Heat Sink

Abstract

Provided is a heat sink capable of improving heat dissipating characteristics and saving space with a reduced fin size. The heat sink is provided with: a base plate which has one surface thermally connected to a heat generating component and which has thermally connected thereto a first heat dissipating fin section composed of a thin plate fin; an upper plate which has a second heat dissipating fin section thermally connected on one surface, the second heat dissipating fin section being composed of two kinds of thin plate fins having different heights; and a plurality of heat pipes which are disposed between the other surface of the base plate and the other surface of the upper plate by being thermally connected to the surfaces and which include a heat pipe that has at least a part thereof inserted into a part of the second heat dissipating fin section.

Description

TECHNICAL FIELD

[0001] The present invention relates to a heat sink used to cool a component to be cooled (hereinafter, referred to as "cooled component"), for example, a heat generating component such as CPU or MPU in an electronic device.

BACKGROUND ART

[0002] Recently, various electric and electronic devices such as a personal computer have been enhanced in performance and downsized. However, enhancement in performance of CPU, MPU and the like mounted on a notebook-size personal computer, a laptop or desktop computer causes an associated increase in generated heat. On the other hand, demands for downsizing of the electric and electronic devices and saving space inside the electric and electronic devices have grown more.

[0003] Cooling of heat generating components such as high-performance CPU and MPU has been always weighted heavily as an important technical issue. Also for electric and electronic devices other than computers, cooling of high-performance heat generating components and heat generating elements has been weighted heavily as an important issue for saving space inside the electric and electronic devices.

[0004] As a method for cooling an electronic component mounted on the electric or electronic device, for example, there is a method of mounting a fan on the device, rotating the fan by an electric motor and using cooling wind to decrease temperatures of air inside the device housing. There is another method of mounting a cooling member on a component to be cooled and cooling the component directly without using a fan.

[0005] Such a cooling member mounted on the component to cool is often of a plate material having excellent thermal performance such as copper or aluminum. Besides, various heat pipes are often used as cooling members. Specifically, a heat sink having a base plate thermally connected to a heat generating component and thin plate fins thermally connected to the base plate is used and combined with various heat pipes.

[0006] Inside a heat pipe, a space is provided as a fluid path of working fluid. The working fluid accommodated in the space is subjected to phase change such as evaporation and condensation and movement so that heat is transferred. That is, at the heat absorbing side of the heat pipe, heat generated by a component to cool and transferred via a material of the heat pipe is used to vaporize the working fluid, and its vapor is transferred to the heat dissipating side of the heat pipe. At the heat dissipating side, the vapor of the working fluid is cooled to go back to liquid again. Then, the working fluid that has got back to fluid is moved to the heat absorbing side again (back-flow). Such phase change and movement of the working fluid causes heat transfer.

CITATION LIST

Patent Literature

[0007] Patent Literature 1 (PL 1): Japanese Patent Application Laid-Open No. 2009-198173

[0008] Patent Literature 2 (PL 2): Japanese Patent Application Laid-Open No. H10(1988)-107192

SUMMARY OF INVENTION

Technical Problem

[0009] For the heat sink having a base plate thermally connected to the heat generating component and thin plate fins thermally connected to the base plate, the thin plate fins are large in size to enhance the heat dissipating performance from the fins and the heat sink is difficult to downsize.

[0010] If a fan is mounted, the fan needs mounting space but it is difficult to arrange it in a space-saving thin housing. Further, if the fan is increased in size to enhance the fan performance or the number of revolutions is increased, there occurs a problem of heavy noise and vibration.

[0011] Accordingly, the present invention has an object to provide a heat sink capable of enhancing the heat dissipating performance and saving space with small-sized fins.

[0012] Here, in PL1, at least one heat pipe is provided extending in the longitudinal direction of plate fins, sandwiched between a first plate member and a second member and thermally connected thereto. However, the heat dissipating performance is not sufficient to cool high-performance heat generating components such as CPU and MPU.

[0013] Besides, if the heat pipe is tried to be inserted via the base surface into the fin section like in PL2, the fins are difficult to arrange at the heat pipe bent R section and there is restriction on design freedom.

Solution to Problem

[0014] In order to solve the above-mentioned conventional problems, the inventors have studied intensively. As a result, they have known that when two kinds of thin plate fins having different heights are used, low thin plate fins are arranged at a main part and high thin plate fins are arranged at ends, all the thin plate fins are thermally connected to heat pipes and a part of a heat pipe is inserted into the high thin plate fins, it becomes possible to enhance the heat dissipating performance from the fins even if the fins are small sized.

