JP3490011B2 - Heat conductive elastomer composition and heat conductive elastomer using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat conductive elastomer composition and a heat conductive elastomer, and more particularly to a heat conductive elastomer composition and a heat conductive elastomer for transmitting heat generated by a heating element.

[0002]

2. Description of the Related Art Electronic parts such as power transistors, CPUs, transistors and transformers generate heat when used,
The heat may reduce the performance of the electronic component.
Therefore, it is necessary to design the heat so that heat does not accumulate, and a heat radiating means (a heat radiating body or a heat absorbing body) is attached to the heat generating element. However, since the heat radiating means is often made of metal, it is not preferable to directly attach the heat radiating means to the heat generating element which is an electronic component because of problems such as electric leakage. for that reason,
A mounting method in which a mica insulating plate, a heat conductive grease, polyester, or the like is installed between a heating element and a heat radiating means is often used.

As a material to be sandwiched between the heat generating element and the heat radiating means, for example, a rubber sheet obtained by adding a heat conductive filler to silicone rubber (Japanese Patent Publication No. 57-19525) or a gel type material having a considerably low rubber hardness ( JP-A-6-15
5517) is frequently used.

[0004]

However, in recent years, the size, thickness, and integration of electric circuits have been considerably reduced, so that the material sandwiched between the heat generating element and the heat radiating means should be thin. And it is required to reduce the tolerance. The minimum processing limit of the general processing thickness of the heat conductive silicone rubber based on the millable silicone rubber is about 100 μm, and the processing tolerance is 0.01 mm to
It was 0.1 mm. On the other hand, in recent years, gel-type heat-conducting sheets that have improved adhesion to heat-generating elements and that facilitate the transfer of heat have become widely used, but it is extremely difficult to make thin films with conventional gel-type heat-conducting sheets. The dimensional accuracy was also very poor. When the thickness of the heating element or heat dissipation means is large, even with the conventional gel type heat conductive sheet, the variation in mounting dimensions did not become a problem, but the thickness of the heating element or heat dissipation means becomes thin. Currently, the conventional gel type heat conductive sheet has a problem that it is difficult to design a heat countermeasure due to variations in mounting dimensions.

In order to solve the above-mentioned problems, the present invention provides a heat-conductive elastomer composition for forming a heat-conductive elastomer which is a thin film with less variation in mounting dimensions, and a heat-conductive elastomer using the same. The purpose is to do.

[0006]

In order to achieve the above object, the heat conductive elastomer composition of the present invention is a heat conductive elastomer composition for forming a heat conductive elastomer, which comprises a liquid silicone elastomer and a thermally conductive filler, and a ceramic sintered body which serves as a spacer, and an average particle diameter of the ceramic sintered body is more than 5 times the average particle diameter of the thermally conductive filler, prior to
The average particle diameter of the heat conductive filler is 0.5 μm to 100 μm.
m range, and the average particle size of the ceramics sintered body is
3 mm or less, the liquid silicone elastomer 1
100 to 100 parts by weight of the heat conductive filler.
1,200 parts by weight of the liquid silicone elastomer
5 to 3 of the ceramic sintered body is added to 100 parts by weight.
It is characterized by containing 0 parts by weight . Since the heat conductive elastomer composition contains a ceramic sintered body having an average particle diameter of 5 times or more the average particle diameter of the heat conductive filler, the heat conductive elastomer composition is sandwiched between a heat dissipation element and a heat dissipation means, for example. Even when forming, the variation in mounting dimensions can be reduced. Furthermore, in the above heat conductive elastomer composition, the heat conductive elastomer that is a thin film can be formed by reducing the average particle diameter of the ceramics sintered body.

In the above heat conductive elastomer composition, the average particle size of the ceramic sintered body is preferably 10 times or more the average particle size of the heat conductive filler. By using a ceramics sintered body having an average particle size of 10 times or more the average particle size of the thermally conductive filler, it is possible to form a thermally conductive elastomer with a particularly small variation in mounting dimensions.

In the above heat conductive elastomer composition,
It is preferable that the ceramic sintered body has a substantially spherical shape.
By using a substantially spherical ceramics sintered body,
For example, when the heat conductive elastomer is formed by sandwiching it between the heat dissipation element and the heat dissipation means, the distance between the heat dissipation element and the heat dissipation means can be made uniform with good in-plane uniformity.
The reliability and heat dissipation of the electric circuit can be improved, and thermal design becomes easy.

