WO2004068924A1

WO2004068924A1 - Apparatus for cooling heat generating components using a plate heat sink and methods for manufacturing the same

Info

Publication number: WO2004068924A1
Application number: PCT/SE2004/000128
Authority: WO
Inventors: Anders Örjes; Jari Tuomela
Original assignee: TYKOFLEX AB
Current assignee: TYKOFLEX AB
Priority date: 2003-01-31
Filing date: 2004-01-30
Publication date: 2004-08-12
Anticipated expiration: 2005-07-31
Also published as: SE0300246L; SE0300246D0; SE524673C2

Abstract

An apparatus is provided for cooling heat generating components. Said apparatus comprising at least two mould halves (2,3) made of a material with good thermal conductivity, and at least one disc-like cooling means(4) placed between the mould halves (2,3) and made of a material non-corrosive against a cooling fluid and forming at least one fluid channel for said cooling fluid. The cooling means (4) is provided with inlet and outlet means (5,6),respectively. The material of the cooling means (4)is preferably selected from the group consisting of stainless steel, copper, titanium, a thermoplastic resin and a rubber. The invention also relates to methods for manufacturing said apparatus.

Description

Apparatus for cooling heat generating components using a plate heat sink and methods for manufacturing the same

FIELD OF THE INVENTION

The invention relates to an apparatus for heat removal from heat generating components according to claim 1, and to methods according to claims 8 and 16 for manufacturing the apparatus .

BACKGROUND OF THE INVENTION

As heat generating components, for instance, electrical devices and integrated circuits, become more complex and as their density increases, they generate more heat when in operation. Therefore, the thermal properties of the components are important, and the ability to remove heat generated from high-powered and high density components has become essential for the performance of said components.

The traditional way of cooling electrical devices, i.e. to transport away the heat generated by said devices, has been through the use of air convection. More recently, since the cooling demand has increased, the cooling of said devices has been done by the use of plate heat sinks, so called cold plates, which are cooled by a cooling fluid, such as water, flowing through cooling channels arranged internally in the plates. An advantage with using water instead of air convection for cooling is that it is silent and it is estimated that cooling by water is about 1000 times more efficient than cooling by air . The heat generating components to be cooled are mounted in mechanical thermal contact, preferably screwed, with a cold plate having internal cooling channels, and the cooling fluid in the cooling channels absorbs heat from the components through the plates. The cooling fluid is then cooled by suitable means .

However, the cold plates are usually made of a light weight material with very good thermal conductivity such as alumin- ium. This is advantageous since the cold plates with fitted components are often mounted in large racks.

US-A-5 826 643 relates to a method of cooling electronic devices in an electronic assembly having at lease one board that houses electronic modules. Said method comprises shaping a light weight plate with apertures so as to compliment the geometric shape of the assembly and board to be cooled, affixing coolant passage tubes in the apertures of the plate and cooling the assembly in contact with the plate and passage tubes by a coolant introduced in the passages. The coolant passage tubes are made of copper and shaped as ordinary tubes .

WO 01/63 667 relates to an apparatus for transporting away heat from heated elements. The apparatus comprises a block of a material having good thermal conductivity, and channels in the form of tubes made of a non-corrosive material are provided in the block. A cooling fluid is forced to flow through said channels. To be able to provide a good thermal contact the tubes are preferably cast in a block of aluminium.

EP-A-0903 971 relates to a metal cold plate provided with internal dissipater fins and ducts. The bottom of said plate is sealed by a lid which - thanks to the presence of several Ion- gitudinal baffles - creates a number of internal ducts in which the cooling liquid circulates. The type of material of which the plate is made is not mentioned.

A problem with known aluminium cold plates provided with cooling channels in the form of tubes is that the cooling of the plates is non-uniform, as seen over the whole surface area of the cold plates, resulting in non-cooled areas between the tubes .

