size of the medium-grained powder to 2 to 11 μm, the filling amount of the heat conductive filler is improved. Further, by setting the average particle size of the fine powder to 0.5 μm or more, the thermal conductivity and the pump-out resistance are further improved. Further, by setting the average particle size of the fine powder to 1 μm or less, the insulating property and the crack resistance become better. By using three types of thermally conductive fillers with different average particle sizes in this way, insulation, crack resistance, thermal conductivity, and pump-out resistance can be achieved at a higher level while maintaining a viscosity suitable for coating. It can be compatible.

The amount of the component (E) in the composition for heat conductive grease is preferably more than 80% by mass to less than 94% by mass, more preferably 90 to 94% by mass, based on the total amount of the composition for heat conductive grease. preferable. When the amount exceeds 80% by mass, the thermal conductivity becomes better. Further, when it is less than 94% by mass, the viscosity at the time of coating becomes better.

In the present embodiment, for example, a colorant such as "Regino Black" manufactured by Regino Color Industry Co., Ltd. is used in an amount of 0.05 to 0.2 parts by mass with respect to 100 parts by mass of the composition for thermally conductive grease. It may be added to the extent that it does not adversely affect the physical properties of the product. Further, if necessary, an antioxidant, a metal corrosion inhibitor, or the like may be blended.

The composition for heat conductive grease of the present embodiment can be produced by kneading with a planetary stirrer, a universal mixing stirrer, a kneader, a hybrid mixer or the like.

The composition for heat conductive grease of the present embodiment is used as heat-dissipating grease (heat conductive grease) in a state where the cross-linking reaction is allowed to proceed by preheating at 25 ° C to 200 ° C for 0.5 to 24 hours, for example. can do. Further, after joining the electronic component and the heat sink, the electronic component and the heat sink may be heated under the same conditions for use.

The composition for heat conductive grease of the present embodiment can form heat conductive grease by cross-linking. That is, the thermally conductive grease of the present embodiment can be said to be a cured product (crosslinked product) of the composition for thermally conductive grease. The heat conductive grease may be formed, for example, by heating and kneading each component of the composition for heat conductive grease.

The heat radiating member of the present embodiment includes a heat radiating material containing heat conductive grease and a cooling unit joined to an electronic component via the heat radiating material. The cooling unit may be, for example, a member having excellent heat dissipation such as a metal housing or a heat sink, or a member such as a water jacket that is cooled by a refrigerant.

