JP2002237554A - Heat conductive resin formation and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conductive resin formation and a heat dissipation member for further improving heat-dissipation characteristic in an electronic apparatus. SOLUTION: A heat conductive resin formation is composed of a plurality of skeletal parts (2), made of heat conductive resin hardening material and a resin part (3), with which part of or all of the follow part formed by the skeletal parts (2) is filled. The skeletal part (2) has Asker C hardness of 55 or below, and the heat dissipation member is made of this heat conductive resin formation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally conductive resin molded article suitable for a heat dissipating member of an electronic device and its use.

[0002]

2. Description of the Related Art In an electronic device, how to remove heat generated during use is an important issue. To solve the problem, an IC, an LSI, a CPU, an MPU have been conventionally used.
Are mounted on a heat sink such as a heat radiating fin or a heat radiating plate via a heat radiating member such as a heat conductive sheet. As the heat conductive sheet, a material obtained by dispersing and containing a heat conductive filler such as boron nitride (BN) in a cured silicone material has been widely used, and recently, its flexibility is reduced to 50 or less in Asker C hardness. By now, soft and flexible heat radiation spacers have been used.

[0003] Today, in such heat dissipating members, further improvement in heat dissipating characteristics is required, and this is addressed by increasing the BN filling rate.
Since the mechanical strength of the sheet is reduced, there is a limit to a method for increasing the filling rate.

By the way, BN is a scaly particle, and its thermal conductivity is about 110 W / mK in the plane direction (a-axis) and about 2 W / mK in the direction perpendicular to the plane direction (c-axis).
Since the plane direction is several tens times better, the plane direction of the BN particles is made the same as the thickness direction of the sheet which is the direction of heat transfer (that is, the BN particles are filled upright in the sheet thickness direction).
This is expected to dramatically improve the heat radiation characteristics of the heat radiation member. However, in conventional molding methods such as a calender roll method and a doctor blade method, the BN particles are oriented during sheet molding, and the plane direction of the flaky particles becomes the same as the sheet surface direction as shown in FIG. Of c
The axial thermal conductivity remained unutilized.

Japanese Patent Publication No. 6-12643 proposes randomly aligning BN particles. Even in this case, the BN particles are oriented in the sheet surface direction.
Since there are still many N particles, the heat radiation characteristics are not sufficiently improved.

Further, Japanese Patent Publication No. 6-38460 discloses that
By blocking the solidified silicone filled with BN particles and then slicing it vertically to form a sheet, the proportion of BN particles oriented in the sheet thickness direction is oriented in the sheet plane direction. It is proposed to make it higher than the percentage. However, in this method, when the block size becomes large, the BN particles are randomly oriented, so that a sufficient improvement in the heat radiation characteristics cannot be expected.

In order to solve this problem, Japanese Patent Laid-Open No. 2000-2000
Japanese Patent Application Laid-Open No. 355654/1992 discloses a high flexibility and high thermal conductivity composed of a plurality of skeleton portions and a resin portion filled and cured in at least a part or all of the voids formed by the plurality of skeleton portions. Has been proposed. Since the heat dissipating member is formed by extruding a resin compound containing BN particles into a rod having a small cross section and assembling a plurality of such members into a skeleton, heat is transferred in the plane direction of the BN particles. Since the direction can be the same as the thickness direction of the sheet, the heat conductivity is high. In addition, since it is highly flexible, the adhesiveness to a heat sink such as a heat radiation fin is increased when the electronic device is incorporated into an electronic device. As a result of these,
The heat radiation characteristics of the electronic device in which the heat radiation member is incorporated become extremely good.

However, in recent years, the speed of high integration and high heat density of electronic devices is remarkably high, and in some devices, the structure disclosed in Japanese Patent Application Laid-Open No. 2000-355654 is no longer sufficient. Further, there is a demand for further improvement in heat radiation characteristics.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to improve the flexibility of a heat dissipating member having the structure disclosed in Japanese Patent Application Laid-Open No. 2000-355654, thereby improving the adhesion when incorporated into an electronic device, and An object of the present invention is to provide a thermally conductive resin molded body capable of further improving the heat radiation characteristics of a device and a heat radiation member of an electronic device.

