Power module

Abstract

Title: Power module The invention relates to a power module (1) comprising: A substrate (3) a first conductor (C+) comprising a connection portion (P+), at least one terminal (B+), and at least one linking portion (PL+); a second conductor (C-) comprising a connection portion (P-) and a terminal (B-); a third conductor (C~) comprising first (P1~) and second connection portions (P2~), at least one terminal (B~), and at least one linking portion (PL~); Characterized in that at least one linking portion (PL+) of the first conductor (C+) spans a connection portion (P~) of the third conductor (C~), or that at least one linking portion (PL~) of the third conductor (C~) spans a connection portion (P+) of the first conductor (C+) Figure for the abstract: Fig. 1

Description

Title of the invention: Power module Technical field of the invention

[0001] The present invention relates to a power module. Technological background

[0002] It is known to use a power module implementing a switching arm with a high-side switch formed of several transistors, called high-side, and a low-side switch also formed of several transistors, called low-side. Generally, the transistors on each side are distributed over two parallel rows deposited on a substrate. The power module further comprises a control circuit with two parts, spaced apart from each other, for controlling respectively the high-side transistors and the low-side transistors. Each of the two parts comprises pins projecting upwards or downwards to be connected to drivers.

[0003] On these power modules, the connection between the rows of transistors and the terminals of the power module is made using conductive tracks on the substrate.

[0004] However, the use of connection tracks on the substrate has several disadvantages.

[0005] Since the space on the substrate is limited, there are strong constraints on the size and path of the conductive tracks. Some tracks have a long path and a small cross-section, therefore a high impedance. This is particularly problematic when all the tracks have very different impedances, which can harm the performance of the power module.

[0006] In addition, the space occupied by the connection tracks requires the transistors to be brought closer together on the substrate. A maximum distance of 1 mm to 1.6 mm is typically obtained between two transistors. This small distance induces thermal coupling between the different components, and increases the thermal impedance of the entire power module.

[0007] Then, the use of connection tracks placed on the same plane as the transistors requires separating a switch formed by several transistors into two groups of transistors in order to allow the passage of connection tracks. This separation into groups of transistors implies an imbalance in the current passing through these groups of transistors, which harms the efficiency of the power module.

[0008] It may thus be desirable to provide a power module which makes it possible to overcome at least some of the aforementioned problems and constraints.

[0009] The invention relates to a power module comprising: • a substrate • a first conductor comprising a connection portion, at least one terminal, and at least one linking portion; • a second conductor comprising a connection portion and a terminal; • a third conductor comprising first and second portions of connection, at least one terminal, and at least one connecting portion; • a flat substrate on which the different conductors are placed. Characterized in that at least one connecting portion of the first conductor spans a connecting portion of the third conductor, or at least one connecting portion of the third conductor spans a connecting portion of the first conductor.

[0010] According to one aspect of the invention, the power module is for example an inverter, or an on-board charger (OBC).

[0011] According to one aspect of the invention, the portions of the conductors of the power module follow one another in a first direction in the order: the connection portion of the second conductor, the first connection portion of the third conductor, the connection portion of the first conductor and the second connection portion of the third conductor;

[0012] According to one aspect of the invention, the power module comprises: • a first switch formed of aligned first transistors, the first transistors being pressed against the first connection portion of the third conductor and electrically connected to the connection portion of the second conductor; • a second switch formed of aligned second transistors, the second transistors being pressed against the connection portion of the first conductor and electrically connected to the second connection portion of the third conductor; and • between the first transistors and the second transistors, a transistor control circuit.

[0013] According to one aspect of the invention, the transistors of a switch are spaced apart by a distance Dt greater than 2 mm, in particular greater than 3 mm, in particular equal to 4 mm.

[0014] According to one aspect of the invention, this substrate is flat, and defines a reference plane. A Z axis is also defined, normal to the plane of the substrate, and directed from the substrate towards the conductors. This Z axis makes it possible to define a height: a plane A will be higher than a plane B if it is further away from the substrate along this vertical Z axis. The distance from a plane to the reference plane is called height.

[0015] Furthermore, an element C will be said to be “above” an element D if this element C is placed higher than element D and the projections of elements C and D on the reference plane overlap.

