Methods for and Apparatuses of a Circuit Board Cooling Device

Abstract

Disclosed are aspects of apparatuses and methods of fitting a cooling device to a circuit board for cooling a high-power electronic component mounted on the circuit board. Cooling apparatuses, and arrangement thereof, are also described. The method provides the cooling device with a cooling surface having a cooling area for thermally connecting to a to-be-cooled surface of the electronic component. Fixing elements are provided for moving the cooling surface towards the circuit board. A distance position “d” of the to-be-cooled surface from the circuit board is determined, and on this basis spacer elements are selected to be interposed between the cooling device and the circuit board to limit the movement by the fixing elements to a position where the cooling area is in proximity to the to-be-cooled surface.

Claims

1. A method comprising: providing a cooling device including a cooling surface having a cooling area for thermally connecting to a to-be-cooled surface of an electronic component; providing one or more fixing elements for moving the cooling surface towards a circuit board; determining a distance position of the to-be-cooled surface from the circuit board; and selecting, based on the determined distance position, one or more spacer elements to be interposed between the cooling device and the circuit board to limit a movement by the one or more fixing elements to a position where the cooling area is in proximity to the to-be-cooled surface.

2. The method according to claim 1, further comprising: selecting the one or more spacer elements to limit the movement by the one or more fixing elements to a position where the cooling area is substantially in contact with the to-be-cooled surface with a minimal air gap.

3. The method according to claim 1, wherein: the cooling surface has at least one respective additional cooling area corresponding to at least one respective to-be-cooled surface of one or more additional electronic components; and the at least one respective additional cooling area is spaced from the circuit board by a distance which is greater than the determined distance position.

4. The method according to claim 1, further comprising: providing, by the one or more fixing elements, a biassing force for moving the cooling surface towards the circuit board.

5. The method according to claim 4, wherein the one or more fixing elements extend between the cooling device and the circuit board for moving the cooling surface towards the circuit board.

6. The method according to claim 1, further comprising: providing one or more couplings for the one or more fixing elements to enable the cooling device to be fitted to the circuit board.

7. The method according to claim 6, wherein the one or more couplings comprise a part of a housing.

8. The method according to claim 1, further comprising: interposing the one or more spacer elements between the cooling device and the circuit board; and moving, using the one or more fixing elements, the cooling surface towards the circuit board.

9. The method according to claim 8, further comprising: limiting, using the one or more spacer elements, the moving of the cooling surface towards the circuit board; and positioning, based on the moving and the limiting, the cooling area of the cooling surface in proximity to the to-be-cooled surface of the electronic component.

10. The method according to claim 9, further comprising: fitting, using one or more couplings, the cooling device to the circuit board such that the cooling area of the cooling surface is in proximity to the to-be-cooled surface of the electronic component.

11. An apparatus comprising: a cooling device including a cooling surface having a cooling area configured to thermally connect to a to-be-cooled surface of an electronic component, the to-be-cooled surface a determined distance position from a circuit board; one or more fixing elements configured to move the cooling surface towards the circuit board; and one or more spacer elements, which are selected based on the determined distance position, configured to interpose between the cooling device and the circuit board to limit a movement by the one or more fixing elements to a position where the cooling area is in proximity to the to-be-cooled surface.

12. The apparatus according to claim 11, wherein the one or more spacer elements are selected to limit the movement by the one or more fixing elements to a position where the cooling area is substantially in contact with the to-be-cooled surface with a minimal air gap.

13. The apparatus according to claim 11, wherein: the cooling surface has at least one respective additional cooling area corresponding to at least one respective to-be-cooled surface of one or more additional electronic components; and the at least one respective additional cooling area is spaced from the circuit board by a distance that is greater than the determined distance position.

14. The apparatus according to claim 11, wherein the one or more fixing elements are configured to provide a biassing force to move the cooling surface towards the circuit board.

15. The apparatus according to claim 11, wherein the one or more fixing elements are sized to extend in use between the cooling device and the circuit board to move the cooling surface towards the circuit board.

