US20100319899A1

US20100319899A1 - Heat sink and method of manufacture thereof

Info

Publication number: US20100319899A1
Application number: US12/795,858
Authority: US
Inventors: Shuji Yokoyama; Goro Nakano
Original assignee: Individual
Current assignee: Sansha Electric Manufacturing Co Ltd
Priority date: 2009-06-23
Filing date: 2010-06-08
Publication date: 2010-12-23
Also published as: CN101927304A; JP2011009266A

Abstract

In a first process of this method of manufacturing a heat sink, into a groove, formed in a base and both of whose side surfaces are provided with projections or concave portions and whose upper portion is open, from the groove open portion, there is fitted a pipe that has a diameter smaller than the gap between the edge portions of the open portion of the groove. Next, the pipe is pressed from above the open portion of the groove and the upper portion of the pipe is deformed so that it follows the plane of the open portion of the groove, and moreover both side portions of the pipe are deformed so that they follow along the inner surfaces of both side portions of the groove. By this second process, both side portions of the pipe are engaged with the projections or concave portions.

Description

CROSS REFERENCE

This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2009-148449 filed in Japan on Jun. 23, 2009, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a heat sink that cools a thermal component, and to a method of manufacturing such a heat sink.
Sometimes a radiator type heat sink is used for cooling a thermal component such as a semiconductor or the like. As this type of heat sink, for example, in the base of the heat sink, its upper portion may be formed by opening up channels (grooves) therein. These channels may have tapers, so that the gaps at the end portions at which they are opened are smaller than the gaps at the bottom portions of the channels. A structure for cooling a thermal component is disclosed in Japanese Patent Publication 11-510962 in which pipes are pressed into these channels and are deformed into almost the same flat plane as the base surface, and the thermal component is cooled by being contacted against this flat plane.
Since, with the heat sink construction described above, it must be ensured that the gap between the edge portions of the open portion of the groove is equal to the diameter of the pipe, accordingly it has been necessary to process the groove and the pipe at high accuracy. Furthermore there is a fear that, when the pipe is being inserted into the groove, damage may be caused to the pipe due to contact between the sides of the pipe and the sides of the grooves. In particular, if the processing accuracy for the groove is bad, and the gap between the exposed edges of the groove is narrower than the diameter of the pipe, then damage will very likely be caused to the pipe while it is being inserted into the groove due to the side surfaces of the pipe and the groove scraping together, and, if the heat sink is used over the long term, there is a fear that it will deteriorate over time and that cooling fluid will leak out from it due to this damage cracking and breaking.
Accordingly, the object of the present invention is to provide a method of manufacturing a heat sink, and a heat sink, with which, when a pipe thereof is being fitted into a groove provided in a base thereof, there is no danger of damage being caused to the pipe due to the side surfaces of the pipe contacting the side surfaces of the groove.

SUMMARY OF THE INVENTION

In the method of manufacturing a heat sink according to the present invention, there are included: a first process of fitting into a groove, formed in a base and both of whose side surfaces are provided with longitudinally extending irregular portions, such as projections or concave portions and whose upper portion is open, from the groove open portion, a pipe that has a diameter smaller than the gap between the edge portions of the open portion of the groove; and a second process of pressing upon the pipe from above the open portion of the groove and deforming the upper portion of the pipe so that it follows the plane of the open portion of the groove, and moreover deforming both side portions of the pipe so that they follow along the inner surfaces of both side portions of the groove, and thereby engaging both side portions of the pipe with the irregular portions. A fluid may be enclosed in the interior of this pipe.
According to this type of structure, it is possible to fit the pipe into the groove that is formed in the base without any damage occurring to the pipe, even if the processing accuracy of the base or the pipe is poor. Furthermore it is possible to fix the pipe in the groove without the use of any adhesive or the like, since, during the process of deformation of the pipe both of the side surfaces of the pipe engage with the projections or concave portions that are provided to the groove. Moreover, by pressing the pipe while fluid is enclosed within the pipe, it is possible to ensure that the pressure over the entire inner surface of the pipe is equal. Due to this, it is possible to deform the pipe so that its outer circumferential surface comes into overall contact against the entirety of both the side surfaces and also the bottom surface of the groove.
In an embodiment of this method of manufacturing a heat sink according to the present invention, the following specialization may be employed.
The second process may include: a third process of installing a guide tool that has a guide surface that guides a pressing tool along the vertical direction against the open portion of the groove; and a fourth process of guiding the pressing tool in the downwards direction along the guide surface of the guide tool that was installed by the third process, so that the upper portion of the pipe is pressed by a pressing surface of the pressing tool, and so that thereby the upper portion of the pipe is deformed so as to follow the plane of the open portion of the groove.
And, in another embodiment of this method of manufacturing a heat sink according to the present invention, the following specialization may be employed.
There may be further included a fifth process of, after deformation by the second process, cutting the upper portion of the pipe and/or the upper portion of the base, so that the upper portion of the pipe and the plane of the open portion of the groove substantially coincide with one another.
Moreover, the heat sink according to the present invention is one that is made by any of the methods detailed above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are respectively a perspective view before assembly of a base and pipes of a heat sink manufactured by the method of manufacture of the present invention, and an enlarged partial sectional elevation view thereof;

