Electrical device and device for retaining a cooling plate of the electrical device

Abstract

Title: Electrical device and cooling plate retaining device for the electrical device. An electrical device comprising a cooling plate, electronic components arranged on said cooling plate, the cooling plate having an upper face facing the power module and an opposite lower face, a thermal attachment means being disposed between at least one power module and the upper face of the cooling plate, a retaining device being made integral with the lower face of the cooling plate, characterized in that the retaining device is formed of a sheet metal comprising local deformation zones suitable for structurally reinforcing the retaining device. (Figure 1)

Description

Title of the invention: Electrical device and device for retaining a cooling plate of the electrical device

[0001] The present invention relates to the field of electronic devices such as electrical devices for electric or hybrid cars.

[0002] Electronic devices include various electronic components such as power modules, coils, or capacitors, without this list being exhaustive. These electronic components produce heat when the electrical device is in use.

[0003] Electronic devices are used in systems that require ever-increasing power levels. This increase in power is accompanied by a growing production of heat during the operation of the electronic devices, necessitating the finding of solutions to reduce these thermal constraints, which can lead to malfunctions in the components of the electrical device.

[0004] More specifically, it is known to equip electrical devices with a cooling plate through which a heat transfer fluid can circulate and which includes a wall against which the electronic components to be cooled are placed, particularly the power modules, which are the components that generate the most heat. The electronic components are joined to the cooling plate by a brazing operation during which the components and the plate are placed in a furnace so as to polymerize material between the electronic components and the cooling plate. In other words, the electronic components, and in particular the power modules, are fixed by means of a thermal bonding method configured to liquefy when it reaches a certain temperature and then geometrically solidify the interface at high temperature.

[0005] The power module is an increasingly used component in electronic systems because it allows a plurality of electronic chips to be assembled in a small space. More specifically, the power module comprises a housing in which electronic chips are arranged side by side. The housing includes a base for supporting the electronic chips and a cover plate that encloses the chips and, in combination with the base, forms an internal volume in which the chips extend. The chips are connected to electrical connection pins that extend outside the power module, notably to allow the electrical connection of the chips. electronic components, housed inside the casing, are connected to an electrical network via a printed circuit board.

[0006] The power module has a rectangular shape, defined by the rectangular shape of the housing. Several power modules are arranged on the cooling plate. The cooling plate has a larger dimension than the corresponding dimension formed by the juxtaposition of the electronic components arranged on the cooling plate. The housing of the power modules is made of an insulating material having thermal characteristics different from those of the cooling plate.

[0007] It is known that cooling plates and / or electronic component housings expand and flex when placed in an oven and then cooled. It follows from the above that when the assembly is placed in the oven and heated, the cooling plate expands differently from the electronic component housings, both due to the difference in material and the difference in dimensions. The rigid assembly of these components creates a deflection resulting from the different types of expansion behavior.

[0008] Such a difference in deformation when the modules are fixed on the cooling plate can then damage the power modules to the point of detaching the electronic components from the cooling plate or create an excessive geometric deformation rendering the device non-compliant.

[0009] The present invention falls within this context and aims to provide an electrical device in which the cooling plate is stiffened in a light and inexpensive manner.

[0010] The present invention proposes an electrical device comprising a cooling plate, electronic components arranged on said cooling plate, the cooling plate having an upper face facing at least one electronic component and an opposite lower face, a thermal attachment means being disposed between the at least one electronic component and the upper face of the cooling plate, a retaining device being made integral with the lower face of the cooling plate, characterized in that the retaining device is formed of a sheet comprising local deformation zones suitable for structurally reinforcing the retaining device.

[0011] The electrical device according to the invention may, for example, be an electrical converter, in particular an inverter or a DC-DC converter, suitable for equipping an electric or hybrid motor vehicle, whose function is, in particular, to enable the transformation of an alternating current supplied by a home charging station into a direct current usable by the electrical components of the electric vehicle, and in particular the components of a drive system of the electric vehicle or the transformation of a direct current supplied by a battery into alternating current to drive an electric machine.

[0012] According to one characteristic, the electronic components may consist of a power module.

