JP2010098004A - Heat sink and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink capable of improving a cooling capacity and capable of controlling the heat sink itself to a fixed temperature range when a heating element generates heat. <P>SOLUTION: To heat radiation fins 4 of a heat sink body 3, a thermally conductive heat storage resin block 5 including a latent heat storage material is attached and worked. Around the heat storage resin block 5, a moisture preventing coating layer 6 is provided. Further, on the attaching surface 3a to the heating element 1 of the heat sink body 3, a highly thermally conductive sheet layer 7 is printed and worked beforehand. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat sink attached to a heat generating portion of a heating element, and more particularly to a heat sink that can utilize a latent heat storage material to improve cooling performance and control the heat sink to a certain temperature range by its latent heat cooling effect. It is.

  In recent years, the performance of electronic devices, particularly computers, has been remarkably improved, and countermeasures against heat generation of computer chips, CPUs, and the like have become important as performance is improved. For example, in a personal computer, conventionally, an air cooling fan is provided inside a casing to promote heat dissipation by forced convection of air, and recently, a higher performance water cooling type has been proposed along with improvement in performance of the personal computer. On the other hand, in order to cool a chip mounted on an internal board or a CPU itself, a heat sink attached to a heat generating portion of a heat generating body such as a chip has been proposed (see Patent Document 1).

  A heat sink uses a metal block with a large surface area with a large number of radiating fins, and is used by being fixed to the heat generating part of the heating element to dissipate the heat generated from the heating element into the air via the radiating fins. The heating element is cooled.

JP 2004-89005 A

  However, the conventional heat sink only dissipates heat using heat conduction by natural convection of air, and the cooling capacity is naturally limited. To increase the cooling capacity of the heat sink, there are methods such as extending the heat dissipation fins to increase the surface area, or combining a fan that causes forced convection of air, but in the former case, if the space for installing the heat sink is narrow In the latter case, there are problems such as an increase in driving power and noise.

  The present invention has been made in view of the above problems, and can improve the cooling capacity without using the above-described conventional means, and can control the heat sink itself within a certain temperature range when the heating element generates heat. The purpose is to provide a heat sink.

  Furthermore, an object of the present invention is to provide a method for manufacturing a heat sink excellent in manufacturing cost.

  In order to solve the above-mentioned problem, the heat sink according to claim 1 of the present invention is characterized in that a heat storage resin body including a latent heat storage material and having heat conductivity is attached to a heat radiation fin of a heat sink body. To do.

  According to the heat sink according to claim 1, heat generated from the heat generating body is transmitted to the heat sink main body attached to the heat generating portion, and the heat storage resin body attached to the heat radiating fin from the heat radiating fin provided on the heat sink main body. Endothermic. In the heat storage resin body, the latent heat storage material included therein stores the latent heat absorbed when the phase changes. Due to the latent heat cooling action of this latent heat storage material, the heat sink itself is forcibly cooled, the cooling capacity for absorbing heat from the heating element is improved, and the temperature of the heat sink itself is controlled within a certain temperature range.

  The heat stored in the latent heat storage body is gradually radiated to the outside from the latent heat storage material by the heat conductive resin.

  In the heat sink according to claim 2 according to the present invention, the heat storage resin body is integrally formed in a plate shape or a block shape by kneading the latent heat storage material in a heat conductive resin, with respect to the heat storage resin body. The tip end side of the heat radiating fin is embedded.

  According to the heat sink of claim 2, the tip portion of the radiating fin is embedded in a heat storage resin body in which the latent heat storage material is kneaded into the heat conductive resin and integrally formed in a plate shape or a block shape. By attaching to the heat sink, the heat sink itself can be forcibly cooled by the latent heat cooling action by the latent heat storage material with a very simple structure. As a result, it is possible to improve the cooling capacity for absorbing heat from the heating element, and to control the temperature of the heat sink itself within a certain temperature range. The plate-shaped or block-shaped heat storage resin body may be pushed and attached so as to be embedded so that the tip end portion of the heat dissipating fin is embedded toward the base side before curing. The mounting space is hardly bulky. Therefore, if there is a space for mounting the conventional heat sink on the heating element, most of the heat sink with the heat storage resin body can be mounted.

