JP3319946B2 - Unvulcanized thermal conductive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally conductive composition, and more particularly, to a heat-generating body such as an MPU, an IC, or a transistor, and to a heat-radiating fin. Heat conductive composition.

[0002]

2. Description of the Related Art Conventionally, a heat conductive composition based on silicone oil, zinc white or alumina powder,
Aluminum nitride powder or a thermally conductive grease composition using two of these in combination (Japanese Patent Publication No. 52-332)
No. 72, JP-B-59-52195, JP-B-60-14
No.792, No.57-36302, No.6-39
No. 591) and a thermally conductive rubber composition (JP-B-47-71).
50, Japanese Patent Publication No. 54-4985, Japanese Patent Publication No. 57-9595,
JP-B-56-23463 and JP-A-55-80461 are known.

[0003] The grease composition is characterized in that it is interposed between the heating element and the radiating fins and can follow the peripheral shape and easily adhere to it. There are drawbacks such as oozing. Further, in the case of a rubber composition, only a heat conductive rubber composition which is cured to become a rubber elastic body is known,
Unvulcanized type is not known. In the case of such a curable rubber composition, the rubber elasticity is damaged, and if a screw is disposed between the heating element and the radiation fin, a difference in thickness occurs between the vicinity of the screw and another portion. This has the drawback that heat conduction is deteriorated due to the formation of a gap, and that the adhesive cannot be attached to the heat radiating surface due to lack of tackiness, so that the usability in actual use is poor.

[0004]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned drawbacks. As a result, the use of a linear high-polymerization degree silicone as a base makes it possible to obtain a grease composition and a rubber composition. The inventors have found that a thermally conductive composition having advantages can be obtained, and have reached the present invention. Therefore, an object of the present invention is to provide a heat conductive composition which does not cause separation of a base and a thickener, has an appropriate tackiness to be attached to a heat dissipation surface, and is easy to use. .

[0005]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
(1) Viscosity at 25 ° C of 20,000 poise to 40
0000 poise linear high polymerization degree silicone 10
0 parts by weight, (2) organic solvent soluble silicone resin 5
200 parts by weight, and (3) a thermally conductive inorganic filler 200
It was achieved by unvulcanized thermally conductive composition, characterized in that it consists of 1500 parts by weight.

[0006] The linear high-polymerization degree silicone of the first component is
Its viscosity at 25 ° C. is 20,000 poise to 40
It needs to be 0000 poise,
This is because, when used as a base for the heat conductive composition, separation or bleeding of the base is avoided. Such a linear high-polymerization degree silicone can also provide an appropriate elasticity, and is therefore most suitable as a base for a heat conductive composition. In the present invention, the general formula R ¹ _a SiO
_{(4-a) / 2} (where R ¹ is a monovalent hydrocarbon group or hydroxyl group having 1 to 14 carbon atoms, and a is 2.00 <a <2.20). It is particularly preferred to use silicone.

[0007] The organic solvent-soluble silicone resin of the second component is necessary in order to provide adequate tackiness in the thermally conductive composition, in the present invention, R ² ₃ SiO _1/2 units and SiO ₂ units It is preferable to use those having a ratio of 0.5: 1 to 2: 1, especially 0.6: 1 to 0.9: 1.
It is preferable to use The above tackiness,
When used as a heat conductive material, it has the effect of lightly adhering it to a heating element or a radiating fin, so that the heat conductive composition of the present invention is easy to use.

[0008] The third component, a thermally conductive inorganic filler, is indispensable as a filler for compounding the unvulcanized rubber and for further enhancing the thermal conductivity. Examples of the thermally conductive inorganic filler used in the present invention include, for example, alumina, zinc white, aluminum nitride, silicon nitride, silicon carbide, boron nitride, carbon, diamond and the like. Aluminum nitride, boron nitride and the like are preferred. These may be used alone or in combination of two or more. In the present invention, the average particle size of the filler is preferably 500 μm or less, and particularly preferably 50 μm or less.