Further, in the above heat conductive elastomer composition, it is preferable that 100 to 1200 parts by weight of the heat conductive filler is contained with respect to 100 parts by weight of the liquid silicone elastomer. With the above structure, it is possible to form a heat conductive elastomer having good heat dissipation.

The heat-conductive elastomer of the present invention is a heat-conductive elastomer which is disposed between a heat-generating element and a heat-dissipating means and which transfers heat generated by the heat-generating element to the heat-dissipating means. Formed using the composition ,
The ceramic in the thermally conductive elastomer composition
It is characterized in that the thickness is controlled by the grain size of the sintered body . Since the heat-conductive elastomer of the present invention uses the heat-conductive elastomer composition of the present invention described above, a heat-conductive elastomer that is a thin film with little variation in mounting dimensions can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(Embodiment 1) In Embodiment 1, a heat conductive elastomer composition of the present invention will be described.

The thermally conductive elastomer composition of the present invention comprises
A composition for forming a heat conductive elastomer,
Liquid silicone elastomer, heat conductive filler,
The average particle size of the ceramics sintered body is 5 times or more of the average particle size of the heat conductive filler.

The above liquid silicone elastomer is, for example, RTV (Ro) which becomes a cured product in the presence of heat.
om Temperature Vulcaniz
e), LTV (Low Temperature Vu)
lcanize) or the like, or silicone oil or silicone grease that does not become a cured product even in the presence of heat can be used. When a liquid silicone elastomer that cures at a relatively low temperature is used, the liquid silicone elastomer can be cured by using the heat generated by the heating element.

RTV, LTV and silicone gel are classified into one-part type and two-part type. Further, the RTV includes a condensation type and an addition type depending on the curing form.

Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, fluorosilicone oil and modified silicone oil.

The heat conductive filler is preferably at least one selected from nitrides, carbides and basic metal oxides.

The nitrides used for the thermally conductive filler include, for example, silicon nitride, aluminum nitride, boron nitride, etc., and the carbides include silicon carbide, titanium carbide, boron carbide, etc., and one or more of these may be used. A mixture of is preferably used. Examples of the basic metal oxide used for the heat conductive filler include aluminum oxide, magnesium oxide, zinc oxide, calcium oxide, zirconium oxide and the like, and one or a mixture of two or more thereof is preferably used.

The particle shape of the nitride, carbide or basic metal oxide used for the thermally conductive filler may be spherical or flake. The average particle size of the thermally conductive filler is preferably in the range of 0.5 μm to 100 μm.

When a nitride or a carbide and a basic metal oxide are used in combination, the ratio of the basic metal oxide to the nitride or the carbide is 1 part by weight of the nitride and the carbide. A range of 0 to 120 parts by weight is preferable. The combination of the nitride or carbide and the basic metal oxide may be one basic metal oxide such as boron nitride and aluminum oxide and one nitride or carbide, or boron nitride and aluminum oxide or magnesium oxide. As described above, two kinds of basic metal oxides and one kind of nitride or carbide may be used, or various combinations such as single use of nitride or carbide may be used.

The basic metal oxide may be treated with a coupling agent. Examples of the coupling agent include a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent, and any one may be used.
The preferred compounding amount of the coupling agent is basic metal oxide 1
It is 0.05 to 2 parts by weight with respect to 00 parts by weight.

The above-mentioned ceramic sintered body is an insulator which functions as a spacer when a heat conductive elastomer is formed. As the ceramic sintered body, for example, silicon nitride balls, alumina balls, zirconia balls, glass beads, etc. can be used. The average particle size of the ceramics sintered body is preferably 5 times or more the average particle size of the heat conductive filler. By setting the average particle size of the ceramics sintered body to be 5 times or more the average particle size of the heat conductive filler, it is possible to reduce variations in mounting dimensions when the heat radiating means is attached to the heating element. In particular, by making the average particle size of the ceramics sintered body 10 times or more the average particle size of the thermally conductive filler, it is possible to particularly reduce the variation in the mounting dimensions. The average particle size of the ceramics sintered body is particularly preferably 13 times or more and 15 times or less than the average particle size of the heat conductive filler.