[0010]

That is, the present invention relates to a method of filling and curing a plurality of skeletons (2) made of a thermally conductive resin cured product and a part or all of the voids formed by the plurality of skeletons. A heat conductive resin molded article, characterized in that the skeleton part has an Asker C hardness of 55 or less. In this case, the skeleton portion comprises (a) boron nitride (BN) particles, (b) a cured silicone material, (c, a silicone oil and / or a flexibility imparting agent comprising a copolymer of ethylene or butylene and propylene, (A) is 40% by volume or more, (b) is 5% by volume or more, (c) is 0.05 ≦ (c) / ｛(b) +
(C) It is preferable that｝ ≦ 0.4.

Further, according to the present invention, the thermal conductive resin molded article has a thermal resistance of 0.2 ° C./W or less and a thickness of 0.05 to 5.0.
mm, which is a heat radiation member of an electronic device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the thermally conductive resin molded article of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1 is a thermally conductive resin molded body, 2 is a skeleton, 3 is a resin, 4
Is a thermally conductive filler. FIG. 3 is a cross-sectional view in the thickness direction of a conventional heat conductive sheet.

The thermally conductive resin molded article 1 of the present invention comprises a plurality of skeleton parts 2 and a resin part 3 which is filled and cured in a part or all of the voids formed by the plurality of skeleton parts. That is, the proportion of the thermally conductive filler 4 oriented in the thickness direction of the resin molded product is extremely large.

The thermally conductive resin molded article of the present invention is different from the resin molded article disclosed in Japanese Patent Application Laid-Open No. 2000-355654 in that the Asker C hardness of the skeleton is 55 or less. In the resin molded body disclosed in JP-A-2000-355654, the Asker C hardness of the skeleton is as small as about 70 in the disclosed resin composition.

The skeletal portion 2 having high flexibility with an Asker C hardness of 55 or less and high thermal conductivity includes, for example, (a)
A kneaded product consisting of boron nitride (BN) particles, (b) a raw material of a cured silicone material, and (c) a specific ratio of a softening agent is extruded into a rod shape, and a plurality of the kneaded products are collected and cured. Can be.

The BN particles (a) preferably have a thickness in the c-axis direction of 0.1 μm or more, and if less than 0.1 μm, the particles may be broken when dispersed in silicone. In addition, the aspect ratio (length / width ratio) of BN particles
Is preferably as large as possible, and is preferably 20 or more from the viewpoint of improving thermal conductivity. Average particle size is 1
Those having a size of about 0 to 100 μm are used. Skeleton BN
The proportion of the particles is at least 40% by volume, and if less than this, the thermal conductivity becomes insufficient.

Such BN particles can be prepared by, for example, mixing crude BN powder in the presence of an alkali metal or alkaline earth metal borate in a nitrogen atmosphere at 1700 to 2200 ° C. × 3 to 15 ° C.
Heat treatment for enough time to develop BN crystals sufficiently, and after grinding,
If necessary, it can be produced by purifying with a strong acid such as sulfuric acid or nitric acid (for example, see JP-A-9-20).
No. 2663).

As a raw material used for forming the silicone cured product (b), an addition-reaction liquid silicone resin, a heat-curable millable silicone resin using a peroxide for vulcanization, and the like are suitable. Specific examples thereof include a one-part silicone having both a vinyl group and an H-Si group in one molecule, or an organopolysiloxane having a vinyl group at a terminal or a side chain and two or more at the terminal or a side chain. A two-part silicone resin with an organopolysiloxane having an H-Si group can be used. Examples of commercially available products include "SE-1886" (trade name, manufactured by Dow Corning Toray Co., Ltd.).

