METHOD FOR MANUFACTURING AN OVERMOLDED POWER MODULE

Abstract

The invention relates to a method for manufacturing (2000) a power module, comprising: obtaining (E2100) at least one first and a second electrical connection piece, each having a main plate; mounting (E2200) at least one electronic component on an upper face of the main plate of the first electrical connection piece; mounting (E2300) at least one electrical linking element electrically connecting said at least one electronic component to the upper face of the main plate of the second electrical connection piece; making (E2400) with an electrically insulating material, for example resin, an overmolding hermetically sealing said at least one electronic component, said at least one electrical linking element and at least a part of the upper faces of the main plates of the first and second electrical connection pieces;characterized in that said manufacturing process further comprises laser ablation cutting (E2800) of a cavity in the upper face of the electrically insulating overmolding such that at least a portion of said at least one electrically connecting element is located in said cavity. Figure for the abstract: Fig. 7;

Description

Title of the invention: METHOD FOR MANUFACTURING AN OVERMOLDED POWER MODULE

[0001] The present invention relates to a method of manufacturing an overmolded power module.

[0002] A power module is an electronic module, most often containing semiconductor chips (for example so-called power transistors), designed to produce energy conversion circuits, such as those of a switching cell, an inverter or even a rectifier bridge.

[0003] Patent application FR2004620 describes a power module comprising: - a first and a second electrical connection part, preferably made of metal, each having a main plate, - an electrical component mounted on an upper face of the main plate of the first electrical connection part; - an electrical connecting element electrically connecting the electrical component to the upper face of the main plate of the second electrical connecting part; and - an electrically insulating overmolding, for example in resin, covering the electrical component, at least part of the upper face of the main plate of the first and second electrical connection parts.

[0004] This power module is further remarkable in that the upper face of the electrically insulating overmolding has a cavity, in that a portion of the electrical connection element is located in the cavity and in that the electrically insulating overmolding covers the remainder of the electrical connection element.

[0005] However, the production of such a power module by a molding process, for example by a transfer molding process, is difficult to implement due to the shape of the mold required to take into account the presence of a part of the electrical connection element in the cavity located on the upper face of the electrically insulating overmolding.

[0006] Furthermore, the electrical connection element risks being damaged by the mold during the overmolding operation.

[0007] The invention aims to at least partially overcome the aforementioned problem.

[0008] A method of manufacturing a power module is therefore proposed, comprising: - obtaining at least a first and a second electrical connection part each having a main plate; - mounting at least one electronic component on an upper face of the main plate of the first electrical connection part; - the mounting of at least one electrical connection element electrically connecting said at least one electronic component to the upper face of the main plate of the second electrical connection part; - the production with an electrically insulating material, for example resin, of an overmolding hermetically sealing said at least one electronic component, said at least one electrical connection element and at least part of the upper faces of the main plates of the first and second electrical connection parts; characterized in that said manufacturing method further comprises laser ablation cutting of a cavity in the upper face of the electrically insulating overmolding so that at least a portion of the at least one electrical connection element is located in said cavity.

[0009] Thus the face of the main plate of the first electrical connection part on which the electronic component is mounted defines a vertical direction HB, “H” representing the top and “B” representing the bottom.

[0010] Laser ablation consists of directing a laser beam onto the upper face of the electrically insulating overmolding so that the interaction between the laser beam and the electrically insulating overmolding locally causes the disintegration of said overmolding.

[0011] In other words, the interaction between the laser beam and the electrically insulating overmolding causes the tearing off of particles from the electrically insulating overmolding.

[0012] Advantageously and thanks to the manufacturing method according to the invention, the cavity is produced after the overmolding step so that the production of the mold is simplified and the risk of damage to the electrical connection element by the mold is removed.

[0013] The manufacturing method according to the invention may further comprise one or more of the following optional features, taken individually or in any technically possible combination.

[0014] Optionally, the main plates are metal plates, for example copper, aluminum or copper.

[0015] Optionally, the upper face of the electrically insulating overmolding is substantially flat.

[0016] Optionally, more than 60%, preferably more than 80% of the upper face of the electrically insulating overmolding is substantially flat.

[0017] Also optionally, the first electrical connection part is a bus bar intended to be connected to a high potential of a power supply (for example a battery).

[0018] Also optionally, the second electrical connection part is a phase bus bar intended to be connected to a phase of a rotating electrical machine.