FIG. 2 is a flow chart for explanation of this method of manufacturing a heat sink;

FIGS. 3A through 3F are sectional views showing how this heat sink is assembled;

FIGS. 4A and 4B are respectively a figure showing the general appearance of a heat sink itself, and a figure showing the general appearance of this heat sink with a thermal component attached thereto; and

FIGS. 5A through 5C are sectional elevation views showing examples of other possible constructions for the grooves.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A and 1B are respectively a perspective view of a base and pipes of a heat sink manufactured by the method of manufacture of the present invention before assembly, and an enlarged partial sectional elevation view thereof.
As shown in FIG. 1A, this heat sink 1 comprises a base 3, a pipe 7A, and a pipe 7B.
The base 3 is a block (a plate) made from aluminum or aluminum alloy, and is provided with grooves 5A and 5B that have exposed sides (exposed faces) at a contacting face 3A that is contacted against a thermal component 9 such as a semiconductor (for example an IGBT) or the like (refer to FIG. 4B). A pipe 7A is fitted into this groove 5A, and a pipe 7B is fitted into the groove 5B. Furthermore, the groove 5A and the groove 5B are provided in positions that contact against the bottom surface of the thermal component 9, so that, when the thermal component 9 is contacted against the contacting face 3A, it is possible to cool the thermal component 9 with good efficiency due to the pipe 7A and the pipe 7B contacting against the bottom surface of the thermal component 9. In other words, the pipes 7A and 7 are provided upon lines which are symmetric with respect to the center line C, along the longitudinal direction of the contacting face 3A. And their lengths are the same as the length L of the base 3 in its short direction.
Furthermore, the contacting face 3A is wider than the bottom surface of the thermal component 9 (refer to FIG. 4B), and four screw holes 4A, 4B, 4C, and 4D are provided near the corners of the contacting face 3A for fixing the thermal component 9.
It should be understood that, although the contacting face 3A is divided into the three surfaces 3A1, 3A2, and 3A2 by the grooves 5A and 5B, in the following explanation these three surfaces will be referred to generally as the contacting face 3A.
The pipes 7A and 7B are straight tubes made from copper whose cross sections are circular. Fluid for cooling the thermal component 9 during use may be enclosed in the interiors of the pipes 7A and 7B during manufacture; or they may be used as heat pipes in which such a fluid flows. The overall length of each of the pipes 7A and 7B is longer than the length L of the grooves 5A and 5B. This overall length of the pipes 7A and 7B may be set to a length corresponding to the position at which the heat sink 1 is used or fixed.
The groove 5A and the groove 5B have the same cross sectional shape. Moreover, the pipe 7A and the pipe 7B have the same cross sectional shape. While, for the sake of brevity, the following explanation is principally phrased in terms of the groove 5A and the pipe 7A, the same description holds for the groove 5B and the pipe 7B as well. As shown in FIG. 1B, the groove 5A is generally rectangular in cross section, and has planar side surfaces 51A and 51B and a planar bottom surface 51C. The corner portion 51D between the side surface 51A and the bottom surface 51C is processed to be formed as a curved surface, and similarly the corner portion 51D between the side surface 51B and the bottom surface 51C is processed to be formed as a curved surface. The horizontal plane at the portion of the groove 5A that opens to the contacting face 3A and that is parallel to the contacting face 3A is termed the exposed surface plane 51F (in FIG. 1B, this exposed surface plane 51F is shown by a double dotted broken line).
Furthermore, at the upper end portions of the side surface 51A and the side surface 51B (i.e. at the portions that border upon the exposed surface plane 51F), the cross section is formed as approximately letter-“λ” shaped projections 53A and 53B respectively. These projections 53A and 53B are for engaging with a pipe which has been fitted into the groove 5A and deformed. These projections 53A and 53B are provided along the groove 5A, and their overall lengths are equal to L.
It should be understood that it is desirable for the edge portions and the root portions of these projections 53A and 53B to be processed into arcuate shapes. By doing this it is possible to prevent damage to the mold, and to prevent the outer circumferential surface of the pipe from suffering damage when the pipe is deformed.
The gap between the edge portions of the open portion of the groove 5A, in other words the open width W of the groove 5A, is a little greater than the diameter D of the pipe 7A in its non-deformed state. Moreover, the width Y between the mutually opposing side surfaces 51A and 51B is somewhat greater than the above described open width W. Furthermore, the depth F of the groove 5A (i.e. the distance between its exposed surface plane 51F and its bottom surface 51C) is somewhat less than the diameter D of the pipe 7A.
Since the groove 5A of the base 3 and the pipe 7A are set to have dimensions as described above, accordingly the pipe 7A is not abraded away by the sides or the projections of the groove 5A when the pipe 7A is being fitted into the groove 5A, even if the processing accuracy of the groove is poor and its dimensions vary somewhat.
