JP2009099878A - Heat sink and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain both the high performance of heat dissipation and reduction in the weight of a heat sink for cooling a heat generating element of an electronic device. <P>SOLUTION: A heat sink is constituted by forming a laminate of a graphite sheet and a metallic thin plate in a corrugated shape and joining the laminate on a heat sink base at a metallic thin plate. The metallic thin plate secures the rigidity of a fin and transmits heat to the heat sink base and the graphite sheet constituting a fin. Since the rigidity is imparted to the fin by the metallic thin plate, a constitution can be formed of sheet-shaped graphite, thus enabling thinning. Since graphite has high heat conductivity, it is possible to reduce the weight of the heat sink while keeping high heat dissipation performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat sink suitable for weight reduction.

  A heat generating element mounted on an electronic device such as a computer (hereinafter referred to as an electronic device) has increased in calorific value as performance is improved. For example, a CPU (central processing unit) mounted on an electronic device has a particularly large calorific value, and a heat sink is generally mounted to cool the element below a specified temperature. The heat sink is increased in size to cope with an increase in the amount of heat generated as the CPU speed increases, and the weight is increased because the number of fins constituting the heat sink is increased.

  When the weight of the heat sink increases, it becomes difficult to assemble and maintain the electronic device, and an excessive load may be applied to the CPU on which the heat sink is mounted. Moreover, it is necessary to increase the strength of the floor to be installed in order to increase the weight of the electronic device itself.

  For this reason, it is necessary to provide a lightweight heat sink without degrading the cooling performance, and as one means thereof, the material used for the heat sink has a high thermal conductivity similar to copper or the like, The use of graphite having a density lower than that of copper has been studied.

  There are the following patent documents in the prior art regarding this type of graphite and heat sink.

JP 2005-537633 A JP 2006-130753 A

  Japanese Patent Publication No. 2005-537633 (Patent Document 1) discloses a structure in which fins of a heat sink are formed of graphite and attached to a metal base.

  However, when forming heat sink fins with graphite, graphite is a brittle material, so it is necessary to increase the thickness to maintain the shape of the fins, and to form many fins on the base of the heat sink. It becomes difficult. Therefore, the surface area of the heat sink cannot be increased, and it is difficult to expand the cooling performance.

  That is, although it is a graphite that has a high thermal conductivity and is suitable for cooling electronic devices, it is a fragile and weak material, so there are various problems in processing graphite as a fin of a heat sink.

  Further, as disclosed in Japanese Patent Laid-Open No. 2006-130753 (Patent Document 2), a technique of laminating a graphite sheet and a base material in a layered manner is also known, but means for forming fins on the base of a heat sink Is not considered.

  An object of the present invention is to provide a heat sink that enhances the heat radiation performance and expands the cooling performance.

  The object is to provide a heat sink that is brought into thermal contact with a heating element and dissipates heat received from the heating element into the atmosphere, a base portion connected to the heating element, a sheet mainly made of graphite, and a metal plate. This is achieved by partially joining the base part and the metal thin plate and thermally connecting the base part and the fin part.

  The above object is achieved by the metal sheet being thinner than the graphite-based sheet.

  The object is achieved by forming a plurality of fin rows by bending the thin metal sheet and a sheet mainly composed of graphite in advance into a corrugated shape multiple times. Is done.

  Also, the object is to provide a block in which the base portion is mainly composed of a metal plate connected to the fin portion and graphite thermally connected to a surface opposite to the surface thermally connected to the fin portion of the metal plate. This is achieved by comprising:

  Further, the above object is achieved by forming a plurality of cut and raised portions on the metal thin plate constituting the fin portion.

  Further, the above object is a method of manufacturing a heat sink which is brought into thermal contact with a heating element and dissipates heat received from the heating element into the atmosphere, and a step of bonding the graphite sheet and the thin metal plate 7 is formed by this process. This is accomplished by comprising a step of bending the formed plate material in a meandering manner to form a plurality of fin rows, and a step of metallicly joining the fin rows and the heat sink base.

  ADVANTAGE OF THE INVENTION According to this invention, the heat sink which aimed at expansion of cooling performance by improving heat dissipation performance can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view of a heat sink provided with a first embodiment of the present invention.

  In FIG. 1, the heat sink 1 of the present embodiment is formed by laminating a graphite sheet and a thin metal plate and joining a fin portion 2 bent in a corrugated shape (meandering shape) on a heat sink base 3. The fin portion 2 is a laminate of a graphite sheet and a thin metal plate. The fin portion 2 and the heat sink base 3 are formed of a metal thin plate constituting the fin portion 2 on the heat sink base, for example, by means of soldering or the like. Be joined. The heat sink base 3 is a metal having a high thermal conductivity such as copper. The CPU 5 serving as a heating element mounted on the wiring board 4 is thermally connected to the heat sink base 3.