The flexibility-imparting agent (c) is used to reduce Asker C hardness of the skeleton to 55 or less.
If this is not used, the Asker C hardness of the skeleton will be 70 or more. As the softening agent, when the main material of the skeleton is a silicone cured product, those having high compatibility with it and low chemical activity are preferable, for example, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl silicone oil, One selected from silicone oils such as alkyl silicone oils, fluorosilicone oils, fatty acid ester-modified silicone oils, and copolymers of ethylene or butylene and propylene such as ethylene-propylene copolymers and butylene-propylene copolymers Alternatively, two or more are used.

The ratio between the silicone cured product (b) and the softening agent (c) is 0.05 ≦ (c) / ｛(b) +
(C) It is preferable that｝ ≦ 0.4. The ratio is 0.0
If it is less than 5, the effect of improving the flexibility of the skeletal portion is insufficient, the adhesion when incorporated into an electronic device is not increased, and the heat radiation characteristics are not improved. On the other hand, when the ratio is more than 0.4, the flexibility of the skeleton becomes excessive, and the shape retention of the resin molded product cannot be maintained. The proportion of the silicone cured product (b) in the skeleton is 5
It is preferably at least volume%. If it is less than 5% by volume,
In some cases, the shape retention of the skeleton portion is not sufficient, and the filled BN particles are lost, and high thermal conductivity cannot be exhibited.

The resin part 3 of the thermally conductive resin molded article of the present invention
Is formed by filling and hardening a resin in part or all of the voids formed by the skeleton portion 2. The material of the resin portion is preferably of the same type as the main material of the skeleton portion in order to enhance the adhesion to the skeleton portion. When the main material of the skeleton portion is a cured silicone, an addition-reaction liquid silicone resin is used. It is preferable to use a heat-curable millable type silicone resin using an oxide for vulcanization, a condensation reaction type silicone resin, or the like.

It is preferable that the resin portion contains a thermally conductive filler as long as the flexibility is not significantly impaired. As the heat conductive filler, when insulating properties are required, silicon nitride, aluminum nitride, silica, alumina,
When ceramic powders such as magnesia are used and insulation is not required, besides these ceramic powders,
Metal powders such as aluminum, copper, silver, and gold, silicon carbide powders, and carbon powders are used. The shape of the heat conductive filler may be any of a crushed shape, a spherical shape, a fibrous shape, a needle shape, a scale shape and the like, and those having an average particle size of about 0.5 to 100 μm are used.

The composition ratio (%) of the skeleton portion or the resin portion of the thermally conductive resin molded article of the present invention is not limited, and the area ratio of the skeleton portion in the cross-sectional area (cross-sectional area of skeleton portion / total cross-sectional area) ) Is 5
Those having 0 to 98% are exemplified.

The cross-sectional shape of the skeleton portion or the resin portion is triangular,
A polygon such as a square, a hexagon, a lattice, a rhombus, and a trapezoid, a circle, an ellipse, a waveform, a concentric circle, a radial shape, a spiral shape, and any combination of the shapes are possible.

Various uses of the heat conductive resin molded article of the present invention can be considered, and particularly, the heat resistance is 0.2 ° C./W.
Hereinafter, those having a thickness of 0.05 to 5.0 mm are suitable as heat dissipating members for electronic devices. In particular, in the X-ray diffraction diagram obtained by irradiating X-rays in the thickness direction of the heat radiating member, the <002> plane (c
The peak ratio (<002> / <100>) is preferably 1 or less.

[0027]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 Liquid A (organopolysiloxane having a vinyl group): B
Liquid (silicone-containing organopolysiloxane having an H-Si group) at a mixing volume ratio of 1: 1 in a two-part addition reaction type liquid silicone (trade name "SE" manufactured by Dow Corning Toray Co., Ltd.).
-1886 ") 28% by volume, 7% by volume of a flexibility-imparting agent composed of an ethylene-propylene copolymer (trade name" LUCANT "manufactured by Mitsui Chemicals, Inc.), BN powder having an average particle diameter of 20 μm and an average particle thickness of 1 μm (electricity 65% by volume of “Dencaboron nitride” (trade name, manufactured by Chemical Industry Co., Ltd.) was mixed with a commercially available mixer to prepare a skeleton-forming compound.