Further, it is preferable that the ceramics sintered body has a substantially spherical shape. By using a substantially spherical ceramics sintered body, the thickness of the heat conductive elastomer can be made uniform with good in-plane uniformity. Further, it is preferable that the particle size of the ceramic sintered body has a small variation. The particle size of the ceramics sintered body is 3 mm.
The following are preferred. In particular, by setting the grain size of the above-mentioned ceramics sintered body to 500 μm or less, it is possible to reduce the mounting dimension when the heat radiating means is attached to the heating element.

The amount of the above-mentioned ceramics sintered body is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the liquid silicone elastomer. This makes it possible to reduce variations in mounting dimensions without impairing thermal conductivity.

In addition to the heat conductive filler, the liquid silicone elastomer may contain, for example, a modifier, a plasticizer, a crosslinking agent, a flame retardant and a pigment. As a sensitizer,
For example, there are lithium soap, aluminum soap, silica, carbon, Teflon powder, calcium carbonate and the like, and one kind or a mixture of two or more kinds is preferably used.

RTV as a liquid silicone elastomer
Alternatively, when LTV is used, a plasticizer may be added if necessary. As the plasticizer to be added, for example,
There are dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, fluorosilicone oil, modified silicone oil and the like, and one kind or a mixture of two or more kinds is preferably used.

RTV as a liquid silicone elastomer
Alternatively, when using LTV, a crosslinking agent may be added, if necessary. As the crosslinking agent to be added, for example,
There are vinyl group polydimethylsiloxane, polymethylhydrosiloxane, polymethylhydrosiloxane copolymer, and the like at both ends and one end, and one kind or a mixture of two or more kinds is preferably used.

The heat conductive elastomer composition of the present invention is
In order to impart flame retardancy, one or a mixture of two or more platinum compounds such as chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum olefin complex or methylpolyvinylsiloxane complex may be contained. Further, as the flame retardant aid, one kind or a mixture of two or more kinds of iron oxide, titanium oxide, carbon black, aluminum hydroxide, magnesium hydroxide and the like may be contained.

According to the heat conductive elastomer composition of the above-mentioned Embodiment 1, a heat conductive elastomer composition which can form a heat conductive elastomer which is a thin film with less variation in mounting dimensions can be obtained.

In the heat conductive elastomer composition of Embodiment 1, the average particle size of the ceramic sintered body is 500 μm.
By setting the thickness to m or less, it is possible to easily form a heat conductive substance having a thickness of 500 μm or less, which is difficult to manufacture with the conventional gel type heat conductive sheet.

Further, in the heat conductive elastomer composition of the first embodiment, by using the liquid silicone elastomer which is hardened by the heat generated by the heat generating element, the heat radiating means and the heat generating element can be easily fixed. it can.

(Embodiment 2) In Embodiment 2, an example of a heat conductive elastomer using the heat conductive elastomer composition of the present invention will be described.

Referring to FIG. 1, the heat conductive elastomer 10 of the present invention is arranged between the heating element 11 and the metal plate 12. Then, FIG. 1 shows a case where the heating element 11 is mounted on the printed wiring board 14 by the terminal 13.

The heat conductive elastomer 10 is the same as that of the first embodiment.
The heat-conductive elastomer composition of the present invention described in 1. above. The heat conductive elastomer 10 has a function of transmitting the heat generated from the heating element 11 to the metal plate 12. Further, the heat conductive elastomer 10 has a function of physically fixing the metal plate 12 to the heat generating element 11.

The heating element 11 includes, for example, a power transistor, a transformer, a CPU, a thyristor and the like. In FIG. 1, the heating element 11 is a BGA (Ball Grid).
It is shown that the CPU is an Array type CPU.

Although the metal plate 12 is used as the heat radiating means in FIG. 1, another heat radiating body or heat absorbing body may be used instead of the metal plate 12 as the heat radiating means. For example,
A fan, a heat sink, a Peltier element, a heat pipe, etc. can be used. Any combination of the heat generating element and the heat radiating body or the heat generating element and the heat absorbing body may be used.

