JPS63140292A - Porous-type heat radiator - Google Patents

Abstract

PURPOSE:To obtain a heat-transmitting body having excellent heat-radiating properties and easy to handle, by providing a porous-type heat-radiating part having an internal part with a sufficient fluid-passing property, a solid base part which is formed in a body with the radiating part and has a surface complementary to a member to be cooled. CONSTITUTION:A porous heat-radiating part has a void ratio of at least about 50%, and is preferably formed of a material having an excellent thermal conductivity. A porous material 2 used for forming the heat-radiating part may be, for example, a metal such as Al, Cu, Fe, Ni, Zn, Sn, Mg, Ti, Au, Ag and Pt or an alloy thereof or a ceramic containing at least one of MgO, Al2O3, SiO2, CaO, ZrO2, SiC, TiC, AlN, TiB2 and ZrB2. Since a porous member is generally unstable in mechanical strength, it is essential to provide a solid base part 1 in a body with the porous member. For preventing thermal conductivity from being lowered, it is necessary that the two components are originally formed in a body, or are integrated to each other by adhesion through melting of the member itself, adhesion by an adhesive, brazing or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat sink. More specifically, the present invention relates to a novel configuration of a heat radiator used for cooling a heat exchanger or an electronic device.

Conventional technology In general, a heat sink is configured to have fins (protrusions) and grooves of various shapes to increase the specific surface area and thermally connect the heat generating body and the cooling medium with a wider heat transfer area. . For this reason, for example, in various finned tubes such as heat exchangers, heat pumps, and heat vibrators, fins and grooves are formed by cutting or pressing the surface of the heat transfer wall, or the fins are welded or brazed. I'll install it. Further, in heat sinks for electronic circuits and the like, aluminum heat dissipating materials manufactured by extrusion molding, die casting, press working, etc. are widely used.

Problems to be Solved by the Invention A heat sink having such a configuration is advantageous in terms of automation of the manufacturing process, so it can be manufactured at a relatively low cost.
The heat transfer area is at most IO times the planar projected area, so the heat dissipation capacity is small, and the weight is generally large. This is contrary to the current trend of various electronic devices, which aim to make devices smaller and lighter.

Therefore, it is possible to use a composite heat transfer material that is integrally composed of a plurality of materials, such as a honeycomb material or a three-dimensional fabric, which has a complex three-dimensional surface shape, as a heat radiator. It is considered.

However, although such a heat dissipation material has a large surface area of the heat transfer wall, the mutual contact area becomes small when connecting the members constituting the heat dissipation body or between the heat dissipation body and the heating element. Heat transfer resistance increases. Therefore, although the heat transfer area is large, the heat dissipation property is not excellent.

In addition, a porous member made of metal or the like has a surface area of 500 m'/m' to 7500 m'/m.
Although it is considered to be preferable as a heat dissipating body, there are restrictions on how to attach it to a member to be cooled because its mechanical strength is generally unstable.

Therefore, the purpose of the present invention is to solve the above-mentioned problems of the prior art. Our goal is to provide the following.

Means for solving the problem, that is, according to the present invention, there is provided a porous heat dissipating section whose interior has sufficient fluid circulation, and a member to be cooled that is integrated with the porous heat dissipating section. According to an aspect of the present invention, there is also provided a porous heat dissipating body characterized in that the porous heat dissipating portion comprises a solid base having complementary surfaces. A porous heat sink characterized by having a void ratio is provided.

Further, according to an aspect of the present invention, at least one of the porous heat dissipating portion and the base has Δ1, Cu, Fe, N1.
2n, Sn, ! Jg, Ti, Au, Ag, P
Provided is a porous heat sink characterized in that it is formed from a heat sink or an alloy thereof.

Further, according to an aspect of the present invention, at least one of the porous heat dissipation portion and the base portion is! , IgO, AI. o3, Si
O□, Can, ZrO□, SiC, TiC, AIN
Provided is a porous heat sink characterized in that it is made of a ceramic containing at least one of 5TiB2 and ZrB2.

Further, according to an aspect of the present invention, there is provided a porous heat radiator characterized in that the porous heat radiator is composed of an integrally formed plate-like solid base and a substantially rectangular porous heat radiator. Ru.

