JP2004207690A - Heat sink made of resin material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink made of a resin material, light in weight, small in size, and excellent in heat exchanging efficiency, by using an inexpensive resin material in a simplified manufacturing process for the achievement of a low cost. <P>SOLUTION: In this heat sink 1 made of a resin material, a multiplicity of heat radiating fins 3 made of the resin material protrude en bloc from a substrate 2 made of the resin material. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention is arranged in such a manner that the heat from the heating element is released by radiating fins for cooling by connecting to a heating element such as an electronic element, or connected to a condenser of a heat pipe, and the heat transferred by the heat pipe to the outside. It relates to a heat sink that emits.

  2. Description of the Related Art Conventionally, in electronic devices such as computers, heat generated by an electronic element such as a semiconductor is enormous. Exchangers are widely used. This metal heat sink is used, for example, by disposing a substrate as a heat receiving portion directly on the surface of a heating element such as an electronic element and fixing the substrate to the heating element by fixing means such as screws. In addition, a thermal paste such as silicon grease may be applied between the substrate and the heating element in order to bring the heating element and the heat sink into close contact with each other and to enhance heat transfer properties and arrangement stability. With such an arrangement, the substrate serves as a heat receiving portion to receive heat from the heating element, and the heat is released to the outside air via the radiation fins, thereby cooling the heating element. There is also a heat exchanger that connects a heat sink to the condensing part of the heat pipe and releases heat transferred from the heating element through the heat pipe to the outside by the heat sink to cool the heating element. I do.

By the way, in recent years, in electronic devices such as the computer, there has been a tendency for more compact and lightweight products to be preferred, and for that purpose, downsizing and weight reduction of a heat sink and a heat exchanger using the heat sink have become important issues. What is required is a small and lightweight one that has high heat exchange performance.
JP-A-2002-1511 JP-A-2002-64170 JP 2002-190558 A

  However, since the conventional heat sink is made of a metal material such as copper, aluminum, a copper-based alloy, or an aluminum-based alloy as described above, there is a limit to the weight reduction even when the lightest aluminum is used. In addition, in order to obtain a product with high heat exchange efficiency even though it is small, it is sufficient to increase the surface area of the heat radiation fin of the heat sink to increase heat radiation and heat absorption, but the conventional heat radiation fin has a cross-sectional shape. It is a simple shape such as a circular, oval, or square pin or a flat plate, and it is difficult to form a complicated shape that increases the surface area of a metal material, and there is a limit to miniaturization.

  Therefore, the present inventors focused on a resin material that is lightweight and excellent in workability, and conducted a comparative experiment of heat exchange performance between a heat transfer surface made of a metal material and a heat transfer surface made of a resin material. It has been found that the heat exchange surface made of a resin material deteriorates only about 4 to 15% in heat exchange performance as compared with the heat transfer surface made of a resin material, depending on conditions. In order to supplement the heat exchange performance of about 4 to 15%, if the surface area of the resin material heat transfer surface is increased by 15% or more, heat exchange performance equal to or greater than that of the metal heat transfer surface can be obtained. I came to the conclusion that I could get it.

  SUMMARY OF THE INVENTION The present invention is to solve the above-described problems. In particular, a heat sink for heat exchange can be formed at a low cost by using a low-priced resin material and a simple manufacturing operation while forming a light-weight and small-sized heat sink. Is to try. Moreover, the object is to obtain a product that is excellent in heat exchange efficiency even if it is lightweight and small.

  In order to solve the above-described problems, the present invention is configured by integrally forming a plurality of resin-made heat radiation fins on a resin-made substrate.

  Further, the radiation fin may be in the form of a pin having a circular, elliptical, polygonal, star, or gear cross section.

  In addition, the radiation fins may be plate-shaped with one or both surfaces flat or curved.

  Further, the heat radiation fins may have fine irregularities and / or protrusions on the surface.

  Further, the substrate and the radiation fins may contain particles and / or fibers having higher thermal conductivity than the resin material forming them.

  Further, the substrate and the radiation fins may contain carbon nanofibers in a resin material forming them.

  Further, the carbon nanofibers may be contained at a content of more than 5 wt% and less than 30 wt%.

  The present invention is configured as described above. By forming the heat sink using a resin material, the heat sink can be reduced in weight and size. As a result, the heat exchanger using the heat sink can be reduced in weight and size. In addition, by using resin material, the degree of freedom during molding is higher than that of metal materials, and the heat transfer area of the radiating fins can be increased. Products with high performance can be manufactured at low cost with easy manufacturing technology.