FIG. 6 is a schematic cross-sectional view showing an embodiment of the heat radiating member. The heat radiating member 1 shown in FIG. 6 includes a heat conductive grease 10 and a cooling unit 20. The cooling unit 20 includes a cooling housing 21 and a circulation line 22 for circulating cooling water in the cooling housing 21, and a heat generating element 2 is installed on the cooling housing 21 via the heat conductive grease 10. Has been done. The heat generating element 2 which is an electronic component is fixed on the cooling housing 20 by a fixture 3. A plurality of heat generating elements 2 are installed on the cooling housing 20 via the heat conductive grease 10, respectively.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Manufacturing of compositions for thermally conductive grease>
The following raw materials were used in the production of the composition for thermally conductive grease.
(A) Ingredients-Wacker, "Silgel 613 A agent", mass average molecular weight 10000
-Momentive, "XE14-B8530 A agent", mass average molecular weight 25000
-Dow Corning, "SE1885 A agent", mass average molecular weight 40,000
-Momentive, "TSE201", mass average molecular weight 800,000
(B) Ingredients-Dow corning, "RD-1", mass average molecular weight 2000, average number of hydrosilyl groups 5-Bluestar Silicone, "BLUESIL FLD 628 V12 H3.5", mass average molecular weight 3000, average hydrosilyl 7 groups, manufactured by Blue Star Silicone, "BLUESIL FLD 626 V30 H2.5", mass average molecular weight 5000, average number of hydrosilyl groups 9, manufactured by Blue Star Silicone, "BLUESIL FLD 626 V70 H0.7", mass average molecular weight 10000, average number of hydrosilyl groups 10 / Blue Star Silicone, "BLUESIL FLD 620 V3", mass average molecular weight 2000, average number of hydrosilyl groups 2 / Blue Star Silicone, "BLUESIL FLD 626 V25 H7", mass average molecular weight 3000 , Average number of hydrosilyl groups 20 (for comparative example)
(C) Ingredients-Wacker, "Silgel 613 B agent", mass average molecular weight 10,000, average number of hydrosilyl groups 1-Momentive, "XE14-B8530 B agent", mass average molecular weight 25000, average hydrosilyl groups 2 "SE1885 B agent" manufactured by Dow Corning, mass average molecular weight 40,000, average number of hydrosilyl groups 4 (D) component-vinyltriethoxysilane, manufactured by Dow Corning, "Z6519"
(E) Component (E-1) Coarse powder / alumina, manufactured by Denki Kagaku Kogyo Co., Ltd., "DAW90", average particle size 90 μm
-Alumina, manufactured by Denki Kagaku Kogyo Co., Ltd., "DAW70", average particle size 70 μm
-Alumina, manufactured by Denki Kagaku Kogyo Co., Ltd., "DAW45", average particle size 45 μm
-Alumina, manufactured by Sumitomo Chemical Co., Ltd., "AA-18", average particle size 18 μm
-Aluminum nitride, manufactured by Denki Kagaku Kogyo Co., Ltd., "SAN", average particle size 20 μm
(E-2) Medium grain powder / alumina, manufactured by Denki Kagaku Kogyo Co., Ltd., "DAS10", average particle size 10 μm
-Alumina, manufactured by Denki Kagaku Kogyo Co., Ltd., "DAW05", average particle size 5 μm
-Alumina, manufactured by Sumitomo Chemical Co., Ltd., "AA-2", average particle size 2 μm
-Zinc oxide, manufactured by Sakai Chemical Co., Ltd., "ZIMC-11", average particle size 11 μm
(E-3) Fine powder / alumina, manufactured by Sumitomo Chemical Co., Ltd., "AA-05", average particle size 0.5 μm,
-Zinc oxide, manufactured by Honjo Chemical Co., Ltd., "type", average particle size 0.5 μm,
-Aluminum nitride, manufactured by Tokuyama Corporation, "H", average particle size 1 μm
(F) Others-Platinum-based catalyst, manufactured by Momentive, "SFG-32"

Various raw materials were kneaded by vacuum heating at 150 ° C. for 3 hours at an absolute pressure of 100 Pa or less at the ratios shown in Tables 1 to 6 to produce several kinds of thermally conductive greases. The mass average molecular weight, average number of hydrosilyl groups, and average particle size of each compounded raw material were measured by the following methods.

[Mass average molecular weight]
The mass average molecular weight in terms of standard polystyrene was determined using GPC (gel permeation chromatography). THF was used as a solvent, and the measurement was carried out using "HLC-8020" manufactured by Tosoh Corporation. An RI (differential refractometer) was used as the detector.

[Average number of hydrosilyl groups]
¹ H-NMR measurement was carried out using "JOEL ECP-300" manufactured by JOEL, and the number ratios of the number of vinyl groups, the number of methyl groups and the number of hydrosilyl groups were quantified. In the case of a hydrosilyl group-containing silicone containing vinyl groups at both ends, the average number of hydrosilyl groups was calculated from the number ratio of vinyl groups to hydrosilyl groups. For hydrosilyl group-containing silicones that do not have vinyl groups, the mass average molecular weight is measured using "HLC-8020" manufactured by Toso Co., Ltd., and then the ratio of the number of methyl groups to the number of hydrosilyl groups and the measured value of the mass average molecular weight. The average number of hydrosilyl groups was calculated from.

