Power switching modular element and dismountable assembly of a plurality of modular elements

Abstract

The invention relates to a modular element (2) comprising a stratification of first and second electroconductive plates (PH2, PB2) which are separated by an intermediate dielectric layer (CD2) and at least one electronic power switching chip (CP1, CP2) which is implanted between the first and second plates, the chip having a upper face comprising a first power electrode and a switching control electrode and a lower face comprising a second power electrode, and the first and second power electrodes being in electrical continuity respectively with the first and second plates. According to the invention, the modular element comprises a plurality of openings (OG2, OA2, OB2, OC2, OD2) extending into the stratification from outer surfaces of the first and second plates and perpendicularly to said outer surfaces, the plurality of openings comprising at least one first opening (OG2) communicating with the switching control electrode and at least one second opening (OA2, OB2) passing through the entire stratification, the first and second openings each comprising a dielectric layer (DE2) and an electroconductive layer (CI2), and the electroconductive layer of the first opening being electrically connected to the switching control electrode.

Claims

1. A power switching modular element comprising a lamination of first and second electroconductive plates that are separated by an intermediate dielectric layer, and at least one electronic power switching chip which is implanted between said first and second electroconductive plates, said electronic power switching chip having an upper face comprising a first power electrode and a switching control electrode, and a lower face comprising a second power electrode, and said first and second power electrodes being electrically connected to said first and second electroconductive plates, respectively, wherein said power switching modular element comprises a plurality of openings which extend into said lamination from the outside surfaces of said first and second electroconductive plates and perpendicularly to said outside surfaces, said plurality of openings comprising at least one first opening that communicates with said switching control electrode, and at least one second opening which passes through the entirety of said lamination, said first and second openings each comprising a dielectric layer and an electroconductive layer, and said electroconductive layer of said first opening being electrically connected to said switching control electrode.

2. The power switching modular element according to claim 1, wherein said openings are distributed in a manner having a fixed spacing pitch.

3. The power switching modular element according to claim 1, wherein said power switching modular element comprises two electronic power switching chips which are mounted in parallel, said electronic power switching chips being implanted side-by-side and having the switching control electrodes thereof facing each other, and comprising a first opening that communicates with said switching control electrodes and having an electroconductive layer that is electrically connected to the switching control electrodes.

4. The power switching modular element according to claim 1, wherein said electronic power switching chip is a transistor chip of the vertical type.

5. A disassemblable power switching assembly comprising at least two power switching modular elements according to claim 1 and a plurality of electroconductive assembly pins, wherein said electroconductive assembly pins are received in said openings of said power switching modular elements and ensure mechanical assembly and electrical connection functions between said power switching modular elements.

6. The disassemblable power switching assembly according to claim 5, wherein said two power switching modular elements are arranged top-to-bottom.

7. The disassemblable power switching assembly according to claim 5, wherein said power switching assembly has, on an outside surface of one of said power switching modular elements, accessibility to a plurality of electrical connections with the switching control electrodes of the electronic power switching chips of said power switching modular elements, said plurality of electrical connections being ensured by means of said first openings of said power switching modular elements and said electroconductive assembly pins.

8. The disassemblable power switching assembly according to claim 5, wherein said power switching assembly comprises a fluid circulation channel defined by a space between said power switching modular elements, said space being determined by a spacing between said power switching modular elements obtained by means of said electroconductive assembly pins.

9. The disassemblable power switching assembly according claim 5, wherein said power switching assembly also comprises at least one assembly and interconnection element that is interposed between said power switching modular elements, said assembly and interconnection element comprising at least one electroconductive bar in which a plurality of through-openings are arranged, said through-openings being distributed by said fixed spacing pitch, and receiving said conductive assembly pins.

10. The disassemblable power switching assembly according to claim 9, wherein said assembly and interconnection element comprises at least two electroconductive bars, said electroconductive bars being arranged having a specified mutual spacing, so as to form a fluid circulation channel.

Description

DESCRIPTION OF THE FIGURES

(1) Other advantages and features of the present invention will emerge more clearly upon reading the detailed description, below, of a plurality of particular embodiments of the invention, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a perspective view showing the architecture of a power switching module according to the prior art;

(3) FIG. 2 is a simplified cross-sectional view showing a first embodiment of a power switching modular element;

(4) FIG. 3 is a simplified view from below showing, in the power switching modular element of FIG. 2, the positioning of an interconnection opening below a grid electrode of a transistor chip;

(5) FIG. 4 is a simplified cross-sectional view showing a second embodiment of a power switching modular element;

(6) FIG. 5 is a simplified view from below showing, in the power switching modular element of FIG. 4, the positioning of an interconnection opening below grid electrodes of transistor chips;

(7) FIG. 6 is a simplified cross-sectional view showing an embodiment of a power switching assembly, comprising a fluid circulation channel;

(8) FIG. 7 is a simplified cross-sectional view showing a first embodiment of an assembly and interconnection element that can be used for achieving power switching assemblies;

(9) FIG. 8 is a simplified cross-sectional view showing another embodiment of a power switching assembly, comprising assembly and interconnection elements as shown in FIG. 7; and

(10) FIG. 9 is a simplified cross-sectional view showing a second embodiment of an assembly and interconnection element that can be used for achieving power switching assemblies.

