JP2002194379A - Heat-releasing grease - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-releasing grease low in infiltrativeness into objects coated therewith and excellent in thermal stability and heat releasing tendency. SOLUTION: This heat-releasing grease comprises (A) a silicone oil shown by the general formula (R1 is at least one hydrocarbon group selected from methyl, ethyl, propyl, butyl, vinyl, allyl and phenyl; R2 is a 6-20C alkyl or aralkyl; and m is an integer of 3-100), (B) at least one inorganic compound selected from zinc oxide, magnesium oxide, aluminum oxide, beryllium oxide, calcium oxide, aluminum nitride, boron nitride and silicon carbide, (C) n- octadecyl-3-(3,5-di-tert-butyl-4-hydroxypheny)propionate and (D) pentaerythrityl tetrakis(3-laurylthiopropionate).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiation grease, and more particularly, to a heat radiation grease having a small amount of infiltration of a base oil into an object to be coated and excellent heat radiation.

[0002]

2. Description of the Related Art A heat radiating member such as a heat sink is used to radiate heat generated from a semiconductor chip to the outside. Usually, a heat radiation grease excellent in thermal conductivity is applied between a semiconductor package having a built-in semiconductor chip and a heat sink or the like in order to reduce contact thermal resistance.

Heretofore, as this kind of heat radiation grease, there has been known a grease based on dimethyl silicone oil which is blended with an inorganic compound such as zinc oxide, aluminum oxide and beryllium oxide.

[0004] However, such a heat radiation grease has the characteristics of excellent thermal stability and high heat radiation, but the base dimethyl silicone oil gradually infiltrates the semiconductor package to be coated, and the heat radiation grease for a long time. The function may be impaired during use.

Accordingly, attempts have been made to improve the wettability by introducing various groups into the side chains of the base polysiloxane, and methylphenyl silicone oils, alkyl-modified silicone oils and the like have been developed.

[0006] However, methylphenyl silicone oil has little effect, while alkyl-modified silicone oil having a so-called long-chain alkyl group such as decyl or dodecyl group introduced into the side chain has improved infiltration properties, There was a problem that the heat dissipation was lower than that using dimethyl silicone oil.

[0007]

As described above, a grease obtained by mixing a metal oxide such as zinc oxide with dimethyl silicone oil has excellent heat stability and heat dissipation,
There is a problem that the infiltration property to an object to be coated is high. On the other hand, the use of the alkyl-modified silicone oil has a problem that although the infiltration property is improved, the heat radiation property is low.

The present invention has been made in view of such problems of the prior art, and has a low infiltration property to an object to be coated.
It is another object of the present invention to provide a heat radiation grease having excellent heat stability and heat radiation.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have found that two kinds of compounds known as antioxidants, namely, n- Octadecyl-3- (3,5-di-tert-
By blending butyl-4-hydroxyphenyl) propionate, and pentaerythrityltetrakis (3-laurylthiopropionate) polysiloxane, heat radiation can be increased, thereby reducing the infiltration property to the object to be coated. Further, the inventors have found that a heat radiation grease having excellent heat stability and heat radiation properties can be obtained, and have completed the present invention.

That is, the heat radiation grease according to the first aspect of the present invention has the following general formula (A):

Embedded image (Wherein, R ¹ is at least one hydrocarbon group selected from a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, an allyl group, and a phenyl group; R ² is an alkyl group having 6 to 20 carbon atoms; Represents an aralkyl group, m represents an integer of 3 to 100), and has a viscosity at 25 ° C. of 10 to 100,000 cS
(B) at least one inorganic compound selected from zinc oxide, magnesium oxide, aluminum oxide, beryllium oxide, calcium oxide, aluminum nitride, boron nitride and silicon carbide; (C) n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and (D) pentaerythrityltetrakis (3-laurylthiopropionate).

The heat radiation grease according to the second aspect of the present invention is the heat radiation grease according to the first aspect,
(A) The component (A) is characterized in that R ¹ is a methyl group, and R ² is an alkyl group or an aralkyl group having 8 to 14 carbon atoms.

The lubricating grease according to the third aspect of the present invention is the heat radiation grease according to the first aspect,
The component (A) is characterized in that R ¹ is a methyl group and R ² contains at least a decyl group.

According to a fourth aspect of the present invention, there is provided a heat radiation grease according to the above heat radiation grease, wherein the viscosity of the component (A) at 25 ° C. is 50 to 10,000 cSt.