[0019] Also optionally, the electronic component is a semiconductor chip, for example a FET (Field-Effect Transistor) type transistor or an insulated gate bipolar transistor, generally designated by the acronym IGBT (Insulated Gate Bipolar Transistor) or even high electron mobility transistors designated by the acronym HEMT (high-electron-mobility transistor).

[0020] For example, FET type transistors are silicon MOSFETs (Si-MOSFETs) or silicon carbide MOSFETs (SiC-MOSFETs) or are gallium nitride FET transistors (GaN-FETs).

[0021] For example, HEMT type transistors are gallium nitride HEMT transistors (GaN-HEMT).

[0022] Also optionally, the electrical connecting element comprises one or more strips and / or one or more wires and / or one or more fuses, each of the strips and / or each of the wires and / or each of the fuses electrically connecting the electrical component and the upper face of the main plate of the second electrical connecting part.

[0023] Also optionally, the ribbons are made of aluminum.

[0024] Also optionally, mounting the electronic component on a upper face of the main plate of the first electrical connection part comprises the electrical connection of this electronic component to the upper face of the main plate of the first electrical connection part.

[0025] Also optionally, the electronic component has the shape of a plate, for example substantially rectangular, having an upper face and a lower face.

[0026] Also optionally, the electronic component has a lower face plated and electrically connected to the upper face of the main plate of the first electrical connection part.

[0027] Also optionally, the electrical connecting element electrically connects the upper face of the electronic component to the upper face of the main plate of the second electrical connection part.

[0028] Also optionally, obtaining the at least one first part and the at least one second electrical connection part comprises: - obtaining a conductive plate, preferably made of metal, extending along a main plane; and - cutting, in the conductive plate, on the one hand, a frame part and said at least one first and one second electrical connection part, the main plates extending along the main plane so as to be substantially coplanar, and, on the other hand, attachment tabs of each main plate with at least one of the other part(s); and the manufacturing method further comprises cutting the attachment tabs to separate each electrical connection part from the other part(s), said cutting being carried out after said overmolding has been carried out.

[0029] Also optionally, the electrically insulating overmolding is carried out in such a way that the electrically insulating overmolding has a lesser thickness at least partially above the electrical connection element.

[0030] Also optionally, the electrically insulating overmolding is produced in such a way that its upper face has a secondary cavity and in that the cavity cut by laser ablation is produced in the bottom of said secondary cavity.

[0031] Also optionally, several successive layers of the electrically insulating overmolding are removed by laser ablation to create said cavity.

[0032] Also optionally, the manufacturing method further comprises the suction of ablation residues resulting from the disintegration of the overmolding during laser ablation.

[0033] Also optionally, the manufacturing method further comprises blowing a flow of air onto the area of ​​the electrically insulating overmolding being ablated.

[0034] Also optionally, the manufacturing method further comprises blowing a flow of air onto the area of ​​the electrically insulating overmolding being ablated in order to facilitate the expulsion of ablation residues from the bottom of the cavity being produced.

[0035] Also optionally, the laser ablation is carried out by means of a pulsed laser, for example with pulses of the order of a nanosecond, or a continuous wave laser or even a gas laser, for example a CO2 laser.

[0036] Also optionally, the wavelength of the laser used is in the infrared or ultraviolet or visible range.

[0037] Also optionally, the manufacturing method further comprises filling said cavity with a gel or a resin having a lesser hardness than that of the electrically insulating overmolding.

[0038] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which:

[0039] [Fig-1] [Fig.l] illustrates the successive steps of a manufacturing process 1000 of a power module according to a first embodiment of the invention.

[0040] [Fig.2] [Fig.2] illustrates the successive steps of a method 1000 for manufacturing a power module produced according to a first embodiment of the invention before the laser ablation cutting step.

[0041] [Fig.3] [Fig.3] illustrates the step of cutting by laser ablation a cavity in the upper face of the electrically insulating overmolding of a power module produced according to a first embodiment of the invention.

[0042] [Fig.4] [Fig.4] is a three-dimensional top view of a power module 110, without overmolding, and obtained by a manufacturing method 2000 according to a second embodiment of the invention,

[0043] [Fig.5] [Fig.5] is a view similar to that of [Fig.3], with overmolding,

[0044] [Fig.6] [Fig.6] is a three-dimensional view from below of the power module figures 4 and 5, with overmolding,

[0045] [Fig.7] [Fig.7] illustrates the successive steps of a method 2000 for manufacturing a power module 110 according to a second embodiment of the invention.