  The heat sink 1 is used for cooling a CPU of a personal computer or a server, for example, and is thermally connected between the CPU 5 mounted on the wiring board 4 and the heat sink base 3 with heat conductive grease (not shown). The The heat generated by the CPU 5 spreads in the plane direction in the heat sink base 3, is thermally conducted to the graphite sheet of the fin portion 2 through the thin metal plate, and is dissipated by the cooling air flowing between the fins after spreading to the front surface of the fin.

  The detail of a fin part is demonstrated using FIGS.

  FIG. 2 is an enlarged cross-sectional view of the fin shown in FIG.

  In FIG. 2, the fin portion 2 is formed by bending a thin plate member formed by bonding a graphite sheet 6 and a thin metal plate 7 into a corrugated shape (meandering shape). Since the graphite sheet 6 is a brittle material, the metal thin plate 7 functions to secure the strength as a fin by bonding together and to enable the joining to the heat sink base 3. Furthermore, it also serves to efficiently transfer heat from the heat sink base 3 to the graphite sheet 6 forming the fins.

  Here, the fin portion 2 is metallically joined to the heat sink base 3 so that a part 8 of the surface of the thin metal plate 7 faces the heat sink base 3. As a result, heat can be transferred from the heat sink base 3 to the fin portion 2 satisfactorily.

  FIG. 3 is a perspective view showing the configuration of the fin portion provided with the first embodiment.

  In FIG. 3, the fin portion 2 is formed by pasting together a planar graphite sheet 6 prepared in advance and a thin metal plate 7 with an adhesive or the like, and then bending the single plate material into a corrugated shape (meandering shape). To do. The metal thin plate 7 is a material having high thermal conductivity such as copper.

  The adhesive that bonds the metal thin plate 7 and the graphite sheet 6 is preferably one that can withstand high temperatures because the metal thin plate 7 and the heat sink base 3 are joined by soldering or the like. In addition, since the entire surface of the graphite sheet 6 is bonded to the metal thin plate 7, it is possible to prevent the graphite piece from peeling off at the end of the graphite sheet 6. This effect is even greater when the metal sheet is larger than the side of the graphite sheet.

  FIG. 4 is a perspective view showing the configuration of the fin portion provided with the second embodiment.

  In FIG. 4, in this embodiment, a three-layer structure comprising a metal thin plate 7, a graphite sheet 6, and a protective layer 9 is bonded. The protective layer 9 is a metal thin plate 7 or a resin film, protects the graphite sheet surface, and prevents the graphite from peeling off.

  If a graphite sheet of the same degree as the thermal conductivity of copper is used, the specific gravity is 1/5 to 1/6 that of copper. Therefore, for example, when a copper plate having a thickness of 1/10 of a graphite sheet is used as a thin metal plate, the fin heat dissipation performance (the thermal conductivity of the fin is equal to or less than 1/3 the weight of the case where the fin is made of copper. Since it is about the same as copper, the heat conduction from the heat sink base 3 to the tip of the fin, that is, the contribution to heat radiation is equivalent). Furthermore, since the metal portion is thinned, processing into a corrugated shape or the like is facilitated.

  FIG. 5 is a cross-sectional view of a heat sink provided with the third embodiment.

  In FIG. 5, the present embodiment is an example in which graphite is also used for the heat sink base 3 in the first embodiment, and the heat sink base 3 includes a graphite block 11, a metal plate 10, and a fixing member 12. The fin part 2 is formed by corrugating the graphite sheet 6 and the metal thin plate 7 in the same manner as in the first embodiment. The fin part 2 and the metal plate 10 are metallically joined by the thin metal plate part 8 of the fin part. What joined the fin part 2 and the metal plate 10 is thermally connected to the graphite block 11 via thermal conductive grease or the like. At this time, the graphite block 11 is fastened with a screw 13 or the like so as to be sandwiched between the fixing member 12 and the metal plate 10 to which the fin portion 2 is joined.

  In general, since graphite and metal cannot be directly metal-bonded, the graphite block 11 and the thin metal plate 7 of the fin portion 2 cannot be metalically bonded. However, according to the said structure, the heat conduction from a graphite block to a fin part can be performed effectively. The metal plate 10 that joins the fin portion 2 is a high heat conductive material such as copper, but the fixing member 12 is hollowed at the center so that the graphite block 11 and the CPU 5 can be directly connected. Any material can be used as long as the strength for fixing the plate 10 can be secured.

  According to the present embodiment, in addition to the effects of the above-described embodiments, the heat spreading effect in the heat sink base comparable to that of copper can be obtained in a lighter weight than when the heat sink base is formed of a metal such as copper. In particular, as the CPU size is smaller than the heat sink base, it is necessary to increase the heat diffusion effect in the heat sink base, that is, the thickness of the heat sink base, and the weight reduction effect by this structure becomes more remarkable.