16. The apparatus according to claim 11, further comprising: one or more couplings for the one or more fixing elements configured to enable the cooling device to be fitted to the circuit board.

17. The apparatus according to claim 11, wherein each spacer element of a plurality of spacer elements of the one or more spacer elements have different lengths relative to one other.

18. The apparatus according to claim 11, further comprising: the circuit board; and the electronic component mounted on the circuit board, the electronic component further comprising a high-power electronic component having the to-be-cooled surface, and the to-be-cooled surface located substantially centrally of the cooling surface of the cooling device.

19. The apparatus according to claim 11, wherein the cooling device, the one or more fixing elements, and the one or more spacer elements together comprise a cooling arrangement, and the apparatus further comprises: the circuit board; the electronic component mounted on the circuit board; and a housing for the circuit board, the electronic component, and the cooling arrangement, the housing comprising one or more couplings configured to enable the one or more fixing elements to fit the cooling device to the circuit board.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Illustrative embodiments will now be described with reference to the accompanying drawings in which:

[0042] FIG. 1 shows a side view of a cooling device and a printed circuit board according to a first embodiment prior to fitting of the cooling device; and

[0043] FIG. 2 shows a side view of the cooling device and the printed circuit board of FIG. 1 after fitting of the cooling device.

DETAILED DESCRIPTION

[0044] In the present description, the term printed circuit board includes a plurality of electronic components which are mounted on a circuit board which includes electrically conducting material to define the electrical connections between the mounted electronic components.

[0045] FIG. 1 shows a side view of a printed circuit board 1 and a cooling device 2. The printed circuit board has a circuit board 3 with a high-power electronic component 4 mounted thereon. The high-power electronic component can be an SOC or other high-performance component needing optimum cooling to avoid damage. Further, low-power electronic components 5 and 6 are also mounted on the circuit board 3 in the locality of the high-power component 4.

[0046] The electrical connections between the mounted components are not illustrated. It will be appreciated that there can be a plurality of components spread mounted across the circuit board including passive components (not shown for clarity).

[0047] As can be seen, the high-power electronic component 4 has a generally planar upper to-be-cooled surface 7 remote from and parallel to the plane of the circuit board 3. This to-be-cooled surface 7 is to be cooled so that excess heat can be removed from the high-power electronic component 4. This surface to-be-cooled is spaced a distance “d” from the plane of the surface of the circuit board 3. In this description, the distance between a plane spaced from the plane of the circuit board 3 is referred to as the height distance above the circuit board, and the to-be-cooled surface 7 is referred to as the upper or top surface of the component 4.

[0048] As can be seen, the low-power electronic components 5 and 6 have respective generally planar to-be-cooled upper surfaces 8 and 9 remote from and parallel to the circuit board 3. These surfaces also are to be cooled so that excess heat can be removed from the respective component. However, the cooling requirement of the components 5 and 6 is less than that of the component 4. It will also be noted that the height distance of the upper surfaces 8 and 9 is greater than that of the upper surface 7. Of course, the upper surfaces 8 and 9 could be lower than the upper surface 7.

[0049] On the printed circuit board 1, holes 10 are provided to extend through the edges of the circuit board perpendicular to the plane of the circuit board 3. Of course, the holes 10 can be provided at any suitable location on the PCB.

[0050] The cooling device 2 in this embodiment is a heat sink and comprises a main solid body 11 (or cold plate for liquid cooling) having a profiled lower cooling surface 12 facing the circuit board 3. Thinned edges 13 and 14 are provided at the edges. Holes 15 are provided to extend through the thinned edges 13 and 14 of the circuit board perpendicular to the plane of the circuit board 3 and aligned with the holes 10.

[0051] It will be appreciated that the solid body can be replaced by a body with fins or other ways of dissipating heat from the cooling device.

