WO2021228767A1 - Electrical module with overmoulding and systems comprising such an electrical module - Google Patents

Abstract

The invention relates to an electrical module (110) comprising first (3041) and second (3042) electrical connection parts each having a main plate (3061, 3062), the main plates (3061, 3062) extending along the same main plane (PP); a first electrical component (1121) mounted on an upper face of the main plate (3061) of the first electrical connection part (3041); a first electrical link element (3261) electrically connecting said at least one electrical component (1121) to the upper face of the main plate (3062) of the second electrical connection part (3042); and an electrically insulating overmoulding (402), for example made of resin, covering at least part of the upper face of the main plate (3061, 3062) of the first (3041) and second (3042) electrical connection parts; said electrical module being characterised in that the upper face of the electrically insulating overmoulding (402) has a first cavity (C1) located at least partially above the first electrical link element (3261).

Description

Description

TITLE: ELECTRICAL MODULE WITH OVERMOLDING AND SYSTEMS INCLUDING SUCH AN ELECTRICAL MODULE

The present invention relates to an electrical module with overmolding, an electronic system and a voltage converter comprising such an electrical module.

It is known from the prior art of electrical modules comprising: at least a first and a second electrical connection parts, preferably made of metal, each having a main plate, the main plates extending along the same main plane so as to be substantially coplanar; a first electrical component mounted on an upper face of the main plate of the first electrical connection piece; a first electrical connection element electrically connecting the first electrical component to the upper face of the main plate of the second electrical connection pieces; and an electrically insulating overmolding, for example made of resin, covering at least part of the upper faces of the main plates.

However, in the event of overheating of the electrical component, for example in the event of a short-circuit if the electrical component is a controllable switch, the heat diffuses into the electrical insulator so that it risks catching fire, endangering the surrounding elements.

[0004] The aim of the invention is to at least partially alleviate the aforementioned problem.

It is therefore proposed, according to a first aspect of the invention, an electrical module comprising: a first and a second electrical connection parts, preferably made of metal, each having a main plate, the main plates extending along the same main plane so as to be substantially coplanar; a first electrical component mounted on an upper face of the main plate of the first electrical connection piece; a first electrical connection element electrically connecting said at least electrical component to the upper face of the main plate of the second electrical connection parts; and an electrically insulating overmolding, for example made of resin, covering at least part of the upper face of the main plate of the first and of the second electrical connection parts.

This electrical module is characterized in that the upper face of the electrical insulating overmolding has a first cavity located at least partially above the first electrical connection element.

The fact that the first cavity is located at least partially above the first electrical connection element geometrically means that the intersection between the orthogonal projection of the first electrical connection element on the main plane and the orthogonal projection of the first cavity on this same main plane is not empty.

Thanks to this technical characteristic, the thickness of the electrical insulating overmolding is adjusted according to the arrangement of the first electrical connection element so that this thickness is less, or even zero above at least part of the first electrical connection element.

[0009] In this way, the holding force of the electrical insulating overmolding exerted on the first electrical connection element is reduced, which allows easier breaking of this first electrical connection element when it heats up.

[0010] Thus, the first electrical connection element in the electrical module according to the invention breaks at a lower temperature than that in the electrical module according to the prior art. Thanks to this rupture at a lower temperature, heating of the first electrical component is limited.

In other words, thanks to the cavity located above the first electrical connection element, the temperature of the electrical insulating overmolding of the electrical module according to the invention remains lower in the event of a malfunction of the first electrical component. than in the electrical module according to the prior art so that the electrical module according to the invention is less likely to catch fire.

An electrical module according to the invention may further include one or more of the following optional characteristics, taken individually or else in any technically possible combination. According to a first characteristic, the first electrical connection part is different from the second electrical connection part.

[0014] According to another characteristic, the first electrical component is not mounted on the upper face of the main plate of the second electrical connection part.

[0015] According to another characteristic, the first electrical connection part is intended to be connected to a positive terminal of a direct voltage source.

[0016] According to another characteristic, the second electrical connection part is intended to be connected to a phase of a rotating electrical machine.

[0017] According to another characteristic, the electrical module is a power module.

[0018] According to another characteristic, the electrical module is an electrical module intended to be installed or used in a motor vehicle.

[0019] According to another characteristic, the electrical module is an electrical module intended to produce a switching arm.

[0020] According to another characteristic, the electrical module is an electrical module intended to produce a switching arm of a voltage converter.

[0021] According to another characteristic, the first electrical connection part comprises at least one electrical connector projecting from its main plate.

According to another characteristic, the electrical connector of the first electrical connection part projects from the main plate of the first electrical connection part into the main plane.

According to another characteristic, the electrical connector and the main plate of the first electrical connection part carrying it are made in one piece by continuity of material.

According to another characteristic, the second electrical connection part comprises at least one electrical connector projecting from its main plate.

According to another characteristic, the electrical connector of the second electrical connection part projects from the main plate of the second electrical connection part into the main plane. According to another characteristic, the electrical connector and the main plate of the second electrical connection part carrying it are made in one piece by continuity of material.

[0027] According to another characteristic, the first electrical component is electrically connected to the upper face of the main plate of the first electrical connection part.

[0028] According to another characteristic, the electrically insulating overmolding is integral in a single piece.

[0029] According to another characteristic, the first cavity is filled with gel or a resin having a lower hardness than that of the electrical insulating overmolding

[0030] According to another characteristic, the electrically insulating overmolding at least partially covers the first electric component.

According to another characteristic, the first cavity is located at least partially above the uppermost part of the first electrical connection element.