Another problem with known aluminium cold plates used for cooling by water of components energized by direct current and in which the cooling channels are made in the aluminium cold plate itself, is that, due to that ion migration occurs, a very severe corrosion of the aluminium of the cold plate takes place, and this will reduced its useful life.

Another problem with known cast cold plates is that casting requires high temperatures, which are costly, and also voids are formed in the aluminium, especially in the vicinity of the walls of the tubes. Also the tubes have to be fixed in a jig before casting which is time consuming. Moreover, an aluminium cold plate made by casting is more porous than an aluminium cold plate made of a rolled aluminium sheet. Also the thick- ness of material of a cast cold plate is thicker than a corresponding one made according to the invention and has a thickness of material of about 25 mm. Due to different coefficient of thermal expansion between the cast material and the material of the cooling means (the tubes) there is a risk that gaps arise between said materials leading to poorer thermal transmittance . To overcome this problem, it has been suggested to make the cooling channels in the 'form of tubes of a non-corrosive material such as stainless steel, copper or the like. However, the thickness of material of said tube walls is rather thick, and as stainless steel has a lower thermal conductivity than aluminium it is important that the tube walls are thin.

Still another problem with cooling channels made of aluminium together with the use of water as cooling medium is that cor- rosion inhibitors have to be used to reduce the corrosion problem of aluminium. When corrosion inhibitors are used possibly microbes start to grow in the water, due to the fact that corrosion inhibitors generally form feeding stuffs to the microbes. Said microbes have a tendency to clog the cooling channels of the cold plate.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide an apparatus for achieving a more efficient cooling of heat generating components by means of a cooling fluid.

Another object of the present invention is to provide an apparatus for cooling heat generating components by which uniform cooling is achieved.

Another object of the present invention is to provide an apparatus in which a very good thermal contact is obtained between the mould halves and the cooling means.

Another object of the present invention is to provide a cold plate in which the mould halves are fastened to each other in a one step operation without external means. Yet another object of the present invention is to provide a cold plate having cooling means made of a material non-corrosive against the cooling fluid, and the thickness of material of said cooling means is reduced versus the thickness of material of prior art cold plates.

Still another object present invention is to provide methods for manufacturing an efficient apparatus for achieving a more efficient cooling of heat generating components with cooling fluid.

To achieve the above-mentioned objects, an apparatus for cooling heat generating components is proposed, comprising at least two mould halves made of a material with good thermal conductivity, and at least one disc-like cooling means placed between the mould halves and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank and is made of a material non-corrosive against a cooling fluid and provided with inlet and outlet means, respectively, and forming at least one fluid channel for cooling fluid, said mould halves being located towards and closely attached to each other. According to the invention one or both sides of the mould halves directed towards the cooling means blank is provided with a cavity with recesses, said recesses form a pattern, and that the cooling means blank is adapted to be shaped after said recesses and said cavity in said mould half (ves) to form said at least one fluid channel having a disc-like fluid pattern in said cooling means, said cooling channels being shaped as the reverse image of the pattern.

To achieve the above-mentioned objects, also a method of manufacturing an apparatus for cooling heat generating components is proposed, which apparatus comprises at least two mould halves made of a material with good thermal conductivity, and at least one disc-like cooling means placed between the mould halves and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank and is made of a material non-corrosive against a cooling fluid and provided with inlet and outlet means, respectively, and forming at least one fluid channel for cooling fluid, said mould halves being located towards and closely attached to each other. The new according to the method of the invention is

- providing a cavity in one or both of said mould halves to accommodate said cooling means blank,

- additionally providing recesses in the form of a pattern in the bottom of said mould half (ves) which is facing the cooling means blank,

- placing said cooling means blank between said mould halves and said mould halves are kept at a certain distance from each other, - connecting the inlet and outlet means, respectively, of said cooling means blank to a suitable fluid pressure source for hydraulic shaping of said cooling means blank into the cooling means which at the same time is provided with at least one cooling fluid channel, said cooling means will thus obtain the mirror image of said pattern, and

- pressing said mould halves against and attaching them to each other while the hydraulic fluid pressure is applied, where after the inlet and outlet means are disconnected, and possible final machining is conducted.