The circumference of the pipe 7A is almost the same as the circumference of the groove 5A with the exposed surface plane 51F included. It should be understood that, although a deformation process is performed so as to make the two side surfaces 51A and 51B and the bottom surface 51C (collectively termed the inner surface of the groove 5A) and the outer circumferential surface of the pipe 7A generally contact against one another, nevertheless, depending upon the nature of the material of the pipe 7A and the exact cross sectional shape of the groove 5A, sometimes it may happen that some portion of the pipe 7A does not contact against the corresponding portion of the inner surface of the groove 5A. Due to this, the circumference of the pipe 7A and the circumference of the groove 5A with the exposed surface plane 51F included, and the cross sectional shape of the groove 5A, should be determined upon by performing actual experiments with deformation of various test pipes 7A, so as to ensure that the upper surface of the pipe 7A after the deformation process conforms to a planar shape that follows the exposed surface plane 51F, and so that its side surfaces and its bottom surface contact as much as possible against the inner surfaces of the groove 5A.
Next, a method for manufacture (i.e. for assembly) of this heat sink will be explained. While here this method of manufacture is principally explained in terms of the groove 5A and the pipe 7A, it will be supposed that similar processing is performed for the groove 5B and the pipe 7B as well.
First, as described in the process chart of FIG. 2, a fluid is enclosed in the interior of the pipe 7A which is fitted into the base 3 (a step S1). In concrete terms, a plug (not shown in the figures) is fitted into an opening portion 7A1 at one end of the pipe 7A shown in FIG. 1A, and is able to close up that opening portion so that fluid cannot leak out therefrom. Then a liquid such as, for example, water or oil or the like, a fine grained powder, or a gas such as air at high pressure or the like is appropriate as the fluid that is enclosed within the pipe. If the fluid to be enclosed within the pipe is a liquid, then this liquid is flowed into the pipe, and, when the pipe is full, another plug (also not shown) is fitted into the opening portion 7A2 of the pipe at its other end, so as to enclose the fluid within the pipe. Furthermore, if the fluid to be enclosed within the pipe is a gas, then plugs (not shown in the figures) may be fitted into the two opening portions 7A1 and 7A2 of the pipe 7A, and gas may be enclosed within the pipe using a dedicated setup (also not shown).
Since, by enclosing the fluid within the pipe in this manner, when the outer circumferential surface of the pipe is pressed, this pressure is applied equally to the inner surface of the pipe, accordingly it is possible to deform the pipe so that its outer circumferential surface contacts entirely against both the sides of the groove and also against its bottom surface.
It should be understood that, depending upon the nature of the material of the pipe 7A and the exact cross sectional shape of the groove 5A, sometimes it may happen that it is possible to deform the pipe so that its outer circumferential surface contacts entirely against both the sides of the groove and also against its bottom surface, without enclosing any fluid within the pipe. In such a case, the processing of the above step S1 in which fluid is enclosed in the pipe, and the processing of a step S7 described hereinafter in which this fluid is extracted from the pipe, both become unnecessary.
Next, as shown in FIGS. 3A and 3B, the pipe 7A is set into (i.e. is fitted into) the groove 5A in the base 3 (a step S2). At this time, since the width W of the groove 5A is greater than the diameter D of the pipe 7A, accordingly no damage is caused to the outer surface of the pipe 7A due to the groove 5A contacting the pipe 7A and scraping against it.
Next, a guide tool 11A and a guide tool 11B are installed along the two edges of the exposed surface plane 51F of the groove 5A (a step S3). As shown in FIG. 3C, these guide tools are tools for guiding a pressing tool 13 along the vertical direction; they may be made from rolled steel and may generally have the shape of rectangular parallelepipeds, with their lengths being longer than or equal to the length L of the grooves 5A and 5B. Moreover, the pressing tool 13 is a tool for pressing upon the pipe 7A, and, likewise, it may be made from rolled steel and may generally have the shape of a rectangular parallelepiped, with its length being longer than or equal to the length L of the grooves 5A and 5B. By installing the guide tools 11A and 11B along the edges of the exposed surface plane 51F, it is possible to prevent any portion of the pipe 7A from sticking up higher than the exposed surface plane 51F and thus projecting above the contacting face 3A of the base 3, when the pipe 7A is pressed by the pressing tool 13 from the direction of the exposed surface plane 51F.
As shown in FIG. 3C, the pressing tool 13 is installed between the two guide tools 11A and 11B (a step S4). Next, as shown in FIG. 3D, the pressing tool 13 is slid downwards along the guide tools 11A and 11B, and presses upon the pipe 7A from above the groove (a step S5). And the pipe 7A is deformed so that its upper portion becomes a surface 7A3 (see FIG. 4) extending substantially along the exposed surface plane 51F, with its other portions contacting against the two side surfaces 51A and 51B and the bottom surface 51C of the groove 5A, and with the edges of its upper portion being engaged by the projections 53A and 53B.