[0013] This electrical device is here characterized by the presence of the retaining device associated with the cooling plate of the electrical device, the retaining device having the function of reducing the deformation of the cooling plate when passing through assembly equipment, for example an oven and / or an assembly press.

[0014] The retaining device deforms less than the cooling plate under the effect of heat. This retaining device, located under the cooling plate and away from the electronic components, limits the deflection of the cooling plate and prevents damage to the power modules during cooling.

[0015] According to one characteristic,

[0016] The retaining device is particularly advantageous here, and notably simple to manufacture and inexpensive, in that it is formed from a sheet metal plate incorporating local deformation zones. The sheet metal of the retaining device is between 0.5 mm and 4 mm thick, preferably between 2.5 mm and 3.5 mm, for example 3 mm. Such a thickness limits the amount of raw material required to manufacture the retaining device and therefore reduces the weight of the electrical device. The rigidity of the retaining device required to provide adequate support for the cooling plate is then increased by creating local deformation zones in the sheet metal plate.

[0017] The local deformation zones allow for the structural reinforcement of the retaining device, thereby limiting its deformation during oven heating and the associated temperature increase. Thus, when the electrical device is placed in an oven to secure the electronic components to the cooling plate via the interposed thermal attachment, the retaining device stiffens the cooling plate and reduces the deformation it undergoes during the temperature decrease. In this way, high stresses are avoided on the electronic component, which retains a substantially constant shape. The retaining device thus ensures the proper functioning of the electrical device by acting as a means of preventing the cooling plate from bending.

[0018] According to an optional feature of the invention, the sheet metal of the retaining device comprises a plurality of folds giving the retaining device the shape of a hollow body.

[0019] The folds represent local deformation zones that structurally reinforce the retaining device. The sheet metal of the retaining device comprises a plurality of folds forming the retaining device, which stiffens the retaining device by multiplying the local deformation zones. These folds are arranged such that the retaining device presents a hollow cross-section in a cutting plane perpendicular to a principal elongation direction along which the folds are formed, i.e., a substantially closed cross-section to further improve the rigidity of the part. The folds increase the second moment of area of ​​the retaining device in the two principal bending axes of the cooling plate.

[0020] According to an optional feature of the invention, the sheet metal of the retaining device is folded so that the retaining device has two main walls substantially parallel to the underside of the cooling plate and spaced apart from each other to define an internal volume.

[0021] The sheet metal is bent so that two walls of the retaining device are parallel to each other and parallel to the underside of the cooling plate. One wall faces the cooling plate. This first wall includes a surface suitable for receiving the cooling plate, optionally with an interposed thermal attachment. The distance between the two walls defines an internal volume. In this way, the retaining device consists of a hollow body that reinforces its structure, and the retaining device therefore has technical characteristics similar to those of a thick wall without the weight and material cost constraints.

[0022] According to an optional feature of the invention, the sheet metal of the retaining device is folded so that one free end edge of the retaining device is in the vicinity of another free end edge to close the internal volume.

[0023] In other words, the various folds made on the sheet metal are made so that free end edges, which are opposite when the sheet metal is originally flat, come together in such a way as to close the section retaining device.

[0024] According to an optional feature of the invention, a free end edge includes a fold forming a notch dimensioned to receive the other free end edge.

[0025] The offset formed by folding a first free end edge is such that the second free end edge of the sheet metal can rest against the first free end edge and still form a flat surface opposite the cooling plate. This ensures correct positioning of the retaining device against the cooling plate and optimal rigidity of the retaining device. since the two free end edges rest against each other instead of just facing each other.

[0026] According to an optional feature of the invention, at least one local deformation zone is formed by a boss resulting from a stamping operation.

[0027] The boss is created by the corresponding shape of a stamping die. The same die can create multiple bosses on the same sheet, and where applicable, on a succession of sheets cut sequentially for large-scale production. The boss can be created on one of the main walls, in particular on the first wall.

[0028] According to an optional feature of the invention, the retaining device has a support wall substantially parallel to the underside of the cooling plate and intended to allow the retaining device to be fixed to the cooling plate, the retaining device further having at least one side wall extending substantially perpendicularly from the support wall and coming into contact with at least one edge of the cooling plate.