To achieve the above-mentioned objects, also a another method of manufacturing an apparatus for cooling heat generating components is disclosed, comprising at least two mould halves made of a material with good thermal conductivity, and at least one disc like cooling means placed between the mould halves and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank and is made of a material non-corrosive against a cooling fluid and provided with inlet and outlet means, respectively, and forming at least one fluid channel for cooling fluid, said mould halves being located towards and closely attached to each other. The new according to this method of the invention is:

- providing a cavity in one or both of said mould halves to accommodate and totally enclose said cooling means blank,

- placing said cooling means blank between said mould halves, and

- pressing said mould halves against and attaching them to each other, where after possible final machining is made.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, the invention will be further described below with reference to accompanying drawing, in which: FIG. 1 a view from the above of one embodiment of a cold plate according to the invention; a part of one of the mould halves has been removed from the drawings in order to illustrate the cooling means; FIG. 2 is a sectional side view of a cold plate according to the invention;

FIG. 3 is a view from above of another embodiment of a cold plate according to the invention in which the cooling means is show by broken lines and a part of one of the mould halves has been removed from the drawings in order to illustrate the cooling means;

FIG. 4 is a half sectional exploded view of a cold plate according to the invention showing the two mould halves sepa- rated and the cooling means in its non-expanded state;

Fig. 5 is a half sectional view of a cold plate according to the invention, but in which the studs of one mould half have been brought into contact with the blind holes in the other mould half and in which cooling means has been expanded to form cooling fluid channels in the same; and

FIG: 6 is a sectional view of a cold plate according to the invention similar to the one in FIG.5, but in which the two mould halves have been brought into contact with and fastened to each other by plastic deformation of the studs .

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an embodiment of a cold plate 1 according to the invention. The cold plate 1 comprises two mould halves, an upper half 2 and a lower half 3. The two mould halves are attached to each other along the edge of the cold plate by suitable fastening means. A cooling means 4 provided with inlet and outlet means 5, 6, preferably of self-closing drip- proof type, and forming at least one fluid passage for a cool- ing fluid is arranged between the mould halves. Moreover, the inlet and outlet means 5, 6 are adapted to be connected to a cooling fluid circuit, not shown.

Said cooling fluid is preferably pure water without any corro- sion inhibitors. The advantage of using water as cooling fluid is that it has no environmental influence and there is no risk of growth of microbes, since there are no feeding stuffs in the water, whereby the risk of clogging of the cooling chan- nels of the cold plate is eliminated. Furthermore, it is inexpensive and has good heat capacitivity.

As can be seen in FIG. 2, the two mould halves 2, 3 are pref- erably riveted together by internal riveting. To achieve the riveting, for instance, one of the mould halves, the upper half 2 in the embodiment shown, is provided with protruding means 7, preferably in the form of stubs 7, and the other one, the lower mould half 3 in the embodiment shown, with blind holes 8, which are placed opposite to each other, so that the studs 7 will fit into the blind holes 8^'.

The blind holes 8 have preferably a diameter increasing towards the bottom of said holes . Due to the fact that the stud 7, when deformed, will expand slightly, a firm inter-engagement between the studs and the blind holes will thus be achieved.

By fastening the mould halves 2, 3 together by internal rive - iπg, the external surfaces of cold plate 1 will be smooth without any holes, and the cooling efficiency of said cold plate will therefore be better, and thus the cooling surfaces are maximized.

According to the invention the two mould halves can also be fastened together by any other commercially available techniques such as by bolts and nuts, gluing, soldering or welding.

