KR20110121881A - Silicone composition having excellent long-term storage stability and heat-radiating function - Google Patents

Abstract

PURPOSE: A silicone composition is provided to exhibit high conductivity by including thermally conductive filler in high content, to maintain fluidity, to avoid a separation phenomenon of components different from oil components in a long-term storage. CONSTITUTION: A heat dissipation silicone composition comprises: (A) organopolysiloxane having a dynamic viscosity at 25°C of 5,000~30,000 mm^2/s; (B) silica processed with hexamethyl disilaznae; and (c) thermally conductive filler. The heat dissipation silicone composition is organopolysiloxane having a structure represented by chemical formula 1. In chemical formula 1, R1 is a C1-12 substituted or unsubstituted monovalent hydrocarbon group; R2 is C1-10 alkyl group, C1-10 alkoxyalkyl group, C2-10 alkenyl group or C1-10 acyl group; m is an integer of 5-100; and n is an integer of 1-3.

Description

Silicone composition having excellent long-term storage stability and heat-radiating function}

The present invention relates to a silicone composition excellent in long-term storage stability and heat dissipation, and more particularly, a high content of thermally conductive fillers to exhibit high thermal conductivity while separating oil components and other components even during long-term storage. The present invention relates to a thermally conductive silicone composition which is stable due to less development, maintains fluidity, has good handleability, and has excellent durability and reliability under high temperature and high humidity conditions.

Since most electronic components generate heat during use, it is necessary to remove heat from the electronic components in order to function properly. In particular, in integrated circuit devices such as CPUs used in personal computers, the amount of heat generated is increased due to the increase in the operating frequency.

Many methods have been proposed as a means of removing this heat. In particular, in electronic components having a large amount of heat generated, a method of repelling heat by interposing a thermally conductive material such as a thermally conductive compound or a thermally conductive sheet between the electronic component and a member such as a heat sink has been proposed.

As such a thermally conductive material, heat dissipating compounding based on silicone oil and containing zinc oxide or alumina powder is known. Further, in order to improve thermal conductivity, a thermally conductive material using aluminum nitride powder includes at least one selected from liquid organo silicon carrier, silica fiber, dendrites zinc oxide, flaky aluminum nitride, and flaky boron nitride. Thixotropic thermal conductive materials are also known.

Japanese Laid-Open Patent Publication No. 2005-374486 discloses a silicone composition obtained by mixing spherical hexagonal aluminum nitride powder having a specific particle size range with a specific organopolysiloxane. This Japanese Laid-Open Patent discloses a thermally conductive silicone composition in which aluminum nitride powder having a fine particle diameter and aluminum nitride powder having a rough particle diameter are combined; A thermally conductive silicone composition combining aluminum nitride powder and zinc oxide powder; A thermally conductive compound composition using aluminum nitride powder surface treated with organosilane; And a thermally conductive silicone composition comprising a silicone resin, diamond, zinc oxide, and a dispersant. The thermal conductivity of aluminum nitride is 70 to 270 W / (m · K), and the diamond thermal conductivity is higher than this to 900 to 2,000 W / (mK).

Japanese Laid-Open Patent Publication 2005-374486

An object of the present invention has a high thermal conductivity, excellent stability in long-term storage, good workability because it maintains excellent fluidity, and further excellent fine heat dissipation performance by following fine unevenness, reducing contact thermal resistance, high temperature It is to provide a high-performance heat dissipating composition that can improve the durability at high humidity in high humidity conditions.

According to the present invention, (A) organopolysiloxane having a kinematic viscosity of 5,000 to 30,000 mm ² / s at 25 ° C., (B) silica treated with hexamethylene disilazane (HMDZ) and (C) thermally conductive filler Provided is a heat dissipating silicone composition comprising a.

