Electronic module including a modular heat dissipation device.

Abstract

The invention relates to an electronic device (1) comprising: An electronic module (2) comprising a first face (20) and a second face (21), the electronic module (2) comprising n openings (22) passing through the electronic module (2), n being a natural whole number greater than or equal to 2, the electronic module (2) comprising at least one connector (23) extending from the second face (21), A thermal conductive plate (4) for extracting heat from the electronic module (2) via the first face (20), A printed circuit (3) distant from the second face (21), connected to the at least one connector (23), m insert (5), m being a natural whole number greater than or equal to 2 and less than or equal to n, each insert (5) being arranged in an opening (22), each insert (5) being a thermal conductor,the inserts (5) mechanically connecting the electronic module (2) to the thermal conductive plate (4) and being configured so as to thermally connect the electronic module (2) to the printed circuit (3). Figure for the abstract: Fig. 1,

Description

Title of the invention: Electronic module comprising a modular heat dissipation device.

[0001] The invention relates to power electronics, in particular power electronics with heat sink.

[0002] Power electronics contains power components, in particular semiconductor elements but also so-called passive elements such as coils or diodes, which must be cooled during operation.

[0003] This task is generally performed by metal heat sinks, which are placed directly against the components to be cooled, so that good heat transfer is ensured. Such a power electronics assembly also generally comprises a printed circuit board also electrically connected to the power module. It is also envisaged to position the printed circuit board close to the power module and to connect the printed circuit board to the heat sink so as to also evacuate the heat from the power module to the heat sink via the printed circuit board.

[0004] However, today, with the increase in the power on board power equipment, printed circuits are not always able to meet the heat dissipation needs.

[0005] Therefore, it becomes necessary for each power module to associate a radiator with it to evacuate the excess heat present at the power module. This radiator is generally in direct contact with the heat sink which provides the thermal bridge function between the electronic component and the radiator which cools this electronic component.

[0006] However, adding a radiator to a power module has many disadvantages.

[0007] Indeed, positioning the radiator against the power module has the disadvantage of reducing the compactness of the power assembly and increasing the total mass of the assembly. However, for certain applications, such as in aeronautics or space, these dimensions represent a real challenge.

[0008] Furthermore, although the sizing is defined to compensate for all effective powers, high powers are in fact rarely reached and are most often of short duration. Exploiting the full power of the power module may also not be required in relation to the desired function. Therefore, oversizing the cooling device may prove ineffective compared to a relatively contained exploitation of the power module.

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[0013] The invention aims to overcome all or part of the problems cited above by proposing an electronic device comprising a power module whose cooling means is adapted to meet the functional need of the power module, i.e. to allow thermal efficiency if the power module generates a moderate amount of energy or increased cooling if the power module generates a greater amount of power. To this end, the invention relates to an electronic device comprising: - An electronic module comprising a first face and a second face opposite the first face, the electronic module comprising n openings passing through the electronic module so as to connect the first face to the second face, n being a natural whole number greater than or equal to 2, the electronic module comprising at least one connector extending from the second face, - A thermal conductive plate comprising a first surface and a second surface, the first surface being in contact with the first face of the electronic power module, the thermal conductive plate making it possible to extract heat from the electronic module via the first face, - A printed circuit arranged opposite the second face of the electronic module, the printed circuit being distant from the second face of the electronic module, the printed circuit being electrically connected to at least one connector, - m insert, m being a natural integer greater than or equal to 2 and less than or equal to n, each insert of the m inserts being arranged in an opening among the n openings, each insert of the m inserts being a thermal conductor, the m inserts mechanically connecting the electronic module to the thermal conductive plate, the m inserts being configured so as to thermally connect the electronic module to the printed circuit to cool the electronic module in a first low dissipation configuration. According to one aspect of the invention, the electronic device comprises a radiator, the radiator being connected to the second surface of the thermal conductive plate, the m inserts mechanically connecting the electronic module, the thermal conductive plate and the radiator, the m inserts being distant from the printed circuit, the radiator being configured to cool the electronic module in a second high dissipation configuration. According to one aspect of the invention, n is equal to m. According to one aspect of the invention, n is equal to 2, the first face and the second face of the electronic module comprising lateral edges, each opening among the n or- edges being positioned at an opposite side edge.