This is extruded from a die provided with 20 holes of 2.5 mm in diameter on the side to form an uncured rod-shaped silicone molded product, cut to a length of 10 cm, and then stacked in a resin frame to form an aggregate. (Side dimensions 50 × 50 mm).

Next, the two-component addition reaction type liquid silicone mixed in the ratio of the above-mentioned liquid A: liquid B = 1: 1 was poured into the frame, and the silicone was kept in a vacuum for 20 minutes.
It was vulcanized and cured at 0 ° C. for 10 hours. Then, it cut | disconnected to 1 mm in thickness, and produced the thermally conductive resin molded object of this invention as shown in FIG.

Example 2 Comparative Examples 1 to 4 A heat conductive resin molded article was produced in the same manner as in Example 1 except that the compounds shown in Table 1 were used as the skeleton forming compounds. In Example 2, silicone oil (trade name “SH” manufactured by Dow Corning Toray Co., Ltd.) was used as the flexibility-imparting agent.
200 ") was used.

The thermal resistance and Asker C hardness of the heat conductive resin molded article obtained above and Asker C hardness of the skeleton were measured in the following manner, and are shown in Table 1.

(1) Thermal resistance: The thermally conductive resin molded body is made of TO
After cutting into a -3 shape (area 6 cm ² ), sandwiching it between a TO-3 type copper heater case and a copper plate, setting with a tightening torque of 5 kgf-cm, a power of 20 W was applied to the copper heater case. After holding for 4 minutes, the temperature difference between the copper heater case and the copper plate was measured and calculated by the following equation.

Thermal resistance (° C./W)=temperature difference (° C.) / Power (W)

(2) Asker C hardness The Asker C hardness of the skeleton portion is determined by molding an uncured rod-shaped silicone molded product such that the area ratio of the resin portion becomes 0, followed by vulcanization and curing, and a height of 10 mm × a diameter of 29 mm. Each of the test pieces was cut out to the size shown in FIG.
SRIS 0101 using a type spring hardness tester
It measured according to.

[0036]

[Table 1]

From Table 1, it can be seen that the thermally conductive resin molded products of the examples have lower thermal resistance and are superior in flexibility as compared with the comparative examples.

The thermally conductive resin molded product (30 mm square × 0.5 mm) obtained in Examples 1 and 2 was adhered to the flat surface of an aluminum radiating fin, and was mounted on a heat-generating electronic component with a load of 0.2 MPa. In each case, the heat radiation characteristics during operation were extremely good.

[0039]

According to the present invention, a heat conductive resin molded article capable of further improving the heat radiation characteristics of an electronic device,
A heat dissipating member for an electronic device is provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a thermally conductive resin molded article of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional view of a conventional heat conductive sheet in a thickness direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal conductive resin molded body 2 Frame part 3 Resin part 4 Thermal conductive filler

Continued on front page F-term (reference) 4J002 BB143 BB153 CP033 CP042 CP083 CP141 DK006 FD016 FD023 GM00 5F036 AA01 BA23 BB21 BD21

Claims (3)

[Claims] 1. A plurality of skeletons (2) made of a cured product of a thermally conductive resin, and a resin part (3) filled and cured in a part or all of a void formed by the plurality of skeletons. Wherein the Asker C hardness of the skeleton is 55 or less. 2. A skeleton comprising (a) boron nitride particles,
(B) a silicone cured product, (c) a silicone oil and / or a flexibility-imparting agent comprising a copolymer of ethylene or butylene and propylene, wherein (a) is 40% by volume or more and (b) is 5% by volume % Or more, (c) is 0.05 ≦ (c)
2. The thermally conductive resin molded body according to claim 1, wherein /{(b)+(c)}≦0.4. 3. The heat conductive resin molded article according to claim 1, which has a thermal resistance of 0.2 ° C./W or less and a thickness of 0.05 to 5.0.
A heat dissipating member for electronic equipment, which is 0 mm.