[0046] [Fig.8] [Fig.8] is a view of a cut conductive part resulting from step E2120 of the method 2000 for manufacturing a power module according to the second embodiment of the invention.

[0047] [Fig.9] [Fig.9] is a three-dimensional top view of a first power module obtained at the end of step E2700 by a manufacturing method 2000 according to the second embodiment of the invention.

[0048] [Fig. 10] [Fig. 10] is a three-dimensional top view of a variant of a power module obtained at the end of step E2700 by a manufacturing method 2000 according to the second embodiment of the invention,

[0049] With reference to Figures 1 to 3, a method 1000 for manufacturing a power module according to a first embodiment of the invention will now be presented.

[0050] [Fig.2] a - 2 d successively illustrate steps E10-E40.

[0051] During a first step E10, a first 36i and a second electrical connection part 362 each having a main plate 6i and 62 are obtained, for example by cutting into a metal plate.

[0052] In the example described here, the metal plate is made of copper. Alternatively, the metal plate could be made of aluminum or even gold.

[0053] During a second step E20, an electronic component 12 is mounted on the upper face of the main plate 6 of the first electrical connection part 36i.

[0054] Thus the face of the main plate 6i on which the electronic component 12 is mounted defines a vertical direction HB, “H” representing the top and “B” representing the bottom.

[0055] During a third step E30, an electrical connection element 32i is mounted so as to electrically connect the electronic component 12 to the upper face of the main plate 62 of the second electrical connection part 362.

[0056] The electrical component 12 may be, for example, a transistor having a lower face and an upper face. Such a transistor is mounted on the upper face of the main plate of the first electrical connection part 36i by welding, for example by soldering, the lower face of the transistor to the upper face of the main plate of the first electrical connection part 36i. The upper face of the transistor 12 is further electrically connected to the upper face of the main plate of the second electrical connection part 362. By virtue of its welding to the upper face of the main plate of the first electrical connection part 36i, the lower face of the transistor is electrically connected to the upper face of the main plate of the first electrical connection part 361.

[0057] The electrical connection element 32i may for example comprise one or more ribbons. The ribbons 32i are made of aluminum and have dimensions of 2mmx0.3mm for example. In an alternative embodiment, the ribbons 32i are made of gold.

[0058] During a fourth step E40, an overmolding 40 by an electrically insulating material of the electronic component 12, of the electrical connection element 32i and of at least a portion of the upper faces of the main plates of the first and of the second electrical connection part is carried out. To do this, the electronic component 12, the electrical connection element 32i and at least a portion of the upper faces of the main plates of the first and of the second electrical connection part are placed inside a mold comprising a lower part 41 and an upper part 42. Then, the electrically insulating material is injected in a liquid form into the cavity through one or more orifices (not shown) in order to fill the interior of the mold. Finally, when the electrically insulating material has solidified, the two parts of the mold are removed.

[0059] The electrically insulating material may for example be resin, for example epoxy resin.

[0060] During a fifth step E50 (illustrated [Fig.3]), a cavity C in the upper face of the electrically insulating overmolding 40 is cut by laser ablation so that at least a portion of the electrical connection element is located in this cavity.

[0061] In other words, the upper part of the electrical connection element 32i is located in the cavity C and is no longer covered with resin after the completion of the fifth step E50.

[0062] The ablation device comprises a support 1 on which is mounted at least one laser head 2 and a deflection cell designed to receive the emitted laser beam 4 by the laser head 2 and to deflect it into one or more laser beams 5 driven by a scanning movement in order to focus the laser beam(s) 5 on the upper face of the electrically insulating overmolding 40 to be ablated.

[0063] The cavity C is thus produced in the upper face of the electrically insulating overmolding 40 by successively removing one or more layers of the electrically insulating overmolding 40. In other words, one or more successive layers of the electrically insulating overmolding are removed by laser ablation to produce said cavity. For example, the thickness of the layers successively removed by ablation is less than 100 μm.

[0064] Laser ablation can be performed using a pulsed laser or a continuous wave laser or a gas laser, for example a CO2 laser.

[0065] In the example described here, the laser ablation is carried out using a pulsed laser, for example with pulses of the order of a nanosecond.