[0014] According to one aspect of the invention, n is equal to 2, the first face and the second face of the electronic module comprising corners, each opening among the n openings being positioned at an opposite corner.

[0015] According to one aspect of the invention, the at least one connector comprises a filed end mechanically connected to the printed circuit.

[0016] According to the aspect of the invention, the m inserts are made of a material whose thermal conduction is equal to a thermal conduction of the thermal conductive plate.

[0017] According to one aspect of the invention, the thermal conductive plate is made of a material among copper, brass or an alloy of nickel, iron and cobalt.

[0018] The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the attached drawing in which:

[0019] [Fig-1] [Fig.l] represents a schematic front view of the electronic device according to the invention in a low power configuration;

[0020] [Fig.2] [Fig.2] represents a schematic front view of the electronic device according to the invention in a high power configuration;

[0021] [Fig.3] [Fig.3] represents a schematic view of the power module of the electronic device according to the invention;

[0022] [Fig.4] [Fig.4] represents the thermal distribution of the electronic device according to the invention in low power configuration;

[0023] [Fig.5] [Fig.5] represents the thermal distribution of the electronic device according to the invention in high power configuration.

[0024] For the sake of clarity, the same elements will bear the same references in the different figures.

[0025] [Fig.l] thus represents a schematic front view of an electronic device 1 comprising an electronic power module 2. The power module 2 comprises in particular a first face 20 and a second face 21 opposite the first face 20 along a vertical axis V. The electronic power module 2 also comprises n openings 22 passing through the electronic power module 2 so as to connect the first face 20 to the second face 21. The number n is a natural whole number greater than or equal to 2. As represented in [Fig.l], the number of openings n is equal to two. In other words, at least two openings 22 pass through the power module 2 and connect the first face 20 and the second face 21. Nevertheless, it can be envisaged that the power module 2 comprises more than two openings 22. The electronic power module 2 also comprises at least one connection 23 which extends from the second face 21.

[0026] The electronic device 1 also comprises a printed circuit 3, also called PCB, arranged opposite the second face 21 of the electronic power module 2. The printed circuit 3 is distant from the second face 21 of the electronic power module 2. The printed circuit 3 is also electrically connected to the at least one connector 23 of the power module 2. In other words, the printed circuit 3 is not connected to the second face 21 and provides an electrical connection function with the power module 2 by means of the at least one connector 23. Thus, a space is identifiable between the second face 21 of the electronic power module 2 and the printed circuit 3.

[0027] The first face 20 thus represents an upper face of the power module 2 while the second face 21 represents the lower face of the power module 2. Therefore, the printed circuit 3 is positioned below the power module 2 relative to the vertical axis V.

[0028] The printed circuit 3 also comprises openings 32. The printed circuit 3 comprises n openings 32. Each opening 32 of the printed circuit faces an opening 22 of the power module 2.

[0029] The electronic device 1 comprises a thermal conductive plate 4 comprising a first surface 40 and a second surface 4L. The first surface 40 is in contact with the first face 20 of the electronic power module 2. The thermal conductive plate 4 extends over the first face 20 of the power module 2. The thermal conductive plate 4 thus makes it possible to extract heat from the electronic power module 2 via the first face 20. In other words, the heat generated by the electronic power module 2 is transmitted to the thermal conductive plate 4 by passing through the first face 20 and the first surface 40.According to a preferred variant, the thermal conductive plate 4 extends over the entire first face 20 of the electronic power module 2 so as to maximize the contact between the power module 2 and the thermal conductive plate 4 and therefore improve the heat exchange by conduction between the electronic power module 2 and the thermal conductive plate 4.

[0030] Thus, according to the vertical axis V, it is possible to observe a superposition of the printed circuit 3, the power module 2 and the thermal conductive plate 4.

