Electronic board and cold plate for said board

[0001] The present invention relates to an electronic card and a cold plate for cooling the card.

[0002] There exist electronic cards, such as those shown, for example, in FR 2 715 773, comprising:

- at least one electronic power element provided with a washer suitable for direct contact with the heat transfer fluid, - a cold plate on which the electronic power element was fitted in a sealed manner with respect to the heat transfer fluid, said cold plate comprising:

• at least one recess, the opening of which under the washer of the electronic power element, • a hole for admitting the heat transfer fluid into the cavity, and • an opening for discharging the heat transfer fluid from the recess.

[0003] In such electronic cards, plastic inserts are inserted into recesses. Each insert comprises several channels fluidly connected on one side to the inlet opening and on the other side extending perpendicular to the electronic power element pad. During operation, each of these channels generates a heat transfer fluid stream perpendicular to the electronic power element pad to optimize thermal exchange.

[0004] The production and in particular cutting of such inserts is complicated.

[0005] The object of the invention is to remedy this drawback by proposing an electronic card cooled as above but simpler to manufacture.

[0006] The subject of the invention is therefore an electronic card in which the cold plate comprises:

- a flat spray plate inserted between the inlet opening and the discharge opening, and - a plurality of straight nozzles passing through this plate from one side to the other along the spray direction, the nozzle length along the spray direction being greater than or equal to the largest nozzle width perpendicular to the same direction in the direction of spraying. to form a heat transfer fluid stream along the spray direction, the spraying direction of each nozzle forms an angle α relative to the direction perpendicular to the washer, and the angle α is between -30 and + 30 °.

[0007] The above electronic card can be made more easily because the manufacture of the plate through which the nozzles pass is easier than the production of the insert containing the channels extending directly into the inlet opening.

[0008] The subject of the invention is also a cold plate, which can be used in the above electronic card.

[0009] Embodiments of this cold plate may include one or more of the following features:

- each nozzle is formed by a hole passing through the spraying plate;

The spraying direction of each nozzle is perpendicular to the front or back side of the spray pad, the front side of the spray plate being the side facing the pad and the back side being the side opposite to the front side, the spray plate being inclined at an angle β relative to the plane pads of the electronic power element, and the angle β is between -30 and + 30 °;

EP 2 108 191 - the cold plate includes conduits suitable for allowing the flow of heat transfer fluid through the inlet and outlet openings, all these conduits being arranged in the same plane parallel to the plane defined by the washer;

- cold plate contains:

• first and second depressions, wherein both the first and the second recess have a hole extending under the washer of the same first electronic power element, • at least one third recess having an opening extending under the second electronic power pad, • drain hole of the first cavity fluidly connected with the inlet opening of the second cavity, passing through the inlet and outlet openings of the third cavity;

The cold plate has at least ten nozzles positioned one against the other to form points of impact of the heat-transfer fluid streams evenly distributed on the washer, i.e. such that the distances between two adjacent impact points are all equal to plus or minus 15%.

[0010] These cold plate embodiments also have the following advantages:

- making nozzles in the form of holes in the plate simplifies the making of the plate, - placing nozzles perpendicular to the front or back of the plate further facilitates the production and production of this plate, - that the sum of transverse surfaces of nozzles is equal to the surfaces of the inlet and outlet facilitates the flow of fluid a heat-insulating cold plate, - placing wires suitable to allow the flow of heat transfer fluid to the inside of the cold plate in the same plane allows to reduce the thickness of this cold plate, and also allows the cooling of the plate in its entire mass, and calorie removal from other elements placed on the a card that does not come into direct contact with the heat transfer fluid, - the use of the first and second cavity,which openings extend under the pad of the same electronic power element and the combination of these two recesses, via a third cavity used to cool the second electronic power element, allows to reduce the cooling differences between the first and second electronic power components in relation to the case where these electronic power components the first and second will be cooled separately by means of a single recess, and - the use of over ten nozzles allows to increase the cooling efficiency.wherein the first and second power electronic components are each cooled separately by means of a single cavity, and - the use of more than ten nozzles allows to increase the cooling efficiency.wherein the first and second power electronic components are each cooled separately by means of a single cavity, and - the use of more than ten nozzles allows to increase the cooling efficiency.

