JP3290127B2 - Heat conductive silicone rubber composition and heat dissipation sheet comprising the heat conductive silicone rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transistor,
Thermal conductive silicone which is arranged between an electric component such as a CPU (Central Processing Unit) of a computer and a radiator and is suitable for forming a heat radiating sheet for conducting heat generated from electronic and electric components to the radiator. The present invention relates to a rubber composition and a heat radiation sheet formed from the thermally conductive silicone rubber composition.

[0002]

2. Description of the Related Art In recent years, with the increase in the number of clocks of personal computers and workstations and the increase in the degree of integration, electronic components 4
The calorific value from the air is increasing. Further, heat generation of the power IC and the like also has various problems. In order to efficiently radiate the heat generated from these electronic components 4, as shown in FIG. 2A, a radiator 5 is attached to the electronic components 4 mounted on the substrate 6 via mounting electrodes 8 such as solder bumps. Is generally performed. Here, if a gap 7 is formed between the electronic component 4 and the radiator 5 as shown in FIG. 2C, the gap 7 becomes a large resistance for heat conduction. The heat radiation sheet 3 is interposed between the heat radiation sheet 5 and the radiator 5 and the electronic component 4, as shown in FIG. 2 (b). The heat generated from the electronic component 4 is efficiently transmitted to the radiator 5.

Conventionally, a rubber sheet having flexibility, a tape coated with an adhesive on both sides, or a material such as an adhesive or grease has been used as a material for the heat radiation sheet 3. In either case, the heat conductive filler is mixed and dispersed in the matrix resin. In this case, as the matrix resin, a silicone rubber having excellent heat resistance and cold resistance and having good compression restorability in a wide temperature range is often used, and as the heat conductive filler, alumina, magnesium oxide, boron nitride is used. And the like. A heat-conductive silicone rubber composition obtained by mixing and dispersing the heat-conductive inorganic filler in a matrix resin at a high filling amount is heat-formed to form a heat dissipation sheet 3. Is formed. Here, the heat conductive filler is used to reduce the thermal resistance of the heat radiating sheet 3 as much as possible, so that the size of the electronic device, the size of the radiator 5 and the size of the electronic component 4 can be reduced.
The heat generated from the electronic component 4 is radiated from the radiator 5 as efficiently as possible in accordance with the tendency of the increase in the calorific value.

[0004]

However, simply increasing the amount of the thermally conductive inorganic filler in the silicone rubber in order to increase the thermal conductivity increases the viscosity of the thermally conductive silicone rubber composition in the molding slurry. The workability is reduced, and the hardness of the formed sheet is increased. When the heat radiating sheet 3 becomes harder in this way, the ability of the joining surface of the electronic component 4 and the radiator 5 to follow a slight undulation or warp is reduced, and the gap between the radiator 5 and the electronic component 4 is reduced. 7 cannot be buried sufficiently. In order to make the heat-radiating sheet 3 of such high hardness follow fine undulations and warpages, it is necessary to apply a considerable load between the electronic component 4 and the heat-radiating sheet 3, resulting in large damage to the electronic component 4. May be given.

[0005] In order to solve the problem of increasing the hardness of the heat radiating sheet 3, it is possible to reduce the hardness by changing the composition ratio of the main agent and the curing agent in the resin, that is, by lowering the crosslinking density of the resin. Although it is possible to achieve both high filling, in such a case, the rubber elasticity of the heat radiating sheet 3 is reduced, and in the measurement of compression set, a new problem such as a remarkable increase in strain or a decrease in tear strength is caused. Will occur.

[0006] When the filling rate of the thermally conductive inorganic filler is high, the heat resistance reliability of the mechanical properties of rubber is significantly reduced. For example, when the data of the change in mechanical properties when left at 150 to 200 ° C. for a long time is measured, when the filling rate of the thermally conductive inorganic filler is increased, the rubber hardness is greatly increased and the material is embrittled ( Hard and brittle). Therefore, when the filling rate of the thermally conductive inorganic filler is increased, the rubber hardness increases, and the tear strength and the tensile strength decrease.

[0007] The present invention has been made in view of the above points, and a heat-conductive silicone rubber composition that imparts flexibility and heat-resistant mechanical properties to a molded product even if the heat-conductive inorganic filler is highly filled. More specifically, the present invention provides the effects of lowering the viscosity of the molding slurry, lowering the compression set of the molded product (giving rubber elasticity), and improving the tear strength. It is an object of the present invention to provide a heat conductive silicone rubber composition and a heat dissipation sheet.