[0066] Generally speaking, the wavelength of the laser used can be chosen in the infrared, ultraviolet or visible ranges depending on the nature of the electrically insulating overmolding and the nature of the electrical connection element.

[0067] In the example described here, the wavelength is located in the infrared range.

[0068] Thus, the use of a pulsed laser whose wavelength is located in the infrared range and with pulses of the order of a nanosecond makes it possible to produce the cavity C without damaging the aluminum ribbons 32i (the thickness of said ribbons remaining substantially equal to within a few pm before and after the laser ablation).

[0069] Furthermore, the ablation device may optionally comprise a suction device 6, for example by creating an air flow F1, of the ablation residues 7 resulting from the disintegration of the overmolding during the laser ablation in order to facilitate the recovery of these ablation residues, for example when these present a risk to human health.

[0070] Similarly, optionally, the ablation device may comprise a device 8 for blowing an air flow F2 onto the area of ​​the electrically insulating overmolding being ablated in order to facilitate the expulsion of ablation residues from the bottom of the cavity C being produced.

[0071] With reference to Figures 4 to 9, a power module 110 obtained by a manufacturing method 2000 according to a second embodiment of the invention will now be described.

[0072] With reference to [Fig.4], the power module 110 comprises several electrical connection parts, preferably made of metal.

[0073] Each electrical connection part 304, 304b 3042, 3043, 3044, 3045 has a main plate 306, 306i, 3062, 3063, 3064, 3055 extending along a main plane Horizontal PP, the same for all the main plates 306, 306i, 3062, 3063, 3064, 3065 so that the main plates 306, 306i, 3062, 3063, 3064, 3065 are substantially coplanar. In particular, in the example described, the main plates 306, 306i, 3062, 3063, 3064, 3065 have respective horizontal upper faces 308, 308b 3082, 3083, 3084, 3085 extending at the same level. For the sake of clarity, the upper faces 308, 308b 3082, 3083, 3084, 3085 are only indicated for a few parts in [Fig.4].

[0074] In particular, the power module 110 comprises a first electrical connection part 304i having a main plate 306i having an upper face 308b, a second electrical connection part 3042 having a main plate 3062 having an upper face 3082, a third electrical connection part 3043 having a main plate 3063 having an upper face 3083, a fourth electrical connection part 3044 having a main plate 3064 having an upper face 3084 and a fifth electrical connection part 3045 having a main plate 3065 having an upper face 3085.

[0075] Furthermore, the main plates 306, 306b 3062, 3063, 3064, 3065 are separated from each other along the main plane PP by at least one gap 310. In the example described, each gap 310 has a width less than or equal to five millimeters. This means that the two main plates delimiting the gap 310 are at most five millimeters apart along this gap 310.

[0076] Generally, at least one of the electrical connection parts 304, 3041, 3042, 3043, 3044, 3045 (all in the example described) further has at least one electrical connector projecting from its main plate 306, 306b 3062, 3063, 3064, 3065. Each electrical connector is for example either in the form of a pin 312b or in the form of a folded tab 3122, 3123, or even in the form of a straight tab 3124.

[0077] In the example described here, the straight tabs 3124 form with their main plates 3062, 3064 phase bus bars intended to be connected to phases of a rotating electrical machine, the folded tab 3123 forms with its main plate 3061 a bus bar intended to be connected to a high potential of an electrical power supply (for example a battery) and the folded tabs 3122 form with their main plates 3063, 3065 bus bars intended to be connected to low potentials of the electrical power supply.

[0078] Each electrical connector 312b 3 122, 3123 has a fixed end 314 fixed to the main plate 306, 306b 3062, 3063, 3064, 3065, a main portion 316 extending vertically in the example described and ending in a free end 318 and an elbow 320 connecting the fixed end 314 to the main portion 316. For the sake of For the sake of clarity, these different elements of the electrical connectors 312b 3122, 3123 are only indicated for two electrical connectors 312b 3122, one in the form of a pin, the other in the form of a tab.

[0079] In the case of a straight tab, the electrical connector 3124 projects into the main plane PP over a large length in order to allow its connection, for example at least one centimeter. In addition, the electrical connector 3124 has a fixed end 314 fixed to the main plate 3062, 3064, this fixed end 314 having a large width to allow the passage of current, for example at least one centimeter.

[0080] The electrical connection parts 304, 304b 3042, 3043, 3044, 3045 are obtained in the example described by cutting out a metal plate.