At least one of the mould halves 2, 3 is provided with a cavity 11, schematically shown in, for instance, FIG:S 4-6 adapted to receive the cooling means 4.. In the bottom of the cavity 11 recesses 12 in a certain pattern are formed. The cavity and the recesses are preferably milled with a cutter in a sheet metal blank of a material having good thermal conductivity, such as aluminium. The thus machined blank forms a mould half. Of course, only one of the mould halves can be provided with the cavity 11 and recesses 12, but according to a preferred embodiment of the invention both mould halves are provided with said cavity and recesses . According to the invention the two mould halves 2, 3 are made of rolled aluminium work pieces.

It should be noted that according to the invention the expression mould half is not limited to only a cast mould half, but encompasses any type of means acting on one hand as support for the cooling means 4 during the hydraulic forming of said cooling means, as will be explained below, and on the other hand as a part of the finished cold plate. It should also be noted that, for instance, the upper mould half 2 could be formed of two or more parts.

The thickness of material of the finished cold plate according to the invention, i.e. the two mould halves with intermediate cooling means, is less than about 15 mm and preferably less than 10 mm.

The cooling means 4 has preferably an elongated disk-like form preferably made of two sheets, an upper and a lower sheet, as can be seen in FIG. 4, welded, preferably laser welded, together along its periphery and possible internal notches, through which fastening means may extend. The welds are shown by broken lines in, for instance, FIG. 1. The two sheets form at least one fluid channel passage for the cooling fluid when expanded. The cooling means 4 is made of a material non-corrosive to the cooling fluid, preferably acid proof stainless steel. The cooling means 4 can also be made of stainless steel, copper or titanium.

Since the cooling means 4 has a disk-like form and extends more or less over the hole area of the cold plate 1, when viewed from above, a uniform cooling of said plate is obtained. Also the fluid pattern in the cooling means 4 is disklike.

Moreover, as can be seen in FIG 5 and 6, the cooling means 4 is expanded from the sheet-like form by hydraulic forming of a cooling means blank 4a (FIG.4) between the mould halves to provide said at least one fluid channel passage and ridges 10, as will be described later. Thus, the external surfaces of the cooling means 4 will obtain the reverse image of the cavity 11 and the recesses 12. The thickness of material of the wall of the cooling means is about 0,4 mm and preferably 0,3 mm or less when it is made of acid proof stainless steel.

Possibly a lubricating and contact oil may be provided between the mould halves 2,3 and the cooling means 4 in order to reduce the friction during the hydraulic forming of the cooling means 4 and to increase the transfer of heat between the mould halves 2,3 and the cooling means 4.

According to one embodiment of the invention the ridges 10 provided on the two sheets of the cooling means 4 extend all the way from the weld at one side of said elongated cooling means 4 to the weld at the other side, as can be seen in FIG. 1. The ridges 10 extend also in an angle to the longitudinal axis of the cooling means 4, and preferably the ridges 10 of the upper sheet extend in an angle different from that in which the ridges 10 of the lower sheet extend. By shaping the cooling means 4 in such a way, the fluid in the fluid channel passage will have a controlled flow with a disc-like fluid pattern, whereby no sedimentation will occur in the fluid channel passage and also a better heat transmission is ob- tained.

The fluid pattern of the cooling fluid in the at least one fluid channel should be such that laminar and turbulent flow is achieved for optimal heat transport, that the risk of clog- giπg of the fluid channels, is minimised, that the risk of contact corrosion in connection with the weld of the cooling means is minimised, and that the fall of pressure in the fluid channels is reduced. Thus, according to the invention the pattern of the cooling means 4 is in one embodiment such that one or both sides of the cooling means 4 is (are) given an increase of the surface area by, in relation to the main direction of the fluid flow in the cooling means, arranging diagonally and equally spaced ridges 10, and limiting surfaces are preferably arranged in relation to each other so that the ex- treme points of the ridges 10 are common to both sides of the cooling means 4, whereby the ridges 10 form a check pattern as can be inferred from the drawings .