It should be understood that the pressing tool 13 is not limited to having a shape as shown in FIG. 13; for example, it would also be acceptable for it to be shiftable along the guide tools 11A and 11B and to have a roller shaped pressing surface. If the length L of the base 3 is very long so that a plurality of thermal components 9 may be fitted thereto, then it may become difficult to deform the entire pipe 7A in one operation with a pressing tool 13 that is formed out of rolled steel in the shape of a rectangular parallelepiped. In this type of case, it is possible to deform the entire pipe 7A so as to shape its upper plane 7A3 to extend substantially along the exposed surface plane 51F of the groove 5A, by pressing a roller shaped pressing tool (not shown) upon the pipe 7A while shifting that pressing tool along the guide tools 11A and 11B.
When the deformation of the pipe 7A has been completed, the guide tools 11A and 11B and the pressing tool 13 are removed (a step S6). And the plugs that were fitted into both the ends of the pipe 7A are removed, and the fluid within the pipe 7A is extracted (a step S7). The pipe 7A does not come out from within the groove 5A, since it has become engaged with the projections 53A and 53B due to the deformation process of the step S5.
According to the dimensions and shapes of the groove 5A and the pipe 7A and the relationship between them, and depending upon the pressure applied in the step S5, sometimes it may happen that the pipe 7A may, after the process of deformation, come to be in a state in which its upper plane surface 7A3 bulges out somewhat above the exposed surface plane 51F, as shown in FIG. 3E. Furthermore sometimes it may happen that, after the process of deformation, the pipe 7A may come to be in a state in which its upper plane surface 7A3 is substantially lower than the exposed surface plane 51F, i.e. is fully within the groove 5A, as shown in FIG. 3F. In other words, sometimes it may happen that the plane 7A3 of the finished pipe 7A, the plane 7B3 of the finished pipe 7B, and the contacting face 3A of the base 3 are not coplanar. In this type of case, a cutting process is performed upon at least one of the pipe 7A or 7B, or the contacting face 3A of the base 3, so as to form the plane 7A3 of the finished pipe 7A, the plane 7B3 of the finished pipe 7B, and the contacting face 3A of the base 3 to be coplanar (a step S8).
When, as shown in FIG. 3E, the pipe 7A is in a state in which its upper plane surface 7A3 bulges out somewhat above the exposed surface plane 51F, it is appropriate for mainly the pipe 7A to be cut down. On the other hand when, as shown in FIG. 3F, the pipe 7A is in a state in which its upper plane surface 7A3 is substantially lower than the exposed surface plane 51F, then it is appropriate for mainly the contacting face 3A of the base 3 to be cut down. By performing a cutting process in this manner, it is possible to ensure that the plane 7A3 of the finished pipe 7A, the plane 7B3 of the finished pipe 7B, and the contacting face 3A of the base 3 become coplanar. By performing processing upon the upper surface of the heat sink in this manner to ensure that it is planar, it is possible to make it closely conform to the bottom surface of the thermal component 9, and thus it is possible reliably to cool the thermal component 9.
It should be understood that, if the pipe 7A is to be cut, then it is necessary to use a pipe of thickness sufficiently greater than the amount to be cut away, in order to ensure that no holes open up in the pipe after it has been cut. Furthermore, if in the step S5 the plane 7A3 of the pipe 7A, the plane 7B3 of the pipe 7B, and the contacting face 3A of the base 3 are already finished as coplanar, then no further cutting process such as the step S8 will be necessary.
When the above described processes of deforming and (possibly) cutting the pipe 7A and the pipe 7B have been completed, the manufacture of the heat sink 1 is finished, as shown in FIG. 4A.
When the heat sink 1 is to be used, it will be sufficient to contact the bottom surface of a thermal component 9 (for example an IGBT module, as shown in the figure) against the upper surface of the heat sink 1 (i.e. against the contacting face 3A of the base 3), as shown in FIG. 4B, and to fix screws 10A through 10D into the screw holes 4A through 4D.
If only one of these heat sinks 1 is to be used, then the opening portion 7A1 of the pipe 7A and the opening portion 7B1 of the pipe 7B are connected together with a joining pipe (not shown in the figures). Moreover, the opening portion 7A2 of the pipe 7A and the opening portion 7B2 of the pipe 7B are connected to a pump (not shown in the figures), via joining conduits (not shown in the figures) or directly, so that fluid may be circulated by the pump through the interiors of the pipes 7A and 7B, thus cooling the thermal component 9.
Furthermore, if a plurality of these heat sinks 1 are to be used, then the opening portions of the pipes 7A and 7B of these heat sinks 1 are connected in sequence with joining conduits, not shown in the figures. And two of them are connected to a pump. Thus, fluid may be circulated by the pump through the interiors of the pipes 7A and 7B of each of the heat sinks 1, thus cooling the thermal component or components 9 that are attached to these heat sinks 1. Furthermore it would also be possible further to increase the length of the heat sink 1, so as to attach a plurality of thermal components 9 to this single heat sink 1 for being cooled.