[0015] That is, the fins can be in contact with the heat pipes along the heat pipes, heat transferred from the heat generating component to the heat pipes is then transferred via the upper plate to the low thin plate fins, dissipated from the thin plate fins and at the same time, the heat is dissipated from the thin plate fins efficiently by the heat pipes inserted into the high thin plate fins. This invention was carried out based on the above-mentioned study results.

[0016] A first aspect of the present invention provides a heat sink comprising: a base plate which has one surface thermally connected to a heat generating component or a base plate which has one surface thermally connected to a heat generating component and which has thermally connected thereto a first heat dissipating fin section composed of a thin plate fin; an upper plate which has a second heat dissipating fin section thermally connected on one surface, the second heat dissipating fin section having two kinds of thin plate fins having different heights; and a plurality of heat pipes which are disposed between an opposite surface of the base plate and an opposite surface of the upper plate by being thermally connected to the opposite surfaces and which include a heat pipe that has at least a part thereof inserted into a part of the second heat dissipating fin section.

[0017] The heat sink according to a second aspect of the present invention is characterized in that the second heat dissipating fin section has a plurality of low thin plate fins that are disposed vertically on the one surface of the upper plate and a plurality of high thin plate fins that are disposed vertically in adjacent to the low thin plate fins.

[0018] The heat sink according to a third aspect of the present invention is characterized in that the second heat dissipating fin section has a plurality of low thin plate fins that are disposed vertically on the one surface of the upper plate and a plurality of thin plate fins that are disposed horizontally at an end of the low thin plate fins.

[0019] The heat sink according to a fourth aspect of the present invention is characterized in that the first heat dissipating fin section comprises a plurality of thin plate fins that are disposed vertically on a part of the one surface of the base plate corresponding to the high thin plate fins.

[0020] The heat sink according to a fifth aspect of the present invention is characterized in that the plurality of heat pipes are consisting of heat pipes and at least one part of each heat pipe is made flatten. Those heat pipes are arranged in parallel at a center thereof and they are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

[0021] The heat sink according to a sixth aspect of the present invention is characterized in that the heat pipe inserted into the part of the second heat dissipating fin section is a heat pipe that is arranged at one side and passes through the vertically disposed high thin plate fins laterally from one direction to another.

[0022] The heat sink according to a seventh aspect of the present invention is characterized in that the heat pipe inserted into the part of the second heat dissipating fin section is a heat pipe that is arranged at each side and passes vertically through the horizontally disposed thin plate fins.

Advantageous Effects of Invention

[0023] According to the heat sink of the present invention, two kinds of thin plate fins having different heights are used in adjacent to each other, low thin plate fins are provided at a main part and high thin plate fins are arranged at ends, and all the thin plate fins are thermally connected to the heat pipes. Besides, as a part of a heat pipe is inserted into the high thin plate fins, it is possible to enhance the heat dissipating performance by the fins even when the fin size is reduced totally. Further, as the thin plate fins are provided on the surface on which side the heat generating component of the base plate is located and thermally connected thereto, it is possible to enhance the heat dissipating characteristics.

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a perspective view for explaining a heat sink according to an embodiment of the present invention;

[0025] FIG. 2 is a view illustrating a back surface of the heat sink according to the embodiment of FIG. 1;

[0026] FIG. 3 is a top view of the heat sink of the present invention;

[0027] FIG. 4 is a rear view of the heat sink of the present invention seen from a high thin plate fin (B) side;

[0028] FIG. 5 is a side view of the heat sink;

[0029] FIG. 6 is a side view of the heat sink seen from the opposite side to FIG. 5;

[0030] FIG. 7 is a perspective view for explaining a heat sink according to another embodiment of the present invention;

[0031] FIG. 8 is a view illustrating a back surface of the heat sink according to the embodiment of FIG. 7;

[0032] FIG. 9 is a top view of the heat sink of the present invention;

[0033] FIG. 10 is a rear view of the heat sink of the present invention, seen from a side of plural laminated thin plate fins (D) in contact with a top surface of a low thin plate fin (E) ;

[0034] FIG. 11 is a side view of the heat sink; and

[0035] FIGS. 12A, 12B and 12C are cross sectional views each schematically illustrating an example of thin plate fins bonded to a base plate or upper plate.