The ridges 10 have two purposes, one is to increase the sur- face area and the other is to function as stiffening means.

In the embodiment shown in FIG.l, the inlet and outlet means 5, 6 are arranged on opposite sides of the cooling means 4. However, inlet and outlet means 5, 6 can be arranged on the same side of the cooling means 4, as seen in FIG. 3.

In FIG. 3 another embodiment of a cold plate 1 according to the invention is shown. In said embodiment the cooling means 4 has a more elaborated design and is provided with suitable partitions for the cooling fluid. Oblong, notches 13 are made between the fluid channels in the cooling means. Possible fastening means (not shown) for both the heat generating means fixed to the external surface (s) of the cold plate 1 and the two mould halves 2, 3 extend through said notches 13. Although some rivers are schematically indicated in said Fig. the number do not correspond to the number actually needed to achieve a firm interengagement between the two mould halves 2, 3. ^'In said embodiment the inlet and outlet means 5, 6 are hidden by and countersinked in the edge of the two interengaged mould halves 2, 3, whereby a larger cooling surface of the cold plate is obtained than of the cold plate according to the embodiment shown in Fig.1.

FIG. 4 is a half sectional exploded view of the cold plate 1 showing the two mould halves separated and the cooling means 4 in the form of a cooling means blank 4a. The cooling means blank 4a comprises in a preferred embodiment two sheets, which are welded along the periphery, and inlet and outlet means 5,

6. Preferably the blank 4a is welded by laser welding and the weld is made at a certain distance from the periphery so that a protrusion 9 is formed. The formation of the protrusion 9 is not necessary, but it is easer to locate the cooling means blank 4a within the mould halves 2, 3 if a protrusion 9 is formed. Of course, at least one of the mould halves 2, 3 must in such a case be provided with a corresponding recess to accommodate said protrusion 9. Furthermore, the inlet and outlet means 5, 6 is attached to the blank 4a by any suitable means such as welding.

It should be noted that the expansion/hydraulic shaping of the cooling means blank 4a is made in such a way that no slit is formed between the sheets forming the cooling means at the side of the weld directed towards cooling fluid. Should a slit be formed between the two sheets contact corrosion may occur which is a severe problem.

In another embodiment, not shown, the cold plate 1 can be provided with more than one cooling means 4 having the inlet and outlet means 5, 6 on the same or different sides of the cold plate.

It should be noted that, according to the invention, the cooling means 4 can extend to the side edge of the cold plate 1, whereby the cooling means 4 is provided with holes/notches through which fastening means extend for fastening the two mould halves to each other, as seen in FIG. 3.

The heat absorbed by the cooling fluid is cooled in the ground, in a well bored in rock or by other types of heat exchanger placed outside a building, as known in the art.

In an other embodiment of the invention (not shown) the two mould halves 2, 3 can have different thickness of material, if the heat generating components are to be fastened at only one side of the cold plate 1. The heat generating components are fastened to the mould halves preferably by self-tapping screws .

In still an other embodiment of the invention (not shown) the two mould halves 2,3 can be made of different materials if the heat generating components are mounted only on one side of the cold plate.

In yet an other embodiment of the invention (not shown) one of the mould halves 2,3 can be made of the same material as that of the cooling means 4 and is not provided with a cavity and recesses. In such a case one of the sheets forming the cooling means blank can be directly welded to one of the mould halves and the other mould half is made and formed as stated above, whereby when the hydraulic forming is performed only the above-mentioned sheet of the cooling means is shaped.

Below a method for manufacturing a cold plate according to the invention will be illustrated with reference to FIG:s 4-6.

As can be seen from FIG.4, in the first step, the two mould halves 2, 3, each having a cavity 11, recesses 12, which form a specific pattern, and fastening means in the form of studs 7 and blind holes 8 facing each other, are placed in a press, preferably a hydraulic press (not shown) , and arranged at a distance from each other with a disc-like cooling means blank 4a placed between said mould halves 2, 3, the inlet and outlet means of which are not shown.