[0031] The thermal conductive plate 4 is made of a material among copper, brass or an alloy of nickel, iron and cobalt or any other material having good thermal conduction.

[0032] The electronic device 1 also comprises m insert 5. The number m is a natural whole number greater than or equal to 2 and less than or equal to the number n. Each insert 5 of the m inserts is arranged in an opening 22 among the n openings 22. The m inserts 5 make it possible to mechanically connect the electronic power module 2 to the thermal conductive plate 4, so that the thermal conductive plate 4 is fixed against the power electronic module 2. Each insert 5 is thus in contact with the thermal conductive plate 4. Each insert 5 of the m inserts 5 is also a thermal conductor.

[0033] Each insert 5 of the m inserts 5 is also connected to the printed circuit 3 without requiring any fixing between the electronic power module 2 and the printed circuit 3. In other words, each insert 5 also passes through the printed circuit 3 via an opening 32.

[0034] The m inserts 5 are thus configured so as to thermally connect the power electronic module 2 to the printed circuit 3 to cool the power electronic module 2 in a first configuration with low energy dissipation as shown in [Fig.l]. The m inserts 5 are made of a material whose thermal conduction is equal to or greater than a thermal conduction of the thermal conductive plate 4 so as to promote the conduction of heat towards the inserts. As an indicative example, the thermal conduction of the thermal conductive plate 4 and the m inserts 5 is greater than 50 W / m*K.

[0035] Indeed, in a low energy dissipation configuration, that is to say when the power module 2 generates a moderate amount of heat, the printed circuit 3 is sufficient to evacuate the heat generated by the power module 2. Therefore, in the low energy dissipation configuration of [Fig.l], the heat generated by the electronic power module 2 is evacuated towards the thermal conductive plate 4 by passing through the first face 20 and the first surface 40. This heat is then transmitted to each insert 5 of the m inserts 5 which transmits it directly to the printed circuit 3 in order to be evacuated, as represented by the propagation direction 6.

[0036] Furthermore, the architecture of the printed circuit 3 may be defined so as to promote heat extraction. For this purpose, in the low heat dissipation configuration, the printed circuit may comprise more conductive thermal elements or the thickness of the printed circuit 3 may be increased so as to increase the number of conductive thermal elements. As an indicative example, it may be envisaged to add copper to the printed circuit 3.

[0037] The electronic device 1 allows, in the low heat dissipation configuration, to provide dissipation through the printed circuit 3. This is possible when the power dissipated by the power module 2 is less than 4 watts.

[0038] Furthermore, each insert 5 of the m inserts 5 comprises a head 51 and a tail 52. The head 51 of each insert 5 is thus placed pressing on the thermal conductive plate 4 so that the head exerts pressure on the thermal conductive plate 4 so as to hold the thermal conductive plate 4 against the module of power 2. And, the tail 52 of each insert 5 of the m inserts 5 is also in contact with the printed circuit 3 so as to allow the m inserts 5 to conduct the thermal energy to be dissipated towards the printed circuit 3.

[0039] In a low heat dissipation configuration, the electronic device 1 thus has the advantage of being compact while allowing adequate cooling of the cooling module 2.

[0040] [Fig. 2] represents a second operating configuration of the electronic device 1 which can be described as a high heat dissipation configuration compared to the configuration of [Fig. 1]. In this high heat dissipation configuration, i.e. when the power electronic module 2 provides a significant amount of energy and heat, cooling via the printed circuit is not sufficient to evacuate the heat generated by the power module 2.

[0041] Therefore, in the high energy dissipation configuration, the electronic device 1 also comprises a radiator 7. The radiator 7 is connected to the second surface 41 of the thermal conductive plate 4. It is thus possible to observe a superposition of the printed circuit 3, the power module 2, the thermal conductive plate 4 and the radiator 7 along the vertical axis V. It should be noted that only the power module 2, the thermal conductive plate 4 and the radiator 7 are in direct contact. The printed circuit 3 is itself distant from the power module 2.