[0052] The cooling surface 12 has a lower surface facing the circuit board which has three portions 16A, 16B, and 16C, as shown in the figure, which are aligned on a single plane parallel to the plane of the circuit board 3. The first portion 16A extends from the left edge in the figure towards the centre of the surface 12 and defines a cooling surface 17A. This surface includes a cooling area for the to-be-cooled surface 8. The second portion 16C extends from the right edge towards the centre of the surface 12 and defines a cooling surface 17C.

[0053] To the right of the portion 16A as shown, the cooling surface 12 has a further portion 16D which extends further towards the circuit board and defines a cooling surface 17D. Thus, the cooling surface 17D is closer to the circuit board than the cooling surface 17A. This surface includes a cooling area for cooling the to-be-cooled surface 7.

[0054] To the left of the portion 16C as shown, the cooling surface has a further portion 16E which extends further away from the circuit board and defines a cooling surface 17E. Thus, the cooling surface 17E is further from the circuit board than the cooling surface 17A. This surface includes a cooling area for cooling the to-be-cooled surface 9.

[0055] The portion 16B is interposed between the portions and has a lower cooling surface 17B.

[0056] As can be seen, the lower cooling surface 12 has a profile so that the cooling surface 17D is opposed to and facing the electronic component 4, the cooling surface 17A is opposed to and facing the electronic component 5, and the cooling surface 17E is opposed to and facing the electronic component 6.

[0057] A method will now be described for fitting the cooling device 2 to the circuit board 3 whereby the surface 17D can be brought into very close contact with the surface 7 and with a minimal air gap.

[0058] Reference is made to FIG. 2. After production of the printed circuit board 1 corresponding to the components 4, 5, and 6 mounted on the circuit board 3, the profile of the components and circuit board can be accurately determined by a suitable measuring device. In one example, an optical 3D-scanner can be used. This can determine the distance position “d” of the to-be-cooled surface 7 from the circuit board. The determined distance will take into account production variations and tolerances for the PCB and any bending of the circuit board during production. This can be done for each individual high-power electronic component.

[0059] Fixing elements are then provided for attaching and moving the cooling device 2 towards the circuit board 3. In FIG. 2, the fixing elements comprise respective screws 20. These are positioned to extend through the respective holes 15 of the cooling device 2 and to extend through the holes 10 in the circuit board 3, and the screws 20 are located and screwed into couplings in the form of internally threaded sleeves 21 provided on the opposite lower side of the circuit board 3.

[0060] Thus, as the screws 20 are screwed into the sleeves 21, the cooling surface 12 of the cooling device 2 is moved towards the circuit board 3. The movement of the cooling device 2 towards the circuit board 3, in the direction of arrow A, aims to get the cooling surface 17D to a position which is as close as possible to the to-be-cooled surface 7 of the high-power electronic component 4—without damage to the component by too much movement and without much of an air gap by too little movement.

[0061] In order to do this, before the screws 20 are passed through the holes 10, a spacer element 22 is interposed between the cooling device 2 and the circuit board 3 to limit the movement of the cooling device towards the circuit board by screwing in the screws. In this respect, the size of the spacer element 22 is selected according to the determined distance position “d” of the to-be-cooled surface 7 from the circuit board 3.

[0062] As shown in FIG. 2, the spacer element can take the form of a tube 22 which can be slid over the screws 20 before they are screwed and tightened into the sleeves 21. As the screws 20 are screwed into the couplings, the movement is limited by the spacer element 22 to a position where the cooling surface 17D and the cooling area thereof is in close proximity to the to-be-cooled surface 7, and additionally without the risk of damage to the high-power electronic component 4 due to over tightening of the screws 20. In this way, the use of TIM in any air gap between the two surfaces can be minimized, or at least reduced, so that the thermal pathway functions in an optimal, or at least enhanced, way.

[0063] As already noted, the additional cooling surfaces 17A and 17E corresponding to the to-be-cooled surfaces 8 and 9 of the additional electronic components 5 and 6 are spaced from the circuit board by a distance which is greater than the determined distance position “d.” The air gap between the cooling areas of the cooling surfaces 17A and 17E and the to-be-cooled surfaces 8 and 9 can be filled with TIM 23 in the known way.