[0081] In the example described here, the metal plate is made of copper. Alternatively, the metal plate could be made of aluminum or even gold.

[0082] Furthermore, the power module 110 comprises transistors 112b 1122, 114i, 1142 each electrically connected between two upper faces 308b 3082, 3083, 3084, 3085 of respectively two of the main plates 306b 3062, 3063, 3064, 3065 for example to pass and interrupt on command a power current, which may for example be greater than one ampere between these two main plates 306i, 3062, 3063, 3064, 3065. Each transistor 112b 1122, 114b 1142 firstly has a lower face pressed against one of the upper faces to which this transistor is electrically connected. Each transistor 112b 1122, 114b 1142 further has an upper face, a part of which is electrically connected to the other of the two upper faces.In the example described, the upper face of the transistor 112b 1122, 114b 1142 further comprises a control part of the transistor 112b 1122, 114b 1142, electrically connected to an upper face of another main plate 306, for example by a wire 328 in the example described.

[0083] In other words, the transistor 112i is mounted on, and electrically connected to, the upper face 3081 of the main plate 3061 of the first electrical connection part 304i and a first electrical connection element electrically connects the transistor 112i to the upper face 3082 of the main plate 3062 of the second electrical connection part 3042.

[0084] The first electrical connection element comprises two strips 326b one end of each metal strip 326i is welded to the upper face 3082 of the main plate 3062 of the second electrical connection part 3042 by a welding method. The second end of each metal strip 3261 is welded directly to the transistor 112i by a welding method. The welding methods used are for example ultrasonic or friction welding methods.

[0085] Similarly, the transistor 114i is mounted on, and electrically connected to, the upper face 3082 of the main plate 3062 of the second electrical connection piece 3042 and a second electrical connection element electrically connects the transistor 114i to the upper face 3083 of the main plate 3063 of the third electrical connection piece 3043.

[0086] The second electrical connection element comprises two strips 3262, one end of each metal strip 3262 is welded to the upper face 3083 of the main plate 3063 of the third electrical connection part 3043 by a welding method. The second end of each metal strip 3262 is welded directly to the transistor 114i by a welding method. The welding methods used are, for example, ultrasonic or friction welding methods.

[0087] Similarly, the lower face of the transistor 1122 is mounted on, and electrically connected to, the upper face 308i of the main plate 306i of the first electrical connection piece 304i and its upper face is electrically connected to the upper face of the main plate 3064 by means of two strips 3263.

[0088] Similarly, the lower face of transistor 1142 is mounted on, and electrically connected to, the upper face 3084 of the main plate 3064 of the fourth electrical connection piece 3044 and its upper face is electrically connected to the upper face of the main plate 3065 by means of two ribbons 3264.

[0089] In the example described, the ribbons 326i, 3262, 3263, 3264 are made of aluminum and have, for example, a section of 2mmx0.3mm. In an alternative embodiment, the ribbons 326b 3262, 3263, 3264 are made of gold.

[0090] In the example described, the wires 328 are made of aluminum and have a diameter of 0.2 mm. In an alternative embodiment, the wires 328 are made of gold.

[0091] In the example described, the pin-shaped electrical connectors 312i are used to connect the power module 110 to a control module 210 whose function is to control the transistors 112b 1122, 114b 1142.

[0092] Furthermore, still in the example described, the electrical connectors 3122 are intended to be connected to the low potential of an electrical power supply and the electrical connector 3123 is intended to be connected to the high potential of this same electrical power supply (for example a battery).

[0093] Furthermore, still in the example described, the two electrical connectors 3124 in the form of a straight tab respectively form two phase bus bars intended to be connected to two phases of a rotating electrical machine.

[0094] With reference to [Fig.5], the overmolding of the power module 110 is shown and bears the reference 402. The upper face of this electrically insulating overmolding is substantially flat. As can be seen in [Fig.5], more than 60% of this upper face is substantially flat.

[0095] The overmolding 402 is an electrical insulator and completely covers each transistor 112i, 1122, 114i, 1142, at least a portion of the upper faces 308i, 3082, 3083, 3084, 3085 of the main plates 306i, 3062, 3063, 3064, 3065 and each wire 328.