According to another characteristic, the first electrical connection element comprises one or more ribbons and / or one or more wires and / or one or more fuses, each of the ribbons and / or each of the wires and / or each of the fuses connecting electrically the first electrical component and the upper face of the main plate of the second electrical connection piece.

According to another characteristic, the first electrical connection element further comprises a first pad, one end of each metal strip and / or of each wire and / or of each fuse is welded to the first pad by a first method welding, for example by ultrasound or by friction, the first pad is welded to the upper face of the main plate of the second electrical connection part by a second welding process, for example by brazing, the weld obtained by the second process welding having a temperature resistance lower than that obtained by the first welding process.

According to another characteristic, the first pad and the end of each metal strip and / or each wire and / or each fuse welded to the first pad are located in the first cavity. According to another characteristic, the electrically insulating overmolding completely covers the first electrical connection element and the first electrical component.

According to another characteristic, part of the first electrical connection element is located in the first cavity and the electrical insulating overmolding covers the rest of the first electrical connection element.

[0037] According to another characteristic, the electrical module further comprises: a third electrical connection part having a main plate extending along the main plane; a second electrical component mounted on the upper face of the main plate of the second electrical connection piece; a second electrical connection element electrically connecting the second electrical component to the upper face of the main plate of the third electrical connection part; and wherein the electrically insulating overmolding covers at least part of the upper face of the main plate of the third electrical connection piece; and in which the upper face of the electrically insulating overmolding has a second cavity located at least partially above the second electric connection element.

[0038] According to another characteristic, the second cavity is filled with gel or a resin having a lower hardness than that of the electrically insulating overmolding (402).

According to another characteristic, the electrically insulating overmolding at least partially covers the second electric component.

[0040] According to another characteristic, the second cavity is located at least partially above the uppermost part of the second electrical connection element.

According to another characteristic, the second electrical connection element comprises one or more ribbons and / or one or more wires and / or one or more fuses, each of the ribbons and / or each of the wires and / or each of the fuses connecting electrically the second electrical component and the upper face of the main plate of the third electrical connection piece. According to another characteristic, the second electrical connection element further comprises a second pad, one end of each metal strip and / or of each wire and / or of each fuse of the second electrical connection element is welded to the second pad by a first welding process, for example by ultrasound or by friction, the second pad being welded to the upper face of the main plate of the third electrical connection piece by a second welding process, for example by brazing, the weld obtained by the second welding process having a temperature resistance lower than that obtained by the first welding process.

[0043] According to another characteristic, the second pad and the end of each metal strip and / or each wire and / or each fuse of the second electrical connection element welded to the second pad are located in the second cavity.

[0044] According to another characteristic, the electrical insulating overmolding completely covers the second electrical connection element and the second electrical component.

According to another characteristic, part of the second electrical connection element is located in the second cavity and the electrical insulating overmolding covers the rest of the second electrical connection element.

According to another characteristic, the electrically insulating overmolding at least partially covers the second electric component.

According to another characteristic, the third electrical connection part comprises at least one electrical connector projecting from its main plate.

According to another characteristic, the electrical connector of the third electrical connection part projects from the main plate of the third electrical connection part into the main plane.

According to another characteristic, the electrical connector and the main plate of the third electrical connection part carrying it are made in one piece by continuity of material.

According to another characteristic, the first electrical component and the second electrical component are transistors called the first and second transistor, respectively. According to another characteristic, the first transistor and the second transistor are electrically connected to each other via the main plate of the second electrical connection part, the main plate of the second connection part electrical being intended to be connected to a phase of an electrical machine.

According to another characteristic, the first transistor is electrically connected to the main plate of the first electrical connection part, the main plate of the first electrical connection part being intended to be connected to a positive terminal of a source of DC voltage, and the main plate of the third electrical connection piece is further intended to be connected to a negative terminal of the DC voltage source.

According to another characteristic, each transistor, on the one hand, has a lower face pressed against one of the two upper faces to which this transistor is electrically connected and, on the other hand, is electrically connected, for example by a or more ribbons or threads, on the other of the two upper faces. According to another characteristic, the first electrical component and / or the second electrical component is a transistor of FET type (standing for “Field-Effect Transistor”) or of IGBT type (standing for “Insulated-Gate”. Bipolar Transistor ”).

According to another characteristic, the FET type transistor is a MOSFET made of silicon (Si-MOSFET) or of silicon carbide (SiC-MOSFET) or is a FET transistor made of gallium nitride (GaN-FET).

According to another characteristic, the first electrical component and / or the second electrical component is a FIEMT (English "high-electron-mobility transistor") transistor, for example made of gallium nitride.

[0057] According to another characteristic, the first transistor in the form of a plate, for example substantially rectangular, having an upper face and a lower face.

According to another characteristic, the second transistor in the form of a plate, for example substantially rectangular, having an upper face and a lower face. According to another characteristic, the first transistor has a lower face pressed against the upper face of the main plate of the first electrical connection part to which the first transistor is connected.

According to another characteristic, the second transistor has a lower face pressed against the upper face of the main plate of the second electrical connection part to which the second transistor is connected.

[0061] According to another characteristic, the overmolding leaves visible at least part of the underside of the main plate of at least one of the electrical connection parts, this part left visible being designed to be pressed against a heat sink.

According to another characteristic, the overmolding has a resin stud projecting downwards.

According to another characteristic, the main plates are separated from each other along the main plane by at least one gap and the overmolding fills each gap and has, in each gap, a lower face flush with the lower faces of the main plates.