[0042] The m inserts 5 then mechanically connect the electronic power module 2, the thermal conductive plate 4 and the radiator 7. Thus, the m inserts 5 ensure fixing of the electronic power module 2, the thermal conductive plate 4 and the radiator 7 between them. Each insert 5 of the m inserts 5 is distant from the printed circuit 3.

[0043] The radiator 7 is then configured to cool the electronic module 2 in the second high dissipation configuration.

[0044] Thus, the transfer of the heat generated by the electronic power module 2 is done in the direction of the radiator 7 and no longer in the direction of the printed circuit 3. In other words, the heat generated by the power module 2 is transmitted to the thermal conductive plate 4 by means of the first face 20 and the first surface 40. The thermal conductive plate 4 then transmits this energy in the form of heat to the radiator 7 by means of the second surface 4L. The radiator 7 then ensures the evacuation of this energy in the form of heat.

[0045] Thus, in the second energy dissipation configuration of [Fig.2], the energy in the form of heat is not transmitted to the printed circuit 3 and is not transmitted to the inserts 5.

[0046] Furthermore, in the second configuration of high energy dissipation, the direction of fixing of each insert 5 of the m inserts 5 is reversed. More precisely, the head 51 is in contact with the second face 21 of the electronic power module 2 and the tail 52 is in contact with the radiator 7. The inversion in the direction of fixing of the inserts 5 has the advantage of improving the compactness of the assembly even with the addition of the radiator 7. Indeed, the head 51 having a certain thickness, each head 51 would protrude relative to the radiator 7. Advantageously, the inversion of the direction of fixing of the inserts 5 allows the radiator 7 to be in direct contact with the thermal conductive plate 4 and to facilitate heat exchange.

[0047] As stated previously, in the second energy dissipation configuration of [Fig.2], there is no heat exchange between the power module 2 and the printed circuit 3 via the inserts 5. Thus, it may be envisaged to add a thermal insulator between the head 51 of each insert 5 and the printed circuit 3 so as to prevent any heat transfer in this direction.

[0048] According to a preferred configuration, the printed circuit 3 is cut out around the heads 51 of the inserts 5 so as to avoid any direct contact between the m inserts 5 and the printed circuit 3. In other words, there is a space 53 between each head 51 and the printed circuit 3 so as to ensure thermal insulation of the inserts 5. It is then simply a matter of increasing the section of the opening 32 along a plane perpendicular to the vertical axis V. This distance between the m inserts 5 and the printed circuit 3 also has the advantage of not over-stressing the mechanical connections between the printed circuit 3 and the power module 2, which are already connected by means of the at least one connector 23. Indeed, further constraining the fixing of the printed circuit 3 can lead to deformation of the printed circuit 3 or even to deterioration of this component.

[0049] Thus, the at least one connector 23 comprises a filed end 230 or a “rat tail” mechanically connected to the printed circuit 3 so as not to mechanically overstress the electronic device 1. This filed end 230 can thus be wound in a spiral around a pin or a complementary connector in the printed circuit 3 so that the printed circuit 3 is held malleably against the electronic power module 2 along the vertical axis V. In other words, the printed circuit 3 is connected against the power module 2 by means of this malleable connection which nevertheless allows relative freedom of movement still along the vertical axis V.

[0050] Therefore, the inserts 5 provide, in the second configuration of high energy dissipation, only a mechanical fixing function of the power module 2, the thermal conductive plate 4 and the radiator 7. The printed circuit 7 only provides an electrical interconnection function. The thermal path is then modified so that the direction of propagation 6 of the heat is now directed towards radiator 7.

[0051] The second energy dissipation configuration reflects operation of the module at higher power and energy dissipation greater than 30% of the power of the power module.