DESCRIPTION OF EMBODIMENTS

[0036] With reference to the drawings, a heat sink of the present invention will be described below.

[0037] The heat sink according to an embodiment of the present invention has a base plate which has one surface thermally connected to a heat generating component and which has thermally connected thereto a first heat dissipating fin section composed of a thin plate fin; an upper plate which has a second heat dissipating fin section thermally connected to one surface, the second heat dissipating fin section being composed of two kinds of thin plate fins having different heights; and a plurality of heat pipes which are disposed between the other surface of the base plate and the other surface of the upper plate by being thermally connected to the surfaces and which include a heat pipe that has at least a part thereof inserted into a part of the second heat dissipating fin section. The first heat dissipating fin section is preferably connected to the base plate, but may not be connected thereto. If it is connected, the first heat dissipating fin section is connected to an entire surface or a part of the base plate other than a part connected to the heat generating component.

[0038] FIG. 1 is a perspective view for explaining the heat sink according to an embodiment of the present invention. In this embodiment, the second heat dissipating fin section composed of two kinds of thin plate fins having different heights has a plurality of low thin plate fins (A) disposed vertically on one surface of the upper plate and a plurality of high thin plate fins (B) disposed vertically in adjacent to the plural low thin plate fins.

[0039] In other words, as illustrated in FIG. 1, on the base plate 2 (lower side in FIG. 1) connected thermally to the heat generating component, the first heat dissipating fin section (described in detail later) is connected thermally thereto at the same side of the heat generating component. The upper plate 3 is disposed at the opposite side of the base plate 2 to sandwich the plural heat pipes 8 between the upper plate 3 and the base plate 2. On the front surface of the upper plate 3 (upper side in FIG. 1), the second heat dissipating fin section 5 is disposed and connected thermally thereto. The second heat dissipating fin section 5 has two kinds of thin plate fins composed of a plurality of low thin plate fins (A) arranged in parallel to each other and a plurality of high thin plate fins (B) arranged in parallel to each other. In this embodiment, both of the low thin plate fins (A) and the high thin plate fins (B) are arranged vertically on the top surface of the upper plate.

[0040] In the second heat dissipating fin section 5, the plural low thin plate fins (A) are disposed vertically almost over the upper plate 3 other than an end of the upper plate 3 and the plural high thin plate fins (B) are disposed vertically on the one end of the upper plate 3. As the low thin plate fins (A) occupy the most part of the upper plate 3, the space required for fins can be reduced.

[0041] The plural high thin plate fins (B) that are large in area are provided in adjacent to the plural low thin plate fins (A) thereby to enhance the heat dissipating performance of the heat sink.

[0042] FIG. 2 is a view illustrating a back surface of the heat sink of the embodiment in FIG. 1. With reference to FIG. 2, description is made about arrangement of heat pipes. As illustrated in FIG. 2, at the one end of the base plate 2 connected thermally to the hat generating component 10, the above-mentioned first heat dissipating fin section 7 is disposed and thermally connected thereto. The first heat dissipating fin section 7 has a plurality of parallel thin plate fins (c) disposed vertically on the surface of the base plate 2 on which side the heat generating component is disposed and thermally connected to the surface. The thin plate fins (C) are arranged at the end corresponding to the high thin plate fins (B) of the second heat dissipating fin section 5. Although this first heat dissipating fin section 7 is preferably arranged at the end corresponding to the high thin plate fins (B) of the second heat dissipating fin section 5, it may be larger in area or may not be arranged.

[0043] As described above, a plurality of heat pipes 8 is arranged between the upper plate 3 and the base plate 2. An example of arrangement of the plural heat pipes 8 is indicated by the dotted line in FIG. 2. In the example of FIG. 2, out of the plural pipes 8, center heat pipes 8-3 and 8-4 are arranged almost straight along the longitudinal direction of the heat sink 1 and one ends of these heat pipes 8-3 and 8-4 are bent outward the heat sink 1. In the example of FIG. 2, the heat pipes 8-1 to 8-4 have thin tubular structures in which operating fluid is inserted. These heat pipes are vertically larger in area and in contact with the base plate 2 and the upper plate 3. In this embodiment, the cross section of a heat pipe is in the shape of a rectangle between the base plate and the upper plate. The cross section of the heat pipe may have an appropriate shape depending on its location. For example, apart of the heat pipe passing through the thin plate fins may be a tubular member having a round cross section or may be larger in width to increase a contact area, and thus, the heat pipe may have various shapes in accordance with required functions and environments.