[Average particle size]
The measurement was performed using a "laser diffraction type particle size distribution measuring device SALD-200" manufactured by Shimadzu Corporation. For the evaluation sample, 50 cc of pure water and 5 g of a heat conductive filler to be measured were added to a glass beaker, stirred with a spatula, and then dispersed with an ultrasonic cleaner for 10 minutes. Using a dropper, the dispersion liquid of the heat conductive filler that had been subjected to the dispersion treatment was added drop by drop to the sampler portion of the apparatus, and the mixture was waited for stabilization until the absorbance became measurable. The measurement was performed when the absorbance became stable in this way. In the laser diffraction type particle size distribution measuring device, the particle size distribution was calculated from the data of the light intensity distribution of the diffracted / scattered light by the particles detected by the sensor. The average particle size was obtained by multiplying the measured particle size value by the relative particle amount (difference%) and dividing by the total relative particle amount (100%).

The physical characteristics of the thermally conductive grease shown in Tables 1 to 6 were measured by the following methods.

[viscosity]
In the rotary rheometer MARSIII manufactured by Thermo Scientific, a 35 mmΦ parallel plate is used as the upper jig, and the heat conductive grease is placed on the 35 mmΦ lower plate whose temperature can be controlled by the Peltier element, and the thickness is increased by the upper jig. It was compressed to 1 mm, the protruding part was scraped off, and the measurement was started. The viscosities of shear rates 0.0001 to 100s ^-1 were measured, and the viscosities of shear rates 10s ^-1 were used for evaluation. When the viscosity is lower than 400 Pas, metal mask / screen printing and squeegee coating are possible, and workability is good. When the viscosity is 400 Pas or more and less than 1200 Pas, metal mask screen printing and coating by squeegee are not possible, but ejection and coating from a syringe by an automatic coating machine are possible. At 1200 Pas or more and less than 1500 Pas, ejection and coating by an automatic coating machine are difficult because it takes time. If it exceeds 1500 Pas, it is impossible to discharge and apply by an automatic coating machine.
As mentioned above, the following indexes were used in the evaluation.
A: Viscosity less than 400 Pas B: Viscosity 400 Pas or more and less than 1200 Pas C: Viscosity 1200 Pas or more and less than 1500 Pas D: Viscosity 1500 Pas or more

[Thermal conductivity]
Thermal conductivity between a square copper jig with a heater embedded and a tip of 100 mm ² (10 mm x 10 mm) and a rectangular copper jig with cooling fins and a tip of 100 mm ² (10 mm x 10 mm). The thermal resistance was measured in the range of 0.05 mm to 0.30 mm in the thickness of the gap with the grease sandwiched between them, and the thermal conductivity was calculated and evaluated from the gradient of the thermal resistance and the thickness. For the thermal resistance, apply 10 W of electric power to the heater and hold it for 30 minutes, measure the temperature difference (° C) between the copper jigs, and measure the thermal resistance (° C / W) = {temperature difference (° C) / electric power (W)}.
Calculated in.
As for the thermal conductivity, if it is 1 W / mK or more due to the use of the thermally conductive grease, it can be used without any problem.
The following indicators were used in the evaluation.
A: Thermal conductivity 2.5 W / mK or more B: Thermal conductivity 1.0 W / mK or more and less than 2.5 W / mK D: Thermal conductivity less than 1.0 W / mK

[Pump out resistance]
A heat conductive grease was applied to an aluminum plate at a size of 60 mm square and a thickness of 100 μm at 0.03 cc × 4 points, and vacuum defoaming was performed for 1 hour. After that, a glass plate was sandwiched and the diameter of the heat conductive grease was adjusted to be a circle of 20 mm.
Next, a 4 kg weight was placed on the glass plate, left for one day, and then both ends of the glass plate were closed and fixed with clips, and the outer periphery of the thermally conductive grease deformed by the load was marked with an oil-based magic. A thermal shock test at -40 ° C to 150 ° C was carried out to evaluate the pump-out resistance. The holding time at −40 ° C. and 150 ° C. was 30 minutes, the elevating temperature from −40 ° C. to 150 ° C. and 150 to −40 ° C. was within 5 minutes, and 300 cycles were carried out. FIG. 1 is a diagram showing a test piece after the pump-out resistance evaluation test of Example 2, and FIG. 2 is a diagram showing a test piece after the pump-out resistance evaluation test of Comparative Example 3.
In the evaluation of pump-out resistance, the evaluation of pump-out resistance was as follows.
Pump-out rate (%) = (Diameter after thermal impact test-Diameter before thermal impact test) / Diameter before cold impact test x 100
A: Pump out rate 0%
B: Pump-out rate 1% or more and less than 5% C: Pump-out rate 5% or more and less than 15% D: Pump-out rate 15% or more