[0064] It will be appreciated that the area of the cooling surface 12 of the cooling device 2 in plan view as viewed along the arrow A can be varied to encompass either a single high-power electronic component alone, or optionally with additional electronic components to be cooled. The cooling device concentrates on the cooling of the one high-power electronic component, preferably located centrally below the cooling device positioned high-power electronic component. This provides the optimum cooling.

[0065] As the area of the cooling surface 12 increases, there is a requirement for extra fixing elements. For example, four screws 20 and associated sleeves 21 and couplings can be used.

[0066] Furthermore, a support frame (not shown) for the high-power component can be located on the opposite side of the circuit board 3 to the high-power electronic component 4 to provide support therefor. This support frame can include holes for additional screws 20 (not shown) which pass through holes 15A in the circuit board to couple with threaded holes in the cooling surface 12 (not shown). Further spacer elements 22 can be located over these additional screws.

[0067] In order to allow for the different production tolerances and component heights, a set of precisely manufactured and dimensioned spacer elements 22 featuring several different heights can be produced and made available. These can be either individually used or combined together to obtain the required limit spacing. For example, they can differ by 1, 2, 3 tenths of a millimeter in a range of sizes combined together to have the required height.

[0068] Alternatively, a set of more specifically dimensioned and standard spacer elements can be used which can be shortened by milling, squeezing with a percussion mechanism, and such like in order to change their heights to what is required. The use of a standard size spacer elements avoids the need to stock different size spacer elements.

[0069] In the present disclosure, the spacer elements 22 take the form of a tube which can slide over the screws before the screws are inserted into the sleeves. Of course, the spacer elements can take other forms and do not have to slide over the screws to provide the function to limit the movement by the fixing elements so that the cooling contact area is in close proximity to the to-be-cooled surface. For example, the spacer elements could fit into recesses or fit over spigots formed as part of the circuit board 3.

[0070] Whilst the sleeves 21 have been described as separate parts, these too can be formed as part of the circuit board. In addition, it will be appreciated that the sleeves 21 could take the form of a coupling integrally formed as part of a housing.

[0071] Due to the use of the spacer elements, movement of the cooling device is precisely limited to produce an accurate and correct spacing between the cooling surface 17D and to-be-cooled surface 7 of the high-power component 4, for example a few tenths of a millimeter. This enables a closer and more precise proximity to be obtained between the high-power component and the respective part of the cooling surface. This means that the thickness of any TIM layer can be reduced compared with other approaches, thereby enabling optimal cooling of the high-power component.

[0072] In addition, the described method ensures that the cooling device and circuit board can be firmly attached and provide this aforementioned advantage without the risk of damage to any components on the circuit board.

[0073] Furthermore, the present disclosure enables the fitting of a single cooling device to the circuit board to provide cooling areas which can thermally connect to the to-be-cooled surfaces of several localised components requiring cooling. In this respect, it is advantageous for the high-power component to be located substantially central of the cooling surface of the cooling device in plan view. In particular, the disclosure enables the cooling to be concentrated on a central high-power component.

[0074] It will be understood that the embodiments illustrated in the drawings and described above show an application only for the purposes of illustration. In practice, embodiments may be applied to many different configurations, the detailed embodiments being straightforward for those skilled in the art to implement.

[0075] For example, it will be appreciated that the fixing elements could comprise spring means which move and or urge the cooling device and circuit board together.

[0076] It will be appreciated that, during the assembly of the device, a movement takes place simply by locating the screws 20 in the holes 10 and tightening them once the spacer element 22 has been provided between the circuit board 3 and the cooling device 2. In practice, the spacer elements are chosen and applied after the actual height-position of the high-power component on the PCB has been measured and in this way the spacer element 22 enables precision of the smallest possible distance between the cooling surface and the high-power component of the final set-up.

