Electronic power card

Abstract

The present invention relates to an electronic power card (1) comprising: - a capacitive laminated busbar (2) in the form of a first stack of two metal layers, in particular made of copper, namely a so-called inner metal layer and a so-called outer metal layer (4) separated from each other by a first layer of electrically insulating material; - a layer of thermal interface material arranged between the first stack and a metal baseplate; - an integrated current sensor comprising a magnetic flux concentrator (9) which is inserted into openings made in the metal baseplate, the magnetic flux concentrator (9) containing a second stack of layers comprising a second layer of electrically insulating material, a layer of conductive material able to conduct the current to be measured, a printed circuit board referred to as PCB, and a component for measuring the current.

Description

[0001] ELECTRONIC POWER BOARD

[0002] Technical field

[0003] The present invention relates to power electronic design, and more particularly to the design of electronic power cards integrating, for example, semiconductors. These power cards are generally implemented in applications related to the conversion of electrical energy in different fields. This may be the field of automotive or aeronautical transport (electric and hybrid motors for automobiles in particular) and the field of energy (electric self-consumption in a home / building, application to intelligent networks known under the Anglo-Saxon term "Smart Grid", vehicle-to-electric network application known under the Anglo-Saxon term "Vehicle-to-Grid" or V2G, etc.).

[0004] Prior art

[0005] There are many configurations for this type of card, each with its own advantages and disadvantages. One problem that must be addressed during their design is, in particular, to provide for the heat dissipation in the card to be as efficient as possible. Patents FR 2801 725 and US8232637 address this issue: the former uses an external heat sink adapted according to the desired power, which increases the overall size of the system, and the latter provides for cooling fluid channels integrated into a card, which complicates its design and operation.

[0006] Another issue is the compactness of the board, and there is a real need to integrate all electrical / electronic components into a single system, which can be as compact / integrated as possible.

[0007] The invention then aims to design an improved power board. Its aim is in particular to provide a board that allows greater integration of its components, while maintaining or improving its performance in terms of heat dissipation.

[0008] Summary of the invention

[0009] The invention firstly relates to an electronic power card comprising

[0010] - a capacitive laminated bus bar in the form of a first stack of two layers of metal, in particular copper, namely an internal metal layer and an external metal layer separated from each other by a first layer of electrically insulating material,

[0011] - a layer of thermal interface material arranged between said first stack and a metal sole,

[0012] - an integrated current sensor comprising a magnetic flux concentrator (9) which is inserted into openings made in the metal sole, said magnetic flux concentrator containing a second stack of layers comprising a second layer of electrically insulating material, a layer of material conductive to the current to be measured, a printed circuit called PCB, and a current measuring component.

[0013] This card is in particular of the insulated metal substrate type, called SMI, in particular multi-layer, for example with two, three or four layers, preferably single-sided. In an exemplary embodiment, it is a two-layer, single-sided insulated metal substrate.

[0014] The term "bus bar", although of Anglo-Saxon origin, is well known in the field of electronic cards, and can be translated by the French term interconnection bar or electrical distribution bar.

[0015] The term "base" is also well known in the field of electronic cards, and corresponds to the support of the card, on which the layers and components are deposited.

[0016] The invention thus proposes a power card which can integrate electronic and / or mechanical and / or electromechanical functions, and whose design allows, in particular, the integration of different components, in particular new generation semiconductor components known as wide band gap components, also known by the Anglo-Saxon term “Wide Band Gap” components, within high power density converters.

[0017] To do this, the invention therefore uses an SMI type card with several layers of metal (generally copper) and not a single layer: a laminated bus bar is thus formed according to the invention, with two metal layers, which can be placed respectively at the positive potential and the negative potential of a voltage source, for example an electric battery, to which the card is intended to be connected. Compared to a conventional power module, the card according to the invention with this laminated bus bar to which ceramic capacitors can be associated, will make it possible to eliminate, or at least drastically reduce, the inductive effects linked to the length of the loops between the positive and negative potentials in question. Indeed, the ceramic capacitors can be placed as close as possible to the semiconductor components.

[0018] Another advantage of the card according to the invention is that it can be produced using conventional manufacturing techniques, in particular with any EMS (Electronic Manufacturing Service) type tool: it is therefore inexpensive / simple to produce. It also remains compatible with most standard discrete packages of surface-mounted semiconductor components.

[0019] Preferably, the magnetic flux concentrator has a bottom wall, in particular of square or parallelepiped shape, and side walls, two of said side walls, in particular opposite walls, being inserted into two openings made in the metal sole.