[Crack resistance]
Thermally conductive grease was applied to an aluminum plate with a size of 60 mm square and a thickness of 100 μm with a squeegee, vacuum defoamed for 1 hour, and then a glass plate was sandwiched.
Next, a thermal shock test at −40 ° C. to 150 ° C. was carried out. The holding time at -40 ° C and 150 ° C was 30 minutes, respectively, and the elevating temperature from -40 ° C to 150 ° C and 150 to -40 ° C was within 5 minutes, and 300 cycles were carried out. FIG. 3 is a diagram showing a test piece after the crack resistance evaluation test of Example 2, and FIG. 4 is a diagram showing a test piece after the crack resistance evaluation test of Comparative Example 2. Further, FIG. 5 is a diagram showing a binarized image of the test piece after the crack resistance test of Comparative Example 2.
As a method of calculating the crack resistance, as shown in FIG. 5, binarization is performed using image processing software (here, GIMP2.0) that can be binarized, and the area of voids (black part) and the area of grease. (White part) was measured.
A: Crack rate 0%
B: Cracking rate 1% or more and less than 5% C: Cracking rate 5% or more and less than 15% D: Cracking rate 15% or more

As shown in Examples and Comparative Examples, the thermally conductive grease using the composition for thermally conductive grease of the present invention was excellent in pump-out resistance and crack resistance, and also had high thermal conductivity.

Claims (7)

(A) Silicone having a mass average molecular weight of 1000 to 800,000 containing vinyl groups at both ends, (B) Mass average containing no vinyl groups in the molecule and an average of 5 to 10 hydrosilyl groups in the molecule Silicone with a molecular weight of 2000 to 10000, (C) Silicone with a mass average molecular weight of 1000 to 40,000 containing vinyl groups at both ends and an average of 1 to 4 hydrosilyl groups in the molecule, (D) Reactive double Contains a silane coupling agent containing a bond and (E) a thermally conductive filler,
A composition for thermally conductive grease, wherein the amount of the component (E) is more than 80% by mass and less than 94% by mass. Claim 1 that the sum of the component (A), the component (B), the component (C) and the component (D) is 6 to 20% by mass based on the total amount of the composition for heat conductive grease. The composition for heat conductive grease according to. Based on the total amount of the composition for heat conductive grease, the content of the component (A) is 2.5 to 15% by mass, the content of the component (B) is 0.005 to 0.1% by mass, and the above. The composition for heat conductive grease according to claim 1 or 2, wherein the content of the component (C) is 1 to 10% by mass, and the content of the component (D) is 0.01 to 0.6% by mass. .. The component (E) comprises one or more selected from the alumina and aluminum nitride or Ranaru group, the thermally conductive grease composition according to any one of claims 1 to 3. The claim that the component (E) includes a coarse powder having an average particle size of 15 to 100 μm, a medium particle powder having an average particle size of 2 to 11 μm, and a fine powder having an average particle size of 0.5 to 1 μm. The composition for thermally conductive grease according to any one of 1 to 4. A heat conductive grease containing a cured product of the composition for heat conductive grease according to any one of claims 1 to 5. The heat radiating material containing the heat conductive grease according to claim 6 and
A cooling unit that is joined to an electronic component via the heat radiating material,
A heat-dissipating member.

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