Next, with regard to the position of the projections 53A and 53B which are provided upon the side surfaces 51A and 51B of the groove 5A that is provided in the base 3, the positions shown in FIGS. 1 and 3 are not to be considered as being limitative of the present invention; other positions for these projections may be employed, provided that the projections are able to engage properly with the pipe 7A. For example in an alternative structure, as shown in FIG. 5A, it would be possible to provide projections 53A2 and 53B2 in positions that are lower than the upper edge portions of the side surfaces 51A2 and 51B2 of the groove 5A2, in other words in positions that do not touch the exposed surface plane 51F2. At this time, the cross sectional shapes of these projections may be processed into shapes whose edges are smooth, for example into tear shapes or into arcuate shapes. Since, by providing the projections 53A2 and 53B2 in positions as described above, these projections bite into the pipe 7A when the pipe 7A has been deformed, accordingly it is possible for the pipe 7A to be reliably embedded within the groove 5A2 and held.
Furthermore, it would also be possible to arrange to provide concave portions on the side surfaces of the groove, rather than projections. Such concave portions should be provided at positions upon the side surfaces of the grooves that are lower than their upper edge portions, in other words at positions that do not contact the exposed surface plane of the groove. For example it is possible, as shown in FIG. 5B, to provide a concave portion 53A3 and a concave portion 53B3 at respective intermediate portions upon the side surface 51A3 and the side surface 51B3 of the groove 5A3. Moreover it is possible, as shown in FIG. 5C, to provide a concave portion 53A4 and a concave portion 53B4 at the respective lower edge portions of the side surface 51A4 and the side surface 51B4 of the groove 5A4 (i.e. at the portions where these side surfaces abut against the bottom surface 51C). Since, by providing such concave portions upon the side surfaces of the groove, corresponding portions of the pipe are forced into these concave portions when the pipe is deformed, accordingly the pipe 7A is engaged within the groove by these corresponding portions projecting into and engaging with the concave portions. Accordingly, it is possible reliably to embed and hold the pipe 7A within the groove 5A3 or the groove 5A4.
It would also be acceptable to arrange to provide the projections or concave portions shown in FIG. 5 intermittently along the depth direction of the groove. By forming the projections or concave portions in this type of shape, it is possible reliably to prevent the pipe 7A from deviating in the direction of the side surface 3S1 or the side surface 3S2 of the base 3.
It should be understood that it is desirable to process the edges and/or base root portions of the projections or the concave portions into arcuate shapes. By doing this it is possible to prevent damage to the mold, and to prevent the outer circumferential surface of the pipe from suffering damage when the pipe is deformed.
It should be understood that, even if the groove provided in the base 3 has a shape as shown in FIG. 5, as explained on the basis of FIG. 1B, still, as seen from the side of the exposed surface plane (i.e. from the side of the contacting face 3A), the opening width W between the two sides of the upper portion of the groove (i.e. the gap between the projections 53A2 and 53B2, or between the side surface 51A3 and the side surface 51B3, or between the side surface 51A4 and the side surface 51B4) is greater than the diameter D of the pipe 7A. Moreover, the width Y between the side surface 51A2 and the side surface 51B2 with the projections 53A2 and 53B2 excluded, or the width X between the two concave portions (i.e. between the concave portion 53A3 and the concave portion 53B3, or between the concave portion 53A4 and the concave portion 53B4), is greater than the above described opening width W. Furthermore, the depth F of the groove 5A (i.e. the distance between its exposed surface plane 51F and its bottom surface 51C) is shorter than the diameter D of the pipe 7A.
Yet further, the circumference of the pipe 7A and the circumference of the groove with its exposed surface plane included, and the cross sectional shape of the groove, should be determined upon by performing actual experiments with deformation of various test pipes 7A, so as to ensure that the upper surface of the pipe 7A after the deformation process conforms to a planar shape that follows the exposed surface plane 51F, and so that its side surfaces and its bottom surface contact as much as possible against the inner surfaces of the groove 5A.
It should be understood that while, in the above explanation, a structure was described in which two pipes were embedded in the base, this is not to be considered as limitative of the present invention; it is also possible to utilize a single such pipe, or more than two such pipes, provided that it is possible to contact that pipe or pipes against the bottom surface of the thermal component with good efficiency so as to cool it well.
Furthermore, with regard to the materials from which the base, the pipes, the guide tools, and the pressing tool are made, it would also be acceptable to utilize other materials, provided that it is possible to deform the pipes with good efficiency, and that it is possible to cool the thermal component with good efficiency.