[0011] The invention will become clearer after reading the following description, given purely by way of non-limiting example and with reference to the drawings in which:

- Fig. 1 is a schematic perspective illustration of an electronic card, - Fig. 2 is a schematic perspective illustration of a cold plate used in the card of Fig. 1, - Fig. 3 is a partial cross-sectional view of a first embodiment of a spray plate useful in the cold plate of Fig. 2, and - Figures 4 and 5 are schematic illustrations, respectively, of the second and third embodiments of the spray plate useful in the cold plate of Fig. 2.

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[0013] In the following description, features and functions well known to those skilled in the art are not described in detail.

[0014] Fig. 1 shows the electronic card 2 equipped with several electronic power components mounted on the cold plate 4.

[0015] The electronic power element is to be understood here as the elements through which alternating or constant currents of several dozen amperes can pass without causing damage. Typically, these are switches that are capable of switching such currents.

[0016] In this case, the card 2 comprises five power switches from 6 to 10. These power switches are made using IGBT (Insulated Gate Bipolar Transistor) transistors. Other electronic components shown in Fig. 1 are not necessary to understand the operation of the cold plate and are therefore not described in detail here.

[0017] The cold plate 4 has on the side edge a receiving plane 13 suitable for accommodating, in a removable way, four connectors 14 to 17 allowing fluid connection of the cold plate 4 with one or more sources of heat transfer fluid. More specifically, the connectors 14 and 17 are upper connections through which the heat transfer fluid enters the interior of the cold plate 4. The joints 15 and 16 are lower connections through which the heat transfer fluid exits the cold plate 4. Each of ports 14 to 17 is provided with an isolation valve suitable for preventing the passage of a heat transfer fluid, in particular when the connectors 14 to 17 are disconnected from the receiving plane 13.

[0018] The plate 4 is also provided here with four valves 20 to 23, each of which allows the flow of the fluid respectively entering or leaving the connectors 14 to 17 to be interrupted.

[0019] The cold plate is intended for cooling various electronic components mounted thereon, and in particular, electronic power elements, such as switches 6 to 10. [0020] Fig. 2 shows the cold plate more detail 4. The cold plate 4 is formed from a plate 26 made of material that is a good heat conductor. A material whose thermal conductivity is greater than 50W / mK is determined by material which is a good heat conductor. For example, the plate 26 is made of aluminum EN AW6082.

[0021] The cold plate 4 also has five hollow inlets 28 to 32 in the thickness of the plate 26. Each of these recesses 28 to 32 only goes to the upper side of the plate 26, respectively directly below the switches 6 to 10. More specifically, the perimeter of the exit aperture of each cavity is entirely under the corresponding switch (IGBT) when it is mounted on the cold plate 4.

[0022] The recesses 28 and 32 are the same here and these recesses differ only in their position in the plate 26. Similarly, the recesses 29, 30 and 31 have exactly the same structure and differ only in their position in the plate 26. Thus, only the depression structure 28 and 29 are described in more detail here.

[0023] The recess 28 is formed of two recesses 36 and 38 placed side by side and separated from one another by a sealed wall 40. The wall 40 is provided to prevent direct passage of a heat transfer fluid present in one of the recesses into the other recess. The recesses 36 and 38 are the same here, and each of them has the shape of a parallelepiped.

Inside each of the recesses 36 and 38 an oblique spray plate 42 and 44, respectively, was mounted.

[0025] The structure of the recess 36 is described hereinafter with reference to Fig. 3.

[0026] The recess 29 also comprises two recesses 48 and 50 separated from each other by a wall 52. However, unlike wall 40, here the wall 52 is provided with one or more holes allowing fluid connection of the recess 48 with the recess 50.

[0027] Both recesses 48 and 50 comprise an inclined spray tile 54 and 56, respectively. The structures of the pits and the slant plates of the recess 29 are similar to those of the recess 28 and have not been described in more detail here.

[0028] The cold plate includes a first coolant circuit of switches 6 and 7, comprising: - a conduit 56 fluidly connecting the joint 14 with a recess 36, - a conduit 57 fluidly engaging a recess 36 with a recess 48, - a conduit fluidly connecting the cavity 50 with a recess 38, and - a line 59 fluidly connecting the recess 38 to the connector 15.

[0029] The cold plate 4 also comprises a second circulation of the heat transfer fluid under the switches 8, 9 and 10, said cycle being formed of:

- a conduit 60 fluidly connecting the connector 17 with a recess on the left side of the cavity 32, - fluidly engaging this recess on the left with the first recess of the recess 31, - a conduit 62 fluidly joining this second recess of the recess 31 with the first recess of the recess 30, connecting the second cavity of the recess 30 with a depression on the right side of the recess 32, and - a duct 64 fluidly connecting the recess on the right side of the recess 32 with the connector 16.