[0008]

The thermally conductive silicone rubber composition according to claim 1 of the present invention comprises a silicone rubber having a silane coupling agent represented by the above general formula (A ).
In Ri formed by the thermally conductive inorganic filler 1 subjected to a surface treatment by dispersing the thermally conductive inorganic filler 1 is thermally conductive silicone
40 vol% to 80 vol% based on the total amount of the rubber composition
Oh and is characterized in Rukoto.

The heat conductive silicone rubber composition according to a second aspect of the present invention has the same structure as the first aspect, and further includes, as the heat conductive inorganic filler 1, a metal oxide, a metal nitride, a metal carbide, It is characterized by using a material selected from a metal boride and a simple metal.

The heat conductive silicone rubber composition according to the third aspect of the present invention is characterized by using alumina as the heat conductive inorganic filler 1 in addition to the constitution of the first or second aspect. is there.

The thermally conductive silicone rubber composition according to claim 4 of the present invention is characterized in that, in addition to any one of claims 1 to 3, silica is used as the thermally conductive inorganic filler 1. Is what you do.

A heat radiation sheet according to a fifth aspect of the present invention is characterized by being formed from the heat conductive silicone rubber composition according to any one of the first to fourth aspects.

[0013]

Embodiments of the present invention will be described below. The thermally conductive silicone rubber composition of the present invention is obtained by dispersing a thermally conductive inorganic filler surface-treated with a silane coupling agent in silicone rubber.

As the silicone rubber, various types such as a two-part or one-part liquid type silicone gel and silicone rubber, and a heat vulcanization type silicone rubber can be used.

As the heat conductive inorganic filler 1, alumina, silica, magnesium oxide, beryllium oxide,
Metal oxides such as titanium oxide, aluminum nitride, boron nitride, metal aluminum, copper powder, and the like can be used, but the use of metal oxides increases the processing efficiency of the coupling agent, By oxidizing part or all of the surface, the processing efficiency of the coupling agent can be improved. The shape of the thermally conductive inorganic filler 1 is not particularly limited, and may be spherical, needle-like, or plate-like. Here, the compounding ratio of the thermally conductive inorganic filler 1 in the thermally conductive silicone rubber composition is 40 vol% to 80 vol% based on the total amount of the thermally conductive silicone rubber composition.
There therefore also with, if less than 40 vol%, it is difficult to obtain a high thermal conductivity, preferably there is a possibility that the cured molding of the thermally conductive silicone rubber composition exceeds 80 vol% is more hard and brittle Absent.

As the silane coupling agent, those represented by the following general formula (A ) can be used.

[0017]

Embedded image

Here, the amount of the silane coupling agent to be treated with respect to the thermally conductive inorganic filler 1 is [the amount of the thermally conductive inorganic filler added (g)] × [the specific surface area of the thermally conductive inorganic filler (m ² / g)] {Minimum covering area of thermal conductive inorganic filler (m ² / g)] Necessary for forming monolayer of silane coupling agent on surface of thermal conductive inorganic filler 1 represented by formula 0.1 of the amount of the silane coupling agent
It is preferable to set it to 15 times. Where 0.1
If it is less than twice, the effect of the treatment with the silane coupling agent will be reduced. If the ratio exceeds 15 times, the cost of the silane coupling agent increases, and a void which may be caused by the generation of methanol may be generated during the heat treatment of the thermally conductive silicone rubber.

Hereinafter, a method for forming the thermally conductive silicone rubber composition of the present invention will be described. The surface treatment of the thermally conductive inorganic filler 1 with the silane coupling agent may be performed by a direct treatment method, an integral blend method, a dry concentrate method, or the like on the thermally conductive inorganic filler 1. The direct processing method includes a dry method, a slurry method, a spray method and the like, and the integral blending method includes a direct method,
There are a master batch method and the like, of which a dry method, a slurry method, and a direct method are often used.