[0020] Preferably, the second stack is secured to the internal face of the sole portion arranged between the two openings, and the opposite face of said sole portion is secured to the bottom wall of the magnetic flux concentrator, in particular by a layer of glue. The term "internal face" means that which is on the side of the stack in question.

[0021] This concentrator thus has, for example, a U-shape, with a flat bottom wall, which receives the second stack, and two side walls which extend perpendicular to the flat wall from two of its opposite edges, and which, by inserting themselves into the openings of the metal sole, press the bottom wall provided with the second stack against one of the faces of the portion of sole which is located between the two openings, while the side walls pass through the sole through its openings and extend on the side of the opposite face of said sole. The other face of the portion of sole in question supports the second stack.

[0022] Making openings in the sole therefore allows the concentrator to be integrated into the card in a simple, efficient and compact way.

[0023] Advantageously, the inner metal layer and / or the outer metal layer may extend relative to each other so as to provide at least one accessible area on the outer surface of each of the outer and inner layers, in particular to form tracks for fixing components thereto, in particular by soldering, of components, in particular at least one chosen from alternating current connectors, direct current connectors, capacitors, power semiconductors, direct or alternating current voltage measurement components. In fact, the outer layer only partially covers the inner layer, areas of the inner layer "exceed" the extent of the outer layer so as to be accessible. The outer layer may also "exceed" the extent of the inner layer: they therefore do not have the same extent, even if the majority of their surfaces overlap (via the intermediate layer of electrical insulation).Preferably, the first part of the outer metal layer of the first stack is provided with a coating of protective material of the varnish type (not shown), and in that other parts of said outer metal layer are devoid of coating and constitute tracks for fixing thereto, in particular by soldering, components, in particular at least one chosen from alternating or direct current connectors, capacitors, power semiconductors, phase voltage measurement components. Indeed, it is known to protect the outer metal layer with a protective varnish, and it is therefore possible to choose to selectively remove the varnish in certain areas (or to deposit it selectively) to leave one or more “bare” areas for connecting / fixing components there.

[0024] Advantageously, the card according to the invention comprises at least one capacitor, in particular of the ceramic type, and / or at least one DC- and DC+ direct current electrical connector, which is fixed, in particular by soldering, respectively by their positive terminal on the external metal layer and by their negative terminal on the internal metal layer of the first stack.

[0025] Advantageously, the card according to the invention comprises at least one AC alternating current connector and / or at least one power semiconductor fixed on the external metal layer or on the internal metal layer: the external and internal metal layers are then preferably equipped with vias directly above the location of said AC alternating current connector(s) and / or said power semiconductor(s). These vias (or microvias) are, in a known manner, produced in the form of pins, made of electrically conductive material, which are placed between the two layers and in contact with them and which thus ensure the sharing of the current between the two metal layers and they also have a role as heat sinks.

[0026] The invention, by integrating the bus bar with two metal layers on the power card, thus allows electrical connections of the latter to different electronic components, and in particular to power semiconductors, ("electronic chips") without needing to resort to filament-type connection means ("wire bonding" in English) between the bus bar and electronic components, which is very advantageous: the filaments are difficult to assemble to a card and can also prove to be fragile / not very robust mechanically in use.

[0027] The card according to the invention may comprise at least one direct or alternating current voltage measuring component, fixed, in particular by soldering, to the external metal layer or to the internal metal layer of the first stack. Advantageously, the card may comprise components capable of emitting heat in operation, fixed to the internal or external metal layer, in particular at least one power semiconductor and / or at least one connector, in particular AC alternating current, and the external and internal metal layers are equipped with vias in the vicinity of said components. These vias (or microvias), as indicated above, ensure current sharing between the two layers, but in addition, here, they will promote heat dissipation from the components most likely to create heat, which is the case of the power semiconductors and the alternating current connectors, towards the metal base of the card.

[0028] According to one embodiment, the metal sole is thermally connected to a heat sink component, which is external to the board. In this case, its thickness is conventional, for example of the order of 1 to 5 mm.

[0029] In another embodiment, the face of the metal sole opposite the face supporting the second layer of electrically insulating material has three-dimensional patterns, including fins. The sole of the card thus becomes the heat sink component of the card, thus eliminating the need for an external heat sink component (or at least using a less efficient / less bulky heat sink component). This achieves an additional level of integration for the card.

[0030] The invention also relates to any multi-layer SMI type power board whose sole is thus configured.