  Since the heat sink of the present invention is configured as described above, the substrate for receiving heat from the heating element and the radiation fins for releasing the heat received by the substrate to the outside are integrally formed of a resin material. Compared with material products, it is possible to obtain products that are particularly lightweight and inexpensive. In general, resin materials are inferior in heat conductivity to metal materials, but are excellent in workability, so that the heat radiation fins can be easily processed into a complicated shape which is difficult to process with metal materials. Therefore, a heat sink having high heat exchange performance can be obtained even if it is made of a resin material by increasing the surface area by forming the radiation fins in a complicated shape. In addition, since the heat exchange performance can be improved by increasing the surface area, the heat sink can be downsized. Further, since the resin material is softer than the metal material and the temperature during processing does not become excessively high, the deterioration of the mold for heat sink molding can be suppressed and the life of the mold can be extended.

  When such a resin heat sink having excellent heat exchange performance is used for cooling an electronic element, a substrate serving as a heat receiving portion is disposed on the surface of the electronic element, and the heat sink is fixed to the device with screws or the like. . Further, as in the conventional case, a thermal paste such as silicon grease may be interposed between the substrate and the electronic element. Then, the heat generated from the electronic element is transferred to the substrate which is the heat receiving portion, and the heat of the substrate is released into the outside air through the radiation fins, so that the electronic element is efficiently cooled.

  In addition, since the heat sink and the thermal paste such as silicon grease are both made of a resin material, the mutual thermal conductivity can be increased. Thermal paste closes the gap between the heating element and the heat sink to increase heat transfer.However, the resin heat sink has better adhesion to the heating element than metal products due to its elastic force. In addition, the use of thermal paste can be reduced, and good heat conductivity can be obtained without using it. Further, the thermal paste has a role as an electric insulator as well as a heat transfer performance. However, when the heat sink is made of a resin material, the heat sink itself can also serve as an electric insulator.

  In the above description, a heat sink is used as a cooling means. However, any of heat exchange such as cooling and heating for heating such as heating for warming the outside air by radiating heat from radiating fins, and for heat transport such as a heat exchanger and air conditioning is used. It can also be used as a means, and has excellent heat exchange performance, so that a lightweight and small product can be obtained.

  Further, the substrate and the radiation fins may be formed integrally at the time of molding, or may be formed separately, and both may be connected in a later step by heat welding or an adhesive. When connecting the board and the radiating fins in a later process, metal products require time and skill for brazing, etc., but welding of resin materials can be performed at a lower temperature than metal materials, and adhesives can be used. The connection is easy and does not require advanced technology, so that the workability can be improved.

  Further, the radiation fins may be in the shape of a pin having a circular, elliptical, polygonal, star-shaped, or gear-shaped cross section. Pin-shaped heat radiation fins such as circular, elliptical, quadrangular, and pentagonal shapes exist even in conventional metal-made products, but there is a limit in elongating the length of a pin formed of a metal material. However, in the resin material, the radiation fin can be formed in a long pin shape which is difficult with a metal material, and the heat transfer area can be increased. Furthermore, even if it is a hexagonal or more polygonal, star-shaped or gear-shaped pin-shaped radiating fin that is difficult to mold or cut with metal material, it can be easily molded with resin material, The area can be increased.

  Further, the radiation fins may be plate-shaped with one or both surfaces flat or curved, and a large number of plate-shaped radiation fins or a large number of curved surfaces may be formed of a resin material which is easy to process. Thereby, the heat transfer area of the plate-shaped radiating fins can be increased.

  Also, if fine irregularities or projections are provided on the surface of the pin-shaped, plate-shaped, or other radiating fins, the heat transfer area can be further increased, the heat dissipation can be improved, and efficient heat exchange can be achieved. Becomes possible. In the case of a resin material, even such minute unevenness and protrusions can be easily provided.

  As described above, even a heat radiation fin having a complicated shape, irregularities, and projections, which is difficult with a metal material, can be easily molded with a resin material, and the heat transfer area of the heat radiation fin is increased, so that the resin material is Even if the heat transfer surface is used, the heat transfer surface will have the same or better heat radiating characteristics as the metal heat transfer surface, and will have excellent heat exchange performance, making it possible to obtain a particularly lightweight heat sink. It becomes possible.

  When carbon nanofibers are contained in the resin material forming the substrate and the radiation fins, the heat conductivity of the resin material heat transfer surface is further increased, and the heat radiation characteristics of the heat sink can be further improved. . In addition, when the carbon nanofiber is contained in a content of more than 5 wt% and less than 30 wt%, the best thermal conductivity can be obtained. If the content of the carbon nanofibers is 5 wt% or less, the effect of improving the heat transfer effect is poor, and it is difficult to include 30 wt% or more in the resin material. No big difference.