[0029] The edge of the cooling plate is a face perpendicular to the lower and upper faces of the cooling plate and the side wall is parallel to the edge of the cooling plate.

[0030] According to an optional feature of the invention, the retaining device comprises two side walls facing two opposite edges of the cooling plate.

[0031] The folds in the sheet metal of the retaining device are made in such a way that the side walls are arranged at a distance from each other which is substantially greater than the corresponding dimension between two opposite edges of the cooling plate.

[0032] The side walls allow the cooling plate to be centered and locked onto the retaining device.

[0033] According to an optional feature of the invention, the side wall is formed by folds in the sheet metal of the retaining device. The side wall is formed by a plurality of folds creating an additional hollow body extending perpendicularly from the main hollow body of the retaining device. The side wall is formed by a first fold at one end of the first wall of the retaining device, by a second fold folding the side wall back on itself, and by a third fold forming the wall parallel to the first wall.

[0034] According to this feature, the side wall has a length, along a longitudinal direction parallel to the plane of the lower face of the cooling plate, which is equal to the length in this same direction of the first wall of the retaining device.

[0035] According to an optional feature of the invention, the side wall is formed by local extensions resulting respectively from a cutout in the first wall and a folding of said cutout to give this cutout a position substantially perpendicular to the first wall. The extension is then a portion of the first wall folded so that it protrudes from the first wall, and it is understood that the side wall is formed of portions shorter than the length of the first wall.

[0036] According to an optional feature of the invention, the retaining device includes a reinforcement extending across the internal volume from a first main wall participating in defining the internal volume to a second main wall participating in defining the internal volume of the retaining device.

[0037] The extent of the reinforcement through the internal volume serves both to stiffen the hollow body, since the reinforcement extending from the first wall bears against the opposite second wall, and to define the height of the retaining device, that is, the vertical dimension between the first and second walls. The extent of the reinforcement therefore affects the vertical positioning of the electronic component attached to the cooling plate, depending on the direction in which this reinforcement is measured from one wall to the other of the retaining device.

[0038] This dimension of the reinforcement can be adjusted so as to position the electronic component vertically in accordance with a desired theoretical position so that it can be connected to a printed circuit board to which the electrical device as a whole is to be connected via the connection pins of the electronic component.

[0039] According to an optional feature of the invention, the reinforcement is a free end edge of the sheet metal of the retaining device.

[0040] The reinforcement is a free end edge participating in defining the first wall of the retaining device and bent to cross the hollow body and come into contact with the second wall so that this reinforcement defines a height of the hollow body between the first wall and the second wall of the retaining device.

[0041] According to an optional feature of the invention, the retaining device is made integral with the cooling plate by means of a thermal attachment.

[0042] According to an optional feature of the invention, the thermal attachment means are solder pastes that secure the electronic component to the cooling plate or the holding device against the cooling plate after it has passed through the assembly means. The thermal attachment means may be solder joints, sintered joints, or joints made of a thermosetting resin (epoxy).

[0043] The use of a similar thermal attachment method to secure the power module to the cooling plate and the cooling plate to the holding device allows for only one pass through a furnace. This reduces manufacturing time while ensuring that the cooling plate remains securely in place during the cooling process.

[0044] According to an optional feature of the invention, the material used for the retaining device has a lower coefficient of thermal expansion than the coefficient of thermal expansion of the cooling plate.

[0045] By exhibiting a lower coefficient of expansion, the retaining device undergoes less deflection when passing through a furnace and thus acts as an anti-deflection system for the cooling plate. The retaining device may include nickel. The retaining device may be made of copper. The retaining device may be made of steel, in particular with a galvanic coating such as nickel, or of stainless steel. The coefficient of thermal expansion (CTE) of the retaining device may be less than 15 ppm / K, in particular 12 ppm / K.