  The heat sink according to claim 3 according to the present invention is characterized in that the latent heat storage material is made of a material that changes from a solid phase to a liquid phase or from a liquid phase to a gas phase in a range of 30 ° C to 120 ° C. And

  The heat sink according to claim 4 of the present invention is characterized in that the latent heat storage material is any one of ice, inorganic hydrated salt, and paraffin.

  The heat sink according to claim 5 of the present invention is characterized in that the latent heat storage material is sodium thiosulfate hydrate.

  The heat sink according to claim 6 of the present invention is characterized in that the thermal conductivity of the thermal conductive resin is 0.3 W / m · k or more.

  The heat sink according to claim 7 of the present invention is characterized in that the heat storage resin body is covered with a moisture-proof coating layer.

  The heat sink according to an eighth aspect of the present invention is characterized in that a high heat conductive sheet layer having flexibility and adhesion is provided on a contact surface of the heat sink body with respect to the heat generating portion of the heat generating element.

  Since the heat conductive sheet layer is provided on the contact surface of the heat sink body, specifically the mounting surface of the heat sink body to the heat generating portion of the heat generating body, the heat generating body generates heat by tightening the heat sink body or holding down the spring. What is necessary is just to fix to a part. The highly heat-conductive sheet layer with flexibility and adhesion absorbs unevenness between the mounting surface of the heat sink body and the heating part of the heating element, so that excessive distortion is not applied to the heating element and may be damaged. Absent. Further, since the minimum thickness of the high thermal conductive sheet layer can be easily controlled by printing, the thermal resistance can be remarkably lowered.

  The heat sink according to claim 9 according to the present invention is characterized in that the high thermal conductive sheet layer is printed in advance on a contact surface of the heat sink body.

  Printing may be screen printing or offset printing. By these printing, the thickness of the high thermal conductive sheet layer can be thinly laminated to a minimum of 30 microns on the contact surface of the heat sink body, the thermal resistance can be significantly reduced, and the cooling performance of the heat sink can be improved. It can be improved further.

  Further, by printing the high heat conductive sheet layer on the contact surface of the heat sink body in advance, the complicated work of attaching the heat conductive sheet to the contact surface of the heat sink body later becomes unnecessary, and the finish quality is excellent.

  In the heat sink manufacturing method according to claim 10 of the present invention, the latent heat storage material is kneaded into a heat conductive resin and molded into a plate shape or a block shape, and the heat storage resin body obtained by molding is used. And before hardening of the said thermal storage resin body, the front-end | tip part side of the radiation fin of a heat sink main body is embed | buried, and the thermal storage resin body is hardened | cured in the said embedded state, It is characterized by the above-mentioned.

  According to the method of manufacturing a heat sink according to claim 10, the heat storage resin body can be easily attached to the heat radiating fin of the heat sink, and the cost for improving the cooling performance is reduced as compared with the case where the fan is combined. be able to.

  As described above, according to the heat sink according to the present invention, the heat generated from the heating element is absorbed into the heat storage resin body through the heat sink fins of the heat sink and stored, thereby utilizing the latent heat cooling action by the latent heat storage material. Thus, the heat sink itself can be forcibly cooled, thereby improving the cooling capacity for absorbing heat from the heating element, and controlling the temperature of the heat sink itself within a certain temperature range to improve the cooling performance. An excellent effect that can be sustained.

  In addition, since no means such as a fan is required, it is possible to simultaneously reduce the power consumption while improving the cooling capacity. Further, the installation space for the fan is unnecessary, so that the space can be saved and the noise reduction effect is also expected. There are excellent effects such as being able to.

  Moreover, according to the heat sink manufacturing method of the present invention, the heat storage resin body can be easily attached to the heat sink fin of the heat sink, and the cooling performance is improved while reducing the cost compared to the case of combining the fans. It has an excellent effect that it can be achieved.

  A first embodiment for carrying out the present invention will be described with reference to FIGS. 1 and 2, reference numeral 1 denotes an electronic component (heating element), and reference numeral 2 denotes a heat sink.

  The heat sink 2 is made of a metal having excellent thermal conductivity such as aluminum and is attached to a heat generating portion of the electronic component 1 as shown in FIG. Has been. A heat storage resin block (heat storage resin body) 5 is attached to the upper end portion (tip portion) 4a of each heat radiation fin 4.