  The term "carbon nanofiber" as used in the present specification indicates a general term including carbon nanotubes, carbon nanohorns, and other nano-unit carbon fibers in the field of nanotechnology. Further, carbon nanotubes, carbon nanohorns, and others may be mixed and contained in the resin material, or may be contained alone. When the carbon nanotube is contained in the resin material, the carbon nanotube may be a single layer or a multi-layer. Further, the aspect ratio of the carbon nanotube does not matter. Further, the thickness, length, and the like of the carbon nanotube are not limited.

  When a black resin material having a black body radiation effect is used, the heat conductivity of the substrate and the radiation fins is increased, and the heat radiation characteristics of the heat sink can be improved. The resin material may contain particles and / or fibers made of a metal material such as copper, aluminum, and stainless steel having high thermal conductivity, a carbon material, or a glass material, or a powder of the metal material may be formed on the surface of the resin material. The heat exchange performance can be improved by applying a coating material or the like or plating or depositing a metal material. Furthermore, when the metal material, the carbon material or the glass material particles and fibers, and / or carbon nanofibers are contained in the resin material having a black body radiation effect with black color, the heat radiation characteristics are further improved. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a resin heat sink provided with a pin-shaped heat dissipating fin having a rectangular cross section in Example 1. FIG. 2 is a perspective view of a resin-made heat sink provided with pin-shaped heat radiation fins having a star-shaped cross section in Example 2. FIG. 3 is a perspective view of a resin heat sink in which a plurality of plate-shaped radiation fins having a corrugated curved surface are provided in parallel in Example 3. FIG. 4 is a plan view of a resin-made heat sink in which a plurality of plate-shaped heat radiation fins having a saw-like curved surface are provided radially in Example 4. FIG. 5 is a perspective view of a heat exchanger using a heat sink provided with a plurality of plate-shaped radiating fins having flat surfaces in parallel. FIG. 6 is a comparison of the heat exchange performance of a pipe having an outer surface coated with PA resin, a pipe having an outer surface coated with PA resin and PP resin, and a pipe formed of only steel pipe. It is a conceptual diagram of an experiment. FIG. 7 is a graph of the result of the comparative experiment.

  First, in carrying out the present invention, a comparative experiment was conducted on the heat exchange performance of a heat transfer surface having a resin surface material. As shown in FIG. 6, in this experimental apparatus, a pipe (32) having a diameter of 8 mm and a length of 1900 mm was arranged in a wind tunnel (31), and a hot water provided with a thermometer (33) was provided in the pipe (32). A tank (34), a pump (35), and a flow meter (36) are connected, and hot water at a temperature of about 60 ° C. is flowed through the pipe (32) at a flow rate of 0.9 L / m. Cooling air is sent into the wind tunnel portion (31) by a fan (37). Then, the heat exchange performance between the cooling air and the hot water in the pipe (32) is measured by measuring the inlet and outlet temperatures of the hot water and calculating the temperature difference. The relationship between the temperature difference and the wind speed is shown in Table 1 below and the graph of FIG. In the experiment, pipes (32) (hereinafter referred to as PA coated pipes) were prepared by subjecting the outer surface of a steel pipe having a wall thickness of 0.7 mm to zinc plating and chromate treatment of 13 μm and further coating with a PA resin having a wall thickness of 50 μm. A pipe (32) (13 mm) which is formed by applying 13 μm zinc plating and chromate treatment to the outer surface of a steel pipe having a thickness of 0.7 mm and further coating it with a PA resin having a thickness of 50 μm and a PP resin having a thickness of 1.0 mm. It was used. Further, as a comparative experiment, the heat exchange performance of a pipe (32) formed only of a steel pipe was also measured. This steel pipe had a wall thickness of 0.7 mm and had no outer surface subjected to any surface treatment.

  In Table 1 below, the reason why the wind speed (m / s) does not completely match between the PA-coated pipe, the PA + PP-coated pipe, and the pipe made of only the steel pipe is that it is technically difficult to obtain a completely matched wind velocity. Because it is. Therefore, an approximate wind speed is generated, and the wind speed shown in Table 1 is obtained by measuring the wind speed.

  According to the above-mentioned experiment, the heat exchange performance of the PA-coated pipe and the PA + PP-coated pipe at a wind speed of about 6 m / s is deteriorated by only about 4 to 15% as compared with the conventional steel pipe alone. Performance was shown. From these experimental results, it is possible to obtain a heat exchange performance equal to or higher than that of the metal material heat transfer surface by increasing the surface area of the resin material heat transfer surface by about 15% or more.