[0046] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given by reference to the accompanying schematic drawings on the other hand, in which:

[0047] [Fig.1] is a schematic representation of an electrical device according to the invention, comprising a first embodiment of a holding device;

[0048] [Fig.2] is a schematic representation of a second embodiment of the support device including bosses;

[0049] [Fig.3] is a schematic representation of a third embodiment of the support device including folds;

[0050] [Fig.4] is a schematic representation of a fourth embodiment of the support device including folds and reinforcements;

[0051] [Fig.5] is a schematic representation of a fifth embodiment of the support device including folds, reinforcements and side walls;

[0052] [Fig.6] is a schematic representation of a sixth embodiment of the support device including folds and reinforcement;

[0053] [Fig.7] is a schematic representation of a seventh embodiment of the support device comprising bosses and side walls;

[0054] [Fig.8] is a schematic representation of an eighth embodiment of the support device including folds.

[0055] Figure 1 is a schematic representation of the electrical device 2. The electrical device 2 comprises a cooling plate 4 suitable for receiving electronic components 8 on an upper surface 6. The electronic components can by An example might consist of a power module, formed of a housing 10 containing electronic chips intended to be connected to an electronic circuit associated with the electrical device. In the following description, a power module 8 will be referred to, but it should be noted that any other type of electronic component could be used without departing from the scope of the invention.

[0056] The power module 8 has a flat shape on the lower portion of its housing 10, the flat shape being configured to overlap a part of the upper face 6 of the cooling plate 4.

[0057] A thermal bonding means 12, such as solder paste, is disposed between the cooling plate 4 and the power module 8. The thermal bonding means 12 is configured to bond to the cooling plate 4 and the power module 8 so that they are joined together. The bonding means may alternatively be a brazed joint, a sintered joint, or a thermosetting resin. The thermal bonding means 12 is specifically designed to expand and then solidify when subjected to high temperatures and then cooled, thereby enabling the power module 8 to be attached to the cooling plate 4. The attachment may be achieved by brazing, sintering, or bonding.For this purpose, the cooling plate 4 and the electronic components intended to rest against this plate are brought into assembly means, for example an oven, for example a furnace, for example a press, to melt the thermal bonding means 12, and then left to rest to cool.

[0058] During these stages, the cooling plate 4 and the power module 8 are subject to deformation, particularly during the temperature increase within the furnace. The coefficients of thermal expansion and the dimensions of the parts are different for the cooling plate 4 and the power module 8, which can lead to significant stresses on the housing 10 of the power module 8, given that the cooling plate 4, to which it is attached, deforms more than the housing 10 of the power module 8. Furthermore, the power module 8 cools down more rapidly than the cooling plate 4, which means that the cooling plate 4 continues to flex while the power module 8 is at ambient temperature. This can deform the power module 8 as the cooling plate 4 continues to cool down.

[0059] According to the invention, a retaining device 14 is associated with the cooling plate 4 to reduce the deflection of said cooling plate 4, and this retaining device 14 takes the form of a sheet metal which is given a configuration enabling it to provide rigidity at a lower cost. The device support 14 is integral with the cooling plate 4, being positioned opposite an underside 16 of this cooling plate 4.

[0060] As will be described with reference to several illustrated embodiments, the retaining device 14 is formed of a sheet 18 comprising local deformation zones 20. The local deformation zones 20 are, for example, folds or bosses made in the sheet 18. Such local deformation zones 20 are made so as to structurally reinforce the retaining device 14, for example by forming a hollow body as resistant to bending as a part made in one piece, it being understood that the realization via a sheet makes it possible to limit the cost and weight of the electrical device 2 thus obtained.

[0061] The cooling plate 4 and the retaining device extend mainly along a longitudinal elongation axis 38, visible in [Fig.8], Figures 1 to 7 illustrating a section plane perpendicular to this elongation axis 38.

[0062] The retaining device 14 has a lower coefficient of thermal expansion than that of the cooling plate 4. The retaining device 14 is intended to deform less than the cooling plate 4 when the electrical device 2 passes through the oven and therefore to reduce the bending of the cooling plate 4 and to limit the stresses on each power module 8 made integral with the cooling plate 4.