In the heat radiation grease, the component (C) and the component (D) are added in a total amount of 100 parts by weight of the silicone oil (A).
It is preferable to contain 1 to 7 parts by weight.

In the heat radiation grease, the compounding ratio of the component (C) and the component (D) is preferably 1: 4 to 4: 1 by weight. As described in item 7, it is more preferable that the compounding ratio of the component (C) and the component (D) is 1: 2 to 2: 1 by weight ratio, and as described in item 8, the component (C) It is even more preferable that the mixing ratio of the component (D) and the component (D) is approximately 1: 1 by weight.

In the above heat radiation grease, (C) n-
By incorporating octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and (D) pentaerythrityltetrakis (3-laurylthiopropionate), the wettability to the substrate is improved. It is possible to improve the heat dissipation while maintaining the characteristic of the component (A), which is low. This is presumably because the blending of both components improves the wettability of the silicone oil of the component (A), thereby increasing the amount of the inorganic compound of the component (B). That is, in order to simply increase the heat dissipation, it is sufficient to increase the amount of the inorganic compound having good thermal conductivity, but if the amount is too large, it is difficult to uniformly disperse the compound and the properties as grease are impaired. Therefore, the filling amount is limited. It is considered that by blending the component (C) and the component (D), the amount of such an inorganic compound that can be filled is increased, and the heat dissipation can be improved. Therefore, according to the present invention, it is possible to obtain a heat-dissipating grease having a small infiltration property with respect to an object to be coated and having excellent thermal stability and heat-dissipating properties.

[0017]

Embodiments of the present invention will be described below.

The heat radiation grease of the present invention has the following general formula (A):

Embedded image (Wherein, R ¹ is at least one hydrocarbon group selected from a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, an allyl group, and a phenyl group; R ² is an alkyl group having 6 to 20 carbon atoms; Represents an aralkyl group, m represents an integer of 3 to 100), and has a viscosity at 25 ° C. of 10 to 100,000 cS
(B) at least one inorganic compound selected from the group consisting of zinc oxide, magnesium oxide, aluminum oxide, beryllium oxide, calcium oxide, aluminum nitride, boron nitride, and silicon carbide; (C) n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and (D) pentaerythrityltetrakis (3-laurylthiopropionate).

The silicone oil (A) is the base of the heat-radiating grease of the present invention. In the general formula [I], R ¹ is at least one selected from a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, an allyl group, and a phenyl group. Preferably, 90% or more of R ¹ present in the molecule is a methyl group, and more preferably, the total amount of R ¹ is a methyl group. R ^{2 is} an alkyl group or an aralkyl group having 6 to 20 carbon atoms, preferably
8 to 14 alkyl groups or aralkyl groups. Carbon number 6
Specific examples of the alkyl group or aralkyl group of -20 include alkyl groups such as hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl;
And aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. In the present invention, particularly from the viewpoint of infiltration, 50 mol% or more of R ² present in the molecule is preferably a decyl group, and more preferably the entire amount of R ² is a decyl group.

The viscosity of the silicone oil (A) is 10 to 100,000 cSt at 25 ° C.
From the viewpoints of thermal stability, workability, and the like, 50 to 10,000 cSt is preferable, and 200 to 10,000 cSt is more preferable. Ten
If it is less than cSt, the thermal stability is poor, and if it exceeds 100,000 cSt, the fluidity is significantly reduced.

The component (B) is at least one inorganic compound selected from zinc oxide, magnesium oxide, aluminum oxide, beryllium oxide, calcium oxide, aluminum nitride, boron nitride and silicon carbide. Zinc oxide, aluminum oxide, and aluminum nitride having good properties are preferable, and zinc oxide is particularly preferable.

The amount of the component (B) is (A)
The amount is preferably 65 to 85 parts by weight, more preferably 75 to 80 parts by weight, based on 100 parts by weight of the silicone oil component. With less than 65 parts by weight, it is not only difficult to maintain a suitable consistency,
Insufficient heat radiation. On the other hand, when the amount exceeds 85 parts by weight, the grease becomes too hard, and it becomes difficult to use the grease as a heat radiation grease.

Component (C) n-octadecyl-3- (3,5-di-
tert-butyl-4-hydroxyphenyl) propionate is used in combination with pentaerythrityltetrakis (3-laurylthiopropionate) as the component (D),
(A) It is an important component of the present invention, which makes it possible to fill a large amount of an inorganic compound into the silicone oil of the component and enhances the heat dissipation of the obtained grease. Such effects cannot be obtained by using either one of the component (C) and the component (D).