According to the present invention, it has high thermal conductivity, excellent stability in long-term storage, and good workability because it maintains excellent fluidity. Furthermore, it has excellent heat dissipation performance by following minute unevenness and reducing contact thermal resistance, and high temperature. It is possible to obtain a heat dissipating composition that has high durability in high humidity conditions and can improve reliability during mounting. The heat dissipating composition according to the present invention may be, for example, a general power source; Electronic devices such as power transistors for power sources, power modules, thermistors, thermocouples, and temperature sensors; Since heat is applied between heat generating electronic parts such as integrated circuit elements such as LSI and CPU and heat dissipating parts such as heat spreaders, heat sinks, heat pipes, and heat sinks, heat can be efficiently transferred from the heat generators to the heat sinks. In addition, heat can be effectively removed from the heating element.

Hereinafter, the heat dissipating composition of the present invention will be described in detail for each component.

(A) organopolysiloxane

The composition of the present invention has a kinematic viscosity of 5,000 to 30,000 mm ² / s, preferably 10,000 to 25 ° C. at 25 ° C. in order to maintain the fluidity of the composition and to provide good handleability even when the thermally conductive filler as the component (C) is highly charged. Organopolysiloxanes of 20,000 mm ² / s are included. In this organopolysiloxane, if the kinematic viscosity at 25 ° C. is less than 5,000 mm ² / s, oil bleed is likely to occur from the composition, and if it exceeds 30,000 mm ² / s, the fluidity of the composition tends to be insufficient. (A) A component may be used individually by 1 type and may use 2 or more types together. The number average molecular weight of component (A) is 5,000 to 10,000.

Preferable (A) component is organopolysiloxane which has a structure represented by following General formula (1).

<Formula 1>

In Formula 1, R1 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R2 is independently an alkyl group having 1 to 10 carbon atoms, an alkoxyalkyl group having 1 to 10 carbon atoms, 2 carbon atoms It is an alkenyl group of 10 to 10 or an acyl group of 1 to 10 carbon atoms, m is an integer of 5 to 100, n is an integer of 1 to 3.

R 1 is independently an unsubstituted or substituted monovalent hydrocarbon group which is C 1 -C 12, and examples thereof include a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group, an aralkyl group, and a halogenation that satisfy this carbon number range. Alkyl group etc. are mentioned. Examples of the linear alkyl group include methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group and dodecyl group. Examples of the branched alkyl group include isopropyl group, isobutyl group, tert-butyl group and 2-ethylhexyl group. As a cyclic alkyl group, a cyclopentyl group and a cyclohexyl group are mentioned, for example. As an alkenyl group, a vinyl group and an allyl group are mentioned, for example. As an aryl group, a phenyl group and a tolyl group are mentioned, for example. As an aralkyl group, 2-phenylethyl group and 2-methyl-2-phenylethyl group are mentioned, for example. Examples of the halogenated alkyl group include 3,3,3-trifluoropropyl group, 2- (nonnafluorobutyl) ethyl group, and 2- (heptadecafluorooctyl) ethyl group. R1 is preferably a methyl group or a phenyl group.

R 2 is independently a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxyalkyl group, a C 2 -C 10 alkenyl group or a C 1 -C 10 acyl group. As a C1-C10 alkyl group, C1-C10 linear alkyl group, branched alkyl group, cyclic alkyl group etc. are mentioned similarly to what was illustrated about R1, for example. As a C1-C10 alkoxyalkyl group, a methoxyethyl group and a methoxypropyl group are mentioned, for example. As a C1-C10 acyl group, an acetyl group and an octanoyl group are mentioned, for example. R 2 is preferably a C 1 -C 10 alkyl group, more preferably a methyl group or an ethyl group.

m is an integer of 5-100. n is an integer of 1-3, Preferably it is 3.

The following are mentioned as a preferable specific example of (A) component.

(B) HMDZ treated silica

In the composition of the present invention, silica treated with hexamethylene disilazane (HMDZ) is used to suppress contact between water vapor and the component (A) at high temperature and high humidity to prevent weaning and to assist in the high filling of the component (C). Included.

Such HMDZ surface treatment agents and treatment methods are known in the art (see US Pat. No. 6,169.142 and US Pat. No. 6,136,758). (B) A component may be used individually by 1 type and may use 2 or more types together.