[0064] According to another characteristic, the resin pad projects from the underside of the overmolding present in the gap.

[0065] According to another characteristic, the electrical connection parts are obtained by cutting a single metal plate.

According to a second aspect of the invention, there is also proposed an electrical system comprising a heat sink and an electrical module according to the first aspect of the invention, and in which the heat sink is in thermal contact with the lower face left visible by the overmolding. According to a third aspect of the invention, there is also proposed a voltage converter comprising an electrical module according to the first aspect of the invention or else an electrical system according to the second aspect of the invention.

This voltage converter is intended to be connected between an electrical power source delivering a DC voltage and a rotating electrical machine to convert between the DC voltage of the electrical power source and at least one phase voltage of the rotating electric machine. According to a fourth aspect of the invention, there is also proposed a switching arm comprising an electrical module according to the first aspect of the invention or else an electrical system according to the second aspect of the invention.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the accompanying drawings in which:

[0071] [Fig. 1] FIG. 1 schematically represents an electrical system comprising a voltage converter implementing the invention in a first embodiment of the invention,

[0072] [Fig. 2] Figure 2 is an exploded three-dimensional view of the voltage converter of Figure 1 in a first embodiment of the invention,

[0073] [Fig.3] Figure 3 is a three-dimensional view from above of a power module of the voltage converter of Figure 2, without overmolding in the first embodiment of the invention,

[0074] [Fig.4] Figure 4 is a view similar to that of Figure 3, with overmolding,

[0075] [Fig.5] Figure 5 is a three-dimensional view from below of the power module of Figures 3 and 4, with overmolding,

[0076] [Fig.6] Figure 6 is a bottom three-dimensional view of a power module in the second embodiment of the invention,

[0077] [Fig.7] Figure 7 is a three-dimensional view from below of a power module in the third embodiment of the invention,

Referring to Figure 1, an electrical system 100 implementing the invention in a first embodiment of the invention will now be described.

The electrical system 100 is for example intended to be installed in a motor vehicle.

The electrical system 100 firstly comprises an electrical power source 102 designed to deliver a direct voltage U, for example between 10 V and 100 V, for example 48 V or else 12 V.

The electric power source 102 is therefore a DC voltage source. This electric power source comprises for example a battery. The electrical system 100 further comprises an electrical machine 130 comprising several phases (not shown) intended to present respective phase voltages.

[0083] The electrical system 100 further comprises a voltage converter 104 connected between the power supply source 102 and the electrical machine 130 to convert between the direct voltage U and the phase voltages.

The voltage converter 104 firstly comprises a positive bus bar 106 and a negative bus bar 108 intended to be connected to the power supply source 102 to receive the direct voltage U, the positive bus bar 106 receiving a high electric potential and the negative bus bar 108 receiving a low electric potential.

The voltage converter 104 further comprises at least one electrical module 110. This electrical module 110 is a power module. The power module 110 comprises one or more phase bus bars intended to be respectively connected to one or more phases of the electric machine 130, to supply their respective phase voltages.

In the example described, the voltage converter 104 comprises three power modules 110 each comprising two phase bus bars 122i, 122 ₂ connected to two phases of the electric machine 130.

More specifically, in the example described, the electric machine 130 comprises two three-phase systems each comprising three phases, and intended to be electrically phase-shifted by 120 ° with respect to each other. Preferably, the first phase busbars 122i of the power modules 110 are respectively connected to the three phases of the first three-phase system, while the second phase busbars 122 ₂ of the power modules 110 are respectively connected to the three phases of the second system. three-phase.

Each power module 110 comprises, for each phase bus bar 122i, a first electrical component, (here a high side switch 112i) connected between the positive bus bar 106 and the phase bus bar 122i and a second component electrical (here a low side switch 114i), connected between the phase bus bar 122i and the negative bus bar 108. Thus, the switches 112i, 114i are arranged to form a switching arm, in which the phase bus bar phase 122i forms a midpoint. Each power module 110 also comprises, for each phase bus bar 122 ₂ , a third electrical component (here a high side switch 112 ₂ ) connected between the positive bus bar 106 and the phase bus bar 122 ₂ and a fourth electrical component (here a low side switch 114 ₂ ) connected between the phase bus bar 122 ₂ and the negative bus bar 108. Thus, the switches 112 ₂ , 114 ₂ are arranged to form a switching arm, wherein the phase bus bar 122 ₂ forms a midpoint.

Each switch 112i, 114i, 112 ₂ , 114 ₂ comprises first and second main terminals 116, 118 and a control terminal 120 intended to selectively open and close the switch 112i, 114i, 112 ₂ , 114 ₂ between its two main terminals 116, 118 as a function of a control signal applied to it. The switches 112i, 114i, 112 ₂ , 114 ₂ are preferably transistors, for example field effect transistors with a metal-oxide-semiconductor structure (standing for “Metal Oxide Semiconductor Field Effect Transistor” or MOSFET) having a gate forming the control terminal 120, and a drain and a source respectively forming the main terminals 116, 118. Alternatively, the switches 112i, 114i, 112 ₂ , 114 ₂ could be insulated gate bipolar transistors (from the English " Insulated Gâte Bipolar Transistor ”or IGBT).

In the example described, the switches 112i, 114i, 112 ₂ , 114 ₂ each have the shape of a plate, for example substantially rectangular, having an upper face and a lower face. The first main terminal 116 extends on the lower face, while the second main terminal 118 extends on the upper face. The switches 112i, 114i, 112 ₂ , 114 ₂ are intended to be crossed, between their main terminals 116, 118, by a current greater than 1 A.