[0044] The heat pipes 8-1 and 8-2 at both sides are arranged straight in parallel to the other heat pipes at the center in the longitudinal direction. One ends of these heat pipes are bent outward the heat sink 1. At the other ends (that is, the ends where the thin plate fins (c) are arranged), the side heat pipe 8-1 is arranged bent toward the outside of the heat sink and the other heat pipe 8-2 is arranged bent toward the outside of the heat sink, raised upward and inserted laterally through the high thin plate fins (B). In the embodiment illustrated in FIG. 2, a tip end 9 of the heat pipe can be recognized. Here, each of the plural heat pipes 8 is flat except a part, compressed in width and has greater contact area with the base plate 2 and the upper plate 3 thereby to facilitate heat transfer.

[0045] As described above, as at least one of the plural heat pipes 8 passes laterally through the plural high thin plate fins (B) that are large in area, heat is transferred from the heat pipes 8 to the thin plate fins (B). Preferably, the heat pipes 8 and the high thin plate fins (B) have as large a contact area as possible and are low in heat resistance. Therefore, for example, through holes of the thin plate fins are formed by burling and the heat pipes 8 are connected by soldering or brazing. Thus, as the heat pipes 8 and the high thin plate fins (B) are connected thermally, the heat dissipating performance of the heat dissipating fins is enhanced. In other words, heat of the heat generating component 10 is transferred via the base plate to the plural heat pipes 8-1, 8-2, 8-3 and 8-4 and further to the upper palate 3 thereby to expedite heat dissipation. Here, in this embodiment, the heat pipe 8-2 is only structured to insert the high thin plate fins (B) therethrough, but other heat pipes 8 may be also structured to insert the high thin plate fins (B) therethrough.

[0046] Further, with the plural pipes 8 having curved parts, the heat is dissipated from all the low thin plate fins (A) disposed vertically on and connected thermally to the top surface of the upper plate 3. Furthermore, as the end of at least one heat pipe out of the plural heat pipes 8 passes laterally through the high thin plate fins (B) having high heat dissipating performance, the heat dissipating performance of the fins is enhanced more. Accordingly, according to the heat sink of the present invention, it is possible to enhance the heat dissipating performance with small sized fins.

[0047] The thin plate fins may be worked to have holes or ends into U shape so that the heat pipes passes therethrough. The holes may be formed by burling. After the heat pipes are inserted into the fins, they may be connected by soldering or brazing where necessary.

[0048] FIG. 3 is a top view of the heat sink of the present invention. As illustrated in FIG. 3, on the top surface of the upper plate, the plural thin plate fins (A) are arranged vertically over the entire surface except one end. Further, at the one end, the plural high thin plate fins that are great in area are disposed in adjacent to the low thin plate fins (A). At parts of both sides of the heat sink, fixing parts 6 are provided to fix the upper plate 3 and the base plate 2 with heat pipes 8 therebetween.

[0049] FIG. 4 is a rear view of the heat sink of the present invention seen from the high thin plate fins (B) side. As illustrated in FIG. 4, an end 9 of one heat pipe of the plural heat pipes 8 arranged between the base plate 2 and the upper plate 3 is raised upward and passes laterally through the plural high thin plate fins (B). In FIG. 4, the thin plate fins (C) are disposed at the position of the base plate corresponding to the high thin plate fins (B).

[0050] FIG. 5 is a side view of the heat sink. FIG. 6 is a side view seen from the opposite side to FIG. 5. As illustrated in FIGS. 5 and 6, at the end of the base plate 2 thermally connected to the heat generating component, the plural parallel thin plate fins (C) of the first heat dissipating fin section 7 is disposed vertically. On the top surface of the upper plate 3, the low thin plate fins (A) and the high thin plate fins (B) of the second heat dissipating fin section 5 are disposed. The high thin plate fins (B) are provided at the end which side corresponds to the thin plate fins (C). The base plate 2 and the upper plate 3 are fixed by the fixing parts 6 with the heat pipes 8 between them. The end 9 of at least one heat pipe of the plural heat pipes 8 is raised upward and passes laterally through the high thin plate fins (B) of the second heat dissipating fin section 5. As described above, the most part of the heat dissipating fin section is composed of the low thin plate fins, the fins are small-sized, the large-area high thin plate fins are disposed at the end and a part of the heat pipe is inserted laterally thereby to increase the heat dissipating performance of the fins.

