JPH05299545A - Heat dissipation body - Google Patents

Abstract

PURPOSE:To provide a heat dissipation body, which is superior in heat dissipation characteristics (heat conductivity) in its thickness direction and has a superior adhesion to a component to be cooled. CONSTITUTION:A heat dissipation body is constituted of an aggregate 3a consisting of heat conductive materials 2a made of at least one kind selected from among a metallic fiber, a thin metal wire, a metal foil and a ceramic fiber. Moreover, the heat dissipation body consists of the aggregate 3a and a matrix resin 4a filled in gap parts in this aggregate 3a. It is better to constitute the heat dissipation body in such a way that at least part of the aggregate 3a is exposed on the surface and rear of the resin 4a. Moreover, it is better to set the ratio of the whole exposed area of the aggregate 3a to the surface area of the heat dissipation body 1a to be 1% or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiator, and in particular, it is excellent in heat radiation and flexibility, and has excellent adhesion to electronic equipment parts such as transistors, capacitors, LSI packages, etc. The present invention relates to a radiator that can be efficiently transmitted to the outside of the system.

[0002]

2. Description of the Related Art Electronic and electrical parts such as transistors, capacitors, and LSI packages have a short life due to heat generated during operation, and their reliability is likely to deteriorate. Therefore, as a countermeasure, a sheet-shaped heat radiator having excellent thermal conductivity and adhesion between the electronic / electrical component and a heat sink (cooling means) such as a heat radiation fan thermally connected to the electronic / electrical component. The device is designed to dissipate heat to the outside of the system via this radiator.

The above-mentioned heat radiator is generally manufactured by forming a heat conductive material (filler) in a matrix resin to form a sheet. For example, silicon rubber is used as the matrix resin, while boron nitride having a particle shape, a plate shape, or a needle shape is used as the heat conductive material.

The heat dissipating body uses the above-mentioned matrix resin and heat conductive material, and is roughly manufactured by the following four manufacturing methods.

In the first method, a matrix resin (for example, silicon rubber) and a heat conductive material (for example, boron nitride) are blended and mixed into a raw material mixture, and this raw material mixture is rolled in the same manner as an ordinary rubber material. , A sheet is formed by a calender, an extruder or the like, and the obtained formed body is pressed and vulcanized.

The second method is to mix a matrix resin (for example, silicon rubber) and a heat conductive material (for example, boron nitride) and dilute them with a solvent, then form a sheet according to the doctor blade method, dry and press. The method is to vulcanize.

The third method is to use a highly-filled compound of a heat conductive material in which 200 parts by weight or more of a heat conductive material (for example, boron nitride) is mixed with 100 parts by weight of a matrix resin (for example, silicon rubber). The manufacturing method used,
In this method, the above raw materials are mixed in a closed kneader such as a kneader to form a powdery rubber material, which is filled in a predetermined sheet molding die in a predetermined amount and pressed to be vulcanized.

In the fourth method, for example, a plate-shaped high thermal conductive substrate made of, for example, an aluminum nitride sintered body is used as a heat radiator as it is, or an electrical insulating material is provided on the surface as necessary to provide a high thermal conductive substrate. There is a method of forming.

FIG. 6 is a sectional view showing the structure of a sheet-shaped heat radiator prepared by the above conventional manufacturing method. That is, in the conventional radiator 10, the matrix resin 11
The filler-like heat conductive material 12 distributed inside is mixed in a state where the major axis of the heat conductive material 12 is oriented along the plane direction (length direction) of the radiator 10.

The orientation of the heat conductive material 12 as described above is
This occurs because the raw material 12 is aligned in the rolling direction and the extrusion direction when the raw material mixture is formed by roll forming or extrusion forming.

On the other hand, as another structural example of the conventional sheet-shaped heat radiator, a heat radiator 10a as shown in FIG. 7 is also used. The heat radiator 10a is formed by dispersing a spherical heat conductive material 12a in a matrix resin 11a.