[0016] When referring to a connecting portion of a conductor spanning the connecting portion of another conductor, it is meant that at least a portion of the connecting portion of the conductor is placed above at least a portion of the connecting portion of the other conductor.

[0017] According to one aspect of the invention, the connection portions of the conductors are flat.

[0018] According to one aspect of the invention, the planar connection portions of the conductors extend parallel to each other, and parallel to the reference plane.

[0019] According to one aspect of the invention, the planar connection portions of the conductors are substantially coplanar, in particular the parallel planes of the planar connection portions of the conductors are at a height of less than 3 mm, in particular a height of less than 2 mm.

[0020] According to one aspect of the invention, the connecting portions of the conductors comprise a conductive bar.

[0021] According to one aspect of the invention, the conductive bars comprise a flat face parallel to the plane of the substrate.

[0022] According to one aspect of the invention, the flat faces of the conductive bars of the first conductor are coplanar and define a connection plane of the first conductor.

[0023] According to one aspect of the invention, the flat faces of the conductive bars of the third conductor are coplanar and define a connecting plane of the third conductor.

[0024] According to one aspect of the invention, the connection plane of the first conductor is higher than the connection plane of the third conductor.

[0025] Alternatively, the bonding plane of the third conductor is higher than the bonding plane of the first conductor.

[0026] Alternatively, the connecting planes of the first and third conductors are at the same height, i.e. at the same distance from the reference plane.

[0027] According to one aspect of the invention, the connecting planes of the first conductor and the third conductor are placed higher than the flat faces of the connection portions of the conductors.

[0028] In particular, the connecting planes of the first and third conductors are placed at a height greater than 2 mm, in particular greater than 3 mm.

[0029] According to one aspect of the invention, the connecting portions of the conductors are welded, brazed or sintered onto the terminals of the conductors. The connecting portions then comprise a fixing area allowing the electrical connection between the terminal of the conductor and the connecting portion of the conductor.

[0030] Alternatively, the connecting portions and terminals of the connectors are made in one piece.

[0031] According to one aspect of the invention, at least one connecting portion comprises a ramp arranged to electrically connect a terminal of the conductor to the conductive bar of a connecting zone of this conductor.

[0032] According to one aspect of the invention, this ramp and the conductive bar are made in one piece.

[0033] According to one aspect of the invention, this ramp comprises two elbows: • An upper elbow placed at the height of the conductor bar • A lower elbow placed at the height of the conductor terminal.

[0034] According to one aspect of the invention, the connecting portions of the first conductor and the third conductor each comprise at least one conductive pad, electrically connected to a conductive bar of the connecting portion of the conductor on the one hand, and to a connection portion of the conductor on the other hand.

[0035] According to one aspect of the invention, the conductive pads are welded, in particular by laser welding, onto the conductive bars of the connecting portions of the conductors.

[0036] According to one aspect of the invention, the conductive pads of the connecting portions are placed between the transistors of a switch.

[0037] According to one aspect of the invention, the conductive pads are parallelepipeds made of conductive material, in particular copper.

[0038] According to one aspect of the invention, the conductive pads are welded, brazed or sintered onto the connection portions of the conductors.

[0039] According to one aspect of the invention, at least one of the conductive bars has a notch, i.e. a portion of lesser thickness.

[0040] For example, the notch is made by stamping.

[0041] According to one aspect of the invention, the connecting portions of the first conductor and the third conductor have a high thickness, for example a thickness of between 0.2 and 2 mm, in particular of between 0.8 mm and 1.2 mm.

[0042] According to one aspect of the invention, the connecting portions of the first conductor and the third conductor have a small thickness at the notch, in particular a thickness of between 0.1 mm and 0.8 mm, in particular 0.6 mm.

[0043] According to one aspect of the invention, the high thickness of the connecting portions of the first conductor and the third conductor makes it possible to reduce the width of these portions while retaining their electrical properties.

[0044] According to one aspect of the invention, the low thickness at the notch makes it easier to assemble the connecting portions of the first conductor and the third conductor. In particular, this low thickness makes it easier to solder the conductive bars to the pads of the connecting portions of the conductors.