The addition amount of (B) component becomes like this. Preferably it is 0.1-10 weight part, More preferably, it is 1-10 weight part with respect to 100 weight part of (A) component. If the amount of component (B) added is less than 0.1 part by weight per 100 parts by weight of component (A), the effect of inhibiting layer separation between the oil and the filler is not sufficient.

(C) thermally conductive filler

The composition of the present invention includes a thermally conductive filler for the heat dissipation effect. Specific examples of component (C) include aluminum, silver, copper, nickel, zinc oxide, alumina, magnesium oxide, aluminum nitride, metal powder, boron nitride, silicon nitride, diamond, graphite, carbon nanotubes, metal silicon, iron oxide, carbon Fiber, glass fiber, glass beads powder, flaren or a combination of two or more thereof. These components may be used individually by 1 type, and may use 2 or more types together.

The average particle diameter of the component (C) is preferably in the range of 0.1 µm to 100 µm, more preferably in the range of 0.1 to 50 µm, even more preferably in the range of 1 to 20 µm. When the average particle diameter of (C) component exists in the said range, since the bulk density of (C) component tends to become large and a specific surface area tends to become small, it is easy to carry out high filling of (C) component in the composition of this invention. On the other hand, when the average particle diameter is too large, there is a possibility that the oil component is separated. The said average particle diameter can be calculated | required as a cumulative average diameter by volume based, for example by Horsfield's Packing Model.

Examples of the shape of the component (C) include spherical shape, polyhedron shape, rod shape, needle shape, disc shape, and indefinite shape, but are not particularly limited.

In the composition of the present invention, the content of the component (C) is preferably 50 to 500 parts by weight, more preferably 50 to 300 parts by weight, even more preferably 100 to 100 parts by weight of the component (A). 300 parts by weight, even more preferably 150 to 300 parts by weight. When content of (C) component is less than 50 weight part with respect to 100 weight part of (A) component, the thermal conductivity of the obtained heat radiating member will fall easily. On the other hand, when the content is larger than 500 parts by weight with respect to 100 parts by weight of the component (A), the viscosity of the resultant composition is too high, which tends to result in poor fluidity and handleability.

In addition, additives or fillers commonly used as optional components, such as antioxidants, wetting agents, antifoaming agents, pigments, flame retardants, and the like, may be further added to the composition of the present invention without departing from the object of the present invention.

The viscosity at 25 ° C. of the composition of the present invention is preferably 200 Pa · s or less (eg 1 to 200 Pa · s), more preferably 100 Pa · s or less (eg 10 to 100 Pa · s) More preferably, it is 100 Pa.s or less (10-100 Pa.s). When the said viscosity is in the said range, since the fluidity | liquidity tends to become favorable in the composition obtained, workability, such as a dispensing property and screen printing property, will improve easily, and it becomes easy to apply | coat a thin composition to a base material.

Further, the composition of the present invention preferably has a thermal resistance at 25 ° C of 1.0 ° C / W or less, more preferably 0.5 ° C / W or less, even more preferably 0.1 ° C / W or less. When the heat resistance is within the above range, the composition of the present invention can efficiently dissipate heat generated from the heat generating element into a heat dissipating part even when applied to a heat generating element having a large amount of heat generation. The degree of wetting is preferably 2% or less.

The composition of the present invention can be prepared by mixing the above components using a mixing device such as dough mixer (kneader), gate mixer, streamlined mixer, planetary mixer and the like. The composition thus obtained has a significant improvement in thermal conductivity and good workability, durability and reliability.

Hereinafter, although an Example and a comparative example are given and this invention is further explained, this invention is not limited to these Examples.

<Example>

Each of the following components was used to prepare an Example and a comparative example composition.