[0063] The retaining device 14 is secured to the cooling plate 4, here via a thermal attachment means 13 similar to the thermal attachment means 12 interposed between the power module 8 and the cooling plate 4. The thermal attachment means 13 can therefore be solder paste such as that described for securing the power module 8 to the cooling plate 4. Of course, it could be envisaged, without departing from the scope of the invention, that the material used to make the thermal attachment means 13 associated with the retaining device 14 is different from that used to make the thermal attachment means 12 associated with the power module 8.Using similar thermal fastening means 12 for fixing the power module 8 and the retaining device 14 to the cooling plate 4 allows only one pass through the oven to secure the entire electrical device 2.

[0064] It should be noted that, alternatively, the retaining device can be made integral with the cooling plate by other means, and for example by welding, bonding, sintering and temperature pressing if the materials of the retaining device and the cooling plate are compatible.

[0065] Figure 1 represents a first embodiment of the retaining device 14, in which the local deformation zones 20 are formed by folds. It should be noted that Figure 1 is a cross-sectional view of the electronic system and in particular of the support device. According to the first embodiment, the local deformation zones 20 are parallel and continuous along the elongation axis 38 of the cooling plate 4.

[0066] The sheet metal 18 is folded to form an internal volume 22 delimited in particular by two portions of the sheet metal 18 which form two main walls 24, 26 of said sheet metal 18, spaced apart and parallel to each other. Thus, when the retaining device 14 is associated with the cooling plate, the two main walls 24, 26 of the sheet metal are parallel to the lower face 16 of the cooling plate 4.

[0067] The sheet metal 18 comprises two free end edges 28, 29 which meet to close the internal volume 22 of the retaining device 14. It is understood that when the sheet metal 18 is flat, before being folded to form the retaining device shown here, the two free end edges are opposite edges. A first free end edge 28 is folded to form a notch 30, allowing the second free end edge 29 to be positioned in the notch 30.

[0068] The notch 30 is a local deformation zone 20 corresponding to a fold in the sheet metal 18, allowing modification of the position of the first free end edge 28 of the sheet metal 18, and in particular allowing local modification of the height of the hollow body in a direction perpendicular to the plane of one of the main walls. The notch 30 extends into the internal volume 22 of the retaining device 14. The notch 30 creates a clearance with a height substantially equal to the thickness of the sheet metal. In this way, the lower face 16 of the cooling plate 4, via the thermal attachment means 12, can be positioned on a flat portion of the retaining device 14 formed by one of the two main walls 24.

[0069] According to a variant not shown in the figures of the first embodiment, the retaining device 14 does not include a detachment 30, so that the free end edges 28, 29 of the sheet 18 are opposite each other.

[0070] In the first embodiment presented [Fig.1], the retaining device 14 further includes a reinforcement 32 formed by the first free end edge 28 of the sheet 18. This first free end edge 28 is folded to form the reinforcement 32 in the extension of the notch 30, it being understood that such a reinforcement 32 could be implemented for the advantages which will be detailed below without a prior notch being made.

[0071] The first free end edge 28 is folded to form the reinforcement 32 in the form of a wall extending perpendicularly to the two main walls 24, 26, from the first main wall 24, which includes the second free end edge 29, towards the opposite second main wall 26. The reinforcement 32 corresponds to an area of Local deformation 20 includes a 90° bend in the sheet metal 18. This bend is in contact with the second main wall 26, which forms a load-bearing wall. The reinforcement 32 thus supports the wall on which the cooling plate 4 is placed, and this structurally reinforces the retaining device 14 to limit its deflection.

[0072] As previously stated, the reinforcement 32 extends between two main walls 24, 26 delimiting the internal volume 22 of the retaining device 14. The reinforcement 32 extends from a first main wall 24 opposite the lower face 16 of the cooling plate 4 and continues until it contacts a second main wall 26 parallel to the first main wall 24, thus forming a bottom wall of the retaining device 14. The arrangement of the reinforcement 32 between the first main wall 24 and the second main wall 26 naturally stiffens the assembly by transferring the load from the first main wall 24 to the opposite second main wall 26. This also allows the height of the internal volume to be defined according to the length of the reinforcement.

[0073] Thus, varying the length of the reinforcement 32 allows the vertical positioning to be modified, according to the direction perpendicular to the planes of the main walls 24, 26 of the retaining device 14, the cooling plate 4 and the electronic component 8, and this makes it possible to ensure that the electronic component 8 is in the correct position to be able to be connected to the rest of an electronic circuit, for example to a printed circuit board not shown in the figures.