It will be appreciated that the positive bus bar 106, the negative bus bar 108 and the phase bus bars 122i, 122 ₂ are rigid electrical conductors designed to withstand electrical currents of at least 1 A intended to pass through the switches. 112i, 114i, 112 ₂ , 114 ₂ . They preferably have a thickness of at least 1 mm.

Furthermore, in the example described, the positive bus bar 106 comprises first of all a positive common bus bar 106A connecting the power modules 110 and, in each power module 110, a positive local bus bar 106B connected to the positive common bus bar 106A. Similarly, the negative bus bar 108 has a common bus bar negative 108A connecting the power modules 110 and, in each power module 110, a negative local bus bar 108B1, 108B2 for each low side switch 114i, 114 ₂ , the negative local bus bars 108B1, 108B2 being connected to the bus bar common negative 108A. The connections are shown in Figure 1 by diamonds.

[0094] Further, in the example described, the positive common bus bar 106A and the negative common bus bar 108A are each formed from a single conductive piece.

[0095] In addition, in the example described, the electric machine 130 is a rotating electric machine having both the function of an alternator and of an electric motor. More precisely, the motor vehicle further comprises a heat engine (not shown) having an output axis to which the electric machine 130 is connected by a belt (not shown). The heat engine is intended to drive the wheels of the motor vehicle through its output axis. Thus, in operation as an alternator, the electrical machine 130 supplies electrical energy to the electrical power source 102 from the rotation of the output shaft. The voltage converter 104 then operates as a rectifier. When operating as an electric motor, the electric machine drives the output shaft (in addition to or instead of the heat engine).

The voltage converter 104 then operates as an inverter.

The electric machine 130 is for example located in a gearbox or in a clutch of the motor vehicle or instead of the alternator.

In the remainder of the description, the structure and the arrangement of the elements of the voltage converter 104 will be described in more detail, with reference to a vertical direction HB, "H" representing the top and "B" representing the bottom. . This vertical direction H-B being denoted in the figures by the reference V.

Referring to Figure 2, the voltage converter 104 comprises a heat sink 206, also called heat sink, having heat exchange surfaces 204 on which are respectively mounted the power modules 110 (a single module of power 110 is shown in Figure 2). The heat exchange between the heat exchange surface 204 of the heat sink 206 and the power module 110 is achieved for example by means of a direct contact or by means of a conductive paste. thermally, between the heat exchange surface 204 of the heat sink 206 and the power module 110.

The voltage converter 104 also includes a support housing 208 on which is fixed a secondary electronic module such as a control module 210. In the example of Figure 1, the control module 210 is a control card. In addition and optionally, the support housing 208 is mounted on the heat sink 206.

[0100] With reference to FIG. 3, the power module 110 comprises several electrical connection pieces 304, 304i, 304 ₂ , 304 ₃ , preferably made of metal.

Each electrical connection piece 304, 304i, 304 ₂ , 304 ₃ has a main plate 306, 306i, 306 ₂ , 306 ₃ extending along a horizontal main plane PP, the same for all the main plates 306, 306i , 306 ₂ , 306 ₃ so that the main plates 306, 306i, 306 ₂ , 306 ₃ are substantially coplanar. In particular, in the example described, the main plates 306, 306i, 306 ₂ , 306 ₃ have respective horizontal upper faces 308, 308i, 308 ₂ , 308 ₃ extending at the same level. For the sake of clarity, the upper faces 308, 308i, 308 ₂ , 308 ₃ are only indicated in FIG. 3 for the main plates 306, 306i, 306 ₂ , 306 ₃ the largest.

[0102] In particular, the power module 110 comprises a first electrical connection piece 304i having a main plate 306i having an upper face 308i, a second electrical connection piece 304 ₂ having a main plate 306 ₂ having an upper face 308 ₂ and a third electrical connection piece 304 ₃ having a main plate 306 ₃ having an upper face 308 _3.

Furthermore, the main plates 306, 306i, 306 ₂ , 306 ₃ 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 equal to one five millimeters. This means that the two main plates delimiting the gap 310 are at most five millimeters apart along this gap 310.

In general, at least one of the electrical connection parts 304 (all in the example described) also has at least one electrical connector projecting from its main plate 306, 306i, 306 ₂ , 306 ₃ . Each electrical connector is for example either in the form of a pin 312i, or in the form a folded tongue 312 ₂ , 312 ₃ , or again in the form of a straight tongue 312 ₄ .

In the example described here, the straight tabs 312 ₄ form with their main plates 306 ₂ , 306 the phase bus bars 122i, 122 ₂ , the folded tab 312 ₃ forms with its main plate 306i the positive local bus bar 106B and the folded tabs 312 ₂ together with their main plates 306 ₃ , 306 form the negative local bus bars 108B1, 108B2.

[0106] Each electrical connector 312i, 312 ₂ , 312 ₃ has a fixed end 314 fixed to the main plate 306, 306 ₂ , 306 ₃ , 306i, 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 clarity, these different elements of the electrical connectors 312i, 312 ₂ , 312 ₃ are only indicated in FIG. 3 for two electrical connectors 312i, 312 ₂ , one in the form of a pin, the other in the form of a tongue.

In the case of a straight tab, the electrical connector 312 ₄ projects into the main plane PP over a great length in order to allow its connection, for example at least one centimeter. In addition, the electrical connector 312 ₄ has a fixed end 314 fixed to the main plate 306, this fixed end 314 having a large width to allow the passage of current, for example of at least one centimeter.

[0108] The electrical connection parts 304 are obtained in the example described by cutting a metal plate.