[0051] FIG. 7 is a perspective view for explaining a heat sink according to another embodiment of the present invention. In this embodiment, the second heat dissipating fin section composed of two kinds of thin plate fins having different heights has a plurality of low thin plate fins vertically disposed on one surface of the upper plate and a plurality of thin plate fins stacked in the horizontal direction on one end of the plural low thin plate fins.

[0052] In other words, as illustrated in FIG. 7, in the base plate 2 (lower side in FIG. 7) connected thermally to the heat generating component, the first heat dissipating fin section 7 is thermally connected thereto at the same side of the heat generating component. The upper plate 3 is disposed to sandwich the plural heat pipes 8. On the front surface of the upper plate 3 (upper side in FIG. 7), the second heat dissipating fin section 5 is thermally connected thereto. The second heat dissipating fin section 5 has a plurality of parallel low thin plate fins (E) arranged vertically on the entire top surface of the upper plate 3 and a plurality of thin plate fins (D) stacked in the horizontal direction on one end of the plural low thin plate fins. In this embodiment, the low thin plate fins (E) are arranged vertically on the top surface of the upper plate 3 and the stacked thin plate fins (D) are arranged stacked in parallel and upward on the top surface of the upper plate 3.

[0053] On the second heat dissipating fin section 5, the plural low thin plate fins (E) are arranged vertically almost over the upper plate 3 and the plural stacked thin plate fins (D) are arranged in parallel to the upper plate on the end top surface of the low thin plate fins (E). In this way, as the low thin plate fins (E) occupy the most part of the upper plate 3, the space required for the fins can be reduced.

[0054] As the plural stacked thin plate fins (D) having larger areas are provided in contact with the end top surface of the plural low thin plate fins (E), the heat dissipating performance of the heat sink is enhanced.

[0055] FIG. 8 is a view illustrating a back surface of the heat sink according to the embodiment of FIG. 7. With reference to FIG. 8, arrangement of the heat pipe is explained. As illustrated in FIG. 8, at an end of the base plate thermally connected to the heat generating component 10, the above-mentioned first heat dissipating fin section 7 is thermally connected thereto. The first heat dissipating fin section 7 has a plurality of parallel thin plate fins (C) vertically disposed on one surface of the base plate 2 on which side the heat generating component is positioned and thermally connected thereto. The thin plate fins (C) are disposed at the end corresponding to the stacked thin plate fins (D) of the second heat dissipating fin section 5. This first heat dissipating fin section 7 may be larger in area unless it is in contact with the heat generating component or may not be disposed.

[0056] As described with reference to FIG. 8, the plural pipes 8 are arranged between the upper plate 3 and the base plate 2. As indicated by the dotted line in FIG. 8, out of the plural heat pipes 8, center heat pipes 8-3 and 8-4 are disposed almost straight along the longitudinal direction of the heat sink and their one ends are bent toward respective outsides of the heat sink 1.

[0057] Side heat pipes 8-1 and 8-2 are disposed straight almost in parallel with the other heat pipes 8-3 and 8-4 at the center in the longitudinal direction. One ends of the heat pipes 8-1 and 8-2 are bent toward respective outsides of the heat sink 1. The other end 9-1 of the heat pipe 8-1 (end where the thin plate fins (c) are arranged) is raised upward and passes through the stacked thin plate fins (D) vertically. In the same way, the end 9-2 of the heat pipe 8-2 is raised upward and passes through the stacked thin plate fins (D) vertically. The plural heat pipes 8 are formed flat except their parts (ends 9-1 and 9-2), compressed in width and their contact areas with the base plate 2 and the upper plate 3 are increased thereby to facilitate heat transfer.

[0058] As described above, as at least two of the plural heat pipes have ends passing through the stacked thin plate fins (D) vertically, the heat dissipating performance of the heat dissipating fins is increased. That is, the heat of the heat generating component 10 is transferred via the base plate to the plural heat pipes 8-1, 8-2, 8-3 and 8-4 and then to the upper plate 3.

[0059] Further, with the plural heat pipes 8 with curved or bent parts, the heat is dissipated from the entire part of the low thin plate fins (E) disposed vertically on and thermally connected to the top surface of the upper plate 3. Furthermore, as at least two heat pipes 8-1 and 8-2 of the plural heat pipes 8 have ends 9-1 and 9-2 passing vertically through the stacked thin plate fins (D) having high heat dissipating performance, the heat dissipating performance is further enhanced. Accordingly, in the heat sink of the present invention, it is possible to enhance the fin heat dissipating performance with small-sized fins.