[0012]

However, it has been found that there is a technical limit to the improvement of the heat dissipation characteristics due to the high integration, high speed and high output of electronic devices and the like in recent years. As a result of various studies on conventional radiators,
For the first time, I found the following problems. That is, in the heat radiator prepared by the above-mentioned first to third conventional manufacturing methods, the heat conductive materials 12 are oriented in the plane direction as shown in FIG. 6, and the adjacent heat conductive materials 12 contact each other. However, so to speak, the heat conductive material 12 is easily formed in a continuous state in the plane direction (length direction) of the sheet-shaped radiator 10.
Therefore, heat is easily conducted in the plane direction of the heat radiator 10, but heat is hard to be conducted in the thickness direction of the heat radiator 10. Therefore, as a heat radiator mainly utilizing the heat dissipation characteristics in the thickness direction. Had a problem of insufficient performance.

On the other hand, as shown in FIG. 7, the shape of the radiator 10a cannot be maintained only by the spherical heat conductive material 12a.
Therefore, the matrix resin 11a is essential to hold the dispersed material 12a at a predetermined position. However, there is a problem that the matrix resin 11a is interposed between the heat conductive materials 12a, the materials 12a are not connected to each other, heat is difficult to be conducted, and the performance as a radiator is insufficient.

On the other hand, the heat radiation characteristics in the thickness direction of the radiators 10 and 10a increase in proportion to the filling rate of the heat conductive materials 12 and 12a dispersed in the matrix resins 11 and 11a. As the temperature rises, there is also a problem that the formability into a sheet shape and the workability deteriorate. In particular, in a radiator with a large amount of hard and brittle material such as ceramics or metal distributed as a heat conductive material in a soft resin matrix, the elastic modulus increases and the flexibility decreases, so heat radiation to the cooled parts When the body is attached, it becomes difficult for the radiator 10 to deform along the irregularities on the surface of the cooled component,
There is also a drawback that the heat dissipation is lowered. Especially the above fourth
The heat radiator prepared by the conventional manufacturing method of 1) has a problem that it is poor in flexibility and lacks in adhesion as a whole. Therefore, there is also a problem that the radiator 10 does not sufficiently adhere to the cooling means such as the radiation fins or the surface of the component to be cooled, the heat transfer resistance increases, and the heat radiation characteristics deteriorate.

With the remarkable development of electronic and electric parts in recent years, electronic devices including semiconductor elements have been highly integrated, operated at high speed, and have high output, and the amount of heat generated has been increased. A radiator is required.

The present invention has been made in order to solve the above-mentioned problems, and particularly provides a heat radiator having excellent heat radiation characteristics (heat conductivity) in the thickness direction and adhesion to a component to be cooled. With the goal.

[0017]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors used various heat conductive materials and confirmed the effect of their shape on the heat dissipation characteristics by experiments. As a result, by using the fibrous or foil-shaped high thermal conductive material aggregate as it is as a radiator, that is, by using the aggregate itself as a radiator, both thermal conductivity and flexibility can be achieved with a simple structure. For the first time, we have obtained the knowledge that an excellent heat radiator can be obtained. Further, it was found that by filling the voids of the aggregate with a resin as a matrix, it is possible to obtain a heat radiator having excellent adhesion and flexibility. In particular, when the heat-dissipating body was constructed such that at least a part of the above-mentioned aggregate was exposed on the front and back surfaces of the matrix resin, a heat-dissipating body having excellent heat-dissipating characteristics was obtained. The present invention has been completed based on the above findings.

That is, the heat radiator according to the present invention is characterized by being composed of an assembly of at least one kind of heat conductive material selected from metal fiber, metal fine wire, metal foil and ceramic fiber.

Further, it is characterized by comprising an aggregate of at least one kind of thermally conductive material selected from metal fibers, thin metal wires, metal foils and ceramics fibers, and a matrix resin filled in voids of the aggregate. And

Further, at least part of the aggregate may be exposed on the front and back surfaces of the matrix resin.

In particular, the ratio of the total exposed area of the assembly to the surface area of the radiator is preferably set to 1% or more.

Further, the assembly may be formed of a heat conductive material having electric insulation.