[0109] In the example described here, the metal plate is made of copper. As a variant, the metal plate could be made of aluminum or even of gold.

[0110] Furthermore, as explained above, the power module 110 comprises the transistors 112i, 112 ₂ , 114i, 114 ₂ each electrically connected between two upper faces 308, 308i, 308 ₂ , 308 ₃ of respectively two of the main plates 306 , 306i, 306 ₂ , 306 ₃ 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 306, 306i, 306 ₂ , 306 ₃ . Each transistor 112i, 112 ₂ , 114i, 114 ₂ first of all has a lower face pressed against one of the two upper faces 308, 308i, 308 _{2 to} which this transistor is electrically connected. Each transistor 112i, 112 ₂ , 114i, 114 ₂ also has a face upper part of which is electrically connected to the other of the two upper faces. In the example described, the upper face of the transistor 112i, 112 ₂ , 114i,

114 _{2 further} comprises a control part of the transistor 112i, 112 ₂ , 114i, 114 ₂ , electrically connected to an upper face of a third main plate 306, for example by a wire 328 in the example described.

In other words, the transistor 112i is mounted on the upper face 308i of the main plate 306i of the first electrical connection part 304i and a first electrical connection element electrically connects the transistor 112i to the upper face 308 ₂ of the main plate 306 ₂ of the second electrical connection part 304 ₂ .

The first electrical connection element comprises two tapes 326i and a pad 390i, one end of each metal tape 326i is welded to the pad 390i by a first welding process, for example by an ultrasonic welding process or by a friction welding process. The pad 390i is also welded to the upper face 308 ₂ of the main plate 306 ₂ of the second electrical connection part 304 ₂ by a second welding process, for example by brazing. The second end of each metal strip 326i is soldered directly to transistor 112i by the first soldering process.

[0113] Thus, the weld obtained by the second welding process has a temperature resistance lower than that obtained by the first welding process.

Likewise, the transistor 114i is mounted on the upper face 308 ₂ of the main plate 306 ₂ of the second electrical connection piece 304 ₂ and a second electrical connection element electrically connects the transistor 114i to the upper face 308 ₃ of the main plate 306 ₃ of the third electrical connection part 304 ₃ .

The second electrical connection element comprises two strips 326 ₂ and a pad 390 ₂ , one end of each metal strip 326 ₂ is welded to the pad 390 ₂ by the first welding process. The pad 390 ₂ is also welded to the upper face 308 ₃ of the main plate 306 ₃ of the third electrical connection part 304 ₃ by the second welding process. The second end of each metal strip 326 ₂ is soldered to transistor 114i by the first soldering process. Similarly, the transistors 112 ₂ and 114 ₂ have their upper face electrically connected to an upper face of a main plate 306 by means of two ribbons 306 and a pad 390.

In the example described, the tapes 326, 326i, 326 ₂ are made of aluminum and have for example a section of 2mm × 0.3mm. In an alternative embodiment, the ribbons 326, 326i, 326 ₂ are made of gold.

In the example described, the studs 390i, 390 ₂ , 390 have the shape of a rectangular plate with a dimension of 9.5mm x 7.5mm and for example have a section of 4.64 x 2.94mm for a thickness of 0.15mm. The pads 390i, 390 ₂ , 390 are for example formed from an assembly of a layer of invar between two layers of copper, said assembly being produced for example by a co-rolling process. Alternatively, the invar layer can be replaced with a molybdenum layer. In another variant, the pads 390i, 390 ₂ , 390 can be made of a composite material, for example molybdenum-copper.

[0119] In the example described, the wire 328 is made of aluminum and has a diameter of 0.2mm. In an alternative embodiment, the wire 328 is made of gold.

[0120] In the example described, the electrical connectors 312i in the form of a pin are used for connecting the power module 110 to the control module 210, in order to take measurements of electrical quantities and to control the transistors 112i, 112 ₂ , 114 _I , 114 ₂ .

[0121] Further, still in the example described, the electrical connectors 312 ₂ are connected to the negative common bus bar 108A and the electrical connector 312 ₃ is connected to the positive common bus bar 106A.

[0122] In addition, still in the example described, the two electrical connectors 312 ₄ in the form of a straight tab respectively form the two phase bus bars 122i, 122 ₂ of the power module 110.

[0123] With reference to FIG. 4, the overmolding of the power module 110 is shown and bears the reference 402. The overmolding 402 is an electrical insulator and partially covers each transistor 112i, 112 ₂ , 114i, 114 ₂ and at least one part of the upper faces 308i, 308 ₂ , 308 ₃ , 308 of the main plates 306i,

306 ₂ , 306 ₃ , 306.

In an alternative embodiment, the transistors 112i, 112 ₂ , 114i, 114 ₂ are not covered by the overmolding 402. In the example described here, the overmolding 402 also partially covers each wire 328. In an alternative embodiment, the overmolding 402 completely covers each wire 328.

[0126] In addition, the upper face of the electrically insulating overmolding 402 has a first cavity C1 located at least partially above the first electrical connection element. In addition, the ribbons 326i and the pad 390i of the first electrical connection element are entirely located in the first cavity C1. Thus, a first part of the first cavity C1 is located above the first electrical connection element and a second part of the first cavity C1 comprises the pad

390 ₁ and 326i ribbons.

[0127] In this way, the electrically insulating overmolding exerts no holding force on the first electrical connection element, which allows easy breaking of the ribbons or of the solder of the block 390i on the upper face of the main plate 306 ₂ of the second electrical connection part 304 ₂ when this first electrical connection element heats up.