  Other embodiments are shown in FIG. 6, FIG. 7, and FIG.

  FIG. 6 is a perspective view of a heat sink provided with the fourth embodiment.

  FIG. 7 is a sectional view of a heat sink provided with the fourth embodiment.

  FIG. 8 is a perspective view of a heat sink for explaining the configuration of the fourth embodiment.

  In the figure, the fin portion is formed by the same method as in the above embodiment, but in this embodiment, the fin portion is formed by pasting the thin metal plate 7 having the cut-and-raised portion 13 on the graphite sheet 6 in advance. .

  This is bent into a corrugated shape as shown in FIG. 7 and connected to the heat sink base 3. Thereby, it is possible to configure a heat sink in which fine secondary fins are formed on the fin surface. The fine structure on the fin surface can increase the surface area, induce a turbulent component in the airflow flowing between the fins, and promote heat transfer from the fin surface.

  Furthermore, as shown in FIG. 8, the heat transfer can be further promoted by shifting and arranging the cut and raised portions 13. Since a fine secondary structure can be arbitrarily formed in advance using a metal thin plate, even a complicated secondary structure on the fin surface can be easily formed.

  In the example of FIGS. 6 and 7, the thin metal plate having the cut and raised portion and the graphite sheet are bonded to each other and then bent into a corrugated shape to form a fin row. The laminated sheet may be attached as it is to a flat heating element.

  Another embodiment is shown in FIG.

  FIG. 9 is a perspective view of a heat sink provided with the fifth embodiment.

  In FIG. 9, the present embodiment is an example in which the fin portion 2 is configured by individual fins 20. Each fin 20 constituting the fin portion 2 is formed by bonding the metal thin plate 7 and the graphite sheet 6, and is attached to penetrate the heat conduction column 30. As shown in FIG. 9 (b), the fin 20 is in thermal contact with the heat conduction column 30 around the graphite sheet 6 provided with a hole 71 through which the heat conduction column 30 penetrates in advance and the through hole 71. The thin metal plate 7 provided with the collar portion 70 is bonded together. The heat conducting column 30 is excellent in heat transport in the axial direction, such as copper and heat pipe, and is connected to a heat generating body and provided on the heat sink base 3, and heat is efficiently transmitted from the heat sink base 3 to the fins 20.

  According to this structure, heat conduction is possible through the heat-conducting support column, so that heat can be radiated from the fins located away from the heat sink base, which is effective in expanding the heat radiation area. Since it is possible to provide a large number of fins, the weight reduction effect by using a graphite sheet for the fins becomes more prominent.

  In the embodiment described with reference to FIGS. 1 to 8, an example in which the fin row is formed by corrugated folding of the fin portion is shown. However, even if individual fins are individually joined to the heat sink base as in the present embodiment. good.

It is sectional drawing of the heat sink provided with the 1st Example of this invention. It is sectional drawing to which the fin shown in FIG. 1 was expanded. It is a perspective view which shows the structure of the fin part provided with the 1st Example. It is a perspective view which shows the structure of the fin part provided with the 2nd Example. It is sectional drawing of the heat sink provided with the 3rd Example. It is a perspective view of the heat sink provided with the 4th example. It is sectional drawing of the heat sink provided with the 4th Example. It is a perspective view of a heat sink explaining the composition of the 4th example. It is a perspective view of the heat sink provided with the 5th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat sink 2 Fin part 3 Heat sink base 4 Wiring board 5 CPU
6 Graphite Sea 7 Metal sheet

Claims (6)

In a heat sink that makes thermal contact with a heating element and dissipates heat received from the heating element to the atmosphere,
The base portion connected to the heating element, and a fin portion formed by laminating a sheet mainly made of graphite and a metal plate, and the base portion and the metal thin plate are partially joined to each other. A heat sink, wherein the fin and the fin are thermally connected. The heat sink according to claim 1.
The heat sink according to claim 1, wherein the metal thin plate is thinner than a sheet mainly composed of the graphite. The heat sink according to claim 1.
The heat sink characterized in that the fin portion is formed by previously laminating and laminating the thin metal plate and a sheet mainly composed of graphite to form a plurality of fin rows by bending it into a corrugated shape a plurality of times. The heat sink according to claim 1.
The base portion includes a block mainly composed of a metal plate connected to the fin portion and graphite thermally connected to a surface opposite to the surface thermally connected to the fin portion of the metal plate. And heat sink. The heat sink according to claim 1.
A heat sink, wherein a plurality of cut-and-raised portions are formed on a thin metal plate constituting the fin portion. In a method of manufacturing a heat sink that is brought into thermal contact with a heating element and radiates heat received from the heating element to the atmosphere,
A step of bonding the graphite sheet and the thin metal plate 7, a step of bending a plate formed by this step into a meandering shape to form a plurality of fin rows, and a step of metallically joining the fin rows and the heat sink base A method of manufacturing a heat sink.

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