[0074] The retaining device 14 according to an unrepresented variant of the first embodiment may not include reinforcement 32. In this variant the two free end edges 28 are superimposed at the level of the detachment 30 or the two free end edges 28 are opposite each other.

[0075] The retaining device 14 according to the first embodiment comprises two side walls 34 which project respectively from the first main wall 24 by means of a series of folds enabling the formation of an additional hollow body which extends along the side of the cooling plate, in line with the main hollow body which is located under the cooling plate 4. In the illustrated example, the flat portion of the retaining device 14 on which the cooling plate 4 is placed comprises on its edges a plurality of folds forming the side walls 34. As previously mentioned, the folds enabling the formation of the flat walls 34 are formed along a direction perpendicular to the cutting plane of [Fig. 1], parallel to the other folds of the retaining device 14.The side walls 34 are arranged, in a transverse direction, at a distance from each other which is substantially greater than the corresponding dimension of the lower face 16 of the cooling plate 4. The positioning of the plate of . cooling 4 is thus centered by the side walls 34 blocking the translation along this transverse direction of the cooling plate 4.

[0076] Each side wall 34 is substantially parallel to an edge of the cooling plate 4. The edges of the cooling plate 4 may include a shoulder, not shown in [Fig. 1], resting on an upper portion of a side wall 34. Thus, the side walls 34 have a height suitable for blocking the cooling plate 4. The height of the side walls 34 is measured in a direction perpendicular to the first main wall 24 of the retaining device 14 and is defined between the first main wall 24 and the upper portion of the side wall 34.

[0077] Figure 2 is a schematic representation of a second embodiment of the retaining device 14 in which the local deformation zones 20 are formed by a plurality of bosses produced by stamping the sheet metal 18. Stamping locally reinforces the sheet metal 18 of the retaining device 14, thereby reducing its bending capacity during passage through a furnace. Stamping involves deforming the sheet metal 18 using a die with the shape of the bosses. The stamping embodiment according to Figure 2 is less expensive to produce because it does not require means for bending the sheet metal. The various bosses can be produced in a single stamping operation. This embodiment reduces the bending of the cooling plate 4 at a lower cost.

[0078] The retaining device 14 may also include a support wall 15 shown in dashed lines in [Fig.2] crimped against the sheet 18 of the retaining device 14. The support wall 15 is crimped against the bosses of the sheet 18. The support wall 15 makes the retaining device 14 more rigid and provides a flat surface allowing for simpler positioning of the thermal attachment means 12.

[0079] Fig. 3 is a schematic representation of a third embodiment of the retaining device 14 in which the sheet metal 18 comprises a plurality of local deformation zones 20 such as folds forming a retaining device 14 simpler than the first embodiment of the retaining device 14. The folds of the local deformation zones 20 are parallel and continuous along the elongation axis 38 of the cooling plate 4.

[0080] According to the third embodiment, the local deformation zones 20 of the sheet metal comprise two folds forming an angle of 180° to fold the sheet metal 18 back on itself, the two folds being formed at each end in the transverse direction so as to form two main walls 24, 26 parallel to each other. The first main wall 24 is the upper wall intended to be opposite the cooling plate 4. The first main wall 24 is flat and continuous with in order to receive the thermal attachment means 14, and it corresponds for this purpose to a central portion of the sheet metal in the transverse direction.

[0081] The second main wall 26 is formed by the two portions of the sheet metal 18 folded under the first main wall 24 and comprising respectively one of the two free end edges 28, 29 along the aforementioned transverse direction. These two free end edges 28, 29 are arranged opposite each other to form the second main wall 26, which is substantially flat and perforated in its center.

[0082] Fig. 4 is a schematic representation of a fourth embodiment of the retaining device 14, inspired by the third embodiment, but differing from it in that the retaining device incorporates reinforcements 32.

