Electronic power board

Abstract

The present invention relates to an electronic power card (1) comprising - a capacitive laminated bus bar (2) in the form of a first stack of two layers of metal, in particular 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 said first stack and a metal sole, - an integrated current sensor comprising a magnetic flux concentrator (9) which is inserted into openings made in the metal sole, said magnetic flux concentrator (9) 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. Figure for the abstract: Fig 2

Description

Title of the invention: Electronic power card Technical field

[0001] 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 motor for automobiles in particular) and the field of energy (electric self-consumption in a home / building, application to intelligent networks known by the Anglo-Saxon term "Smart Grid", vehicle-to-electric network application known by the Anglo-Saxon term "Vehicle-to-Grid" or V2G, etc.). Prior art

[0002] There are many configurations for this type of card, all of which have their advantages and disadvantages. One problem that must be addressed during their design is, in particular, to provide for the heat dissipated in the card to be evacuated as efficiently as possible. Patents FR 2801 725 and US8232637 thus address this problem: the first uses an external heat sink adapted according to the desired power, which increases the overall size of the system, and the second provides cooling fluid channels integrated into a card, which complicates its design and operation.

[0003] Another issue is the compactness of the board, and there is a real need to integrate all the electrical / electronic components into a single system, which can be as compact / integrated as possible.

[0004] The invention then aims to design an improved power card. Its aim is in particular to provide a card which allows greater integration of its components, while maintaining, or improving, its performance in terms of heat dissipation. Summary of the invention

[0005] The invention firstly relates to an electronic power card comprising - 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, - a layer of thermal interface material arranged between said first stack and a metal sole, - 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] The invention thus proposes a power card which can integrate electronic and / or mechanical and / or electromechanical functions, and whose design makes it possible, in particular, to integrate different components, in particular new generation semiconductor components known as wide band gap components, also known by the English term “Wide Band Gap” components, within high power density converters.

[0010] 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 type 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 arranged as close as possible to the semiconductor components.

[0011] Another advantage of the card according to the invention is that it can be produced using conventional manufacturing techniques, in particular with any EMS type tool (for the acronym of the Anglo-Saxon term “Electronic Manufacturing Service”): It is therefore inexpensive / simple to produce. It also remains compatible with most standard discrete surface-mount semiconductor component packages.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] Advantageously, the internal metal layer and / or the external metal layer may extend relative to each other so as to provide at least one accessible area on the external surface of each of the external and internal layers, in particular to constitute 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 external layer only partially covers the internal layer, areas of the internal layer "exceed" the extent of the external layer so as to be accessible.The outer layer can 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).

[0016] Preferably, the first part of the external 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 external 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 one can therefore choose to selectively remove the varnish in certain areas (or deposit it selectively) to leave one or more “bare” areas to connect / fix components there.

[0017] Advantageously, the card according to the invention comprises at least one capacitor, in particular of the ceramic type, and / or at least one direct current DC- and DC+ electrical connector, which is fixed, in particular by welding, respectively by their positive terminal on the external metal layer and by their negative terminal on the internal metal layer of the first stack.

[0018] 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.

[0019] 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.

[0020] Advantageously, the card may comprise components capable of emitting heat in operation, fixed on 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 the heat dissipation of 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.

[0021] According to one embodiment, the metal sole is thermally connected to a heat sink component, which is external to the card. In this case, its thickness is conventional, for example of the order of 1 to 5 mm.

[0022] According to another embodiment, the face of the metal sole which is opposite that supporting the second layer of electrically insulating material has three-dimensional patterns, in particular fins. The sole of the card thus becomes the heat dissipating component of the card, it is thus possible to no longer need an external heat dissipating component (or at least to use a lower-performance / less bulky heatsink component). This achieves an additional level of integration for the card.

[0023] The invention also relates to any multi-layer SMI type power card whose base is thus configured.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The invention also relates to the use of the card described above for controlling the electrical power supply of an electrical machine (an electric motor). Description of the embodiments

[0028] The invention will be described below in more detail using figures and non-limiting examples implementing it. List of figures

[0029] [Fig.l] [Fig.l] is a schematic representation of a power stage of the voltage inverter type [Fig.2] [Fig.2] is a top view representation of an example of a card according to the invention. [Fig.3] [Fig.3] is a bird's eye view representation of the example card according to the invention according to [Fig.2]. [Fig.4] [Fig.4] is a simplified representation of a portion of the example map according to Figures 2 and 3. [Fig.5] [Fig.4] is a simplified representation of a variant of the portion of the example map according to Figures 2 and 3. [Fig.6] [Fig.6] is a representation of the metal base of an example of a card according to the invention, in accordance with [Fig.4]. [Fig.7a] and [Fig.7a] 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. [Fig.8] [Fig.8] is a simplified representation of a magnetic concentrator integrated into an example of a card according to the invention, as represented in particular in Figures 2 and 3.

[0030] The figures are not limiting, are extremely schematic for at least some of them, and do not necessarily respect the scale between the different components represented.

[0031] The same references designate, from one figure to another, the same components / elements.

[0032] A non-limiting example of a card will be described below using the various figures: [Fig.l] 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: - direct current connections 18,19 to the positive and negative terminals (DC+ and DC-) - 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 - AC 16 electromechanical alternating current connectors - 8 current sensors - 20 ceramic capacitors

[0033] 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 components most likely to give off heat, in particular power semiconductors, and finally a metal sole 7.

[0034] [Fig. 4] represents in a simplified manner in cross section a portion of the structure of the capacitive laminated bus bar 2: it comprises a layer of electrical insulation 5 arranged between a metal layer (copper) 3 called internal, and a metal layer (copper) 4 called external, constituting a first stack. The layer of electrical insulation 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. 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.

[0035] [Fig.5] is a variant of [Fig.4] concerning the shape of the sole: here, the sole 7' is worked so as to present on its external face (i.e. the face opposite 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, we can provide a fairly thick sole, several millimeters (at least 8 to 10 mm, for example between 10 and 30 or between 10 and 20 mm), so that the desired patterns can be engraved 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.

[0036] [Fig. 6] shows the outer face of the sole 7' according to [Fig. 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.

[0037] 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 [Fig.4], only the overlapping portions of the two layers were represented. But, as is known, they present - areas, in particular delimited by the dotted lines 4a shown in [Fig.7b], where the external layer 4 completely covers the internal layer 3, - 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 [Fig.7b], to provide tracks where components and connectors can be fixed / connected on this internal layer. 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.

[0038] Thus, as shown in [Fig.7a], the external 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.

[0039] And as shown in [Fig.7b], the internal layer 3 is provided (also preferably by welding) with a DC-19 direct current connector.

[0040] [Fig.8] details the structure of the current measuring sensor 8 and the way in which it is integrated into the card 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 CI).

[0041] 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 internal, 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 so lidarized to layer 12 of conductive material and to layer 14 of current measuring element by gluing (glue layers not shown).

[0042] 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 deposited).

[0043] 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).

[0044] It can be seen that this card perfectly meets the increasingly advanced integration needs in the field of power electronics, whatever the electrical system targeted. It can in particular be used advantageously in the field of electrified transport.

Claims

Claims

1. Electronic power card (1) comprising - a capacitive laminated bus bar (2) in the form of a first stack of two layers of metal, in particular copper, namely a so-called inner metal layer (3) and a so-called outer 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 component (14) for measuring the current.

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 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.

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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