[0045] In addition, the presence of a notch makes it easier to position the conductive bars on the pads during assembly of the connecting parts of the first and third conductors.

[0046] According to one aspect of the invention, at least one conductive bar of the connecting portions of the conductors comprises at least one welding zone, and at least one holding zone arranged to allow the conductive bar to be locked in position during assembly of the conductive bar on the conductive pad of the connecting portion, in particular during welding of the conductive bar on the conductive pad.

[0047] According to one aspect of the invention, at least one conductive bar comprises two peripheral holding zones arranged on either side of the central welding zone.

[0048] According to one aspect of the invention, at least one conductive bar comprises two peripheral welding zones arranged to be welded to two adjacent conductive pads, and located on either side of a central holding zone.

[0049] According to one aspect of the invention, all of the conductive bars of the power module comprise a central welding zone.

[0050] Alternatively, all of the conductive bars of the power module comprise two peripheral welding zones.

[0051] Alternatively, the power module comprises at least one conductive bar comprising a central welding zone, and at least one conductive bar comprising two peripheral welding zones.

[0052] The invention therefore advantageously allows the crossing of the power connections without using the surface of the substrate of the power module.

[0053] Not using the surface of the substrate thus makes it possible to move the transistors making up a switch away.

[0054] The use of conductive bars raised relative to the substrate makes it possible to reduce the length of the electrical connection and to increase their cross-section, which makes it possible to reduce the impedance of the connection portions and therefore to avoid losses.

[0055] The use of conductive pads placed between the transistors of a switch advantageously makes it possible to increase heat dissipation, and therefore to reduce the overall thermal impedance of the power module. List of figures

[0056] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0057] [Fig-1] [Fig. 1] is a top view representation of a power module according to the invention;

[0058] [Fig.2] [Fig.2] is a representation of a conductive bar of a power module according to the invention and its connection with a conductive pad;

[0059] [Fig.3] [Fig.3] is a representation of a conductive bar of a power module according to the invention.

[0060] [Fig.4] [Fig.4] is a representation of a conductive bar of a power module according to the invention.

[0061] [Fig.5] [Fig.5] is a top view of a power module according to another embodiment of the invention;

[0062] [Fig.6] [Fig.6] is a top view of a power module according to another embodiment of the invention;

[0063] [Fig.7] [Fig.7] is a top view of a power module according to another embodiment of the invention;

[0064] [Fig.8] [Fig.8] is a top view of a power module according to another embodiment of the invention;

[0065] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0066] [Fig.l] shows a power module 1 comprising three conductors C+, C-, C~ placed on a substrate 3

[0067] The first conductor C+ comprises a connection portion P+, two terminals B+, and two connection portions PL+.

[0068] The second conductor C- comprises a connection portion P- and a terminal B-.

[0069] The third conductor C~ comprises first and second portions of connection Pl~, P2~, a terminal B~, and a portion of connection PL~.

[0070] The portions of the conductors of the power module follow one another in a first direction DI in the order: the connection portion P- of the second conductor C-, the first connection portion Pl~ of the third conductor C~, the connection portion P+ of the first conductor C and the second connection portion P2~ of the third conductor C~.

[0071] The two connecting portions of the first conductor PL+ span the first connecting portion of the third conductor P1-.

[0072] In addition, the connecting portion of the third conductor PL- spans the connecting portion of the first conductor P+.

[0073] The connection portions of the conductors P+, P-, PI-, P2- are flat, parallel to each other and coplanar. They are deposited on the substrate 3.

[0074] The connecting portions PL+, PL- of the conductors each comprise a conductive bar 4.

[0075] These conductive bars 4 comprise a flat face defining the connection planes of the first and third conductors.

[0076] In the embodiment illustrated in [Fig. 1], the connection planes of the first and third conductors C+, C~ are coplanar and placed higher than the flat connection portions P+, P-, PI-, P2- of the conductors, at a height of 3mm.

[0077] The connecting portions of the conductors PL+, PL- are welded, brazed or sintered on the terminals B+, B- of the conductors C+, C~ at the level of a fixing pad 5 allowing the electrical connection between the terminal of the conductor and the connecting portion of the conductor.