DETAILED DESCRIPTION

(11) In the prior art, the encapsulation of the power chips for achieving power switching modules largely makes use of a technology derived from the technology known as IMS (insulated metal substrate). The chip is implanted in a sandwich structure, between two conductive copper plates. Electrolytic deposition of copper and silver sintering techniques are used for the electrical interconnection of the chip. Dielectrics made of epoxy-type resins, reinforced, or not, by fiberglass, or polyimides, are used for the electrical isolation. Laser beam cutting and drilling are frequently used for material removal. Copper tracks and pads for the electrical interconnection are typically obtained by means of wet etching of a copper sheet.

(12) Thus, as shown for example in the prior art of FIG. 1, the 3D stack of a power switching module PM formed of a switching bridge branch comprises transistor chips T.sub.HS and T.sub.LS, busbars +DC and −DC, a central busbar OUT, conducive interconnection sheets CG.sub.U and CG.sub.L, and dielectric electrical isolation layers IS1.sub.U, IS2.sub.U and IS1.sub.L, IS2.sub.L. The busbars +DC, −DC and OUT, and the conductive interconnection layers CG.sub.U and CG.sub.L are made of copper, and the dielectric electrical insulation layers IS1.sub.U, IS2.sub.U and IS1.sub.L, IS2.sub.L are typically made of the above-mentioned materials based on epoxy resins or polyimides.

(13) In this case, the transistor chips T.sub.HS and T.sub.LS are of the vertical type and comprise source electrodes and drain electrodes (not shown) that are located on the upper and lower faces, respectively, of the chip. The source and drain electrodes are electrically connected to the busbars. The grid electrode G.sub.U, G.sub.L of the transistor chip T.sub.HS, T.sub.LS is located on the upper face of the chip. The grid electrodes G.sub.U and G.sub.L are connected to the conductive interconnection sheets CG.sub.U and CG.sub.L by means of conductive tracks C.sub.U and C.sub.L and are in electrical continuity with contact terminals GP.sub.U and GP.sub.L, respectively. The dielectric electrical insulation layer IS1.sub.U, IS1.sub.L ensures electrical insulation between the busbar +DC, −DC and the conductive interconnection sheet CG.sub.U, CG.sub.L, respectively. The dielectric electrical insulation layer IS2.sub.U, IS2.sub.L ensures electrical insulation between the conductive interconnection sheet CG.sub.U, CG.sub.L and the central busbar OUT, respectively.

(14) The electrical connections of the chips T.sub.HS and T.sub.LS to continuous supply voltages are ensured by the busbars +DC and −DC. The control of the grid electrodes G.sub.U and G.sub.L is ensured by the contact terminals GP.sub.U and GP.sub.L. The midpoint of the switching branch PM is available on the central busbar OUT which is dedicated to the alternating voltage.

(15) As can be seen in FIG. 1, the contact terminals GP.sub.U and GP.sub.L, for access to the grid electrodes of the chips, are located laterally on the structure, i.e. on the edge thereof. The location of the contact terminals GP.sub.U and GP.sub.L is often a disadvantage. Indeed, additional connection means have to be provided in order to bring the electrical connections as far as the control circuit, which is typically arranged on the upper or lower face of the structure.

(16) With reference to FIGS. 2 and 3, in the following a first particular embodiment 1 of a power switching modular element, as well as an assembly of two modular elements of this kind, will be described.

(17) In the concept of the invention, the power switching modular element is a standardizable component. Advantageously, the power switching modular element is implemented using printed circuit board (PCB) production techniques. The techniques are mastered perfectly, and allow for low-cost production.

(18) Thus, in order to implement the power switching modular elements, it is possible to make use of a combination of different production techniques, including lamination, photolithography, electrodeposition of metal, wet etching, and others. For the purpose of the interconnection of power chips, it is possible to make use of transient liquid phase (TLP) welding, sintering of metal nanoparticle powder, or diffusion welding. Laser cutting and laser drilling are also used and, optionally, other means such as punch die-casting for cutting isolating and copper films or sheets.

(19) FIG. 2 shows two standard power switching modular elements 1.sub.A and 1.sub.B, in a pre-assembly state. The power switching modular elements 1.sub.A and 1.sub.B are arranged top-to-bottom. Three conductive assembly pins 2.sub.1, 2.sub.2 and 2.sub.3 are also provided, so as to be accommodated in the openings of the power switching modular elements 1.sub.A and 1.sub.B.