Further, according to an aspect of the present invention, there is provided a porous heat radiator characterized in that the porous heat radiator is constructed by impregnating a portion of a porous member with molten metal.

Function One of the main features of the heat sink according to the present invention is that its heat dissipation portion is formed of a porous member.

That is, the porous member has a much larger specific surface area than a conventional heat dissipating body whose heat dissipating portion is a simple protrusion (fin) or groove. Therefore, it is expected that the cooling efficiency will also be greatly improved.

However, the heat dissipation section must not obstruct the flow of the cooling medium that comes into contact with it. This is because if a cooling medium such as air or water stays inside the heat dissipation section, heat dissipation is actually hindered.

The flowability of the fluid in the heat dissipation section varies depending on the viscosity of the cooling medium, the shape of the holes in the heat dissipation section, etc., but the inventors have considered from the examples described below that the cooling medium is a gas. It has been found that in some cases it is preferable for the porous heat dissipation portion to have a porosity of about 50% or more. However, this is just one index and does not limit the present invention.

It goes without saying that the heat dissipating body itself is preferably made of a material with excellent thermal conductivity; preferable porous materials include A1, Cu, Fe, N1,
Zn, Sn, ! Jg, Ti, A, u, Ag,
Metals such as F' or their alloys, or! ,
IgO, Al2O5, SiO□, CaO, ZrO2, S
Examples include ceramics containing at least one of iC, TiC5AIN, 5TiB2.1rB2.

In addition, in order to make these materials porous and give them +4, there are methods of foaming molten metal, foaming granular metal, and heating a mixture of metals and metals with substances that generate gas when heated to high temperatures. Alternatively, a method using a single mold, etc. can be used.

Now, the heat sink of the present invention has a solid base 813! ij'j
Its main characteristic is that it is light.

That is, as described above, porous members generally have unstable mechanical strength, and it is practically impossible to screw them, for example, to a member to be cooled. This becomes more serious as the space ratio increases as a heat sink.

Therefore, according to the present invention, it is essential for a practical heat dissipation body to have a solid base integrally.

Also, as mentioned above, in the case of porous members, it is difficult to increase the contact area with the member to be cooled, so from this point of view as well, it is difficult to increase the contact area with the member to be cooled. It is desirable to have a real base.

However, interfering with heat conduction between the base and the above-mentioned heat dissipation section means abandoning the function as a heat dissipation body.

Therefore, both must be integrally constructed without reducing heat conduction.

For this purpose, it is necessary that the two be integrally constructed from the beginning, or that they be integrated by fusing the members themselves, adhering with an adhesive with good thermal conductivity, brazing, etc.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

Production example 1 Commercially available polyurethane foam with open cell structure (size 1
A commercially available paraffin wax slope (
Size: 170 x 70 x 6 mm, melting point: 126°C
) were glued together using chloroprene adhesive to make a model.

Next, such a model was made with an inner diameter of 200 mm and a depth of 23 mm.
A mixture of cast river gypsum and industrial heavy calcium carbonate with water added thereto was poured as a casting material into a +m iron container, and after vibration was applied to fill the gaps in the model, it was hardened.

Thereafter, it was heated in an electric furnace at a temperature of 150°C for 12 hours, and then further heated at a temperature of 650°C for 6 hours to eliminate the model and obtain a mold.

Next, in a vacuum, a second mold was placed in an aluminum alloy (AC2
After casting A) and cooling, the casting was taken out from the iron container, immersed in 5N nitric acid to remove the mold, and washed with water. In this way, a heat sink consisting of a solid metal part 1 and a porous metal part 2 as shown in FIG. 1 was produced.

Production example 2 Commercially available polyurethane foam with open cell structure (size 1
00X 100X 200mm) commercially available PMM on one side
A plate (polymethyl methacrylate, size 1oox 2
00
A heat sink having a solid metal part and a porous metal part having the same shape as the model was obtained.