[0078] In an embodiment not shown, at least one connecting portion PL+, PL- comprises a ramp, formed in one piece with the conductive bar 5, connecting the fixing area to the conductive bar of the connecting portion. This ramp then comprises a lower elbow placed at the height of the fixing area, and an upper elbow placed at the height of the conductive bar.

[0079] The power module 1 also comprises two switches between which a transistor control module 2 is placed.

[0080] The first switch is formed of first aligned TLS transistors, pressed against the first connection portion PI- of the third conductor C~ and electrically connected to the connection portion P- of the second conductor C-;

[0081] The second switch formed of second aligned THS transistors, the second THS transistors being pressed against the connection portion P+ of the first conductor C+ and electrically connected to the second connection portion P2- of the third conductor C~;

[0082] The transistors TLS, THS of a switch are separated by a distance Dt equal to 4 mm.

[0083] Each connecting portion also comprises two conductive pads 6, not visible in this figure and shown in [Fig.2]. These pads are placed between the transistors TLS, THS of a switch. They are electrically connected to a conductive bar 4 of the connecting portion PL+, PL- of the conductor C+, C~ on the one hand, and to a connection portion P+, PI-, P2- of the conductor on the other hand.

[0084] [Fig.2] shows the connection of a conductive bar 4 of the power module 1 to a conductive pad 6. The conductive pad, the conductive bar and the connection portion P shown in this figure can belong indifferently to the first or to the third conductor C+, C~.

[0085] The conductive pad 6 is parallelepipedal in shape and is made of conductive material, in particular copper.

[0086] It is welded by laser welding on the conductive bars 4 on the one hand, and welded, brazed or sintered on the connection portion P on the other hand.

[0087] The conductive bar comprises a notch 9 produced by stamping, in which the thickness e1 is less than the thickness e2 of the conductive bar 4.

[0088] The thickness e2 makes it possible to guarantee the electrical properties of the conductive bar 4, and the smaller thickness el at the level of the notch 9 makes it possible to position the conductive bar on the conductive pad and to facilitate welding.

[0089] Figures 3 and 4 show a conductive bar 4 of a power module 1 according to two embodiments of the invention. In these two figures, the conductive bar shown can belong indifferently to the first or third conductor C+, C~.

[0090] In [Fig.3], the conductive bar 4 has a central welding zone 7, and two peripheral holding zones 8 are arranged to allow the conductive bar to be locked in position when the conductive bar is welded to the conductive pad.

[0091] These two peripheral holding zones 8 are arranged on either side of the central welding zone 7.

[0092] In [Fig.4] on the other hand, the conductive bar 4 has two welding zones 7 peripherals arranged on either side of a central holding zone 8, and arranged to be soldered onto two adjacent conductive pads 6.

[0093] [Fig.5] shows a power module 1 according to another embodiment of the invention, in which the terminals B+, B~ of the conductors and the connecting portions PL+, PL- are formed in a single piece.

[0094] [Fig.6] shows a power module 1 according to another embodiment of the invention, in which the first conductor C+ comprises a single connection portion PL+.

[0095] In addition, the connection planes of the first and third conductors C+, C~ are not coplanar, and the connection plane of the third conductor is placed higher than the connection plane of the first conductor.

[0096] [Fig.7] shows a power module 1 according to another embodiment of the invention. Here, the first conductor C+ comprises a single connection portion PL+ and the connection plane of the third conductor is placed higher than the connection plane of the first conductor.

[0097] The connecting portions PL+, PL- of the first and third conductors C+, C~ here have a “U” shape, and are superimposed.

[0098] [Fig. 8] shows a power module 1 according to another embodiment of the invention. Here, the first conductor C+ comprises two connecting portions PL+ and the connecting plane of the third conductor C~ is placed lower than the connecting plane connection of the first conductor.