When the treatment is carried out by a dry method, for example, a predetermined amount of a silane coupling agent diluted 2 to 5 times with water or an aqueous alcohol solution (water / alcohol = 1/9) is stirred until it becomes uniform. I do. On the other hand, a predetermined amount of the thermally conductive inorganic filler 1 is charged into a device such as a Herschen mixer and stirred, and the silane coupling agent solution is dropped over several tens of minutes into the stirred thermally conductive inorganic filler 1 or Spray spray. After the total amount of the silane coupling agent has been added, stirring is continued for 10 minutes in this state. The thermally conductive inorganic filler 1 thus treated is spread evenly on a shallow tray or the like, and dried at 100 to 150 ° C. for 1 hour.
After drying, some of the thermally conductive inorganic fillers 1 are agglomerated and are pulverized by a ball mill or the like.

When the treatment is performed by the slurry method,
For example, a water or alcohol aqueous solution (water / alcohol = 1/9) is added to a predetermined amount of the thermally conductive inorganic filler 1 to form a slurry, and a predetermined amount of a silane coupling agent is added to the slurry of the thermally conductive inorganic filler 1. I do. After stirring for several tens minutes after the addition, decantation or filtration is performed to take out the thermally conductive inorganic filler 1 treated with the silane coupling agent. The thermally conductive inorganic filler 1 thus treated is spread evenly on a shallow tray or the like, and dried at 100 to 150 ° C. for 1 hour. After drying, some of the thermally conductive inorganic fillers 1 are agglomerated and are pulverized by a ball mill or the like.

In the case of performing the treatment by the direct method of the integral blending method, the heat conductive inorganic filler 1 is simultaneously mixed with the silicone rubber when the heat conductive inorganic filler 1 is kneaded. In this case, it is preferable to increase the amount of the silane coupling agent to be added as compared with the case of a direct treatment method such as a slurry method or a dry method.

Silicone rubber and thermally conductive inorganic filler 1
When a one-pack type silicone rubber is used, the thermally conductive inorganic filler 1 previously subjected to the coupling treatment with the silane coupling agent can be kneaded with the silicone rubber using a kneader. Thus, a thermally conductive silicone rubber composition can be formed. As described above, an untreated thermally conductive inorganic filler, a silane coupling agent, and a silicone rubber can be integral blended as in the direct method of the integral blending method. When a two-pack type silicone rubber is used, a slurry is formed by previously mixing a desired amount of the thermally conductive inorganic filler 1 with a main agent and a curing agent, and the main agent slurry and the curing agent slurry are kneaded. The heat conductive inorganic filler 1 may be added after mixing the main agent and the curing agent.

The thermally conductive silicone rubber composition formed as described above is formed into a slurry. The heat-radiating sheet 3 can be formed by press-molding the heat-conductive silicone rubber composition into a sheet and then heat-curing the sheet. In addition to molding in a compound state as described above, a molded article obtained by impregnating a base material such as a glass cloth with a silicone rubber composition can be heated and cured. The heat-dissipating sheet 3 formed in this manner is an IC mounted on a substrate 6 via a mounting electrode 8 made of a solder bump or the like as shown in FIG.
A power supply module, a power transistor, an electronic component 4 such as a CPU, and a radiator 5 such as a heat sink, a heat pipe, and a housing are disposed between the radiator 5 and the bonding surface of the radiator 5 and the electronic component 4 as shown in FIG. By arranging the heat radiating sheet along a subtle warp or swell, it is possible to prevent a void 7 having a large thermal resistance from being generated at the joint surface between the radiator 5 and the electronic component 4 as shown in FIG. The generated heat is efficiently conducted to the radiator 5.

Here, the thermally conductive inorganic filler 1 surface-treated with the silane coupling agent as described above.
1 is as shown in FIG. That is, YSi (OMe) ₃ (OMe) is used as a silane coupling agent.
Is a methoxy group, and Y is an aliphatic long-chain alkyl group having 6 or more carbon atoms). When a silane coupling agent is hydrolyzed to YSi (OH) ₃ as in the following formula, several silane coupling agents are used. Are oligomerized by a dehydration reaction.

[0026]

Embedded image

Further, by reacting with the hydroxyl groups on the surface of the thermally conductive inorganic filler 1, the surface of the thermally conductive inorganic filler 1 is covered with a hydrophobic long-chain alkyl group 2 as shown in FIG. . Thus, the hydrophilic heat conductive inorganic filler 1
Is covered with the hydrophobic long-chain alkyl group 2, thereby significantly improving the compatibility between the thermally conductive inorganic filler 1 and the silicone rubber as the matrix. The greater the number of carbon atoms of the alkyl group represented by Y in the above formula (A ) , the more the compatibility between the thermally conductive inorganic filler 1 and the silicone rubber of the matrix is improved. It has been confirmed that the alkyl groups having up to 18 carbon atoms are stably present.
Upper limit of the carbon number of in represented by that group has a 18.