Here, as the matrix resin, silicone rubber, polyolefin elastomer, etc. are used, while as the heat conductive material, aluminum nitride,
Boron nitride, silicon nitride, silicon carbide, BeO, CB
A material having high thermal conductivity and electrical insulation, such as N, diamond, or HP-TiC alumina ceramics, is used. It is also possible to use metal materials having high thermal conductivity and conductivity, such as gold, copper, aluminum, tungsten, molybdenum, and ceramic fibers such as carbon fibers. In particular, as the metal material, fibers, thin wires or foils of the above various metals may be used.

It is also possible to collect the above-mentioned various heat-conductive materials into a sheet or a bulk to form an aggregate, which can be used as a radiator as it is. Further, the voids of the aggregate are filled with resin as a matrix. Then, a heat radiator may be formed. Further, by forming at least a part of the aggregate formed of the various heat conductive materials on the front surface and the back surface of the matrix resin, a continuous heat dissipation path is formed so as to penetrate in the thickness direction of the heat radiator. Therefore, heat generation can be efficiently transmitted in the thickness direction of the heat radiator as compared with a conventional heat radiator formed by dispersing a discontinuous heat conductive material in a matrix resin.

The diameter and length of the heat conductive material are not particularly limited, but generally the diameter is 10 μm to.
It is recommended to use continuous fibers with a size of several mm. In particular, by appropriately selecting metal fibers, metal wires, foils and ceramic fibers having the above diameters and lengths, even when an external force such as a compressive stress is applied, the stress is sufficiently absorbed and the heat is less deformed. You can get a body.

Further, by setting the ratio of the total exposed area of the aggregate to the surface area of the radiator to be 1% or more, the thermal conductivity of the entire radiator is increased as compared with a radiator sheet made only of a general-purpose resin material. Can be turned into.

[0027]

According to the heat radiator having the above-mentioned structure, the heat conductive materials composed of the metal fibers, the metal fine wires, the metal foils, the ceramic fibers and the like are entangled with each other to form an assembly of a predetermined shape, and the assembly is formed only by this assembly. Therefore, since the structure is simple and easy to manufacture, a continuous heat dissipation path is formed by the heat conductive material in the thickness direction of the radiator, so the heat dissipation characteristics in the thickness direction are It can be greatly improved.

Further, according to the heat radiator formed by filling the voids of the aggregate with the matrix resin, the matrix resin holds the heat conductive material in a predetermined position to reduce the change in shape and to make it flexible. The heat-resistant matrix resin improves the adhesion of the radiator to the component to be cooled, and the heat transfer resistance is reduced to further improve the heat dissipation characteristics.

Further, since at least a part of the aggregate is exposed on the front surface and the back surface of the matrix resin, a continuous heat dissipation path is formed through the front and back surfaces of the heat radiator, so that the thickness of the heat radiator is increased. The heat transfer efficiency in the depth direction can be further improved.

[0030]

Embodiments of the present invention will now be described more specifically with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a sectional view showing a first embodiment of a heat radiator according to the present invention. This radiator 1 is made of metal fiber having a diameter of 200 μm,
It is formed of an aggregate 3 of the heat conductive material 2 having a high heat conductivity such as thin metal wires or ceramic fibers.

Metallic materials such as gold, copper, aluminum, tungsten, molybdenum, etc. can be used as the metal fibers and fine metal wires, and carbon fibers can be used as the ceramics fibers. There is no particular limitation as long as it is a high material. If necessary, chemical fibers such as polyester and nylon may be used together. Further, a chemical fiber obtained by surface-treating the chemical fiber and integrally forming the thin film of the metal may be used.

According to the radiator 1 of the first embodiment described above, it is formed of the aggregate 3 of the heat conductive material 2 having flexibility such as metal fiber, metal fine wire, metal foil or ceramic fiber. Therefore, the radiator 1 is excellent in flexibility as a whole, and even when an external force such as a compressive stress acts on the radiator, the stress absorbing effect is large and the deformation is small. Further, since the radiator 1 has high flexibility, even when the radiator 1 is used by being bonded to an electronic / electrical component, the degree of adhesion is high, and the generated heat is a heat sink (cooling means) such as a radiator fin via the radiator. ) Is efficiently transmitted. In particular, since it is composed of an aggregate of the heat conductive material 2, the heat conductive material 2 is formed in the thickness direction.
Since the heat dissipation path is formed by continuously connecting the two, the heat transfer characteristics in the thickness direction of the heat radiator can be significantly improved. Further, by filling the space in which air is sealed in the peripheral space or the internal space of the semiconductor chip with the heat radiator of this embodiment, it becomes possible to effectively prevent the retention of heat and improve the heat radiation characteristics. Can be made

Embodiment 2 FIG. 2 is a sectional view showing a second embodiment of the heat radiator according to the present invention, and FIG. 3 is a perspective view of the heat radiator shown in FIG.