  The heat storage resin block 5 includes a latent heat storage material, which will be described later, absorbs heat generated from the electronic component 1 through the heat radiation fins 4 of the heat sink body 3, and absorbs the internal latent heat storage material when the phase changes. It is designed to store latent heat. Due to the latent heat cooling action by the latent heat storage material, the heat sink 2 itself is forcibly cooled, thereby improving the cooling capacity for absorbing heat from the electronic component 1 and the temperature of the heat sink 2 itself within a certain temperature range. It can be controlled to (30 ° C. to 120 ° C.).

The heat storage resin block 5 is obtained by kneading a latent heat storage material into a heat conductive resin and molding it into a plate shape or a block shape. Typical examples of the latent heat storage material include ice (water) (H ₂ O), inorganic hydrated salt, and paraffin. Examples of the inorganic hydrate salt system include calcium chloride hydrate (CaCl ₂ · 6H ₂ O), sodium sulfate hydrate (Na ₂ SO ₄ · 10H ₂ O), and sodium thiosulfate hydrate (Na ₂ S ₂ O). ₃ · _5H 2 O), sodium acetate hydrate _{(CH 3 COONa · 3H 2 O} ) is used. As the paraffin type, C ₁₈ H ₃₈ , C ₂₀ H ₄₂ , C ₂₂ H _{46 and the} like are used.

  The heat conductive resin is mainly composed of an epoxy resin or a silicone resin, and includes a heat conductive filler, an additive, and the like. Carbon, silicon carbide, or the like is used for the thermally conductive filler, and a silane coupling agent or the like is used for the additive. The blending ratio is 1 to 50 parts by weight of an imidazole curing agent, 1 to 20 parts by weight of a resin thickener, and 1 to 150 parts by weight of carbon and 0 to 250 parts of silicon carbide with respect to 100 parts by weight of the epoxy resin. Part by weight, 0 to 20 parts by weight of a silane coupling agent are blended, and further 1 to 350 parts by weight of sodium thiosulfate hydrate (latent heat heat storage material) is blended as a latent heat storage material. Moreover, 1 to 20 parts by weight of a resin thickener, 1 to 150 parts by weight of carbon, and 0 to 250 parts by weight of silicon carbide are blended with respect to 100 parts by weight of the silicone resin, and further sodium thiosulfate water as a latent heat storage material. 1 to 350 parts by weight of a Japanese product (latent heat storage material) is blended. The heat conductivity of the heat conductive resin is 0.3 W / m · k or more.

  As shown in FIG. 2, a moisture-proof coat layer 6 is coated on the entire surface of the heat storage resin block 5. The moisture-proof coating layer 6 prevents the liquid phase from being drained from the heat storage resin block 5 when the latent heat storage material in the heat storage resin block 5 is changed from a solid phase to a liquid phase due to latent heat. The moisture-proof coating layer 6 contains an epoxy resin as a main component and includes a heat conductive filler, an additive, and the like. Carbon, silicon carbide, or the like is used for the thermally conductive filler, and a silane coupling agent or the like is used for the additive. The blending ratio is 1 to 50 parts by weight of imidazole curing agent, 1 to 150 parts by weight of carbon, 0 to 250 parts by weight of silicon carbide, and 0 to 20 parts by weight of silane coupling agent with respect to 100 parts by weight of epoxy resin. .

  In addition, the moisture-proof coat layer 6 may be a coating of the entire surface of the heat storage resin block 5 with a metal foil such as aluminum.

  As shown in FIG. 1, a heat conductive sheet layer 7 having a thickness of about 120 microns having flexibility and adhesion is provided on the mounting surface 3a of the heat sink body 3 in advance by printing. The heat conductive sheet layer 7 has flexibility and adhesion, absorbs unevenness between the mounting surface 3a of the heat sink body 3 and the heat generating portion 1a of the electronic component 1, and has a very small thickness. It is possible to significantly reduce the thermal resistance.

  The heat conductive sheet layer 7 is mainly composed of an epoxy resin or a silicone resin, and includes a heat conductive filler and an additive. Carbon, silicon carbide, or the like is used for the thermally conductive filler, and a silane coupling agent or the like is used for the additive. The blending ratio is 1 to 50 parts by weight of imidazole curing agent, 1 to 150 parts by weight of carbon, 0 to 25 parts by weight of silicon carbide, and 0 to 20 parts by weight of silane coupling agent with respect to 100 parts by weight of the epoxy resin. 1 to 150 parts by weight of carbon and 1 to 20 parts by weight of a resin thickener are blended with respect to 100 parts by weight of the silicone resin.