As described above, in the thermally conductive silicone rubber composition of the present invention, the compatibility between the thermally conductive inorganic filler 1 and the silicone rubber of the matrix can be improved. Even if the silicone rubber of the present invention is highly filled with the thermally conductive inorganic filler 1, the viscosity of the slurry of the thermally conductive silicone rubber composition in the form of a slurry does not increase and the molding processability does not decrease. It is possible to improve the moldability of the thermally conductive silicone rubber composition in which the inorganic filler 1 is highly filled to increase the thermal conductivity.

Further, by improving the compatibility with the silicone rubber, the aggregation of the thermally conductive inorganic fillers 1 is prevented, and the secondary aggregation of the thermally conductive inorganic fillers 1 in the silicone rubber matrix is reduced. It can be in a dispersed state, thus improving the flexibility of the cured product of the thermally conductive silicone rubber composition, improving the rubber elasticity, and significantly improving the tensile strength, tear strength and compression set characteristics. it is possible.

When the compatibility with the silicone rubber is improved, oxidation of the silicone rubber due to heat aging (leaving at high temperature) is less likely to occur, and aggregation of the thermally conductive inorganic fillers 1 at this time is also less likely to occur as described above. Therefore, it is possible to reduce the change in the mechanical properties of the cured product of the thermally conductive silicone rubber composition in the heat resistance test.

Therefore, it is possible to improve the moldability when forming the heat radiating sheet 3 with the heat conductive silicone rubber composition of the present invention, and the formed heat radiating sheet 3 has high rubber elasticity and strength. high because, when disposed between the radiator 5 and the electronic component 4, without multiplying the strong load on the electronic component 4 can be filled easily warp or undulation of the joint surface of the radiator 5 and the electronic component 4 Since the air gap 7 having high thermal resistance is not formed between the radiator 5 and the electronic component 4 and the heat radiating sheet 3 has high thermal conductivity, the efficiency of heat conduction from the electronic component 4 to the radiator 5 is improved. And the heat generated from the electronic component 4 can be easily radiated. Further, since the change in the mechanical properties in the heat resistance test is low, the change in the mechanical properties due to the heat generated from the electronic component 4 is small, and it can be used stably for a long period of time. Thus, the heat conductive silicone rubber composition of the present invention is suitable for forming the heat radiation sheet 3.

[0032]

The present invention will be described below in detail with reference to examples. (Example 1) An addition reaction type silicone gel (manufactured by Toray Dow Corning Co., Ltd., product number "SE1885") composed of two liquids of a main agent and a curing agent was used as a silicone rubber, and alumina (manufactured by Showa Denko KK) was used as a thermally conductive inorganic filler 1. ), N-hexyltrimethoxysilane was used as a silane coupling agent, and a silane coupling agent was added to the thermally conductive inorganic filler 1 by the dry method of the direct treatment method described above, and 100 parts by weight of the thermally conductive inorganic filler was used. 0.5 parts by weight of
The thermally conductive inorganic filler 1 subjected to this surface treatment was blended with each of the main component and the curing agent of the silicone rubber so that the volume fraction (Vf) of the thermally conductive inorganic filler 1 became 60%. The main component and the curing agent of the kneaded product were kneaded at a one-to-one ratio to obtain a slurry-like thermally conductive silicone rubber composition.

The heat conductive silicone rubber composition is sandwiched between release films, formed into a sheet having a thickness of 2 mm by press molding, and cured at 120 ° C. for 2 hours to form a heat radiation sheet 3. did. (Examples 2 to 8 and Comparative Examples 1 to 9) The same operation as in Example 1 was performed except that the silane coupling agent and the treatment amount were as described below.