Component (C) n-octadecyl-3- (3,5-di-
Tert-butyl-4-hydroxyphenyl) propionate is a white crystalline powder represented by the following structural formula [II], and pentaerythrityltetrakis as component (D).
(3-Laurylthiopropionate) has the following structural formula [II
I], which are white flakes or powders, all of which are known as antioxidants for polyolefins, styrene resins, various synthetic rubbers and the like.

[0025]

Embedded image

The n-octadecyl component (C)
The blending amounts of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and pentaerythrityltetrakis (3-laurylthiopropionate) as the component (D) are the total amount of the component (A). 0.1 to 7 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the silicone oil. If the amount is less than 0.1 part by weight, the effect of improving the heat radiation property is small, and if it exceeds 7 parts by weight, precipitation of these components may occur at low temperatures.

The mixing ratio of these two components (C):
(D) is preferably 1: 4 to 4: 1 in weight ratio, and if it is out of this range, the effect of the combined use, that is, the effect of improving the heat radiation property will not be sufficiently obtained. A more preferable range of the compounding ratio (C) :( D) of the two components is 1: 2 to 2: 1 and particularly preferably approximately 1: 1.

In addition to the above-mentioned components, the heat-radiating grease of the present invention includes amino-based and mercaptan-based protective materials which are conventionally used in this type of thermal grease as long as the effects of the present invention are not impaired. Rust agents, phenol-based, amine-based, organic sulfur-based antioxidants, viscosity control agents such as silicon dioxide powder, and additives such as coloring agents may be added.

In order to produce the heat radiation grease of the present invention, the above components are charged into a heating vessel equipped with a stirrer, heated and kneaded, then returned to room temperature, and homogenized using a three roll, paint roll or the like. And a method of homogenizing a mixture obtained by uniformly mixing without heating with a three-roll roll, a paint roll, or the like.

The heat-dissipating grease of the present invention is particularly useful for applications such as power transistors and power ICs, which generate a large amount of heat, because they have little infiltration of the base oil into the object to be coated and are excellent in thermal stability and heat dissipation.

[0031]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight”.
And the viscosity is a value measured at 25 ° C.

Example 1 In formula [I], R ¹ is a methyl group, R ² is an n-decyl group and the viscosity is 700 cSt, 20 parts of methyl decyl silicone oil, 80 parts of zinc oxide and n-octadecyl-3 -(3,5-di-tert
0.5 part of -butyl-4-hydroxyphenyl) propionate and 0.5 part of pentaerythrityltetrakis (3-laurylthiopropionate) were charged into a heating vessel equipped with a stirrer, and were heated and kneaded to homogenize. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Example 2 In the general formula [I], R ¹ is a methyl group, R ² is an n-decyl group, and 25 parts of a methyldecyl silicone oil having a viscosity of 500 cSt, 75 parts of zinc oxide, and n-octadecyl-3 -(3,5-di-tert
-Butyl-4-hydroxyphenyl) propionate (0.1 part) and pentaerythrityltetrakis (3-laurylthiopropionate) (0.1 part) were charged into a heating kettle equipped with a stirrer, kneaded by heating and homogenized. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Example 3 In the general formula [I], R ¹ is a methyl group, R ² is an n-dodecyl group, 25 parts of methyl dodecyl silicone oil having a viscosity of 1100 cSt, 75 parts of zinc oxide, and n-octadecyl-3 -(3,5-
0.7 parts of di-tert-butyl-4-hydroxyphenyl) propionate and 0.7 parts of pentaerythrityltetrakis (3-laurylthiopropionate) were charged into a heating kettle equipped with a stirrer, and were heated and kneaded to homogenize. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Example 4 In the general formula [I], R ¹ is a methyl group, R ² is an n-hexyl group, 20 parts of methylhexyl silicone oil having a viscosity of 3000 cSt, 80 parts of zinc oxide, and n-octadecyl-3 -(3,5-
0.2 parts of di-tert-butyl-4-hydroxyphenyl) propionate and 0.2 parts of pentaerythrityltetrakis (3-laurylthiopropionate) were charged into a heating vessel equipped with a stirrer, and were heated and kneaded to homogenize. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Example 5 In the general formula [I], R ¹ is a methyl group and 70 mol% of R ² is
30 parts by mole of n-decyl group, 30 parts by weight of methyloctyldecyl silicone oil having a viscosity of 440 cSt, 60 parts of zinc oxide, 10 parts of aluminum oxide, and n-octadecyl-
0.5 parts of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and pentaerythrityltetrakis (3-
Lauryl thiopropionate) was charged into a heating kettle equipped with a stirrer, and kneaded with heat to homogenize. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Example 6 Methyl octyl silicone oil having a viscosity of 700 cSt, wherein R ¹ is a methyl group and R ² is an n-octyl group in the general formula [I].
75 parts, aluminum nitride 25 parts, n-octadecyl-3-
0.3 parts of (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 0.4 parts of pentaerythrityltetrakis (3-laurylthiopropionate) were charged into a heating vessel equipped with a stirrer, and heated and kneaded. And homogenized. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