[0060] FIG. 9 is a top view of the heat sink of the present invention. As illustrated in FIG. 9, the plural low thin plate fins (E) are disposed vertically on the entire top surface of the upper plate 3. Further, on one end top surface of the low thin plate fins (E), the plural stacked thin plate fins (D) are disposed in contact with the top surface of the low thin plate fins (E). At parts of both outsides of the heat sink 1, fixing parts 6 are provided to fix the upper plate 3 and the base plate 2 with the plural heat pipes 8 therebetween.

[0061] FIG. 10 is a rear view of the heat sink of the present invention seen from the side of the plural stacked thin plate fins (D) in contact with the top surface of the low thin plate fins (E). As illustrated in FIG. 10, among of heat pipes sandwiched by base plate 2 and upper plate 3, two heat pipes rise upward so as to be inserted into the stacked thin plate fins (D) in vertical direction. According to FIG. 10, the thin plate fins (C) are arranged at a part of the base plate corresponding to the stacked thin plate fins (D). A through hole is formed in each of the thin plate fins (D) for insertion in the vertical direction and this through hole may be formed by burling. After the pipes are inserted into the fins, they may be connected by soldering, brazing or the like where necessary.

[0062] FIG. 11 is a side view of the heat sink. As illustrated in FIG. 11, the plural parallel thin plate fins (C) of the first heat dissipating fin section 7 are disposed vertically on the end of the base plate 5 thermally connected to the heat dissipating component. On the top surface of the upper plate 3, the low thin plate fins (E) and the stacked thin plate fins (D) of the second heat dissipating fin section 5 are arranged. The stacked thin plate fins (D) are provided at the end corresponding to the thin plate fins (C) and in contact with the top end surfaces of the low thin plate fins (E). The base plate 2 and the upper plate 3 are fixed by the fixing parts 6 with the plural heat pipes 8 sandwiched therebetween. At least two heat pipes 8-1 and 8-2 of the plural heat pipes 8 have ends 9-1 and 9-2 raised upward and passing vertically through the stacked thin plate fins (D) of the second heat dissipating fin section 5. As described above, the low thin plate fins occupy the most part of the heat dissipating fin section, the fins are small-sized, the stacked thin plate fins are arranged at ends of the fins, and the parts of the heat pipes are inserted into the fins vertically thereby to increase the heat dissipating performance of the fins.

[0063] FIGS. 12A, 12B and 12C are cross sectional views each for explaining the form of the thin plate fins of the heat sink of the present invention bonded to the base plate, the upper plate and the like. The thin plate fins may take various shapes in accordance with the location of the heat sink, space where it can be arranged and other conditions. Besides, the thin plate fins having various shapes may be combined freely. In FIGS. 12A, 12B and 12C, the bonding forms of each of the thin plate fins C when the thin plate fin section 7 is provided on the base plate 2 are illustrated. These forms may be applied to the cases of the thin plate fins A and B bonded to the upper plate 3.

[0064] In the form illustrated in FIG. 12A, the thin plate fins each of which is composed of a bottom surface, a vertical surface and top surface and has a U shaped cross section are arranged in parallel in the lateral direction to forma heat dissipating fin section. In this form, plural bottom surfaces are arranged in parallel to form a flat heat receiving surface, which is thermally connected to the base plate 2. At the same time, plural top surfaces of the thin plate fins are also arranged in parallel to form a flat surface. The connecting method may be of any well-known technique such as soldering or brazing (the same goes for other examples).

[0065] In the form illustrated in FIG. 12B, the thin plate fins each of which is composed of a bottom surface and a vertical surface and has an L shaped cross section are arranged in parallel to form a heat dissipating fin section. Also in this form, the plural top surfaces are arranged in parallel to form a flat heat receiving surface, and the heat dissipating fin section is open at the top surface side.