[0096] Furthermore, the upper face of the electrically insulating overmolding 402 has been cut so as to have a first cavity C1 located at least partially above the first electrical connection element. Furthermore, a portion of the ribbons 326i is located in the first cavity C1 and the electrically insulating overmolding 402 covers the remainder of the ribbons 326i. In other words, the electrically insulating overmolding 402 partially covers the ribbons 326i so that only the highest portion, relative to the top-bottom direction, of the ribbons 326i is not covered by the electrically insulating overmolding 402 and is further located in the first cavity C1.

[0097] In this way, the electrically insulating overmolding exerts little or no holding force on the uppermost portion of the 326i ribbons, which allows for easy breaking of these ribbons when these ribbons heat up.

[0098] Similarly, the upper face of the electrically insulating overmolding 402 has been cut so as to present a second cavity C2 located at least partially above the ribbons 3262.

[0099] A portion of the ribbons 3262 is located in the second cavity C2 and the electrically insulating overmolding 402 covers the remainder of the ribbons 3262. In other words, the electrically insulating overmolding 402 partially covers the ribbons 3262 so that only the highest portion, relative to the top-bottom direction, of the ribbons 3262 is not covered by the electrically insulating overmolding 402 and is further located in the second cavity C2.

[0100] For the same reasons as previously, the electrically insulating overmolding 402 exerts little or no holding force on the highest part of the ribbons 3262 which allows easy rupture of these ribbons when these ribbons heat up.

[0101] Finally, the upper face of the electrically insulating overmolding 402 has also been cut so as to have a third cavity C3 and a fourth cavity C4 located respectively at least partially above the strips 3263 of the transistor 1122 and the strips 3264 of the transistor 1142. These two cavities have a depth such that only the upper part of the strips 3263 of the transistor 1122 and the upper part of the strips 3264 of the transistor 1142 are located respectively in the third cavity C3 and in the fourth cavity C4 and that the electrically insulating overmolding 402 covers the rest of the strips 3263 and 3264.

[0102] The overmolding 402 is for example made of resin, for example still made of epoxy. Preferably, the overmolding 402 is integral in a single piece.

[0103] In the embodiment described herein, the cavities are free of material. Alternatively, the cavities are filled with a gel, for example dielectric and / or silicone. The gel may also have a viscosity of between 230 and 600 mPa-s, preferably between 400 and 500 mPa-s, for example 465 mPa-s and / or a hardness of between 65 and 180g, preferably between 110 and 160g, for example 123g or 154g.

[0104] In another variant, the cavities are filled with a resin different from the resin forming the electrically insulating overmolding 402. In particular, the resin filling the cavities has a lesser hardness than that forming the electrically insulating overmolding 402. For example, the electrically insulating overmolding 402 is formed from an epoxy resin, for example having a hardness between 70 and 90 shore and the cavities are filled with an elastomeric resin, for example having a hardness between 20 and 40 shore. The resin filling the cavities may also belong to the UL 94 V-0 fire class, as defined by the certification company Underwriters Laboratories.

[0105] Furthermore, the overmolding 402 leaves the lower face 502i of the main plate 306i of the first electrical connection part 304p visible.

[0106] This part visible in [Fig.6] and left exposed is designed to be pressed against a heat sink.

[0107] Thus, the heat sink is in thermal contact with the lower face 502i left visible by the overmolding 402. This thermal contact can be direct contact or via an insulating and thermally conductive electrical connection element.

[0108] Likewise, overmolding 402 leaves the lower faces 5022, 5023, 5024, 5025 of the main plates 3062, 3063, 3064, 3065 of each of the other electrical connection parts 3042, 3043, 3044, 3045 visible. These parts left visible are designed to be pressed against the heat sink. Thus, the heat sink is in thermal contact with the lower faces 5022, 5023, 5024, 5025 left visible by the overmolding 402. This thermal contact can be direct contact or via an insulating and thermally conductive electrical connection element.

[0109] Furthermore, the overmolding 402 fills each gap 310 and has, in each gap 310, a lower face flush with the lower faces 502b 5022, 5023, 5024, 5025 of the main plates 306i, 3062, 3063, 3064, 3065.

[0110] The overmolding 402 has at least one resin pad 506 projecting downwards and designed to come into direct contact with the heat sink in order to define a predefined spacing between the lower faces 502i, 5022, 5023, 5024, 5025, of the main plates 3063, 3062, 3063, 3064, 3065 and the heat sink, and thus the thickness of the thermally conductive element filling this gap. In the example described, each resin pad 506 projects from the lower face of the overmolding present in one of the gaps 310 between the main plates 306b 3062, 3063, 3064, 3065.