That is, the radiator 1a according to the second embodiment is
It is composed of an aggregate 3a formed by assembling fine copper wires having a diameter of 200 μm as the heat conductive material 2a, and a matrix resin 4a filled in the voids of the aggregate 3a.

As the matrix resin 4a, silicone rubber, polyolefin elastomer or the like is used.
Further, as the heat conductive material 2a, a member having a high heat conductivity such as a thin copper wire is used. Further, the heat conductive material 2a is randomly gathered in the shape of a commercially available metal scrubber to form an aggregate 3a, and the voids of the aggregate 3a are filled with a matrix resin 4a as a molding material to form the radiator 1a. It

In addition to the matrix resin 4a and the heat conductive material 2a, the molding material for the radiator 1a is
You may mix | blend additives, such as a hardening | curing agent and a processing aid, as needed.

Next, the method of manufacturing the radiator 1a will be described more specifically. First, a thermally conductive material 2a such as copper is formed to have a predetermined thickness (for example, a wire diameter of 10 to 200 μm).
m) and the copper thin wires are randomly entwined in a metal scrubber shape to form a thin sheet-like aggregate 3
a. Then, a coating agent such as a surfactant (for example, an amide-based surfactant) having a strongly lipophilic group was applied to the surface of the aggregate 3a. Thus, by applying the coating agent to the surface of the aggregate 3a, the wettability between the matrix resin 4a and the heat conductive material 2a is improved, and the heat conductive material 2a in the entire radiator 1a is improved.
It is possible to increase the amount of heat conductivity and provide thermal conductivity proportional to the amount of material.

After coating the matrix resin on the aggregate 3a, the heat radiating body 1a according to the present invention can be manufactured by performing a process such as thermocompression bonding, press compression bonding, or roll rolling.

An aggregate 3a made of the heat conductive material 2a
In order to expose at least a part (upper and lower ends in the figure) of the sheet-shaped assembly 1a to the surface, the addition amount of the matrix resin 4a is adjusted, or the surface of the radiator 1a is slightly grounded, or The heat radiator 1a is etched to expose the heat conductive material 2a to the surface of the sheet.

The heat radiating body 1a according to the second embodiment thus obtained, as shown in FIGS. 2 and 3, forms the aggregate 3a by randomly intertwining the heat conductive materials 2a. The void portion of the aggregate 3a is filled with the matrix resin 4a to form a sheet. And the heat conductive material 2a
The materials 2a are connected to each other by the entanglement of
Part of the aggregate 3a is exposed on the front and back surfaces of the matrix resin 4a. Therefore, since a continuous heat dissipation path is formed from the front surface to the back surface of the sheet-shaped aggregate 1a, that is, in the thickness direction, heat is generated.
Is effectively conducted in the thickness direction.

Further, the aggregate 3 with respect to the surface area of the radiator 1a
When the ratio of the total exposed cross-sectional area of a was 1% or more, the thermal conductivity higher than that of the radiator formed only of the matrix resin was obtained. In particular, by setting the above ratio to 15% or more, a radiator having a thermal conductivity 10 times or more that of a conventional general-purpose radiator was obtained. However, it has been found that when the ratio exceeds 80%, the flexibility of the heat radiator decreases, the adhesion to the cooled component decreases, and practical application is difficult. Further, it was confirmed that the range of the above ratio satisfying both the thermal conductivity and the adhesiveness is 15 to 70%.