[0031] In particular, in this embodiment, a fairly thick metal sole can be provided, for example at least 5 mm, or more than 5 mm, in particular at least 8 or 10 mm, and even several tens of millimeters. Its thickness can in particular be between 10 and 30 mm or between 10 and 20 mm, so as to have a sufficient thickness to engrave the fin or spike type patterns while maintaining the continuity of the sole.

[0032] According to yet another embodiment, the face of the metal sole which is opposite that supporting the second layer of electrically insulating material is provided, in particular by brazing or additive manufacturing, with a layer, in particular continuous or discontinuous, of metallic material which has three-dimensional surface patterns, of the fin type. Here, a heat sink component is therefore integrated by securing it to the sole.

[0033] Advantageously, the card according to the invention comprises power semiconductors: it forms an inverter for controlling an electrical machine, said inverter comprises a plurality of switching arms, each switching arm comprising power semiconductors.

[0034] The invention also relates to the use of the card described above to control the electrical power supply of an electrical machine (an electric motor).

[0035] Description of the embodiments

[0036] The invention will be described below in more detail using figures and non-limiting examples implementing it.

[0037] List of figures

[0038] Figure 1 is a schematic representation of a voltage inverter type power stage

[0039] Figure 2 is a top view representation of an example of a card according to the invention, Figure 3 is a bird's eye view representation of the example of a card according to the invention according to Figure 2.

[0040] Figure 4 is a simplified representation of a portion of the example map according to Figures 2 and 3.

[0041] Figure 4 is a simplified representation of a variant of the portion of the example map according to Figures 2 and 3.

[0042] Figure 6 is a representation of the metal base of an example of a card according to the invention, in accordance with Figure 4.

[0043] Figures 7a and 7b represent the two layers of metal (Cu) used in an example of a card, as shown in particular in Figures 2 and 3.

[0044] Figure 8 is a simplified representation of a magnetic concentrator integrated into an example of a card according to the invention, as shown in particular in Figures 2 and 3.

[0045] The figures are not exhaustive, are extremely schematic for at least some of them, and do not necessarily respect the scale between the different components represented.

[0046] The same references designate, from one figure to another, the same components / elements.

[0047] A non-limiting example of a card will be described below using the various figures: Figure 1 represents the electronic diagram of an example of a card according to the invention, according to the conventions known in the field. The following are represented:

[0048] - direct current connections 18,19 to the positive and negative terminals (DC+ and DC-)

[0049] - a capacitive laminated bus bar with the two layers of metal (copper), which in fact corresponds to an assembly comprising the connectors 18, 19 and the capacitors 20 - power semiconductors 21

[0050] - AC 16 electromechanical alternating current connectors

[0051] - 8 current sensors

[0052] - 20 ceramic capacitors

[0053] Figures 2 and 3 are complementary views of an example of a card implementing this electronic scheme: we see a card 1 comprising power semiconductors 21, the external metal layer 4 of the laminated bus bar 2 (described later), direct current connectors 18, 19, electromechanical alternating current connectors 16, ceramic capacitors 20, current sensors integrated in magnetic concentrators 9 (detailed later), all these components being fixed / connected to the laminated bus bar 2 as detailed later, vias 23 to ensure electrical continuity between the two metal layers 3 and 4, in particular in the area of ​​the alternating current connector, and / or to facilitate heat dissipation in the vicinity of the components most likely to release heat, in particular the power semiconductors, and finally a metal sole 7.

[0054] Figure 4 shows in a simplified cross-section a portion of the structure of the capacitive laminated bus bar 2: it comprises an electrical insulating layer 5 arranged between a metal (copper) layer 3 called internal, and a metal (copper) layer 4 called external, constituting a first stack. The electrical insulating layer 5 can for example be based on polymers, based on polyimide or epoxy type polymer possibly reinforced, for example by glass fibers, for example those marketed by the company Arlon.

[0055] This first stack is secured by its internal metal layer 3 to the metal sole 7 by a layer 6 of thermal interface material. This layer 6 may also be based on polymer(s), in particular those designated under the term of polymer with controlled thermal expansion (“Controlled Thermal Expansion” in English), in particular those marketed by the company Arlon Electronics under the name SMT, which may be based on epoxy or polyimide, reinforced with woven or non-woven aramid. The sole 7 is preferably made of aluminum.