Production example 3 Inside a stainless steel container (size 300 x 200 x 1
5 mm), a part of the polyurethane foam with an open cell structure is immersed in this, the polyethylene is cooled and solidified, and then the polyurethane foam with the polyethylene attached is taken out from the container. Except for obtaining the model, a mold was prepared in the same manner as in Example 1, aluminum alloy was cast, and then cooled to obtain a heat sink having a solid metal part and a porous metal part having the same shape as the model.

1 Production example 4 Alumina ceramic container (size 150 x 200
X70 city, wall pressure 10n+m) is heated and molten aluminum alloy (A1070) is drawn into it to a thickness of 5mm, and porous nickel (average number of cells 8 cells/inch, void ratio 95%, (size 70 x 70 x lOmm) and porous aluminum (average cell count 10 cells/inch, void ratio 97%, size 80 After natural cooling, heat sinks made of an aluminum plate and porous nickel, and an aluminum plate and porous aluminum were obtained.

Example By the method shown in Preparation Example 1, a porous metal part (size 14
5 x 75 x 44mm, void ratio 97%, average number of cells 6
/inch) part and solid metal part (S/Rs 11i5X
75x6mm) aluminum heat sink (weight 2
00g) was produced. A transistor was attached to this heatsink and a heat radiation test was conducted in a thermostatic chamber at a temperature of 65°C.The results were 360W with forced air cooling and 90W without forced air cooling. Even with power consumption of W, the surface temperature of the transistor is 100℃
It was below. In other words, this radiator generates 90W during natural air cooling.
1. When forced air cooling, it had a heat dissipation performance of 360W.

For comparison, we also used a commercially available extruded aluminum heat sink (Material A 1070, size 145 x 75 x 50 m) that is generally used for transistor cooling.
A similar test was also conducted on the sample (m, weight: 485 g). This heatsink is made of aluminum plate with dimensions of 75X45X1.5.
24 fins of mI[l are provided at equal intervals.

A transistor was attached to this heatsink as described above, and the temperature during operation of the transistor was similarly measured to measure the cooling performance. This heat radiator exhibited a heat radiation performance of 45 W during natural air cooling and 180 W during forced air cooling.

Thus, the heat radiator according to the present invention has much better heat dissipation performance than the conventional ones.

Effects of the Invention As detailed above, the heat dissipation body according to the present invention has extremely excellent heat dissipation performance and is easy to store and handle in practical use.

That is, since a porous member is used as the heat dissipating body, the specific surface area of the heat dissipating body is extremely large, and it efficiently radiates heat to the cooling medium. On the other hand, since it has a solid base, it is easy to attach it to the member to be cooled, and the attachment is also mechanically stable. Further, since this solid portion is interposed between the cooled part and the heat radiating body, the heat of the cooled part is effectively conducted to the heat generating body.

Furthermore, the porous member has a large void ratio relative to its bulk;
The heat dissipation body can be constructed with extremely light weight. Therefore, the heat sink according to the present invention can be suitably used in electronic products that require reduction in weight or size.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the configuration of a heat sink according to the present invention. [Reference number] 1. Solid metal portion 2. Porous metal portion

Claims (6)

[Claims] (1) A porous heat dissipating section whose interior has sufficient fluid circulation, and a solid base that is integrated with the porous heat dissipating section and has a surface complementary to the member to be cooled. A porous heat sink characterized by comprising: (2) The porous heat dissipation body according to claim 1, wherein the porous heat dissipation portion has a void ratio of 50% or more. (3) At least one of the porous heat dissipation part and the base is made of Al, Cu, Fe, Ni, Zn, Sn, Mg, Ti.
, Au, Ag, Pt, or an alloy thereof, as claimed in claim 1 or 2. (4) At least one of the porous heat dissipation part and the base is made of MgO, Al_2O_3, SiO_2, CaO, Z
rO_2, SiC, TiC, AlN, TiB_2, Zr
The porous heat sink according to any one of claims 1 to 3, characterized in that the porous heat sink is made of ceramic containing at least one of B_2. (5) Claims 1 to 4, characterized in that the porous heat radiator is composed of an integrally formed plate-shaped solid base and a substantially rectangular porous heat radiator. The porous heat sink according to any one of the above. (6) The porous heat radiator is constructed by impregnating a portion of a porous member with molten metal, as set forth in any one of claims 1 to 4. Porous heat sink.