As described above, the sheet-shaped heat radiator 1a according to the present embodiment is sandwiched between the electronic / electrical component such as an LSI package and the heat sink (cooling means) such as a heat radiation fan to generate in the electronic / electrical component. The generated heat was effectively transmitted in the thickness direction of the sheet-shaped radiator 1a, and could be efficiently cooled by the heat sink. Further, the radiator 1a configured as described above has excellent elasticity and has a structure capable of absorbing unevenness and inclination of the contact surface of the component to be cooled to be adhered, so that there is no contact failure with the component to be cooled. The cooling parts could be cooled uniformly.

Next, a third embodiment of the radiator according to the present invention will be described with reference to FIG. That is, in the radiator 1b according to the third embodiment, the copper thin wire having a diameter of 200 μm used in the first and second embodiments is used as the heat conductive material 2b, and the heat conductive material 2b is oriented in a coil shape. At the very least, the aggregate 3b is manufactured by filling the voids of the aggregate 3b with the matrix resin 4b and exposing the upper end and the lower end of the aggregate 3b to the surface of the matrix resin 4b. ing.

Therefore, the aggregate 3 oriented in a coil shape
By the exposed portion 5 of b, a heat radiation path penetrating in the thickness direction of the sheet-shaped heat radiator 1b is formed, and this heat radiation path is shortened as compared with the case of the above-described first and second embodiments, The resistance can be reduced. Further, since the coil-shaped aggregate 3b has excellent elasticity in the thickness direction and the plane direction, the aggregate 3b can be freely deformed according to the surface shape of the cooled component on which the radiator 1b is mounted, and the adhesion can be improved. be able to.

Next, fourth to sixth embodiments according to the present invention will be described with reference to FIG. That is, the diameter is 200 μm
After using the copper thin wires of No. 3 as the heat conductive material 2c and bundling the copper thin wires to form an aggregate 3c, the aggregate 3c
Was embedded in a silicon resin as the matrix resin 4c so as to have a volume ratio of 70% to manufacture a radiator 1c according to the fourth example. It should be noted that both ends of the assembly 3c were exposed on the surface in contact with electronic / electrical components such as an LSI package and a heat sink (cooling means) such as a radiation fin to enhance the heat radiation effect.

Similarly, copper thin wires having a diameter of 200 μm are bundled to form an aggregate 3d, and the aggregate 3d is embedded in an epoxy resin as a matrix resin 4d so that the volume ratio is 70%, and the fifth embodiment is performed. The heat radiator 1d was manufactured.

On the other hand, an aluminum foil having a thickness of 50 μm is used as the heat conductive material 2e, and this aluminum foil is folded to form an aggregate 3e, and the aggregate 3e is cut into a predetermined shape to radiate heat according to the sixth embodiment. Body 1e.

The radiators 1c according to the above fourth to sixth embodiments.
According to 1e, since the aggregates 3c to 3e are formed of flexible heat conductive materials 2c to 2e such as metal fibers or metal foils, external forces such as compressive stress are applied to the radiators 1c to 1e. Even when it acts, the effect of absorbing the external force is remarkable, and the contact between each heat radiator and the electronic / electrical component is sufficiently ensured. Therefore, the heat generated in the parts to be cooled is the radiator 1c.
The heat is efficiently transmitted to a heat sink (cooling means) such as a heat radiation fin through 1e.

Then, the radiators 1c to 1e according to the fourth to sixth embodiments are interposed between electronic / electrical components such as an LSI package and a heat sink (cooling means) such as a radiator fin to evaluate the heat radiation characteristics. As a result, the heat generated in the electronic / electrical components was effectively transferred in the thickness direction of the radiators 1c to 1e, and the heat sink could be efficiently cooled. In particular, the thermal conductivity of the entire radiators 1c to 1e according to the fourth to sixth embodiments is the same as that of the conventional radiator 1 shown in FIGS. 6 and 7.
It is at least 2 to 3.5 times that of 0,10a,
It was confirmed that it exhibits excellent heat dissipation characteristics. It is to be noted that, by appropriately adjusting the types and blending ratios of these heat conductive materials and matrix resin, further excellent heat dissipation characteristics can be obtained.

In the radiators 1c to 1e according to the fourth to sixth embodiments, the radiators 1c to 1e are used in a state of being interposed between electronic / electrical components and a heat sink such as a radiation fin. In particular, there is a case where electrical insulation is partially required. In this case, an electric insulating layer may be formed on the surfaces of the heat radiators 1c to 1e in an appropriate predetermined shape to maintain the electronic insulating property.