Likewise, the upper face of the electrically insulating overmolding 402 has a second cavity C2 located at least partially above the second electrical connection element 326 ₂ . In addition, the pad 390 ₂ and the ribbons 326 ₂ of the second electrical connection element are entirely located in the second cavity C2. Thus, a first part of the second cavity C2 is located above the second electrical connection element 326 ₂ and a second part of the second cavity C2 comprises the pad 390 ₂ and the ribbons 326 ₂ .

[0129] For the same reasons as above, the electrically insulating overmolding exerts no holding force on the second electrical connection element, which allows easy breaking of the ribbons or of the solder on the upper face of the main plate 306 _3. of the third electrical connection part 304 ₃ of the stud

390 ₂ when this second electrical connection element heats up.

Finally, the upper face of the electrically insulating overmolding 402 also has a third cavity C3 and a fourth cavity C4 located respectively at least partially above the strips 326 of the transistor 112 ₂ and of the transistor 114 ₂ and sufficiently deep so that the ribbons 326 and the pads 390 are located in the cavities C3, C4.

The overmolding 402 is for example in resin, for example also in epoxy. Preferably, the overmolding 402 is integral in one piece. In the embodiment described here, the cavities are devoid of material. As a variant, the cavities are filled with a gel, for example dielectric and / or silicone. The gel can also have a viscosity between 230 and 600 mPa-s, preferably between 400 and 500 mPa-s, for example 465 mPa-s and / or a hardness between 65 and 180g, preferably between 110 and 160g, for example 123g or 154g.

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 lower 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 be of the UL 94 V-0 fire class, as defined by the Underwriters Laboratories certification company.

[0134] As can be seen in FIG. 5, the overmolding 402 leaves visible the lower face 502i of the main plate 306i of the first electrical connection part 304i. This part left visible is designed to be pressed against the heat sink 206. Thus, the heat sink 206 is in thermal contact with the lower face 502i left visible by the overmolding 402. This thermal contact can be a direct contact or else via an element. insulating and thermally conductive electrical connection.

[0135] Likewise, overmolding 402 leaves the lower faces 502, 502 ₂ , 502 ₃ of the main plate 306, 306 ₂ , 306 ₃ of each of the other electrical connection pieces 304, 304 ₂ , 304 ₃ visible. These parts left exposed are designed to be pressed against the heat sink 206. Thus, the heat sink 206 is in thermal contact with the lower faces 502, 502 ₂ , 502 ₃ left visible by the overmolding 402. This thermal contact can be a contact. direct or via an insulating and thermally conductive electrical connection element.

[0136] Furthermore, it will be appreciated that the fixed end 314 of each electrical connector 312i, 312 ₂ , 312 ₃ , 312 ₄ has a lower face entirely uncovered with overmolding 402. In addition, the overmolding 402 fills each gap 310 and has, in each gap 310, a lower face flush with the lower faces 502 of the main plates 206. [0137] The overmolding 402 has at least one resin pad 506 projecting downwards and designed to come into direct contact with the heat sink 206 in order to define a predefined spacing between the lower faces 502, 502i, 502 ₂ , 502 ₃ of the main plates 306, 306i, 306 ₂ , 306 ₃ and the heat sink 206, and thus the thickness of the thermal conductor element filling this gap. In the example described, each resin stud 506 projects from the underside of the overmolding present in one of the interstices 310 between the main plates 306, 306i, 306 ₂ , 306 ₃ .

In a variant of this first embodiment of the invention, the first electrical connection element comprises only the two tapes 326i. A first end of each metal strip is welded directly to the top face of the main plate 306 ₂ of the second electrical connection piece 304 ₂ by the first or by the second welding process and a second end of each metal strip is soldered directly to transistor 112i by the first soldering process.

In this variant, the second electrical connection element comprises only the two tapes 326 ₂ . A first end of each metal strip is welded directly to the top face of the main plate 306 ₃ of the third electrical connection piece 304 ₃ by the first or by the second welding process and a second end of each metal strip is soldered directly to transistor 114i by the first soldering process.

[0140] In this variant also, the transistors 112 ₂ and 114 ₂ have their upper face electrically connected to an upper face of a main plate 306 by means only of the two ribbons 306, ie without the use of a pad 390.

[0141] With reference to Figure 6, a second embodiment of the invention will now be presented. Elements identical or similar to those of the first embodiment bear the same numerical reference in the description of the second embodiment.

In this second embodiment, the overmolding 402 completely covers each transistor 112i, 112 ₂ , 114i, 114 ₂ , at least part of the upper faces 308i, 308 ₂ , 308 ₃ , 308 of the main plates 306i, 306 ₂ , 306 ₃ , 306 and totally each wire 328. In this second embodiment, the upper face of the electrically insulating overmolding 402 has a first cavity C1 ′ located at least partially above the ribbons 326i.

[0144] In this embodiment, part of the ribbons 326i is located in the first cavity C1 ′ and the electrically insulating overmolding 402 covers the rest of the ribbons 326i and the pad 390i. In other words, the electrically insulating overmolding 402 partially covers the ribbons 326i so that only the highest part, with respect to the up-down direction, of the ribbons 326i is not covered by the electrically insulating overmolding 402 and is also located in the first cavity C1 ′.

[0145] In this way, the electrically insulating overmolding exerts no holding force on the uppermost part of the tapes 326i which allows easy breaking of these tapes when these tapes heat up.

Likewise, the upper face of the electrically insulating overmolding 402 has a second cavity C2 ′ located at least partially above the ribbons 326 ₂ .