[0052] The electronic device 1 thus has the advantage of being able to adapt to different operating configurations, either a low-power configuration reflecting low energy dissipation, in which the printed circuit 3 is sufficient to dissipate the heat, or a high-power configuration reflecting high energy dissipation, in which the radiator 7 takes over from the printed circuit 3 to ensure the dissipation of energy in the form of heat from the electronic module 2. The transition from one configuration to the other, that is to say from the configuration of [Fig. 1] to the configuration of [Fig. 2], only requires a change in the direction of fixing of the m inserts 5 relative to the vertical axis V. The electronic device 1 thus meets a large number of energy constraints by allowing a greater operating and heat dissipation range while being advantageously compact.From then on, the heat dissipation function switches from the printed circuit 3 to a radiator 7 depending on the power developed by the electronic power module 2.

[0053] [Fig. 3] represents a view perpendicular to the vertical axis V of the electronic device 1 and more precisely of the thermal conductive plate 4 positioned above the power module 2.

[0054] As indicated previously, the thermal conductive plate 4 extends over the first face of the power module 2. The first surface 40 of the thermal conductive plate 4 is directly in contact with the first face 20 of the power module 2. And as observed in [Fig.3], the thermal conductive plate 4 extends over the entire first face 20 of the power module 2.

[0055] Similar to the power module 2 and the printed circuit 3, the thermal conductive plate 4 comprises n openings 42, as shown in [Fig. 3], allowing each insert 5 to pass through the thermal conductive plate 4, of the power module 2 and of the printed circuit 3. In the configuration of [Fig. 3], the thermal conductive plate 4 comprises two openings 42, just as the electronic power module 2 comprises two openings 22. The printed circuit 3, although not shown in [Fig. 3], also comprises two openings 32.

[0056] Preferably, the electronic device 1 comprises the same number of openings as inserts 5. In other words, the number n of openings 22 is equal to the number m of inserts 5. Thus, an opening 22 of the power module 2, and therefore an opening 42 of the thermal conductive plate 4 (and an opening 32 of the printed circuit) is occupied by an insert 5.

[0057] In an ideal architecture, the number n of openings 22 and the number m of inserts 5 is equal to two, as shown in [Fig.3]. The first face 20 of the electronic module 2 comprises corners 200, 201, 202 and 203. In an identical manner, the second face 21 also comprises corners. And, each opening 22 among the two openings 22 is arranged so as to be at a distance from the other opening 22 among the two openings 22. The greater the distance between the two openings 22, the better the distribution of the heat in the thermal conductive plate 4. Indeed, the two openings 22 making it possible to ensure the thermal link between the thermal conductive plate 4 and the two inserts 5, in the low energy dissipation configuration, the fact of moving the two openings 22 away from each other makes it possible to distribute over the entire first face 20 the transmission of the energy in the form of heat to the two inserts 5.

[0058] Preferably, the two openings 22 are positioned on opposite lateral edges. In other words, a first opening 22' can be arranged at a first corner 200 and a second opening 22" can be arranged at a third corner 202. This architecture makes it possible to have symmetry in the distribution of the heat transfer towards the inserts 5.

[0059] Alternatively, the second opening 22” may be arranged at the second corner 201 or the fourth corner 203.

[0060] Similarly, it may also be envisaged to distribute the two openings 22 along two lateral edges 205, 206, 207, 208. Preferably, the two lateral edges are opposite so as to promote good thermal distribution on the thermal conductive plate 4 between the two inserts 5.

[0061] Furthermore, if the number of openings 22 and inserts 5 is equal to 3, then it may be envisaged to position a first opening at the first corner 200, a second opening at the second corner 201 and a third opening at the third corner 202 or at the fourth corner 203 or even to position the first opening at the first lateral edge 205, the second opening at the second lateral edge 206 and the third opening at the third lateral edge 207 or at the fourth lateral edge 208.

[0062] It may also be envisaged to position a first opening at a corner of the first face 20 and a second opening at a lateral edge of the first face 20.