In each of the embodiments described above, the heat-dissipating members 1 to 1d or the aluminum foils having thermal conductivity are formed by using copper thin wires having conductivity as the heat-conducting materials 2 to 2d. Although the heat radiating body 1e which is used as the material 2e and is made into an assembly is shown, in addition to this, boron nitride,
The same effect was confirmed when the assembly was formed by a fine wire member of ceramics having a high thermal conductivity such as aluminum nitride and alumina ceramics and having electric insulation. Further, in addition to copper, by forming an aggregate with a metal member such as gold or aluminum having a high thermal conductivity and conductivity, it has conductivity, and the thermal conductivity in the thickness direction of the sheet is high. It was also possible to produce a good radiator.

[0053]

As described above, according to the heat dissipating member of the present invention, the heat conductive materials composed of the metal fibers, the metal fine wires, the metal foils, the ceramic fibers and the like are intertwined with each other to form an assembly having a predetermined shape, Because it is formed of this aggregate,
The structure is simple and easy to manufacture, and since the continuous heat dissipation path is formed by the heat conductive material in the thickness direction of the heat radiator, the heat dissipation characteristics in the thickness direction are significantly improved compared to the conventional one. be able to.

Further, according to the radiator formed by filling the voids of the above-mentioned assembly with the matrix resin, the matrix resin holds the heat conductive material in a predetermined position so that the shape change is reduced and the flexible material is flexible. The heat-resistant matrix resin improves the adhesion of the radiator to the component to be cooled, and the heat transfer resistance is reduced to further improve the heat dissipation characteristics. In addition, since a metal material such as metal fiber, thin metal wire, and metal foil is mixed, the tensile strength of the radiator is increased and the handling life is extended.

Further, since at least a part of the aggregate is exposed on the front surface and the back surface of the matrix resin, a continuous heat dissipation path is formed through the front and back surfaces of the heat radiator, so that the thickness of the heat radiator is large. The heat transfer efficiency in the depth direction can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a radiator according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of a radiator according to the present invention.

FIG. 3 is a perspective view of the radiator shown in FIG.

FIG. 4 is a sectional view showing a third embodiment of a radiator according to the present invention.

FIG. 5 is a cross-sectional view showing fourth to sixth embodiments of the radiator according to the present invention.

FIG. 6 is a cross-sectional view showing a configuration example of a conventional radiator.

FIG. 7 is a cross-sectional view showing another configuration example of a conventional radiator.

[Explanation of symbols]

 1, 1a, 1b, 1c, 1d, 1e Heat radiator 2, 2a, 2b, 2c, 2d, 2e Thermal conductive material 3, 3a, 3b, 3c, 3d, 3e Aggregate 4, 4a, 4b, 4c, 4d , 4e Matrix resin 5 Exposed part 10, 10a Heat radiator 11, 11a Thermally conductive material (filler)

Front page continued (72) Inventor Shun Monma 4 4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa, Ltd., Toshiba Keihin Office (72) Inventor Ryosuke Fujimori 1st Komukai-Toshiba, Saiwai-ku, Kawasaki, Kanagawa Company Toshiba Research and Development Center (72) Inventor Ichizo Shimotori 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock Company Toshiba Yokohama Office (72) Inventor Naoyuki Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Stock Company Toshiba Yokohama Office

Claims (5)

[Claims] 1. A heat radiator comprising an aggregate of at least one kind of heat conductive material selected from a metal fiber, a metal fine wire, a metal foil and a ceramic fiber. 2. An aggregate of at least one thermally conductive material selected from metal fibers, thin metal wires, metal foils and ceramics fibers, and a matrix resin filled in the voids of the aggregate. Characteristic heat radiator. 3. The heat radiator according to claim 2, wherein at least a part of the aggregate is exposed on the front surface and the back surface of the matrix resin. 4. A heat radiator characterized in that the ratio of the total exposed area of the assembly to the surface area of the heat radiator is 1% or more. 5. The radiator according to claim 1, wherein the assembly is formed of a heat conductive material having electrical insulation.