[0066] In the form illustrated in FIG. 12C, the above-mentioned thin plate fins each of which is composed of a bottom surface, a vertical surface and a top surface and has a U shaped cross section and the above-mentioned thin plate fins each of which is composed of a bottom surface and a vertical surface and has an L shaped cross section are combined appropriately to form a thin dissipating fin section 4. Combination is not limited to the form illustrated in FIG. 12C, but may be determined freely. For example, the heat dissipating fin section explained with reference to FIG. 12B may be arranged at each end and the heat dissipating fin section explained with reference to FIG. 12A may be combined into the center thereof. The above-described thin plate fins illustrated in FIGS. 12A, 12B and 12C have the bottom surfaces which are bonded and fixed to the base plate 2 by soldering, brazing or the like. Here, out of the thin plate fins illustrated in FIGS. 12A, 12B and 12C, thin plate fins having identical shapes or different shapes may be combined appropriately on both surfaces of the base plate 2. For example, the thin plate fins illustrated in FIG. 12A may be mounted on the bottom surface of the base plate 2 and the thin plate fins illustrated in FIG. 12A may be mounted on the top surface of the base plate 2.

[0067] As described up to this point, the heat sink of the present invention uses two kinds of thin plate fins having different heights, which are provided in adjacent to each other with almost no space therebetween. The heat pipes can be in contact with the fins all over the second heat dissipating fin section including the plural parallel high thin plate fins (B) or stacked thin plate fins (D) thereby to enhance the heat dissipating performance and save space with small-sized fins. Further, as the thin plate fins are provided vertically on the surface on which side the heat generating component of the base plate is located an thermally connected thereto, it is possible to enhance the heat dissipating characteristics.

REFERENCE NUMERALS

[0068] 1 heat sink [0069] 2 base plate [0070] 3 upper plate [0071] A low thin plate fin [0072] B high thin plate fin [0073] C thin plate fin [0074] 5 second heat dissipating fin section [0075] 6 fixing part [0076] 7 first heat dissipating fin section [0077] 8 heat pipe [0078] 9 end of heat pipe [0079] 10 heat generating component

Claims

1. A heat sink comprising: a base plate which has one surface thermally connected to a heat generating component or a base plate which has one surface thermally connected to a heat generating component and which has thermally connected thereto a first heat dissipating fin section composed of a thin plate fin; an upper plate which has a second heat dissipating fin section thermally connected on one surface, the second heat dissipating fin section having two kinds of thin plate fins having different heights; and a plurality of heat pipes which are disposed between an opposite surface of the base plate and an opposite surface of the upper plate by being thermally connected to the opposite surfaces and which include a heat pipe that has at least a part thereof inserted into a part of the second heat dissipating fin section.

2. The heat sink of claim 1, wherein the second heat dissipating fin section has a plurality of low thin plate fins that are disposed vertically on the one surface of the upper plate and a plurality of high thin plate fins that are disposed vertically in adjacent to the low thin plate fins.

3. The heat sink of claim 1, wherein the second heat dissipating fin section has a plurality of low thin plate fins that are disposed vertically on the one surface of the upper plate and a plurality of thin plate fins that are disposed horizontally at an end of the low thin plate fins.

4. The heat sink of claim 2, wherein the first heat dissipating fin section comprises a plurality of thin plate fins that are disposed vertically on a part of the one surface of the base plate corresponding to the high thin plate fins.

5. The heat sink of claim 3, wherein the first heat dissipating fin section comprises a plurality of thin plate fins that are disposed vertically on a part of the one surface of the base plate corresponding to the high thin plate fins.

6. The heat sink according to claim 1, wherein the heat pipes are heat pipes having at least one flatten part respectively which are arranged in parallel at a center thereof and which are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

7. The heat sink according to claim 2, wherein the heat pipes are heat pipes having at least one flatten part respectively which are arranged in parallel at a center thereof and which are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

8. The heat sink according to claim 3, wherein the heat pipes are heat pipes having at least one flatten part respectively which are arranged in parallel at a center thereof and which are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

9. The heat sink according to claim 4, wherein the heat pipes are heat pipes having at least one flatten part respectively which are arranged in parallel at a center thereof and which are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

10. The heat sink according to claim 5, wherein the heat pipes are heat pipes having at least one flatten part respectively which are arranged in parallel at a center thereof and which are bent toward respective outsides of the upper plate at both longitudinal ends of the upper plate.

11. The heat sink of claim 2, wherein the heat pipe inserted into the part of the second heat dissipating fin section is a heat pipe that is arranged at one side and passes through the vertically disposed high thin plate fins laterally from one direction to another.

12. The heat sink of claim 3, wherein the heat pipe inserted into the part of the second heat dissipating fin section is a heat pipe that is arranged at both longitudinal ends of the upper plate and passes vertically through the horizontally disposed thin plate fins.