[0083] More particularly, according to the fourth embodiment, the free end edges 28 of the retaining device 14 include a local deformation zone 20 consisting of a fold towards the inside of the retaining device, this fold forming a reinforcement 32 suitable for contacting the first main wall 24 of the retaining device 14. The reinforcements 32 make it possible to structurally strengthen the retaining device 14 and to prevent even more effectively bending of the cooling plate 4 by stiffening the retaining device 14 at a lower cost.

[0084] Fig. 5 is a schematic representation of a fifth embodiment of the retaining device 14 which differs from the fourth embodiment in that this time it is the second main wall 26 which is the portion of the retaining device 14 opposite the cooling plate 4 and the thermal attachment means 12 interposed between the cooling plate 4 and the retaining device 14 and in that of the presence of side walls 34.

[0085] The opening present in the center of the second main wall is not penalizing insofar as the folded portions participating in forming this second main wall 26 of the retaining device 14 extend substantially in the same plane and cannot collapse due to the presence of the reinforcements 32 formed by folding as previously mentioned.

[0086] The side walls 34 extend, as in the first embodiment, to the transverse ends of the retaining device 14 and also allow the cooling plate 4 to be centered and held transversely before the electrical device 2 is passed through an oven. The side walls 34 ensure the correct relative positioning of the cooling plate 4 and the retaining device 14.

[0087] In this fifth embodiment, the side walls 34 are also formed by a local deformation 20. However, they are obtained by a prior local cutting operation 36 in the holding device 14, the side walls 34 resulting from a local deformation 20, and in particular a folding, of the cut area. It follows from this process that the side walls 34 do not extend over the entire dimension of the retaining device 14, unlike other embodiments of the side walls 34. In other words, the side walls 34 are again projecting from the first main wall 24 of the retaining device 14, and the local deformation zones 20 forming these side walls 34 are parallel to the elongation axis 38, but here they are not continuous along the elongation axis 38 of the cooling plate 4, since they do not extend over the entire dimension of the retaining device 14.

[0088] Figure 6 is a schematic representation of a sixth embodiment of the retaining device 14, which differs from the preceding one in that the sheet metal 18 forming the retaining device 14 comprises a single local deformation zone 20, which can be considered a fold, to form the two main walls 24, 26 parallel to each other. The local deformation zones 20 are parallel and continuous along the elongation axis 38 of the cooling plate 4.

[0089] The free end edge 28 of the second wall 26 includes, as before, a reinforcement 32 extending from the second wall 26 to the first main wall 24. In this sixth embodiment, the reinforcement 32 allows the first main wall 24 to be kept parallel to the second main wall 26, and, if necessary, allows the height of the retaining device 14 to be adjusted as described in the first embodiment. The first main wall 24 is a flat wall suitable for receiving the thermal attachment means 12 as well as the underside 16 of the cooling plate 4. The internal volume 22 is defined between the fold and the reinforcement 32 of the retaining device 14.

[0090] Figure 7 is a schematic representation of a seventh embodiment of the retaining device 14, based on the second embodiment previously described with reference to Figure 2, and distinguished here by the inclusion of side walls 34 formed by folds, here substantially at right angles, at each free end edge 28, 29 of the sheet metal. The folds forming the side walls 34 are parallel and continuous along the elongation axis 38 of the cooling plate 4.

[0091] Figure 8 is a schematic representation of an eighth embodiment of the retaining device 14 comprising a plurality of local deformation zones 20. The local deformation zones 20 of this embodiment are folds. Four parallel folds in the sheet metal 18 form the retaining device 14.

[0092] In this embodiment, the free end edges 28, 29 of the sheet 18 are turned in opposite directions, moving away respectively from the elongation axis 38 of the sheet 18 of the retaining device 14. The local deformation zones 20 are parallel to each other, and continuous, along the elongation axis 38 of the cooling plate 4.

[0093] The sheet 18 of the retaining device 14 comprises five parts PI, P2, P3, P4, P5 between each of the local deformation zones 20. Each fold is formed by an angle of 180°. The sheet 18 comprises a succession of folds opposite with respect to the elongation axis 38 of the sheet 18, so that the sheet 18 of the retaining device 14 has a symmetrical shape with respect to a plane containing the elongation axis 38 of the sheet 18.