The heat-conductive elastomer composition forming the heat-conductive elastomer has fluidity before mounting, but may be in the form of being gradually cured by utilizing heat from the heat-generating element, or after mounting, like a grease. It may be in a form that maintains fluidity.

Next, an example of a method for attaching the metal plate 12 to the heating element 11 using the heat conductive elastomer 10 will be described.

First, the heat conductive elastomer composition 15 described in the first embodiment is placed on the heating element 11 mounted on the printed wiring board 14.

Then, the metal plate 12 is placed on the heat conductive elastomer composition 15, and as shown in FIG. 2, the metal plate 12 is gradually pressurized in the direction of the arrow (direction of the heating element 11), The heat conductive elastomer composition 15 is gradually extended. The states of the thermally conductive elastomer composition 15 before and after pressurization are shown in FIGS. 3 and 4, respectively. Before pressurization (FIG. 3), the ceramic sintered body 16 in the heat conductive elastomer composition 15 is randomly dispersed in the heat conductive elastomer composition 15. on the other hand,
After pressurization (FIG. 4), the ceramic sintered body 16 serves as a spacer, and the thickness of the thermally conductive elastomer composition 15 does not become smaller than the particle diameter of the ceramic sintered body 16. Here, since the ceramic sintered body 16 has a substantially spherical shape, the spacing between the heating element 11 and the metal plate 12 can be set to a constant spacing with good in-plane uniformity. Furthermore, in the heat conductive elastomer composition 15, by using the ceramics sintered body 16 having an average particle diameter of 5 times or more the average particle diameter of the heat conductive filler (not shown), the heat generating element 1
The distance between the metal plate 1 and the metal plate 12 can be set to a constant distance with high accuracy. Further, in the heat conductive elastomer composition 15, the film thickness of the obtained heat conductive elastomer can be freely changed by changing the particle size of the ceramic sintered body 16.

Thereafter, the heat conductive elastomer composition 15 is cured if necessary. As a method of curing the heat conductive elastomer composition 15, there are a method using heat and a method using a curing agent. Further, when the heat conductive elastomer composition 15 is cured by heat, the heating element 1
Heat-conductive elastomer composition 15 due to heat generated from
May be cured.

In this way, the heat conductive elastomer 10
Can be formed.

According to the above heat conductive elastomer 10,
It is possible to obtain a heat conductive elastomer that is a thin film with a small variation in mounting dimensions.

Further, since the heat conductive elastomer 10 has heat conductivity and electric insulation, the heat conductive elastomer 10 can improve the reliability of the electric circuit including the heating element.

Further, in the heat conductive elastomer 10, the average particle size of the ceramics sintered body is set to 500 μm or less, so that the heat conductivity of 500 μm or less which is difficult to manufacture by the conventional gel type heat conductive sheet. The elastomer can be easily formed.

[0046]

EXAMPLES Examples of the present invention will be described in detail below.

Example 1 Example 1 shows an example of the heat conductive elastomer composition of the present invention. In the heat conductive elastomer composition of Example 1, 100 parts by weight of SH4 (Toray Dow Corning Silicone Co., Ltd.) as a liquid silicone elastomer, 30 parts by weight of aluminum oxide (average particle size 20 μm) as a heat conductive filler, ceramics sintering. Zirconia balls as the body (average particle size 500μ
m) 10 parts by weight were used. Then, these materials were blended and kneaded to obtain a heat conductive elastomer composition.

By using the above materials, a thermally conductive elastomer composition having fluidity before mounting and not curing after mounting was obtained.

Example 2 In Example 2, another example of the thermally conductive elastomer composition of the present invention will be shown. In the heat conductive elastomer composition of Example 2, 100 parts by weight of JCR6101 (Toray Dow Corning Silicone Co., Ltd.) as a liquid silicone elastomer, 30 parts by weight of aluminum oxide (average particle size 20 μm) as a heat conductive filler, ceramics sintering. As the body, 10 parts by weight of zirconia balls (average particle size 500 μm) were used. Then, these materials were blended and kneaded to obtain a heat conductive elastomer composition.

By using the above materials, a thermally conductive elastomer composition having fluidity before mounting and being cured after mounting was obtained.