  In carrying out the present invention, the use of a resin material or the like as shown in Table 2 below provides not only excellent heat exchange performance, but also a heat sink having excellent corrosion resistance and heat resistance, and a heat exchanger using the heat sink. Can be obtained. Further, if heat resistance is not so required, more kinds of resin materials can be used.

  The heat sink and the heat exchanger using the heat sink shown in FIGS. 1 to 5 were formed from the resin material. First, the first embodiment shown in FIG. 1 will be described in detail. (1) is a heat sink, which is made of a resin material or the like as shown in Table 2 above, and is particularly lighter in weight than a conventional metal material product. At the same time, an inexpensive product having excellent heat resistance can be obtained. The heat sink (1) comprises a substrate (2) and a plurality of pin-shaped radiating fins (3) projecting from one surface of the substrate (2) and having a rectangular cross section. The fin (3) and the fin (3) are integrally formed at the time of molding. Although the pin-shaped heat radiation fins (3) having a square cross section exist in conventional metal products, they can be used as long pin heat radiation fins (3) that are difficult to form and cut with metal materials. By increasing the heat transfer area, it is possible to obtain a thermal conductivity equal to or higher than that of a metal product.

  Further, in the above, since the substrate (2) and the radiation fin (3) are integrally formed at the time of molding, the number of manufacturing steps is small, and simple manufacturing is possible. Further, as another different manufacturing procedure, the substrate (2) and the radiation fin (3) may be separately formed, and both may be connected in a later step. In this case, since resin materials are bonded together, they can be heat-welded at a lower temperature than brazing metal materials, or can be easily performed with an adhesive, etc., and require advanced manufacturing technology and labor. And easy work becomes possible.

  When the heat sink (1) formed as described above is used for cooling a heating element (not shown) such as an electronic element, a substrate (2) as a heat receiving unit is disposed on the surface of the heating element. Further, the heating element may be fixed by fixing means such as a screw (not shown). Also, a thermal paste such as silicon grease is applied between the substrate (2) and the heating element, and the heating element and the heat sink (1) are brought into close contact with each other without any gap, thereby improving heat transfer and mounting stability. Is also good. Further, in this case, heat can be efficiently transmitted between the heat sink (1) made of the resin material and the silicon.

  With the arrangement as described above, the substrate (2) serves as a heat receiving portion to receive heat from the heating element, and the heat is released to the outside air via the radiating fins (3) serving as the heat radiating portion. In the heat radiation fin (3) of this embodiment, since the pin-shaped heat radiation fin (3) is formed in a long length to increase the heat transfer area and enhance the heat conductivity, heat exchange with the outside air is efficient. The heating element can be cooled well.

  In the first embodiment, the cross-sectional shape of the pin-shaped heat radiation fins (3) is square, but in the second embodiment shown in FIG. 2, the cross-sectional shape is star-shaped. Even with such a complicated shape, by using a resin material, the radiation fins (3) can be easily formed, and the heat transfer area can be further increased, and the heat exchange performance can be enhanced. . Further, the pin-shaped heat radiation fins (3) may be not only the above-described square and star but also a conventional circle, ellipse, polygon other than the square, or a gear.

  In the first and second embodiments, the radiation fin (3) is formed in a pin shape. In another different third embodiment, as shown in FIG. 3, the radiation fin (3) is formed in a plate shape. ing. The surface of the plate-shaped heat radiation fin (3) is formed into a wavy curved surface, and a plurality of heat radiation areas are arranged in parallel with the substrate (2) to increase the heat transfer area and improve the heat exchange performance of the heat radiation fin (3). Is increasing.

  In the fourth embodiment shown in FIG. 4, a plurality of plate-shaped heat radiation fins (3) having a saw-like curved surface are radially arranged on the substrate (2). Even with such a shape, it can be easily formed of a resin material, and the heat transfer area of the radiation fin (3) can be increased.

  In the fifth embodiment shown in FIG. 5, a heat exchanger (4) is formed by using a heat sink (1) having a plurality of plate-shaped heat radiation fins (3) provided in parallel with a substrate (2). are doing. The heat exchanger (4) is provided with a heat pipe (5) containing a working fluid such as water or alcohol in a closed space provided therein, and heat of a heating element is applied to one end of the heat pipe (5). A flat heat receiving body (6) that receives heat and transfers the heat to the heat pipe (5) is connected, the heat sink (1) is connected to the other end of the heat pipe (5), and the working fluid of the heat pipe (5) is used. The transmitted heat can be released to the outside via the radiation fins (3).