[0063] The positioning of the thermal conductive plate 4 above the power module 2 along the vertical axis V thus has the advantage of allowing good transfer of energy in the form of heat to the direction of the inserts 5 during the low energy dissipation configuration and also allowing good transfer of energy in the form of heat to the direction of the radiator 7 during the high energy dissipation configuration. In addition, this position of the thermal conductive plate 4 also has the advantage of allowing easy interfacing with the radiator 7 which can be added without too much effort in the case of a significant dissipation requirement. The thermal conductive plate 4 can be machined so as to have a second surface 41 as smooth as possible to promote heat transfer towards the radiator 7 and a first surface 40 adapting to the height of the components of the power module 2 to minimize the thermal resistance between the power module 2 and the thermal conductive plate 4.

[0064] [Fig. 4] represents a schematic view of the thermal distribution in the electronic device 1 when the electronic device 1 is in the low energy dissipation configuration. This view clearly represents a heat distribution centered mainly at the thermal conductive plate 4, at the inserts 5 and at the printed circuit 3 which is then dissipated.

[0065] Conversely, [Fig. 5] represents a schematic view of the thermal distribution in the electronic device 1 when the electronic device is in the heat dissipation configuration. Thus, [Fig. 5] presents a heat distribution more centered around the thermal conductive plate 4 and the radiator 7 in order to dissipate it.

[0066] The temperature increase is of the order of a degree and allows a strong increase in the thermal performance of the power module 2 and much more efficient cooling.

Claims

Claims

1. Electronic device (1) comprising: - An electronic module (2) comprising a first face (20) and a second face (21) opposite the first face (20), the electronic module (2) comprising n openings (22) passing through the electronic module (2) so as to connect the first face (20) to the second face (21), n being a natural whole number greater than or equal to 2, the electronic module (2) comprising at least one connector (23) extending from the second face (21), - A thermal conductive plate (4) comprising a first surface (40) and a second surface (41), the first surface (40) being in contact with the first face (20) of the electronic power module (2), the thermal conductive plate (4) making it possible to extract heat from the electronic module (2) via the first face (20), - A printed circuit (3) arranged opposite the second face (21) of the electronic module (2), the printed circuit (3) being distant from the second face (21) of the electronic module (2), the printed circuit (3) being electrically connected to the at least one connector (23), - m inserts (5), m being a natural integer greater than or equal to 2 and less than or equal to n, each insert (5) of the m inserts (5) being arranged in an opening (22) among the n openings (22), each insert (5) of the m inserts (5) being a thermal conductor, the m inserts (5) mechanically connecting the electronic module (2) to the thermal conductive plate (4), the m inserts (5) being configured so as to thermally connect the electronic module (2) to the printed circuit (3) to cool the electronic module (2) in a first low dissipation configuration.

2. Electronic device (1) according to claim 1, comprising a radiator (7), the radiator (7) being connected to the second surface (21) of the thermal conductive plate (4), the m inserts (5) mechanically connecting the electronic module (2), the thermal conductive plate

3.

4.

5.

6.

7.

8. (4) and the radiator (7), the inserts (5) being distant from the printed circuit (3), the radiator (7) being configured to cool the electronic module (2) in a second high dissipation configuration. Electronic device (1) according to any one of claims 1 or 2, wherein n is equal to m. Electronic device (1) according to claim 3, wherein n is equal to 2, the first face (20) and the second face (21) of the electronic module (2) comprising lateral edges (205, 206, 207, 208), each opening (22) among the n openings (22) being positioned at an opposite lateral edge (205, 206, 207, 208). Electronic device (1) according to claim 3, wherein n is equal to 2, the first face (20) and the second face (21) of the electronic module (2) comprising corners (200, 201, 202, 203), each opening (22) among the n openings (22) being positioned at an opposite corner (200, 201, 202, 203). Electronic device (1) according to any one of the preceding claims, wherein the at least one connector (23) comprises a filed end (230) mechanically connected to the printed circuit (3). Electronic device (1) according to any one of the preceding claims, in which the m inserts (5) are made of a material whose thermal conduction is equal to a thermal conduction of the thermal conductive plate (4). Electronic device (1) according to any one of the preceding claims, wherein the thermal conductive plate (4) is made of a material among copper, brass or an alloy of nickel, iron and cobalt.

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