Claims

1. A method of manufacturing a heat sink in which a heat sink is manufactured by fitting a pipe into a groove formed in a base, comprising:

a first process of fitting into a groove, formed in a base and both of whose side surfaces are provided with longitudinally extending irregular portions and whose upper portion is open, from said groove open portion, a pipe that has a diameter smaller than the gap between the edge portions of said open portion of said groove; and

a second process of pressing upon said pipe from above said open portion of said groove and deforming the upper portion of said pipe so that it follows the plane of said open portion of said groove, and moreover deforming both side portions of said is pipe so that they follow along the inner surfaces of both side portions of said groove, and thereby engaging both side portions of said pipe with said irregular portions.

2. A method of manufacturing a heat sink according to claim 1, wherein said irregular portions are projections.

3. A method of manufacturing a heat sink according to claim 1, wherein said irregular portions are concave portions.

4. A method of manufacturing a heat sink according to claim 1, wherein, in said first process, a fluid is enclosed in said pipe.

5. A method of manufacturing a heat sink according to claim 1, wherein said second process comprises:

a third process of installing a guide tool that has a guide surface that guides a pressing tool along the vertical direction against said open portion of said groove; and

a fourth process of guiding said pressing tool in the downwards direction along said guide surface of said guide tool that was installed by said third process, so that said upper portion of said pipe is pressed by a pressing surface of said pressing tool, and thereby said upper portion of said pipe is deformed so as to follow said plane of said open portion of said groove.

6. A method of manufacturing a heat sink according to claim 1, further comprising a fifth process of, after deformation by said second process, cutting said upper portion of said pipe and/or the upper portion of said base, so that said upper portion of said pipe and said plane of said open portion of said groove substantially coincide with one another.

7. A method of manufacturing a heat sink according to claim 1, wherein said projections or concave portions are provided at positions on said side surfaces of said groove that do not contact its said open portion.

8. A heat sink manufactured by the method of claim 1.

9. A heat sink manufactured by the method of claim 2.

10. A heat sink manufactured by the method of claim 3.

11. A heat sink manufactured by the method of claim 4.