In this embodiment, part of the ribbons 326 ₂ is located in the second cavity C2 ′ and the electrically insulating overmolding 402 covers the rest of the ribbons 326 ₂ and the pad 390 ₂ . In other words, the electrically insulating overmolding 402 partially covers the ribbons 326 ₂ so that only the highest part, relative to the up-down direction, of the ribbons 326 ₂ is not covered by the electrically insulating overmolding. 402 and is further located in the second cavity C2 '.

For the same reasons as above, the electrically insulating overmolding 402 exerts no holding force on the uppermost part of the ribbons 326 ₂ , which allows these ribbons to be easily broken when these ribbons heat up.

Finally, the upper face of the electrically insulating overmolding 402 also has a third cavity C3 'and a fourth cavity C4' located respectively at least partially above the strips 326 of the transistor 112 ₂ and of the transistor 114 ₂ and sufficiently deep of so that only the upper part of the ribbons 326 of the transistor 112 ₂ and the upper part of the ribbons 326 of the transistor 114 ₂ are located respectively in the third cavity C3 'and in the fourth cavity C4' and so that the electrical insulating overmolding 402 covers the rest of the ribbons 326 and the pads 390. [0150] As in the first embodiment, the cavities are devoid of materials or, in a variant, can be filled with a gel or a resin different from the resin forming the electrically insulating overmolding 402.

[0151] In a variant of this second embodiment of the invention, the first electrical connection element comprises only the two ribbons 326i.

A first end of each metal strip is welded directly to the top face of the main plate 306 ₂ of the second electrical connection piece 304 ₂ by the first or by the second welding process and a second end of each metal strip is soldered directly to transistor 112i by the first soldering process.

In this variant, the second electrical connection element comprises only the two ribbons 326 ₂ . A first end of each metal strip is welded directly to the top face of the main plate 306 ₃ of the third electrical connection piece 304 ₃ by the first or by the second welding process and a second end of each metal strip is soldered directly to transistor 114i by the first soldering process.

[0153] In this variant also, the transistors 112 ₂ and 114 ₂ have their upper face electrically connected to an upper face of a main plate 306 by means only of the two tapes 306, ie without the use of a pad 390.

[0154] With reference to Figure 7, a third embodiment of the invention will now be presented. Elements identical or similar to those of the first and second embodiment bear the same numerical reference in the description of this third embodiment.

In this third embodiment of the invention, the overmolding 402 completely covers each transistor 112i, 112 ₂ , 114i, 114 ₂ and at least part of the upper faces 308i, 308 ₂ , 308 ₃ , 308 of the main plates 306i, 306 ₂ ,

306s, 306.

In the example described here, the overmolding 402 also completely covers each wire 328 and each electrical connection element 326i, 326 ₂ , 326. In other words, the overmolding 402 completely covers the ribbons 326i, 326 ₂ , 326 and the studs 390i, 390 ₂ , 390.

[0157] In addition, the upper face of the electrically insulating overmolding 402 has a first cavity C1 ”located at least partially above the ribbons 326i. In the example described here, the first cavity C1 ”is located at least partially at the above the highest part, relative to the up-down direction, of the ribbons

3261.

[0158] In this way, the electrically insulating overmolding exerts a holding force on the highest part of the ribbons 326i which is less than in the absence of the first cavity C1 ”which allows easier breaking of these ribbons when these ribbons heat up.

Likewise, the upper face of the electrically insulating overmolding 402 has a second cavity C2 ”located at least partially above the ribbons 326 ₂ . In the example described here, the second cavity C2 ”is located at least partially above the highest part, with respect to the up-down direction, of the ribbons.

326 ₂ .

[0160] For the same reasons as above, the electrically insulating overmolding 402 exerts a holding force on the uppermost part of the ribbons 326 _{2 which is} less than in the absence of the second cavity C2 ”which allows more breaking. easy of these ribbons when these ribbons heat up.

Finally, the upper face of the electrically insulating overmolding 402 also has a third cavity C3 ”and a fourth cavity C4” located respectively at least partially above the strips 326 of the transistor 112 ₂ and of the transistor 114 ₂ . The third cavity C3 ”and the fourth cavity C4” are located at least partially above the uppermost part, with respect to the up-down direction, of the ribbons 326.

[0162] As in the first and in the second embodiment, the cavities are devoid of materials or, alternatively, can be filled with a gel or a resin different from the resin forming the electrically insulating overmolding 402.

[0163] In a variant of this third embodiment of the invention, the first electrical connection element comprises only the two ribbons 326i.

A first end of each metal strip is welded directly to the top face of the main plate 306 ₂ of the second electrical connection piece 304 ₂ by the first or by the second welding process and a second end of each metal strip is soldered directly to transistor 112i by the first soldering process.

In this variant, the second electrical connection element comprises only the two tapes 326 ₂ . A first end of each metal ribbon is welded directly to the upper face of the main plate 306 ₃ of the third electrical connection piece 304 ₃ by the first or by the second welding process and a second end of each metal strip is welded directly to the transistor 114i by the first welding process.

[0165] In this variant also, the transistors 112 ₂ and 114 ₂ have their upper face electrically connected to an upper face of a main plate 306 by means only of the two ribbons 306, ie without the use of a pad 390.

[0166] 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 the light of the teaching which has just been disclosed to him.

[0167] For example, the invention is not limited to a power module as described above but applies to all types of electrical module comprising two electrical connection parts, a first electrical component mounted on the upper face. of one of the two electrical connection parts, a first electrical connection element electrically connecting the first electrical component to the upper face of the main plate of the other of the two electrical connection parts and an electrical insulating overmolding covering at least one part of the two electrical connection pieces to prevent this first electrical component from overheating to the point of igniting the electrical insulating overmolding.