Example 2 n-hexyltrimethoxysilane 1.0 part by weight (based on 100 parts by weight of filler) Example 3 n-hexyltriethoxysilane 0.5 part by weight (based on 100 parts by weight of filler) Example 4 n-hexyltriethoxysilane Hexyltriethoxysilane 1.0 part by weight (based on 100 parts by weight of filler) Example 5 n-octyltriethoxysilane 0.5 part by weight (based on 100 parts by weight of filler) Example 6 1.0 part by weight of n-octyltriethoxysilane Part (to 100 parts by weight of filler) Example 7 0.5 parts by weight of n-decyltrimethoxysilane (100 parts by weight of filler) Example 8 1.0 part by weight of n-decyltrimethoxysilane (100 parts by weight of filler) The ratio Comparative examples 1 silane coupling agent untreated Comparative example 2 methyltrimethoxysilane, 0.5 parts by weight (with respect to the filler 100 parts by weight) Comparative Example 3 Methyltrimethoxysilane 1.0 part by weight (based on 100 parts by weight of filler) Comparative Example 4 Methyltriethoxysilane 0.5 part by weight (based on 100 parts by weight of filler) Comparative Example 5 1.0 part by weight of methyltriethoxysilane Comparative Example 6 0.5 part by weight of dimethyldimethoxysilane (100 parts by weight of filler) Comparative Example 7 1.0 part by weight of dimethyldimethoxysilane (100 parts by weight of filler) Comparative Example 8 Dimethyldiethoxysilane 0.5 parts by weight (based on 100 parts by weight of filler) Comparative Example 9 1.0 part by weight of dimethyldiethoxysilane (100 parts by weight of based on filler) (Examples 9 to 11 , Comparative Examples 10 to 12) In Examples 9 to 11 , 1.0 part by weight of n-decyltrimethoxysilane as a silane coupling agent was added to 100 parts by weight of the filler. Comparative Examples 10 to 12 In the silane coupling agent is untreated, except that used was the following as the thermally conductive inorganic filler 1 was carried out in the same manner as in Example 1.

Example 9 Silica (manufactured by Tatsumori Corp.) Example 10 Magnesium oxide (manufactured by Kyowa Chemical Co., Ltd.) Example 11 Titanium oxide (manufactured by Ishihara Sangyo Co., Ltd.) Comparative Example 10 Silica (manufactured by Tatsumori Corp.) Comparative Example 11 Magnesium oxide (manufactured by Kyowa Chemical Co., Ltd.) Comparative Example 12 Titanium oxide (manufactured by Ishihara Sangyo Co., Ltd.) The following evaluation tests were performed on each of the above Examples and Comparative Examples. (Measurement of Molding Slurry Viscosity) The slurries of the thermally conductive silicone rubber compositions of the respective Examples and Comparative Examples were measured for viscosity with a rheometer at a shear rate of 5 (1 / S). (Measurement of compression set) The heat radiation sheet 3 of each of the examples and comparative examples was compressed by 50%, and
After treatment at 20 ° C. for 10 h, it was measured what percentage of the compression remained as strain. (Measurement of tear strength) The heat dissipation sheet 3 of each of Examples and Comparative Examples was subjected to JIS.
It was measured according to No. 2 type A type by K6301. (Rubber hardness measurement) The heat dissipation sheet 3 of each of the examples and the comparative examples was measured according to JIS.
It measured according to K6301A. Moreover, after treating the heat radiation sheet of each example and the comparative example at 150 ° C. for 1000 hours,
Similarly, the rubber hardness was measured, and the change in rubber hardness after heating was measured.

The above results are shown in Tables 1 and 2.

[0037]

[Table 1]

[0038]

[Table 2]

Here, -OMe in the table is a methoxy group, -O
Et represents an ethoxy group .

As can be seen from Tables 1 and 2, Examples 1 to
It was confirmed that the sample of No. 11 exhibited a reduction in the permanent compression set, an improvement in the tear strength, and a change in the rubber hardness after heating as a whole as compared with the samples of Comparative Examples 1 to 12.

Table 2 shows a list of Examples and Comparative Examples classified according to the structure of the silane coupling agent.
Table 4 shows a list of measurement results of compression set classified by the structure of the silane coupling agent, Table 4 shows a list of measurement results of tear strength classified by the structure of the silane coupling agent, and Table 5 shows a structure of the silane coupling agent. A list of the measurement results of the rubber hardness classified by the above is shown below.

[0042]

[Table 3]

[0043]

[Table 4]

[0044]

[Table 5]

[0045]

[Table 6]

As can be seen from Table 4, it was confirmed that the compression set was reduced by the treatment with the silane coupling agent having an aliphatic alkyl group having 6 or more carbon atoms. Specifically, when the coupling agent was not treated, 98% (Comparative Example 1) and the alkyl group of the silane coupling agent had 1 carbon atom.
In the case of a methyl group, the content is 85 to 95% (Comparative Examples 2 to 9), but it can be confirmed that the use of an alkyl group having 6 or more carbon atoms has reduced the content from 30% to 50%. Was.