(Example 3) In Example 3, an example will be described in which a heat dissipation plate is attached to a heating element using the heat conductive elastomer composition of the present invention.

In Example 3, the heat conductive elastomer composition of Example 2 was used as the heat conductive elastomer composition, and the heat conductive elastomer was formed by the method described in FIG. Further, an aluminum plate is used as a heat radiating means, an epoxy resin substrate reinforced with glass cloth fiber is used instead of the printed wiring board, and a BGA (BallG) is used as a heating element.
A grid array type heating element was used. On the other hand, as a comparative example, a heat-dissipating sheet having a thickness of 500 μm (conventional gel type heat-dissipating sheet, manufactured by Fuji Polymer Industries Co., Ltd.) was used, and an aluminum plate was similarly attached to the heating element.

When pressing the aluminum plate, a micro load cell having a high degree of parallelism was used and pressure was applied at a pressure of 1 kg / cm ² . Then, in order to cure the heat conductive elastomer composition, the aluminum plate was pressed and left at room temperature for 3 hours. On the other hand, when the aluminum plate is attached to the heating element with the heat dissipation sheet of the comparative example, the same condition (pressure is 1 k
g / cm ² , left at room temperature for 3 hours).

Thereafter, the mounting thickness of the heating element mounted by the above process was measured. The mounting thickness used was one that can be measured without contact. The mounting thickness was defined as the height from the lower surface of the epoxy resin substrate to the upper surface of the aluminum plate.

The thickness was measured at five points in the same sample. The arrangement of measurement points is shown in FIG.

The measurement results are shown in Table 1.

[0057]

[Table 1]

As is clear from Table 1, when the heat conductive elastomer composition of Example 2 was used, the variation in the mounting thickness was smaller than when the conventional heat dissipation sheet was used. .

[0059]

As described above, according to the heat conductive elastomer composition of the present invention, a heat conductive elastomer composition which can form a thin film heat conductive elastomer with less variation in mounting dimensions can be obtained.

Further, according to the heat conductive elastomer of the present invention, it is possible to obtain a heat conductive elastomer which is a thin film with less variation in mounting dimensions.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a heat conductive elastomer of the present invention.

FIG. 2 is a cross-sectional view showing a process of manufacturing the heat conductive elastomer of the present invention.

FIG. 3 is a cross-sectional view showing another manufacturing process of the heat conductive elastomer of the present invention.

FIG. 4 is a cross-sectional view showing another manufacturing process of the heat conductive elastomer of the present invention.

FIG. 5 is a plan view showing a position where a mounting thickness is measured in an example using the heat conductive elastomer of the present invention.

[Explanation of symbols]

10 Thermally conductive elastomer 11 Heating element 12 metal plate 13 terminals 14 Printed wiring board 15 Thermally conductive elastomer composition 16 Ceramics sintered body

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-41362 (JP, A) JP-A-11-307698 (JP, A) JP-A-9-296114 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08K 3/00-3/40 C08L 83/04-83/12 H01L 23/36-23/373

Claims (3)

(57) [Claims] 1. A heat conductive elastomer composition for forming a heat conductive elastomer, which comprises a liquid silicone elastomer and a heat conductive filler.
A ceramic sintered body that functions as a spacer, wherein the average particle diameter of the ceramic sintered body is 5 times or more the average particle diameter of the thermally conductive filler, and the average particle diameter of the thermally conductive filler is 0. 5 μm to 100
and the average particle size of the ceramics sintered body is 3 mm or less.
Based on 100 parts by weight of the liquid silicone elastomer
Including 100 to 1200 parts by weight of the heat conductive filler.
Seen, with respect to the liquid silicone elastomer 100 parts by weight
A thermally conductive elastomer composition comprising 5 to 30 parts by weight of the ceramics sintered body . 2. The heat conductive elastomer composition according to claim 1 , wherein the ceramics sintered body has a substantially spherical shape. 3. A heat conductive elastomer which is disposed between a heat generating element and a heat radiating means and which transfers heat generated by the heat generating element to the heat radiating means, wherein the heat conductive elastomer composition according to claim 1 or 2 is used. A thermally conductive elastomer formed by using the thermally conductive elastomer, the thickness of which is controlled by the particle diameter of the ceramics sintered body in the thermally conductive elastomer composition.