[0056] Figure 5 is a variant of Figure 4 concerning the shape of the sole: here, the sole 7' is worked so as to present on its external face (that is to say the face opposite to that in contact with the layer 6) reliefs, such as fins or spikes, so as to create a high exchange surface with the exterior. The sole can then fully play the role of an integrated heat sink, making it possible to consider eliminating any external heat sink (or at least to provide one that is less efficient or more compact than that to be provided conventionally). In this case, a fairly thick sole can be provided, several millimeters (at least 8 to 10 mm, for example between 10 and 30 or between 10 and 20 mm), so as to be able to engrave the desired patterns on the external face over a certain thickness, to develop as much as possible the exchange surface of the sole with the exterior, while maintaining the continuity of the sole of course.

[0057] Figure 6 shows the outer face of the sole 7' according to Figure 5, with three-dimensional patterns in the form of spikes, which are distributed uniformly over the entire outer surface in question. Alternatively, non-homogeneous distributions of the patterns can be provided, with greater concentrations of patterns in certain areas of the sole. The patterns can always be the same or vary in their shape or size on the surface of the sole.

[0058] Figures 7a and 7b respectively represent the outer metal layer 4 and the inner metal layer 3 of the laminated bus bar 2. In the stack described in Figure 4, only the superimposed portions of the two layers were represented.

[0059] But, as is known, they present

[0060] - areas, in particular delimited by the dotted lines 4a shown in figure 7b, where the external layer 4 completely covers the internal layer 3,

[0061] - and areas of the internal layer 3 which “exceed” the external layer 4, in particular a substantially square or rectangular area delimited by the dotted lines 3a shown in figure 7b, to provide tracks where components and connectors can be fixed / connected on this internal layer.

[0062] The outer layer 4 is provided with a protective varnish (not shown), in a known manner, except in specific areas to provide tracks where components and connectors can be fixed / connected.

[0063] Thus, as shown in Figure 7a, the outer layer 4 is provided (preferably by welding) with a direct current connector DC+ 18, at least one capacitor 20, an alternating current connector AC 16, and at least one power semiconductor 21.

[0064] And as shown in Figure 7b, the inner layer 3 is provided (also preferably by soldering) with a DC-19 direct current connector.

[0065] Figure 8 details the structure of the current measurement sensor 8 and how it is integrated into the board 1: it comprises a U-type magnetic concentrator 9, i.e. having a bottom wall 91 and two opposite side walls 92 perpendicular to the bottom wall. This concentrator is inserted into the sole 7 through two openings 10 made in the sole 7 with the appropriate dimensional adjustments so that the concentrator 9 can be held in position with its bottom wall 91 which is arranged against the external face of the portion of sole 7 which is located between the two openings 10. Its side walls 92 extend on the side of the opposite, internal face of said portion of sole.In the concentrator 9, there is a stack of layers which successively comprises a layer 11 of insulating dielectric material (in particular of the polymer type, in particular based on polyimide or epoxy, such as those marketed by the company ARLON), a layer 12 of material conducting the current to be measured (for example copper), a printed circuit 13 (RF4 PCB) and the current measuring element 14 (for example an integrated current measuring circuit called Cl)).

[0066] It can be seen that the side walls 92 of the concentrator 9 are higher than this stack of layers / components. This stack of layers and components 11, 12, 13, 14 is therefore located on one of the faces, called the internal one, of the sole portion 7 which is located between the two openings 10 through which the concentrator 9 has been inserted. The layers are secured to each other by known techniques, in particular by gluing. Thus, the printed circuit layer 13 is preferably secured to the layer 12 of conductive material and to the layer 14 of current measuring element by gluing (glue layers not shown).

[0067] And to secure the assembly (stack on sole portion 7) to the concentrator 9, for example, a layer of glue 23 is also used. This glue is therefore placed between the internal face of the bottom wall 91 of the concentrator 9 and the external face of the sole portion (i.e. the face opposite the internal face on which the stack has been placed).

[0068] It is understood that the power card according to the invention can comprise a variable number of components depending on the needs / specifications (ceramic capacitors, power semiconductors, voltage or current measurement components).

[0069] We can see that this card perfectly meets the increasingly advanced integration needs in the field of power electronics, whatever the electrical system targeted. It can be used advantageously in the field of electrified transport in particular.

[0070] We also see that this card remains simple to assemble, and that it can notably avoid having to use connection filaments for the bus bar. It should also be noted that the assembly of the different components of the card can be envisaged without high precautions, without being constrained to assembly in a clean room for example, when the semiconductors (the "chips" are not bare (are not "bare-die" in English), which is preferred in the present invention.