The composition of the present invention includes, for example, amine compounds such as isopropoxydiphenylamine and N-phenyl-α-naphthylamine, and 4,4′-methylene-bis-2 as long as the properties of the present invention are not impaired. , 6-di-tert-butylphenol and the like, and, for example, Opras Red RR and Orient Oil Bull-IIN
Additives such as colorants (all manufactured by Orient Chemical Co., Ltd.), CI Pigment Yellow 81 and CI Pigment Yellow 110 (all manufactured by Sanyo Dye Co., Ltd.) can be added.

[0010] The heat conductive composition of the present invention comprises
It can be easily produced by kneading the component, the second component, the third component, and the like, but in particular, 100 to 180
℃, kneading for several hours, high uniformity,
Preferred for obtaining a stable composition. As a kneading machine, two rolls, Banbury mixer, Shinagawa mixer,
Any of a planetary mixer and the like may be used, but in the present invention, a heating and pressure type kneader is particularly optimal.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The thermally conductive composition of the present invention comprises 25
100 parts by weight of a linear high-polymerization degree silicone having a viscosity of 20,000 to 400,000 poise at 5 ° C., 5 to 200 parts by weight of an organic solvent-soluble silicone resin, and 200 to 1500 parts by weight of a thermally conductive filler are kneaded. Can be easily obtained.

[0012]

The thermal conductive composition of the present invention contains a linear high-polymerization degree silicone as a base, so that it does not separate from the thickener even when used for a long period of time, and has an appropriate degree. Easy to use because it has tackiness. Furthermore, since it is not vulcanized, even if it is arranged between the heating element and the radiating fin, it does not cause a gap.

[0013]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. still,
The measurement of the consistency in the present embodiment is performed according to JIS-K-2220.
The measurement of the thermal conductivity was performed using a thermal conductance tester C-matic manufactured by Dynatech, USA.

Example 1 The viscosity at 25 ° C. was 300,
2,000 poise linear high polymerization degree dimethyl silicone 10
0 parts by weight, (CH ₃ ) ₃ SiO _1/2 / SiO ₂ = 0.7
After weighing 25 parts by weight of an organic solvent-soluble silicone resin having a ratio of 1: 1 and 375 parts by weight of zinc white having an average particle diameter of 0.3 μm, the mixture was kneaded well at 160 ° C. for 2 hours using a heating kneader. A rubber compound-like thermally conductive composition having a property was obtained. Physical properties of the obtained composition were as follows: a consistency (unmixed) of 72, a specific gravity of 2.67 at 25 ° C., and a thermal conductivity of:
2.18 × 10 ⁻³ cal / cm · sec · ° C., all of which were good values.

When the above-mentioned heat conductive composition is mounted between a power transistor and a heat radiating fin, it has an appropriate tackiness and thus easily adheres to the heat radiating fin. Was
The workability was excellent and the power transistor could be easily screwed. Further, even after one year, the base linear dimethyl silicone having a high degree of polymerization did not show any separation or bleeding.

Example 2. The viscosity at 25 ° C. was 100,
2,000 poise linear high polymerization degree dimethyl silicone 10
0 parts by weight, (CH ₃ ) ₃ SiO _1/2 / SiO ₂ = 0.6
24.7 parts by weight of a 5/1 organic solvent-soluble silicone resin, aluminum nitride having an average particle size of 1.8 μm.
3 parts by weight and zinc white 12 having an average particle size of 0.25 μm
After weighing 7.5 parts by weight, using a heating kneader,
The mixture was heated and mixed at 180 for 1 hour to obtain a rubber compound heat conductive composition having excellent tackiness. The physical properties of this composition were as follows: a consistency (unmixed) of 63;
33, thermal conductivity 3.85 × 10 ⁻³ cal / cm · se
c · ° C., all of which were favorable values.

When the obtained heat conductive composition was used in the same manner as in Example 1, it adhered well to the radiating fins because it had an appropriate tackiness, and did not fall even in a vertical state. Mounting to the transistor was performed quickly and reliably. Further, even after one year, no separation or bleeding of the base linear high polymerization degree dimethyl silicone was observed at all.