Regarding the treatment amount of the silane coupling agent, since the difference in the compression set between 0.5 part by weight and 1.0 part by weight is small, the treatment amount of the silane coupling agent is 0.5 part by weight. It is considered that the effect of reduction is sufficiently obtained.

Further, it can be confirmed that the compression set tends to decrease as the chain length of the alkyl group increases from C ₆ to C _10, and the length of the alkyl group is important for the effect of reducing the compression set. It was confirmed that it had an effect.

As can be seen from Table 5, it was confirmed that the treatment with the silane coupling agent having an aliphatic alkyl group having 6 or more carbon atoms improved the tear strength. Specifically, when the coupling agent was not treated (Comparative Example 1) and when the alkyl group of the silane coupling agent was a methyl group having 1 carbon atom (Comparative Examples 2 to 9), the tear strength was 0.4 to 0. .
While it was about 5 kgf / cm ² , it was observed that by using an alkyl group having 6 or more carbon atoms, the tear strength was doubled to 1 kgf / cm ² or more.

Also, regarding the tear strength, since the difference in the tear strength between 0.5 parts by weight and 1.0 parts by weight is small,
It is considered that the effect of improving the tear strength can be sufficiently obtained with the treatment amount of 0.5 part by weight.

Further, it can be confirmed that the tear strength tends to increase as the chain length of the alkyl group increases from C ₆ to C _10, and the tear strength tends to be slightly higher in the case of bifunctional than in the case of trifunctional. It was confirmed that the length and number of the alkyl groups had a great influence on the tear strength.

As can be seen from Table 6, the treatment of the silane coupling agent having an aliphatic alkyl group having 6 or more carbon atoms reduces the change in rubber hardness after heat treatment, that is, the effect of improving the heat-resistant mechanical properties. It was confirmed that it would occur.
Specifically, when the coupling agent was not treated (Comparative Example 1),
The change in rubber hardness after the heat treatment significantly increases to +40, and when the alkyl group of the silane coupling agent is a methyl group having 1 carbon atom (Comparative Examples 2 to 9), it is about +10 to +25, Alkyl groups with 6 or more carbon atoms, although reduced, but greatly increased by comparison
, The change in rubber hardness after the heat treatment is +1
It was confirmed that it was reduced to less than 0.

It was also confirmed that as the chain length of the alkyl group increased from C ₆ to C ₁₀ , the change in rubber hardness after heat treatment tended to decrease. Was confirmed to have a significant effect on In addition, a tendency was observed that the change in rubber hardness was reduced in the case of bifunctional than in the case of trifunctional.

The rubber hardness before the heat treatment tends to decrease as the chain length of the alkyl group increases from C ₆ to C _10, and the addition amount of the silane coupling agent ranges from 0.5 parts by weight to 1. It was confirmed that the rubber hardness before the heat treatment was significantly affected by the number of carbon atoms and the amount of the alkyl group of the silane coupling agent.

[0055]

As described above, the thermally conductive silicone rubber composition according to the first aspect of the present invention comprises a silicone rubber,
A thermal conductive inorganic filler which has been subjected to surface treatment with the silane coupling agent represented by the general formula (A ) is dispersed.
Ri, thermally conductive inorganic filler thermoelectric Shirubesei silicone rubber sets
40vol% ~80vol% der because respect Narubutsu total amount, the surface of the thermally conductive inorganic filler is covered with the alkyl group of the hydrophobic long chain improves compatibility with the silicone rubber,
Even when the matrix silicone rubber is highly filled with a thermally conductive inorganic filler to enhance thermal conductivity, the viscosity of the slurry of the thermally conductive silicone rubber composition in the form of a slurry increases and the molding processability decreases. It is possible to improve the moldability of the thermally conductive silicone rubber composition which is highly filled with the thermally conductive inorganic filler, prevent aggregation of the thermally conductive inorganic fillers, and reduce the amount of the silicone rubber. A good dispersion state with little secondary aggregation of the thermally conductive inorganic filler in the matrix can be achieved, the flexibility of the cured molded product of the thermally conductive silicone rubber composition is improved, and the rubber elasticity is improved. Together with the tensile strength,
A <br/> shall be able to reduce the enhancement and compression set tear strength, and the thermal conductive inorganic filler grains as described above with is difficult to cause oxidation of the silicone rubber by thermal aging (high-temperature storage) This hardly causes agglomeration of the heat-conductive silicone rubber composition, and can reduce changes in mechanical properties such as changes in rubber hardness in a heat resistance test of a cured molded product of the heat conductive silicone rubber composition. Also heat transfer
Conductive inorganic filler is the total amount of thermally conductive silicone rubber composition
High thermal conductivity by being at least 40 vol%
And 80% by volume or less, it has thermal conductivity
Hardened and brittle cured silicone rubber composition
Can be prevented.