Example Implementations

[0077] Example 1: A method of fitting a cooling device to a circuit board for cooling a high-power electronic component mounted on the circuit board, the method comprising the steps of: providing a cooling device with a cooling surface having a cooling area for thermally connecting to a to be cooled surface of the electronic component; providing fixing elements for moving the cooling surface towards the circuit board; determining a distance position of the to be cooled surface from the circuit board; and selecting, on the basis of the determined distance position, spacer elements to be interposed between the cooling device and the circuit board to limit the movement by the fixing elements to a position where the cooling area is in close proximity to the to be cooled surface.

[0078] Example 2: A method according to example 1 wherein the spacer elements are selected to limit the movement by the fixing elements to a position where the cooling area is substantially in contact with the to be cooled surface with a minimal air gap.

[0079] Example 3: A method according to example 1 or 2 for cooling one or more additional electronic components mounted on the circuit board, wherein the cooling surface has a respective additional cooling area corresponding to a respective to be cooled surface of the one or more additional electronic components; wherein the or each additional cooling area is spaced from the circuit board by a distance which is greater than said determined distance position.

[0080] Example 4: A method according to any preceding example wherein the fixing elements provide a biassing force for moving the cooling surface towards the circuit board.

[0081] Example 5: A method according to any preceding example wherein the fixing elements extend between the cooling device and the circuit board for moving the cooling surface towards the circuit board.

[0082] Example 6: A method according to any preceding example wherein couplings are provided for the fixing elements to enable the cooling device to be fitted to the circuit board.

[0083] Example 7: A method according to any preceding example wherein couplings comprise a part of a housing.

[0084] Example 8: A cooling arrangement to cool a high-power electronic component mounted on a circuit board, the cooling arrangement comprising: a cooling device with a cooling surface having a cooling area for thermally connecting to a to be cooled surface of the electronic component, wherein the to be cooled surface is a determined distance position from the circuit board; fixing elements for moving the cooling device towards the circuit board; and spacer elements, selectable on the basis of the determined distance position, for interposing between the cooling device and the circuit board to limit the movement by the fixing elements to a position where the cooling area is in close proximity to the to be cooled surface. Thus, the cooling arrangement can comprise: a cooling device with a cooling surface having a cooling area for thermally connecting to a to be cooled surface of the electronic component, wherein the to be cooled surface is a determined distance position from the circuit board; fixing elements for moving the cooling device towards the circuit board; and spacer elements, selectable on the basis of the determined distance position, for interposing between the cooling device and the circuit board to limit the movement by the fixing elements to a position where the cooling area is in close proximity to the to be cooled surface.

[0085] Example 9: A cooling arrangement according to example 8 wherein the spacer elements are selected to limit the movement by the fixing elements to a position where the cooling area is substantially in contact with the to be cooled surface with a minimal air gap.

[0086] Example 10: A cooling arrangement to example 8 or 9 to cool one or more additional electronic components mounted on the circuit board, wherein the cooling surface has a respective additional cooling area corresponding to a respective to be cooled surface of the one or more additional electronic components; wherein the or each additional cooling area is spaced from the circuit board by a distance which is greater than said determined distance position.

[0087] Example 11: A cooling arrangement according to any one of examples 8 to 10 wherein the fixing elements include means to provide a biassing force for moving the cooling surface towards the circuit board.

[0088] Example 12: A cooling arrangement according to any one of examples 8 to 11 wherein the fixing elements are sized to extend in use between the cooling device and the circuit board for moving the cooling surface towards the circuit board.

[0089] Example 13: A cooling arrangement according to any one of examples 8 to 12 further comprising couplings provided for the fixing elements to enable the cooling device to be fitted to the circuit board.

[0090] Example 14: A cooling arrangement according to any one of examples 8 to 13 wherein a plurality of spacer elements having different lengths are provided for selection.

[0091] Example 15: A cooling arrangement according to any one of examples 8 to 14 to cool a single high-power electronic component having a to be cooled surface which is located centrally of the cooling surface.