Example 3. The viscosity at 25.degree.
000 poise, 100 parts by weight of linear high-polymerization methylphenylsilicone (phenyl group 5 mol%), (CH ₃ ) ₃
33 parts by weight of an organic solvent-soluble silicone resin having SiO _1/2 / SiO ₂ = 0.6 / 1, 467 parts by weight of boron nitride having an average particle diameter of 3.0 μm, and an average particle diameter of 0.4 μm
133 parts by weight of zinc white
The mixture was heated and mixed at 0 ° C. for 6 hours to obtain a rubber compound heat conductive composition having excellent tackiness. The physical properties of this thing
It had a consistency (not mixed) of 56, a specific gravity of 1.95 at 25 ° C., and a thermal conductivity of 3.20 × 10 ⁻³ cal / cm · sec · C, showing good thermal conductivity.

The obtained heat conductive composition was used in the same manner as in Example 1. The heat conductive composition adhered well to the radiation fins because of the appropriate tackiness, and the heat conductive composition fell even in a vertical state. Since there was no power transistor, the installation of the power transistor could be carried out smoothly. Further, even after one year, no separation or bleeding of the base linear high polymerization degree methylphenyl silicone was observed at all.

Example 4. The viscosity at 25 ° C. was 200,
2,000 poise linear high polymerization degree dimethyl silicone 10
0 parts by weight, (CH ₃ ) ₃ SiO _1/2 / SiO ₂ = 0.8
20 parts by weight of an organic solvent-soluble silicone resin and 280 parts by weight of alumina having an average particle diameter of 6 μm were mixed by heating at 120 ° C. for 5 hours using a heating kneader, and the heat conduction of a rubber compound having excellent tackiness was achieved. The composition was obtained.
The physical properties of this composition were as follows: a consistency (not mixed) of 90, a specific gravity of 2.36, and a thermal conductivity of 2.50 × 10 ⁻³ cal / cm ·
sec. ° C., indicating good thermal conductivity.

When the obtained heat conductive composition was used in the same manner as in Example 1, it had an appropriate tackiness, so that it adhered well to the radiation fins and did not fall even in a vertical state. The mounting of the transistor could be performed reliably and quickly. Even after one year, no separation or bleeding of the base linear high polymerization degree dimethyl silicone was observed at all.

Comparative Example 1 A heat conductive composition was obtained in exactly the same manner as in Example 1 except that the second component was removed from the composition of Example 1. The resulting composition has a consistency (unmixed) of 70, a specific gravity of 2.52 at 25 ° C., and a thermal conductivity of 2.16 × 10 ⁻³ cal.
/ Cm · sec · ° C.
However, because of the lack of tackiness, it did not adhere to the radiation fins, and when used in the same manner as in Example 1, the mounting of the power transistor was not easy.

Comparative Example 2 Commercially available oil compound for heat radiation (KS-609: manufactured by Shin-Etsu Chemical Co., Ltd.)
In the same way as in Example 1, it was grease-like, so it adhered to the radiating fins temporarily. However, when the radiating fins were set vertically without screws, the power transistor slipped down and the power transistor was easily mounted. Was not. One year after the use, the base oil had oozed out to the periphery. Comparative Example 3 A commercially available rubber sheet for heat radiation (TC-2
0A: manufactured by Shin-Etsu Chemical Co., Ltd.) in the same manner as in Example 1. The rubber sheet had no tackiness, and thus did not adhere to the radiation fins or power transistors.
Mounting was not easy.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 83/04 C08K 3/22 C08K 3/28 C08K 3/38

Claims (2)

(57) [Claims] (1) A viscosity at 25 ° C. of 20,000
100 parts by weight of a linear high-polymerization degree silicone having 0 to 400,000 poises, (2) 5-200 parts by weight of an organic solvent-soluble silicone resin, and (3) 200 to 1500 parts by weight of a thermally conductive inorganic filler. unvulcanized thermally conductive composition, characterized in that it consists of. 2. A method according to claim 1 as described in (1) to component unvulcanized thermally conductive composition obtained by heating and kneading at 100 to 180 ° C. (3).