The thermally conductive silicone rubber composition according to the second aspect of the present invention is characterized in that, in addition to the constitution of the first aspect, a metal oxide, a metal nitride or a metal nitride is used as the thermally conductive inorganic filler.
Since a metal carbide, a metal boride, and a metal simple substance are used, the heat conductivity of the heat conductive silicone rubber composition can be efficiently improved, and the heat conductive inorganic filler can be easily removed. It can be subjected to a silane coupling treatment.

Further, in the thermally conductive silicone rubber composition according to the third aspect of the present invention, since alumina is used as the thermally conductive inorganic filler, the reactivity between the thermally conductive inorganic filler and the silane coupling agent is good. It can improve the processing efficiency of the silane coupling agent with respect to the thermally conductive inorganic filler, and can also reduce the cost of the thermally conductive inorganic filler and increase the amount of the thermally conductive inorganic filler. .

Further, in the thermally conductive silicone rubber composition according to the fourth aspect of the present invention, since silica is used as the thermally conductive inorganic filler, the reactivity between the thermally conductive inorganic filler and the silane coupling agent is good. It can improve the processing efficiency of the silane coupling agent with respect to the thermally conductive inorganic filler, can also reduce the cost of the thermally conductive inorganic filler, and can increase the amount of the thermally conductive inorganic filler. is there.

In the heat radiation sheet according to the fifth aspect of the present invention, the heat conductive silicone rubber composition according to any one of the first to fourth aspects is molded, so that the moldability in forming the heat radiation sheet is improved. The heat dissipation sheet has high rubber elasticity and high strength.
When placed between the radiator and the electronic component, the warpage and undulation of the joint surface between the radiator and the electronic component can be easily filled without applying a strong load to the electronic component. Since the heat dissipation sheet has high thermal conductivity, there is no space with high thermal resistance, and the heat conduction efficiency from the electronic component to the radiator is improved, and the heat from the electronic component is easily radiated. Is what you can do. Further, since the change in the mechanical properties in the heat resistance test is low, the change in the mechanical properties due to the heat generated from the electronic components is small, and the device can be used stably for a long period of time.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A) is a schematic diagram showing a thermally conductive inorganic filler surface-treated with a silane coupling agent, and (b) is a partially enlarged schematic diagram of (a).

Figure 2 (a) is a sectional view showing an example of application of the thermal sheet release of the present invention, (b) is an enlarged view of a portion of (a), (c)
FIG. 4 is a partial cross-sectional view showing a joint surface between a radiator and an electronic component when a heat radiating sheet is not used.

[Explanation of symbols]

 1 thermal conductive inorganic filler 3 heat dissipation sheet

Continuation of the front page (56) References JP-A-9-321191 (JP, A) JP-A-7-292251 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83 / 04 C08K 7/04 C08K 9/06 C08K 3/20 C08K 3/28 C08K 3/34 C08K 3/38

Claims (5)

(57) [Claims] To 1. A silicone rubber, Ri formed by dispersing thermally conductive inorganic filler surface-treated with a silane coupling agent represented <br/> by the following general formula (A), the thermally conductive inorganic Fi
Is 40% based on the total amount of the thermally conductive silicone rubber composition.
vol% ~80vol% der Rukoto thermally conductive silicone rubber composition characterized. Embedded image 2. The heat conduction according to claim 1, wherein the heat conductive inorganic filler is selected from the group consisting of metal oxides, metal nitrides, metal carbides, metal borides, and simple metals. Silicone rubber composition. 3. The thermally conductive silicone rubber composition according to claim 1, wherein alumina is used as the thermally conductive inorganic filler. 4. The thermally conductive silicone rubber composition according to claim 1, wherein silica is used as the thermally conductive inorganic filler. 5. A heat dissipation sheet formed by molding the heat conductive silicone rubber composition according to claim 1.