In the detailed presentation of the invention which is given above, the terms used should not be interpreted as limiting the invention to the embodiments presented in the present description, but should be interpreted to include therein all the equivalents including forecasting 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

Claims [1] Electrical module (110) comprising: a first (304i) and a second (304 ₂ ) electrical connection pieces, preferably made of metal, each having a main plate (306i, 306 ₂ ), the main plates (306i, 306 ₂ ) extending along the same main plane (PP) so as to be substantially coplanar; a first electrical component (112i) mounted on an upper face of the main plate (306i) of the first electrical connection piece (304i); a first electrical connection element (326i) electrically connecting said at least electrical component (112i) to the upper face of the main plate (306 ₂ ) of the second electrical connection part (304 ₂ ); and an electrically insulating overmolding (402), for example made of resin, covering at least part of the upper face of the main plate (306i, 306 ₂ ) of the first (304i) and of the second (304 ₂ ) connection pieces electric; said electrical module being characterized in that the upper face of the electrical insulating overmolding (402) has a first cavity (C1, C1 ', C1 ”) located at least partially above the first electrical connection element (326i). [2] Electrical module (110) according to the preceding claim wherein said first cavity is filled with gel or a resin having a lower hardness than that of the electrical insulating overmolding (402) and / or wherein said electrically insulating overmolding (402 ) at least partially covers said first electrical component (112i). [3] Electrical module (110) according to one of the preceding claims wherein the first cavity (C1, C1 ', C1 ”) is located at least partially above the highest part of the first electrical connection element ( 326i). [4] Electrical module (110) according to one of the preceding claims wherein the first electrical connection element (326i) comprises one or more ribbons and / or one or more wires and / or one or more fuses, each of said ribbons and / or each of said wires and / or each of said fuses electrically connecting the first electrical component (112i) and the upper face (308 ₂ ) of the main plate (306 ₂ ) of the second electrical connection piece (304 ₂ ). [5] Electrical module (110) according to the preceding claim wherein the first electrical connection element further comprises a pad (390i), one end of each metal strip (326i) and / or each wire and / or each fuse is welded to said pad (390i) by a first welding process, for example by ultrasound or by friction, said pad (390i) being welded to the upper face of the main plate (306 ₂ ) of the second electrical connection part (304 ₂ ) by a second welding process, for example by brazing, the weld obtained by the second welding process having a temperature resistance lower than that obtained by the first welding process [6] Electrical module (110) according to the preceding claim wherein said pad (390i) and the end of each metal strip (326i) and / or each wire and / or each fuse welded to said pad (390i) are located in the first cavity (C1). [7] Electrical module (110) according to one of claims 1 to 5 wherein the electrical insulating overmolding completely covers the first electrical connection element (326i) and the first electrical component (112i). [8] Electrical module (110) according to one of claims 1 to 5 wherein part of the first electrical connecting element (326i) is located in the first cavity (C1 ') and wherein the electrical insulating overmolding (402) covers the remainder of the first electrical connection element (326i). [9] Electrical module (110) according to one of the preceding claims further comprising: A third electrical connection piece (304 ₃ ) having a main plate (306 ₃ ) extending along the main plane (PP); a second electrical component (114i) mounted on the upper face (308 ₂ ) of the main plate (306 ₂ ) of the second electrical connection piece (304 ₂ ); a second electrical connection element (326 ₂ ) electrically connecting said second electrical component (114i) to the face upper (308 ₃ ) of the main plate (306 ₃ ) of the third electrical connection piece (304 ₃ ); and wherein the electrically insulating overmolding (402) covers at least part of the upper face (308 ₃ ) of the main plate (306 ₃ ) of the third electrical connection piece (304 ₃ ); and in which the upper face of the electrically insulating overmolding (402) has a second cavity (C2, C2 ', C2 ”) located at least partially above the second electrical connection element (326 ₂ ). [10] Electrical module (110) according to the preceding claim wherein the first electrical component (112i) and the second electrical component (114i) are transistors called respectively first and second transistor; the first transistor (112i) and the second transistor (114i) are electrically connected to each other through the main plate (306 ₂ ) of the second electrical connection piece (304 ₂ ), the main plate (306 ₂ ) of the second electrical connection piece (304 ₂ ) being intended to be connected to a phase of an electrical machine (130), the first transistor (112i) is furthermore electrically connected to the main plate (306i) of the first electrical connection piece (304i), said main plate (306i) of the first electrical connection piece (304i) being intended to be connected to a positive terminal of a direct voltage source (102), and in which the main plate (306 ₃ ) of the third electrical connection piece (304 ₃ ) is further intended to be connected to a negative terminal of said direct voltage source (102). [11] Electrical module (110) according to one of the preceding claims wherein the overmolding (402) leaves visible at least part of the lower face (502, 502 _I , 502 ₂ , 502 ₃ ) of the main plate (306 , 306i, 306 ₂ , 306 ₃ ) of at least one of the electrical connection parts (304, 304i, 304 ₂ , 304 ₃ ), this part left visible being designed to be pressed against a heat sink (206). [12] An electrical system (100) comprising a heat sink (206) and an electrical module according to the preceding claim, and wherein the heat sink thermal (206) is in thermal contact with the lower face left exposed by the overmolding. [13] Voltage converter (104) comprising an electrical module (110) according to any one of claims 1 to 11 or an electrical system (100) according to claim 12.