[0111] With reference to [Fig.7], a method 2000 for manufacturing the power module 110 according to a second embodiment of the invention will now be described.

[0112] During a step E2100, the electrical connection parts 304b 3042, 3043, 3045 are obtained, each of these parts having a main plate 306b 3062, 3063, 3064, 3065 extending along the same main plane PP so that the main plates 306i, 3062, 3063, 3064, 3065 are substantially coplanar.

[0113] In the embodiment described here, step E2100 comprises two sub-steps E2110, E2120. During step E2110, a conductive plate extending along a main plane is obtained. During step E2120, this conductive plate is cut to define, on the one hand, a frame part 902 and the electrical connection parts 304, 304b 3042, 3043, 3045 and, on the other hand, attachment tabs 904 of each main plate 306, 306b 3062, 3063, 3065 with at least one of the other part(s) cut from the conductive plate. In the conductive plate are further formed secondary attachment tabs 908 of each electrical connector to be folded with at least one other electrical connection piece or with the frame piece 902.

[0114] An example of a cut conductive plate resulting from step E2120 is shown in [Fig.8].

[0115] In the example described here, the conductive plate is made of metal, for example copper. Alternatively, the conductive plate could be made of another metal such as aluminum or gold.

[0116] During a step E2200, the transistors 112i and 114i are respectively fixed and electrically connected by their lower face to the main plates 306b 3062 of the connection parts 304b 3042. During this same step E2200, the transistors 1122 and 1142 are respectively fixed and electrically connected by their lower face to the main plates 306b 3064 of the connection parts 304b 3044.

[0117] During a step E2300, the transistors 112i and 114i are respectively electrically connected by the electrical connection elements 326b 3262 to the main plates 3062, 3063 of the connection parts 3042 and 3043. During this same step E2300, the transistors 1122 and 1142 are respectively electrically connected by the electrical connection elements 3263, 3264 to the main plates 3064, 3065 of the connection parts 3044 and 3045.

[0118] During a step E2400, the overmolding 402 is produced with an electrically insulating material, for example resin, so as to completely cover the wires 328, the transistors 112b 1122, 114b 1142, at least a portion of the upper faces 308b 3082, 3083, 3084, 3085 of the main plates 306b 3062, 3063, 3064, 3065 as well as the electrical connection elements 326b 3262, 3263, 3264.

[0119] To do this, the conductive plate cut in step E2120 is placed inside a mold comprising a lower part 41' and an upper part 42' so that the transistors 112b 1122, 114b 1142 the electrical connection elements 326b 3262, 3263, 3264 and at least a part of the upper faces 308b 3082, 3083, 3084, 3085 of the main plates 306b 3062, 3063, 3064, 3065 are placed inside the mold. Then, the electrically insulating material is injected in a liquid form into the mold through one or more orifices in order to fill the interior of the mold. Finally, when the electrically insulating material has solidified, the two parts of the mold are removed.

[0120] The electrically insulating material is in the example described here resin, for example epoxy resin.

[0121] During a step E2500, the secondary attachment tabs 908 of the electrical connectors 312b 3122, 3123 are cut.

[0122] During a step E2600, the electrical connectors 312b 3122, 3123 are folded to place their main portions vertically in the example described.

[0123] During a step E2700, the attachment tabs 904 are cut to separate each electrical connection part 304b 3042, 3043, 3045 from the other part(s) 902, 304!, 3042, 3043, 3045.

[0124] At the end of step E2700, a power module such as that shown in [Fig.9] is thus obtained.

[0125] During a step E2800, a cavity C1 in the upper face of the electrically insulating overmolding 402 is cut by laser ablation (using an ablation device similar to that described in the first embodiment) so that at least a portion of the electrical connection element 326i is located in this cavity. In other words, in the example described here, the two highest portions of the ribbon(s) 326i are located in the cavity C1 and are no longer covered with resin after the completion of step 2800.

[0126] During this step E2800, cavities C2, C3, C4 are also cut by laser ablation in the upper face of the electrically insulating overmolding 402 so that at least a portion of each of the electrical connection elements 3262 3263, 3264 is respectively located in these cavities C2, C3, C4.

[0127] At the end of step E2800, a power module 110 is thus obtained such as that shown in [Fig.5].