  In the heat exchanger (4) as described above, the use of a resin material allows the heat sink (1), the heat pipe (5), and the heat receiving body (6) to be integrally formed at the time of molding. Is possible, and the material is inexpensive and easy to manufacture, so that an inexpensive product can be obtained. Of course, the heat sink (1), the heat pipe (5), and the heat receiving body (6) may be formed separately and connected to each other by welding or an adhesive. Alternatively, only the heat sink (1) may be made of a resin material, and the heat pipe (5) and the heat receiving body (6) may be made of a metal material. It becomes possible.

  Further, in order to cool the heating element using the heat exchanger (4), when the heat of the heating element is transmitted to the heat receiving element (6) arranged in contact with the heating element, the heat is transferred to the heat pipe. The working fluid in (5) is heated and evaporates. The vapor of the working fluid flows to the heat sink (1) through the internal space, and the heat of the working fluid is transmitted to the heat sink (1). Alternatively, the latent heat of evaporation between the working fluid and the cooling medium such as cooling water or cooling air is transferred. Due to the transfer of the latent heat of vaporization, the working fluid is condensed and rapidly returns to the heat receiving body (6). The evaporation of the working fluid by the new heat transfer from the heating element to the heat receiving body (6) and the condensation of the working fluid by the heat radiation in the heat sink (1) are repeated simultaneously and in parallel, thereby cooling the heating element. It is performed continuously. Since the heat sink (1) having high heat exchange performance is used, a heat exchanger (4) having a high cooling effect can be obtained, and downsizing can be realized.

  In each of the above embodiments, the substrate (2) of the heat sink (1) and the radiating fins (3) and / or the heat pipe (5) made of a resin material and / or the heat receiver (6) made of a resin material are used. ), The resin material forming these contains particles or fibers of a metal material such as copper, aluminum, and stainless steel having high thermal conductivity, particles or fibers of a glass material, particles or fibers of a carbon material, or the like. Alternatively, a paint in which a powder of a metal material is mixed may be applied to the surface, or the metal material may be plated or vapor-deposited.

  In addition, even when a black resin material having a black body radiation effect is used, the heat conductivity of the heat transfer surface of the heat sink (1), the heat pipe (5) or the heat receiving body (6) is increased, and the heat radiation characteristics are improved. The heat sink (1) and the heat exchanger (4) having a higher cooling effect can be obtained. Furthermore, the metal material, carbon material, glass material particles and fibers, and / or carbon nanofibers may be contained in the resin material having a black body radiation effect in black, further improving the cooling effect. Becomes possible.

  Further, by including carbon nanofibers in the resin material, the heat radiation characteristics of the heat sink (1) and / or the heat pipe (5) made of the resin material and / or the heat receiving body (6) made of the resin material are further improved. The cooling performance of the heat sink (1) and the heat exchanger (4) can be effectively improved. When carbon nanofibers are contained in a resin material, the best heat transfer effect can be obtained by containing carbon nanofibers in a content of more than 5 wt% and less than 30 wt%.

FIG. 4 is a perspective view of the first embodiment in which the heat radiation fins have a rectangular pin shape in cross section. FIG. 9 is a perspective view of a second embodiment in which the radiation fins have a star-shaped cross section. FIG. 11 is a perspective view of a third embodiment in which the heat radiation fins are formed in a plate shape having a wavy curved surface. FIG. 14 is a plan view of a fourth embodiment in which the radiation fins are plate-shaped having a saw-like curved surface. FIG. 14 is a perspective view of a heat exchanger according to a fifth embodiment using a heat sink. The conceptual diagram of a heat exchange performance comparison experiment. Heat exchange performance graph.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Heat sink 2 Substrate 3 Heat radiation fin

Claims (7)

A resin-made heat sink, wherein a plurality of resin-made heat radiation fins are integrally formed on a resin-made substrate. The heat sink made of resin according to claim 1, wherein the radiation fin has a pin shape having a circular, elliptical, polygonal, star, or gear cross section. The heat sink made of resin according to claim 1, wherein the radiation fin is formed in a plate shape having one or both surfaces flat or curved. The heat sink made of a resin material according to claim 1, wherein the heat radiation fin has fine irregularities and / or protrusions provided on a surface thereof. The resin heat sink according to claim 1, 2, 3, or 4, wherein the substrate and the radiation fin contain particles and / or fibers having higher thermal conductivity than the resin material forming them. The resin heat sink according to any one of claims 1, 2, 3, 4 and 5, wherein the substrate and the radiation fin include carbon nanofibers in a resin material forming them. 7. The resin material heat sink according to claim 6, wherein the carbon nanofibers are contained at a content of more than 5 wt% and less than 30 wt%.

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