  Next, the manufacturing procedure of the heat sink 2 will be described with reference to FIGS.

  First, in the epoxy resin solution after dissolving the epoxy resin (main agent) with a solvent, at a predetermined blending ratio, an imidazole curing agent, a heat conductive filler (carbon, silicon carbide), a resin thickener, an additive, Sodium thiosulfate hydrate is added and kneaded, and the obtained heat storage resin solution 8 is poured into the first container 9 as shown in FIG. Then, as shown in FIGS. 3 (A) to 3 (B), each of the radiating fins 4 is arranged with the tip end portion 4a of the radiating fin 4 facing downward from above the heat storage resin solution 8 poured into the first container 9. The heat storage resin solution 8 is impregnated to the predetermined depth D in the front end portion 4a side, and the heat storage resin solution 8 is cured in this state.

  When the heat storage resin solution 8 in the first container 9 is cured after a certain period of time, the heat storage resin block 5 that has been cured is taken out from the first container 9 together with the heat sink 2. Thereby, the heat sink 2 in which the heat storage resin block 5 is attached and processed on the front end portion 4a side of each radiating fin 4 is obtained.

  Next, the heat storage resin block 5 at the tip end portion 4 a of the heat radiating fin 4 is coated with a moistureproof resin that becomes the moistureproof coating layer 6. Addition and kneading of curing agent, heat conductive filler (carbon, silicon carbide), and additive (silane coupling agent) at the specified blending ratio to the epoxy resin solution in which the epoxy resin (main agent) is dissolved in a solvent A moisture-proof resin solution 10 is obtained. Then, as shown in FIG. 4A, the moisture-proof resin solution 10 is poured into the second container 11, and the heat storage resin block 5 at the front end portion 4a of the heat radiating fin 4 of the heat sink 2 is placed downward, as shown in FIG. As shown in B), the heat storage resin block 5 is immersed in the moisture-proof resin solution 10 in the second container 11, and the entire surface of the heat storage resin block 5 is covered with the moisture-proof resin solution 10. The periphery of the heat storage resin block 5 is completely hardened with moisture-proof resin.

  Next, when the moisture-proof resin solution 10 in the second container 11 is cured after a certain period of time, the heat sink 2 is taken out from the second container 11. Then, as shown in FIG. 5, the heat conductive sheet layer 7 is printed on the mounting surface 3 a of the heat sink 2. Printing is performed by screen printing. Thereby, the heat sink 2 shown in FIG. 1 and FIG. 2 is completed.

The inventor injects the heat storage resin solution obtained from the materials and blends shown in Table 1 into a 2.5 cm square, 2 cm high container to a depth of about 3 mm, and a 2 cm square, 3 cm high heat sink. It was dipped in and allowed to stand at 50 ° C. for one day to cure. Next, the moisture-proof resin solution obtained by mixing the materials shown in Table 2 into a 2.5 cm square and 2 cm high container is poured to a depth of about 1 mm, and the heat storage resin block in the heat sink is immersed in the container to prevent moisture. The same solution was poured from above into the portion not immersed in the resin solution, completely covering the periphery of the block, and allowed to stand at 50 ° C. for one day to be cured. Finally, the material of Table 3 on the mounting surface of the heat sink body and the heat conductive sheet material obtained by blending were screen-printed to a thickness of 120 μm and heat-dried at 80 ° C. for 3 hours to form a heat conductive sheet layer. Was cured. As a comparative example, a heat storage resin block was not provided, and a heat conductive sheet layer was printed on the heat sink mounting surface.

The heat sink of the example and the heat sink of the comparative example were respectively attached to the upper surface of the heat generating body (130 ° C.), and the temperature change at the back side of the heat generating part receiving surface of each heat sink and the front end side of the heat sink fin of the heat sink was measured. Tables 4 and 5 show the results. According to the results shown in Table 4, the heat sink of the comparative example had a temperature on the back side of the heat generating portion receiving surface reaching 120 ° C. in 60 minutes, whereas the heat sink of the example was below 100 ° C. even in 180 minutes. Further, according to the results of Table 5, the heat sink of the comparative example had a temperature on the tip side of the radiation fin reaching over 100 degrees in 180 minutes, whereas the heat sink of the example was less than 60 degrees in 180 minutes. From these results, it was found that the heat sink of the example was effectively absorbed by the heat storage resin block from the heat sink as compared with the comparative example.