Claims

Claims

1. Power module (1) comprising: • A substrate (3) • a first conductor (C+) comprising a connection portion (P+), at least one terminal (B+), and at least one linking portion (PL+); • a second conductor (C-) comprising a connection portion (P-) and a terminal (B-); • a third conductor (C~) comprising first (Pl~) and second connection portions (P2~), at least one terminal (B~), and at least one linking portion (PL~); Characterized in that at least one linking portion (PL+) of the first conductor (C+) spans a connection portion (P~) of the third conductor (C~), or that at least one linking portion (PL~) of the third conductor (C~) spans a connection portion (P+) of the first conductor (C+).

2. Power module (1) according to claim 1, wherein the connection portions (P+, P-, Pl~, P2~) of the conductors (C+, C-, C~) of the power module follow one another in a first direction (Dl) in the order: the connection portion (P-) of the second conductor (C-), the first connection portion (Pl~) of the third conductor (C~), the connection portion (P+) of the first conductor (C+) and the second connection portion (P2~) of the third conductor (C~);

3. Power module (1) according to one of the preceding claims, comprising: • a first switch formed of first aligned transistors (LS), the first transistors being pressed against the first connection portion (Pl~) of the third conductor (C~) and electrically connected to the connection portion (P-) of the second conductor (C-); • a second switch formed of second aligned transistors (THS), the second transistors being pressed against the connection portion (P+) of the first conductor (C+) and electrically connected to the second connection portion (P2~) of the third conductor (C~); • and between the first transistors (TLS) and the second transistors (THS), a transistor control circuit (2).

4. Power module (1) according to claim 3, in which the transistors (TLS, THS) of a switch are spaced apart by a distance (Dt) greater than 2 mm.

5. Power module according to one of the preceding claims, in which the flat connection portions (P+, P-, Pl~, P2~) of the conductors (C+, C-, C~) extend parallel to each other, and parallel to the plane of the substrate (3).

6. Power module (1) according to one of the preceding claims, in which the connecting portions (PL+, PL~) of the conductors (C+, C-, C~) comprise a conductive bar (4) comprising a flat face parallel to the plane of the substrate (3).

7. Power module (1) according to claim 6, in which the flat faces of the conductive bars (4) of the first conductor are coplanar and define a connection plane of the first conductor (C+).

8. Power module (1) according to one of claims 6 to 7, in which the flat faces of the conductive bars (4) of the third conductor (C~) are coplanar and define a connection plane of the third conductor.

9. Power module (1) according to claims 6 to 8, wherein the connection planes of the first conductor (C+) and of the third conductor (C~) are placed higher than the flat faces of the flat connection portions (P+, P-, Pl~, P2~) of the conductors (C+, C-, C~).

10. Power module (1) according to one of the preceding claims, in which the connecting portions (PL+, PL~) of the first conductor (C+) and of the third conductor (C~) each comprise at least one conductive pad (6), electrically connected to a conductive bar (4) of the connecting portion (PL+, PL~) of the conductor on the one hand, and to a connection portion (P+, P~) of the conductor on the other hand.

11. Power module (1) according to claim 10, in which the conductive pads (6) are welded, in particular by laser welding, onto the conductive bars (4) of the connecting portions (PL+, PL~) of the conductors (C+, C~).

12. Power module (1) according to one of claims 10 to 11, in which the conductive pads (6) are welded, brazed or sintered on the connection portions (P+, Pl~, P2~) of the conductors (C+, C~).

13. Power module (1) according to one of claims 10 to 12, in which at least one of the conductive bars (4) of the first conductor (C+) and of the third conductor (C~) has a (9), that is to say a portion of lesser thickness.

14. Power module (1) according to one of claims 10 to 13, in which at least one conductive bar (4) of the connecting portions (PL+, PL~) of the conductors (C+, C~) comprises at least one welding zone (7), and at least one holding zone (8) arranged to allow the conductive bar (4) to be locked in position during assembly of the conductive bar on the conductive pad (6) of the connecting portion, in particular during welding of the conductive bar on the conductive pad.

15. Power module (1) according to one of claims 10 to 14, in which at least one conductive bar (4) comprises two peripheral holding zones (8) arranged on either side of the central welding zone (7).

16. Power module (1) according to one of claims 10 to 14, in which at least one conductive bar (4) comprises two peripheral soldering zones (7) arranged to be soldered to two adjacent conductive pads (6), and located on either side of a central holding zone (8).

Images