[0094] Given this symmetry of the sheet metal 18, half of the retaining device 14 will be described. A 180° bend is located at the end of the central portion P3, the bend being positioned so that it generates a portion of sheet metal that extends over the upper side of the central portion P3. Following this bend, an extension portion P2 extends between the bend of the central portion P3 and a second 180° bend. The second 180° bend is positioned so that it generates a portion of sheet metal that extends over the upper side of the extension portion P2. From the second fold extends the upper part PI which, when the symmetry of the sheet 18 is achieved, forms the flat wall against which the thermal attachment means 12 and the cooling plate 4 are placed. Each symmetrical part of the retaining device 14 forms a coil allowing to improve the structural resistance of the retaining device 14.

[0095] The invention, as described above, achieves its intended purpose and allows for the proposal of an electrical device. Variations not described here could be implemented without departing from the scope of the invention, provided that, in accordance with the invention, they include a cooling plate retaining device capable of reducing the deflection of said cooling plate in accordance with the invention.

Claims

Demands

1. Electrical device (2) comprising a cooling plate (4), electronic components disposed on said cooling plate (4), the cooling plate (4) having an upper face (6) facing at least one electronic component (8) and an opposite lower face (16), a thermal attachment means (12) being disposed between the at least one electronic component (8) and the upper face (6) of the cooling plate (4), a retaining device (14) being made integral with the lower face (16) of the cooling plate (4), characterized in that the retaining device (14) is formed of a sheet (18) comprising local deformation zones (20) suitable for structurally reinforcing the retaining device (14).

2. Electrical device (4) according to the preceding claim, wherein the sheet metal of the retaining device comprises a plurality of folds giving the retaining device the shape of a hollow body.

3. Electrical device (2) according to any one of the preceding claims, wherein the sheet metal (18) of the retaining device (14) is bent so that the retaining device (14) has two main walls (24, 26) substantially parallel to the underside (16) of the cooling plate and spaced apart to define an internal volume (22).

4. Electrical device (2) according to any one of the preceding claims, wherein the sheet metal of the retaining device is bent so that a free end edge (28) of the retaining device (14) joins another free end edge (29) to close the internal volume (22).

5. Electrical device (2) according to the preceding claim, wherein a free end edge (28) includes a fold forming a notch (30) dimensioned to receive the other free end edge (29).

6. Electrical device (2) according to any one of the preceding claims, wherein at least one local deformation zone (20) is formed by a boss resulting from a stamping operation.

7. An electrical device (2) according to any one of the preceding claims, wherein the retaining device (14) has a support wall substantially parallel to the underside of the cooling plate (4) and intended to allow attachment of the retaining device (14) on the cooling plate, the retaining device further having at least one side wall (34) extending substantially perpendicularly from the support wall and coming into contact with at least one edge of the cooling plate (4).

8. Electrical device (2) according to the preceding claim, wherein the retaining device (14) comprises two side walls (34) facing two opposite edges of the cooling plate (4).

9. Electrical device (2) according to any one of claims 7 or 8, wherein the side wall (34) is formed by folds in the sheet metal (18) of the retaining device (14).

10. Electrical device (2) according to any one of claims 7 to 9 in combination with claim 3, wherein the retaining device (14) comprises a reinforcement (32) extending across the internal volume (22) from a first main wall (24) participating in defining the internal volume (22) to a second main wall (26) participating in defining the internal volume (22) of the retaining device (14).

11. Electrical device (2) according to the preceding claim, wherein the reinforcement (32) is a free end edge (28) of the sheet metal (18) of the retaining device (14).

12. Electrical device (4) according to any one of the preceding claims, wherein the retaining device (14) is secured to the cooling plate (4) by means of a thermal attachment (13).

13. An electrical device (2) according to the preceding claim, wherein the thermal attachment means (12, 13) are solder pastes for securing the electronic component (8) to the cooling plate (4) or the retaining device (14) to the cooling plate (4) after it has been in an oven

14. Electrical device (2) according to any one of the preceding claims, wherein the material used for the holding device (14) has a lower coefficient of thermal expansion than the coefficient of thermal expansion of the cooling plate (4).