In the next step, FIG. 5, the studs 7 of mould half 2 are brought into contact with the bottom of the blind holes 8 of mould half 3, so that a fixed distance is obtained between the two mould halves, where after the inlet and outlet means 5, 6 of the cooling means blank 4a are connected to a suitable hy- draulic fluid pressure source (not shown) for hydraulic shaping the cooling means blank 4a, in such a way that the upper and lower sheets of the blank will expand into the cavity 11 and the recesses 12, and will thereby obtain the mirror image of said pattern, while maintaining the distance between the mould halves 2, 3. Thus, the finished cooling means 4 will be obtained. By shaping while maintaining a distance between the mould halves 2, 3, the cooling means 4 is over-expanded. The over-expansion is performed due to the fact on one hand the finished cooling means will contract slightly, when the pressure of the hydraulic fluid is relieved from the cooling means, and on the other hand a better contact and thereby better capacity of heat transmission is obtained between the cooling means 4 and the two mould halves 2, 3. The fixed distance between the two mould halves defined by, for instance, the height of the studs 7, defines the over-expansion of the cooling means, and this over-expansion corresponds to the contraction of the material of which the cooling means is made, whereby a good thermal contact is obtained between the mould halves 2, 3 and the cooling means 4.

In the third step, FIG. 6, the two mould halves 2, 3 are brought into contact with each other, while hydraulic fluid pressure is applied, whereby the studs 7 are deformed by plas<- tic deformation, where after the inlet and outlet means 5, 6 are disconnected from the hydraulic fluid pressure source, whereupon a possible final machining is made.

Due to the fact that the blind holes 8 have a diameter which increases slightly towards the bottom, a firm fastening between the two mould halves 2, 3 is obtained.

In an embodiment not shown it is contemplated within the scope of protection conferred by the invention that the cooling means 4 can be made of a highly elastic thin material, such as a thermoplastic resin, elastomer or rubber, and provided with suitable, preferably pre-cast means for connection to the inlet and outlet means 5, 6. In this embodiment of the inven- tion the cooling means 4 has to be totally enclosed by the mould halves 2, 3 and is shaped as the reverse image of the mould halves as said cooling means is pressurized by the cooling fluid. Thus, in said embodiment of the invention the steps of connecting the inlet and outlet means 5, 6 to a suitable fluid pressure source for hydraulic shaping of said cooling means blank into the finished cooling mean and pressing said mould halves against and attaching them to each other while the hydraulic fluid pressure is applied, where after the inlet and outlet means are disconnected, are omitted. By this embodiment of the invention a less expensive cold plate can be manufactured. However, in this embodiment it is important that the thickness of material of the walls of the cooling means are very thin to increase the heat of transmission from the heat generating components mounted on the mould halves to the cooling fluid within the elastic cooling means.

Claims

1. An apparatus for cooling heat generating components, comprising at least two mould halves (2,3) made of a material with good thermal conductivity, and at least one disc-like cooling means (4) placed between the mould halves (2,3) and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank (4a) and is made of a material non-corrosive against a cooling fluid and pro- vided with inlet and outlet means (5,6), respectively, and forming at least one fluid channel for cooling fluid, said mould halves (2,3) being located towards and closely attached to each other, characterized in

- that one or both sides of the mould halves (2,3) directed towards the cooling means blank (4a) is provided with a cavity (11) with recesses (12) , said recesses (12) form a pattern, and

- that the cooling means blank (4a) is adapted to be shaped after said recesses (12) and said cavity (11) in said mould half (ves) (2,3) to form said at least one fluid channel having a disc-like fluid pattern in said cooling means (4) , said cooling channels being shaped as the reverse image of the pattern.

2. The apparatus according to claim 1, characterized in that the cooling means (4) is made of a material selected from the group consisting of stainless steel, copper, titanium, a thermoplastic resin and a rubber.