[0030] All of these conduits 56 to 64 were placed in the same plane parallel to the upper side of the plate 26.

[0031] Fig. 3 shows in more detail the recess 36 and the plate 42.

[0032] The duct 56 extends into the cavity 36 through the inlet opening 70 of the heat transfer fluid. After passing through the recess 36, the heat transfer fluid emerges from the recess 36 via the discharge port 72. The aperture 72 is formed by a conduit 57 which extends into the interior of the recess 36. At this point, the openings 70 and 72 are coaxial.

[0033] As illustrated in Fig. 3, a recess opening 28 extending onto the upper side of the plate 26 is surrounded by a groove 74. A circular seal 76 is provided in this groove 74. The seal 76 allows sealing between the washer 78 of the switch 6 and the upper side of the plate 26 Typically, the washer 78 is the inner side of the switch 6 and is made of a material that is a good conductor of heat, such as copper.

[0034] Since the washer 78 completely covers the opening of the recess 28 extending onto the upper side of the plate 26, this opening is hermetically sealed with a washer 78 in such a way that the heat transfer fluid can not flow out of this opening. It is also noted that with such assembly, the washer 78 is in direct contact with the heat transfer fluid in the cavity 36.

[0035] Fig. 3 shows two orthogonal directions X and Y. The direction Y is perpendicular to the plane of the washer 78. The direction X is parallel to the plane of the washer 78.

[0036] The shower plate 42 has a front side 80 facing the washer 78 and a back side 82 facing the opening 70.

[0037] The holes pass through the plate 42, and each hole forms a nozzle suitable for forming a flow of a heat transfer fluid impinging directly with the washer 78 along the direction of spray essentially perpendicular to the washer 78. That the jets are substantially perpendicular to the washer 78 increases cooling efficiency. By a stream substantially perpendicular to the washer 78, it is to be understood herein to refer to a jet with a spray direction P having an angle α between -30 and + 30 ° with respect to the direction Y. The spray direction P is represented by the vector P in Fig. 3.

[0038] In Fig. 9, only the 5 holes 86 to 90 are shown. Each of these holes extends along the direction of spray P. In this embodiment, the direction of spray P corresponds to the direction perpendicular to pages 80 and 82. The greater transverse width of each holes were chosen as smaller or equal to the length of the hole along the direction P.

[0039] Furthermore, here, the smallest width of each of these holes is chosen as being greater than or equal to 0.5 millimeters.

[0040] In this embodiment, each hole has a round fixed cross-section. The hole diameter is here also selected so that the sum of the transverse surface of the holes is equal to the lateral surface of the opening 70.

[0041] The surface of the opening 72 is also equal to the area of ​​the opening 70.

[0042] The cross-section of the conductors 56 to 59 is fixed.

The plate 42 is inserted between the opening 70 and the opening 72 in such a way that more than 85% of the heat transfer fluid passing through the cavity 36 also passes through the holes formed in the plate 42. For this purpose, the plate 42 rests directly on the wall of the upper recess 36 along the line 94 below the opening 70. On the other hand, the plate 42 rests directly on the wall of the bottom recess 36 along the line 96 below the opening 72. The plate 42 is removable here. For example, it is simply positioned inside the recess 36 and is held in place by the washer plate 42 when the heat transfer fluid passes through the holes 86 to 90. For example, the washer forms a stop element for the plate in such a way that the direction of fluid spraying heat-insulating material was kept essentially perpendicular to this washer.

[0044] In Fig. 3, lines 94 and 96 are perpendicular to the plane of the figure and are therefore represented by points. [0045] The plate 42 is also in contact with the wall 40 and with the wall opposite to the wall 40 of the cavity 36.

[0046] In order for the direction P to be substantially perpendicular to the washer 78, here, the plane of the plate 42 forms an angle β with respect to the plane of the washer 78 comprised between -30 and 0 °. This angle β is shown in relation to the direction X in Fig. 3.

[0047] By way of example, in this embodiment, the diameter of each hole is 3 mm and the thickness of the plate 42 is also 3 mm.

During operation of the cold plate 4, the heat transfer fluid enters the interior of the recess 36 via the opening 70. Next, it is sprayed in the form of streams from 100 to 104 along the direction P. Each of these streams directly impacts the washer 78. Then, after by impacting the washer 78, the heat transfer fluid is discharged through the opening 72.

The fluid discharged from the cavity 36 is thus guided by the rod 57 to the recess 48.