In addition, the inventor applied the heat conductive sheet material shown in Table 3 to a thickness of 120 μm on the upper surface of the aluminum plate and thermally dried, and the product obtained by adding a commercially available thermal sheet to the upper surface of the aluminum plate. Two were prepared, a heating element of 130 ° C. was fixed on each of them, the back surface temperature of each aluminum plate was observed by thermography, and the temperature change was measured. Table 6 shows the results. From the results in Table 6, it was confirmed that the thermally conductive sheet layer in Table 3 was superior in the thermal conductivity effect.

  The heat sink according to the present invention can increase the cooling capacity, and can be used as a heat sink capable of controlling the heat sink itself within a certain temperature range when the heat generating element generates heat.

The side view which shows 1st Embodiment and shows the state which attached the heat sink to the heat-emitting part of an electronic component, 1 is a cross-sectional view of the heat sink shown in FIG. FIG. 1 is a diagram for explaining a manufacturing method of the heat sink shown in FIG. 1, (A) and (B) are explanatory diagrams showing the manufacturing procedure; FIG. 1 is a diagram for explaining a manufacturing method of the heat sink shown in FIG. 1, (A) and (B) are explanatory diagrams showing the manufacturing procedure; It is explanatory drawing which shows the manufacturing procedure, explaining the manufacturing method of the heat sink shown in FIG.

Explanation of symbols

1 Electronic component (heating element)
DESCRIPTION OF SYMBOLS 1a Heat generating part 2 Heat sink 3 Heat sink main body 3a Mounting surface 4 of heat sink main body Heat radiation fin 4a Upper end part 5 of heat radiation fin Thermal storage resin block (thermal storage resin body)
6 Moisture-proof coating layer 7 Thermally conductive sheet layer 8 Thermal storage resin solution 9 First container 10 Moisture-proof resin solution 11 Second solution H Depth of impregnating the tips of the heat radiation fins into the thermal storage resin solution in the first container

Claims (10)

  A heat sink attached to a heat generating portion of a heat generating body, wherein a heat storage resin body including a latent heat storage material and having thermal conductivity is attached to a heat radiating fin of a heat sink body.   In the heat storage resin body, the latent heat storage material is kneaded into a heat conductive resin and integrally formed into a plate shape or a block shape, and the tip end side of the heat radiation fin is embedded in the heat storage resin body. The heat sink according to claim 1, wherein the heat sink is characterized.   The said latent heat storage material is comprised in the range of 30 to 120 degreeC from the material which changes from a solid phase to a liquid phase, or a liquid phase to a gaseous phase, The Claim 1 or Claim 2 characterized by the above-mentioned. heatsink.   The heat sink according to any one of claims 1 to 3, wherein the latent heat storage material is one of ice, inorganic hydrated salt, and paraffin.   The heat sink according to any one of claims 1 to 4, wherein the latent heat storage material is sodium thiosulfate hydrate.   The heat sink according to any one of claims 1 to 5, wherein the thermal conductivity of the thermal conductive resin is 0.3 W / m · K or more.   The heat sink according to any one of claims 1 to 6, wherein the latent heat storage body is covered with a moisture-proof coating layer.   The high heat conductive sheet layer which has a softness | flexibility and adhesiveness is provided in the contact surface of the heat sink main body with respect to the heat-emitting part of a heat generating body, The Claim 1 thru | or 7 characterized by the above-mentioned. Heat sink.   The heat sink according to claim 8, wherein the high thermal conductive sheet layer is pre-printed on a contact surface of the heat sink body.   In the manufacturing method of the heat sink attached to the heat generating part of the heating element, the latent heat storage material is kneaded into the heat conductive resin and molded into a plate shape or block shape, and before the molded heat storage resin body is cured, A method of manufacturing a heat sink, characterized in that a heat storage resin body is embedded at a tip end side of a heat radiation fin of a heat sink body, and the heat storage resin body is cured in the embedded state.

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