3. The apparatus according to claim 2, characterized in that the cooling means (4) is made of acid proof stainless steel.

4. The apparatus according to claim 1, characterized in that one of the mould halves (2,3) is provided with protruding means (7) and the other with blind holes (8) , said protruding means (7) and blind holes (8) are placed opposite to each other, and so adapted that, when said mould halves (2,3) are pressed against each other, the protruding means (7) are deformed by plastic deformation and engaged in said blind holes (8), whereby said mould halves (2,3) are fastened to each other.

5. The apparatus according to claim 4, characterized in that said protruding means (7) are made as studs.

6. The apparatus according to claim 4 , characterized in that the blind holes (8) have a diameter which increases towards the bottom of said blind holes (8) .

7. The apparatus according to claim 1, characterized in that a lubricating and contact oil is provided between the mould halves (2,3) and the cooling means (4) .

8. A method of manufacturing an apparatus for cooling heat generating components, comprising at least two mould halves made of a material with good thermal conductivity, and at least one disc like cooling means placed between the mould halves and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank and is made of a material non-corrosive against a cooling fluid and provided with inlet and outlet means, respectively, and forming at least one fluid channel for cooling fluid, said mould halves being located towards and closely attached to each other, characterized by

- additionally providing recesses in the form of a pattern in the bottom of said mould half (ves) which is facing the cooling means blank, - placing said cooling means blank between said mould halves and said mould halves are kept at a certain distance from each other,

- connecting the inlet and outlet means, respectively, of said cooling means blank to a suitable fluid pressure source for hydraulic shaping of said cooling means blank into the cooling means which at the same time is provided with cooling fluid channels, said cooling means will thus obtain the mirror image of said pattern, and

- pressing said mould halves against and attaching them to each other while the hydraulic fluid pressure is applied, where after the inlet and outlet means are disconnected, and possible final machining is made.

9. The method according to claim 8, characterized by providing one of the sides of the mould halves facing each other with protruding means and the other one with blind holes placed opposite to each other, and so adapted that, when said mould halves are pressed against each other, the protruding means are deformed and engaged in said blind holes, whereby said mould halves are fastened to each other.

10. The method according to claim 9, characterized in that the protruding means are made as studs .

11. The method according to claim 9, characterized in that the blind holes have a diameter which increases towards the bottom of said blind holes.

12. The method according to claim 8, characterized in that the cooling means blank is made of sheets welded together and that the hydraulic shaping of the cooling means blank is made in such a way that no slit is formed between the welded sheets at the side of the weld directed towards the cooling fluid.

13. The method according to claim 8, characterized in that the hydraulic shaping of said cooling means blank is made by over- expanding said cooling means to such an extent that said over- expansion corresponds to the contraction of the material of which the cooling means is made.

14. The method according to any of claims 8-13, characterized in that the cooling means is made of a material selected from the group consisting of stainless steel, copper and titanium.

15. The method according to claim 8, characterized in that a lubricating and contact oil is provided between the mould halves and the cooling means.

16. A method of manuf cturing an apparatus for cooling heat generating components, comprising at least two mould halves made of a material with good thermal conductivity, and at least one disc like cooling means placed between the mould halves and in good thermal contact with said mould halves, said cooling means being originally in the form of a blank and is made of a material non-corrosive against a cooling fluid and provided with inlet and outlet means, respectively, and forming at least one fluid channel for cooling fluid, said mould halves being located towards and closely attached to each other, characterized by

- providing a cavity in one or both of said mould halves to accommodate and totally enclose said cooling means blank, - additionally providing recesses in the form of a pattern in the bottom of said mould half (ves) which is facing the cooling means blank,

- placing said cooling means blank between said mould halves, and

17. The method according to claim 16, characterized in that the cooling means is made of a material selected from the group consisting of a thermoplastic resin, elastomer and rubber.