In the recess 48, in a manner similar to that described for the recess 36, the heat transfer fluid is sprayed in the form of streams substantially perpendicular to the shim of the switch 7, before being discharged into the recess 50 via a hole or holes made in the wall 52.

[0051] In the recess 50, the heat transfer fluid is sprayed in the form of streams substantially perpendicular to the washer of the switch 7 and then is discharged via the conduit 58 into the cavity 38.

In the recess 38, the heat transfer fluid is sprayed in the form of streams substantially perpendicular to the washer 78, and is then discharged through the conduit 59 before returning it to the source of the heat transfer fluid. The source of the heat transfer fluid typically comprises a pump suitable for setting the heat transfer fluid within the circuits from 56 to 59.

Given that the cold fluid enters through the joint 14, the temperature difference between the heat-exchange fluid present in the cavity 36 and the washer 78 is greater than the same difference between the fluid present in the cavity 48 and the washer of the switch 7. In fact, the heat-transfer fluid heats as it moves inside the cooling circuit. Consequently, the cooling capacity in the cavity 36 is high, and on the contrary, relatively weak in the cavity 38. It can also be considered that the cooling capacity in the recesses 48 and 50 is relatively average. It is to be understood that by fluidly connecting the cavity 36 to the recess 38 via the recesses 48 and 50, it becomes possible that the cooling of the switches 6 and 7 becomes even. Indeed,

[0054] Fig. 4 shows another embodiment of a cold plate 110 identical to the cold plate 4 with the exception that the plate 42 is replaced by the plate 112. The plate 112 is fixed within the cavity 36 in the same manner as described for the plate 42. In fact, the plate 112 differs from the plate 42 only in that the holes are made along the direction of spray that is not perpendicular to the front and back sides of the plate 112. More specifically, in the embodiment of Fig. 4, five holes 114 to 118 are shown. These holes 114 to 118 extend along the spray direction P. In this embodiment, the direction of spray P forms an angle γ with respect to the direction perpendicular to the front side 113. Here, the angle γ is equal to the angle β in such a way that the angle γ was between -30 and 0 °.

[0055] Fig. 5 shows another embodiment of a cold plate 120 identical to the cold plate 4 except that the plate 42 is replaced with a plate 132. The plate 132 differs from the plate 42 essentially in that it is not flat, but consists of three adjacent planes 134 to 136 connected by edges. [0056] The plane 134 is an inclined plane extending from the line 34 below the opening 70 until the middle position located halfway between the washer 78 and the bottom of the recess 36.

[0057] The plane 135 is a plane parallel to the washer 78.

[0058] Finally, the plane 136 is another inclined plane extending from a substantially central position to a contact line 96 below the opening 72.

[0059] Here, holes from 138 to 141 forming nozzles suitable for forming a flow of a heat transfer fluid perpendicular to the washer 78 only pass through the horizontal plane 135.

[0060] However, numerous other embodiments are possible. For example, the number of holes made in plates may vary. At least two holes must be present, and preferably the number of holes should be greater than twenty.

[0061] In one variant, there is only one recess under each cooled electronic power element. This embodiment is particularly indicated when the input and output connectors

The heat exchanger fluid can be found on the opposite edges of the plate 26. In contrast, in order to further improve the uniformity of the cooling of the various electronic power elements, more than two recesses under the same electronic power element can be made.

[0062] Typically, the heat transfer fluid is water. However, it can also be oil, a mixture of water and antifreeze, or any other heat transfer fluid.

[0063] In one variant, the opening 70 is formed at the bottom of the recess and not on the side wall. In this embodiment, the β and γ angles are between -30 and + 30 °.

[0064] The cross-section of the holes may be square or have any shape. In particular, the cross-section of each hole may be narrowing in the direction of the flow of the heat-transfer fluid. In this case, the sum of the smallest cross-sectional areas of the holes is equal to the lateral surface of the opening 70.

[0065] The transverse surface of the opening 70 or aperture 72 does not necessarily have to be equal to the sum of the transverse surfaces of the holes or nozzles. For example, the transverse surface of the opening 70 or aperture 72 is 20% to 200% of the sum of the transverse surface of the holes.

[0066] Several inlet and / or heat removal openings may be provided in the same cavity.

[0067] In the embodiments described here, the holes form the spray nozzles directly without having to add any material. In one embodiment, the hoses forming the nozzles were embedded in each of the holes made in the plates. The ends of each of these hoses may extend beyond the plate on both the front and back sides.