Claims

Claims 1. Electronic power board (1) comprising - a capacitive laminated bus bar (2) in the form of a first stack of two layers of metal, in particular copper, namely an internal metal layer (3) and an external metal layer (4) separated from each other by a first layer (5) of electrically insulating material, - a layer (6) of thermal interface material arranged between said first stack and a metal sole (7), - an integrated current sensor (8) comprising a magnetic flux concentrator (9) which is inserted into openings (10) made in the metal sole (7), said magnetic flux concentrator (9) containing a second stack of layers comprising a second layer (11) of electrically insulating material, a layer (12) of material conductive to the current to be measured, a printed circuit (13) called PCB, and a current measuring component (14).

2. Card (1) according to the preceding claim, characterized in that it is a card of the insulated metal substrate type known as SMI, in particular multi-layer, in particular double-layer and single-sided.

3. Card (1) according to one of the preceding claims, characterized in that the magnetic flux concentrator (9) has a bottom wall (91), in particular of square or parallelepipedal shape, and side walls (92), two of said side walls, in particular opposite walls, being inserted into two openings made (15) in the metal sole (7).

4. Card (1) according to the preceding claim, characterized in that the second stack is secured to the internal face of the sole portion arranged between the two openings (15), and in that the opposite face of said sole portion is secured to the bottom wall (91) of the magnetic flux concentrator (9), in particular by a layer of glue (23).

5. Card (1) according to one of the preceding claims, characterized in that the internal metal layer (3) and / or the external metal layer (4) extend relative to each other so as to provide at least one accessible area on the external surface of each of the external (4) and internal (3) layers, in particular to constitute tracks for fixing components there, in particular by soldering, of components, in particular at least one chosen from alternating current connectors (16), direct current connectors (18, 19), capacitors (20), power semiconductors (21), components (22) for measuring direct or alternating current voltage.

6. Card (1) according to one of the preceding claims, characterized in that a first part of the external metal layer (4) of the first stack is provided with a coating of protective material of the varnish type, and in that other parts of said external metal layer (4) are devoid of coating and constitute tracks for fixing thereto, in particular by soldering, components, in particular at least one chosen from alternating or direct current connectors (16, 18, 19), capacitors (20), power semiconductors (21), phase voltage measurement components (22).

7. Card (1) according to one of the preceding claims, characterized in that at least one capacitor (20), in particular of the ceramic type, and / or at least one DC- and DC+ direct current electrical connector (18, 19) is fixed, in particular by soldering, respectively by their positive terminal on the external metal layer (4) and by their negative terminal on the internal metal layer (3) of the first stack.

8. Card (1) according to one of the preceding claims, characterized in that it comprises at least one AC alternating current connector (16, 17) and / or at least one fixed power semiconductor (21) fixed on the external metal layer (4) or on the internal metal layer (3), and in that the external (4) and internal (3) metal layers are equipped with vias (23) directly above the location of said AC alternating current connector(s) (16) and / or said power semiconductor(s) (21).

9. Card (1) according to one of the preceding claims, characterized in that it comprises at least one component (22) for measuring direct or alternating current voltage, fixed, in particular by welding, on the external metal layer (4) or on the internal metal layer (3) of the first stack.

10. Card (1) according to one of the preceding claims, characterized in that the card comprises components capable of emitting heat in operation, fixed on the internal (3) or external (4) metal layer, in particular at least one power semiconductor (21) and / or at least one connector, in particular AC alternating current (16, 17), and in that the external (4) and internal (3) metal layers are equipped with vias (23') in the vicinity of said components.

11. Card (1) according to one of the preceding claims, characterized in that the metal sole (7) is thermally connected to a heat dissipating component.

12. Card (1) according to one of the preceding claims, characterized in that the face of the metal sole (7') which is opposite that supporting the second layer of electrically insulating material (6) has three-dimensional patterns, in particular fins.

13. Card (1) according to the preceding claim, characterized in that the metal sole (7') has a thickness of at least 5 mm, in particular at least 8 or 10 mm, in particular between 10 and 30 mm.

14. Card (1) according to one of the preceding claims, characterized in that the face of the metal sole (7) which is opposite that supporting the second layer of electrically insulating material (6) is provided, in particular by soldering or additive manufacturing, with a layer, in particular continuous or discontinuous, of metallic material which has three-dimensional surface patterns, of the fin type.

15. Card (1) according to one of the preceding claims, characterized in that said card comprises power semiconductors (21), and in that it forms an inverter for controlling an electrical machine, said inverter comprises a plurality of switching arms, each switching arm comprising power semiconductors (21).

16. Use of the card according to one of the preceding claims for controlling the electrical power supply of an electric motor.

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