[0038] Comparative Example 1 formula [I] in which R ¹ is a methyl group, with R ² is n- decyl group, and 30 parts of methyl decyl silicone oil with a viscosity of 440CSt, with stirrer and 70 parts of zinc oxide heated kettle And homogenized by heating and kneading. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

Comparative Example 2 In the general formula [I], 28 parts of dimethyl silicone oil having a viscosity of 1000 cSt and R ¹ and R ^{2 each} being a methyl group and 72 parts of zinc oxide were charged into a heating kettle equipped with a stirrer, and mixed by heating. It was kneaded and homogenized. The mixture was allowed to cool to room temperature and mixed with a paint roll to prepare grease.

The grease obtained in each of the above Examples and Comparative Examples was evaluated for heat resistance and infiltration property, and at the same time, was measured for compatibility with JIS K 2220 and thermal conductivity. In addition, the infiltration property was measured using a silicone rubber sheet (GE
Toshiba Silicone's silicone rubber (trade name TSE221-5)
A vulcanizing agent was added to U), and after press-curing, grease was applied to the surface of a sheet obtained by post-curing at 200 ° C. × 4 hours , and the volume change after 120 ° C. × 7 days was measured. Table 1 shows the results.

[0041]

[Table 1]

As can be seen from Table 1, the lubricating grease of the present invention has n-octadecyl-3- (3,5-di-tert-butyl-4-
The thermal conductivity is improved by the blending of (hydroxyphenyl) propionate and pentaerythrityltetrakis (3-laurylthiopropionate), and it also has good properties with respect to the infiltration property to the object to be coated.

[0043]

As described above, the heat-radiating grease of the present invention has low infiltration to an object to be coated, and is excellent in heat stability and heat radiation. Therefore, it is useful for applications such as power transistors and power ICs that generate a large amount of heat,
The stability and longevity of those devices can be provided.

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Claims (8)

[Claims] (A) A general formula: (Wherein, R ¹ is at least one hydrocarbon group selected from a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, an allyl group, and a phenyl group; R ² is an alkyl group having 6 to 20 carbon atoms; Represents an aralkyl group, m represents an integer of 3 to 100), and has a viscosity at 25 ° C. of 10 to 100,000 cS
(B) at least one selected from zinc oxide, magnesium oxide, aluminum oxide, beryllium oxide, calcium oxide, aluminum nitride, boron nitride and silicon carbide
One inorganic compound, (C) n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and (D) pentaerythrityltetrakis (3-laurylthiopropionate) A heat radiation grease characterized by containing: 2. The component (A) wherein R ¹ is a methyl group and R ²
The heat-dissipating grease according to claim 1, wherein is a C8-C14 alkyl group or an aralkyl group. 3. The component (A) wherein R ¹ is a methyl group and R ²
Contains at least a decyl group.
Thermal grease as described. 4. The viscosity of the component (A) at 25 ° C. is 50.
The heat radiation grease according to any one of claims 1 to 3, wherein the heat radiation grease has a viscosity of up to 10,000 cSt. 5. A total amount of component (C) and component (D) of 100 parts by weight of silicone oil (A).
The heat radiation grease according to any one of claims 1 to 4, wherein the grease is contained in an amount of 1 to 7 parts by weight. 6. The composition according to claim 1, wherein the mixing ratio of the component (C) and the component (D) is 1: 4 to 4: 1 by weight.
The heat radiation grease according to any one of the above. 7. The composition according to claim 1, wherein the mixing ratio of the component (C) to the component (D) is 1: 2 to 2: 1 by weight.
The heat radiation grease according to any one of the above. 8. The heat radiation grease according to claim 1, wherein the mixing ratio of the component (C) and the component (D) is approximately 1: 1 by weight.