[0128] Optionally, during a step E2900, the cavities C1, C2, C3 and C4 are filled with a gel, for example dielectric and / or silicone.

[0129] In a variant of this second embodiment of the invention, the mold used in step E2400 to produce the overmolding 402 has a shape delimiting in the overmolding 402 four secondary cavities C1', C2', C3', C4'. Each of these secondary cavities C1', C2', C3', C4' being positioned at the location of one of the future cavities C1, C2, C3, C4 and is distinguished from the latter only by a lesser depth chosen so that the electrical connection elements 326b 3262, 3263, 3264 are entirely covered by the overmolding 402. With such a mold, a power module such as that shown in [Fig. 10] is obtained at the end of step E2700.

[0130] In this variant embodiment, the bottoms of the secondary cavities C1', C2', C3', C4' are hollowed out by laser ablation during step E2800 in order to obtain the cavities C1, C2, C3, C4 characteristic of a power module 110 such as that shown in [Fig.5].

[0131] In other words, the electrically insulating overmolding 402 is produced in such a way that its upper face has secondary cavities C1', C2', C3', C4' and in that the cavities C1, C2, C3, C4 cut by laser ablation are produced in the bottom of the secondary cavities C1', C2', C3', C4'.

[0132] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0133] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiments set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

1.

2. Claims Method of manufacturing (1000, 2000) a power module (10, 110), comprising: - obtaining (E10, E2100) at least a first (36i, 304i) and a second (362, 3042) electrical connection part each having a main plate; - the mounting (E20, E2200) of at least one electronic component (12, 1120 on an upper face of the main plate of the first electrical connection part (36b 3040; - the mounting (E30, E2300) of at least one electrical connection element (32b 3260 electrically connecting said at least one electronic component (12, 1120 to the upper face of the main plate of the second electrical connection part (36 2, 3042); - the production (E40, E2400) with an electrically insulating material, for example resin, of an overmolding (40, 402) hermetically sealing said at least one electronic component (12, 1120, said at least one electrical connection element (32b 3260 and at least part of the upper faces of the main plates of the first and second electrical connection parts; said manufacturing method further comprises cutting (E50, E2800) by laser ablation of a cavity (C, Cl) in the upper face of the electrically insulating overmolding (40, 402) so that at least a part of said at least one electrical connection element (32b 3260 is located in said cavity (C, Cl), said manufacturing method being characterized in that the electrically insulating overmolding (402) is produced in such a way that its upper face has a secondary cavity (CE) and in that the cavity (Cl) cut by laser ablation is produced in the bottom of said secondary cavity (CE). Method of manufacturing (2000) a power module according to the preceding claim in which obtaining (E2100) the at least one first part (3040) and the at least one second part (3042) of electrical connection comprises: - obtaining (E2110) a conductive plate, preferably made of metal, extending along a main plane (PP); and - cutting (E2120), in the conductive plate, on the one hand, a frame part (902) and said at least one first (304i) and one second (3042) electrical connection part, the main plates extending along the main plane so as to be substantially coplanar, and, on the other hand, attachment tabs (904) of each main plate with at least one of the other part(s); and said method further comprising cutting the attachment tabs (904) to separate each electrical connection part from the other part(s), said cutting being carried out after said overmolding has been carried out.

3. Manufacturing method (2000) of a power module according to one of the preceding claims, characterized in that the electrically insulating overmolding (402) is produced in such a way that the electrically insulating overmolding (402) has a lesser thickness at least partially above said electrical connection element (326i).

4. Manufacturing method (1000, 2000) according to one of the preceding claims in which several successive layers of the electrically insulating overmolding (40, 402) are removed by laser ablation to produce said cavity (C, Cl).

5. Manufacturing method (1000, 2000) according to one of the preceding claims further comprising the suction of the ablation residues (7) resulting from the disintegration of the overmolding during the laser ablation.

6. Manufacturing method (1000, 2000) according to one of the preceding claims further comprising blowing an air flow (F2) onto the area of ​​the electrically insulating overmolding (40, 402) being ablated.

7. Manufacturing method (1000, 2000) according to one of the preceding claims in which the laser ablation is carried out by means of a pulsed laser or a continuous wave laser or even a gas laser, for example a CO2 laser.

8. Manufacturing method (1000, 2000) according to one of the preceding claims further comprising filling said cavity (C, Cl) by a gel or resin having a hardness less than that of the electrically insulating overmolding (40, 402).

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