(A) organopolysiloxane having an alkoxy group bonded to a silicon atom

(25 ℃ kinematic viscosity: about 15,000 mm ² / s, number average molecular weight: about 7,500)

(B) Hexamethylene disilazane (HMDZ) treated silica (DEGUSSA R812)

(C) thermally conductive filler

Z-1: Zinc oxide (average particle diameter 3 micrometers)

Z-2: Zinc oxide (average particle diameter 10 micrometers)

A-1: Alumina Powder (average particle diameter 50.0 µm)

A-2: Aluminum powder (average particle diameter 5 micrometers)

A-3: zinc oxide powder (average particle diameter: 0.5 mu m)

 [The average particle diameter of the said (C) component is the cumulative average diameter of the volume reference | measured by the micro track MT3300EX which is the particle size analyzer manufactured by Nikiso Corporation. "

The components (A) to (C) were weighed and added to a 1 liter planetary mixer at the composition ratios (parts by weight) shown in Table 1, followed by mixing at 25 ° C. for 3 hours, to give Examples 1 to 3 and Comparative Examples 1 to 3, respectively. A composition was obtained.

The physical properties of the obtained composition were measured by the following test method, and the results are shown in Table 1.

[Viscosity]

After leaving the obtained composition for 24 hours at 25 degreeC constant temperature room, the viscosity in rotation speed of 10 rpm was measured using the viscometer (brand name: spiral viscometer).

[Thermal conductivity]

The obtained composition was poured into a 3 cm-thick mold, and a kitchen wrap was placed thereon, and the thermal conductivity of the composition was measured by a thermal conductivity meter (trade name: QTM-500) manufactured by Kyoto Denshi Kogyo Co., Ltd.

[Thermal resistance]

The obtained composition was applied to a CPU actually applied, and the thermal resistance was measured at 25 ° C. by a thermolab TLS-M thermal resistance measuring instrument (Standard-Modified ASTM5470-06).

[Heat resistance after high temperature]

After the obtained composition was left to stand in a 120 degreeC atmosphere for 1,000 hours, it measured again by the same thermal resistance measuring instrument as mentioned above.

[Reason]

After standing at 120 ° C. for 24 hours, the amount of separated oil was measured.

[Reason after temperature]

After 48 hours at 90 ℃ 95% constant temperature and humidity, the temperature of the separated oil was measured by standing at 120 ℃ 24 hours.

 Table 1

Claims (9)

(A) organopolysiloxanes having a kinematic viscosity of 5,000 to 30,000 mm ² / s at 25 ° C.,
(B) silica treated with hexamethylene disilazane and
(C) A heat dissipating silicone composition comprising a thermally conductive filler.
The heat dissipating silicone composition according to claim 1, wherein component (A) is an organopolysiloxane having a structure represented by the following general formula (1):
<Formula 1>

In Formula 1, R1 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R2 is independently an alkyl group having 1 to 10 carbon atoms, an alkoxyalkyl group having 1 to 10 carbon atoms, 2 carbon atoms It is an alkenyl group of 10 to 10 or an acyl group of 1 to 10 carbon atoms, m is an integer of 5 to 100, n is an integer of 1 to 3.

The heat dissipating silicone composition of claim 1, wherein component (A) is any one of the following organopolysiloxanes, or mixtures thereof:

The heat dissipating silicone composition according to claim 1, wherein the content of component (B) is 0.1 to 10 parts by weight per 100 parts by weight of component (A). The method of claim 1, wherein component (C) comprises aluminum, silver, copper, nickel, zinc oxide, alumina, magnesium oxide, aluminum nitride, metal powder, boron nitride, silicon nitride, diamond, graphite, carbon nanotubes, metal silicon, iron oxide , Carbon fiber, glass fiber, glass beads powder, flaren or a combination of two or more thereof. The heat dissipating silicone composition according to claim 1, wherein the average particle diameter of component (C) is in the range of 0.1 to 50 mu m.
The heat dissipating silicone composition according to claim 1, wherein the content of component (C) is 50 to 300 parts by weight per 100 parts by weight of component (A). The heat-dissipative silicone composition according to any one of claims 1 to 7, wherein the viscosity at 25 ° C is 100 Pa · s or less. The heat dissipating silicone composition according to any one of claims 1 to 7, wherein the degree of wetting is at most 2% at 120 ° C x 1000 hours.