(20) In this case, the power switching modular elements 1.sub.A, 1.sub.B each comprise one transistor chip CP.sub.A, CP.sub.B, respectively. Other embodiments of the modular element may comprise a plurality of transistor chips.

(21) In this embodiment, the transistor chip CP.sub.A, CP.sub.B, the upper face of which is shown in FIG. 3, is of the vertical type and comprises source electrodes S and drain electrodes (not shown) which form power electrodes that are located on the upper and lower faces, respectively, of the chip. The grid electrode G of the transistor chip CP.sub.A, CP.sub.B, which forms a switching control electrode, is located on the upper face of the chip, at the center thereof. The transistor chip CP.sub.A, CP.sub.B is buried in the structure, in a sandwich formation, between two upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates, typically made of copper. An intermediate dielectric layer CD.sub.A, CD.sub.B separates the upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates, which plates are thus electrically isolated from one another. The transistor chip CP.sub.A, CP.sub.B is contained in a recess arranged in the intermediate dielectric layer CD.sub.A, CD.sub.B and comprises the upper source face and the lower drain face thereof, which are electrically connected to the upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates, respectively.

(22) According to the invention, an opening OG1.sub.A, OG1.sub.B is provided in the upper conductive plate PH.sub.A, PH.sub.B. The opening OG1.sub.A, OG1.sub.B extends from the upper face of the upper conductive plate PH.sub.A, PH.sub.B, as far as the surface of the grid electrode G of the transistor chip CP.sub.A, CP.sub.B. The opening OG1.sub.A, OG1.sub.B is intended for electrical connection, via the upper conductive plate PH.sub.A, PH.sub.B, of the grid electrode G of the transistor chip CP.sub.A, CP.sub.B. The opening OG1.sub.A, OG1.sub.B is typically formed by means of laser drilling, and comprises a dielectric layer DE.sub.A, DE.sub.B and an internal conductive layer CI.sub.A, CI.sub.B. The dielectric layer DE.sub.A, DE.sub.B electrically isolates the upper conductive plate PH.sub.A, PH.sub.B and the internal conductive layer CI.sub.A, CI.sub.B from one another. The internal conductive layer CI.sub.A, CI.sub.B is typically achieved by means of copper metallization. As can be seen in FIG. 3, the internal conductive layer CI.sub.A, CI.sub.B is in electrical contact with the grid electrode G. The opening OG1.sub.A, OG1.sub.B, by way of the internal conductive layer CI.sub.A, CI.sub.B thereof, makes it possible to bring the electrical connection to the grid electrode as far as the upper face of the upper conductive plate PH.sub.A, PH.sub.B.

(23) A plurality of other openings OA1.sub.A, OA1.sub.B to OD1.sub.A, OD1.sub.B are arranged in the power switching modular elements 1.sub.A, 1.sub.B.

(24) As can be seen in FIG. 2, the openings OA1.sub.A, OA1.sub.B, and OB1.sub.A, OB1.sub.B are through-openings, passing through the upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates, and the intermediate dielectric layer CD.sub.A, CD.sub.B. The dielectric DE.sub.A, DE.sub.B and internal conductive CI.sub.A, CI.sub.B layers are present in the openings OA1.sub.A, OA1.sub.B, and OB1.sub.A, OB1.sub.B.

(25) The openings OC1.sub.A, OC1.sub.B and OD1.sub.A, OD1.sub.B are simple openings, without a dielectric layer, which are formed, for example, by drilling in the upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates, respectively. In the modular element 1.sub.A, 1.sub.B, the openings OC1.sub.A, OC1.sub.B and OD1.sub.A, OD1.sub.B are not through-openings, and are aligned on the same axis in the conductive plates PH.sub.A, PH.sub.B and PB.sub.A, PB.sub.B, respectively. The openings OC1.sub.A, OC1.sub.B and OD1.sub.A, OD1.sub.B remain continuous in the thickness of the conductive plates PH.sub.A, PH.sub.B, and PB.sub.A, PB.sub.B, respectively, thus avoiding any risk of a short-circuit between the upper conductive plates PH.sub.A, PH.sub.B, and PB.sub.A, PB.sub.B, when the conductive assembly pins 2.sub.1, 2.sub.3 are accommodated in the openings.

(26) In a general manner, all of the openings OG1.sub.A, OG1.sub.B and OA1.sub.A, OA1.sub.B to OD1.sub.A, OD1.sub.B are made along axes perpendicular to the upper and lower surface planes of the upper PH.sub.A, PH.sub.B and lower PB.sub.A, PB.sub.B conductive plates.

(27) As can be seen in FIG. 2, the openings OG1.sub.A, OG1.sub.B and OA1.sub.A, OA1.sub.B to OC1.sub.A, OC1.sub.B are spaced apart by the same spacing pitch P in the upper conductive plate PH.sub.A, PH.sub.B in order to allow for the openings to coincide during assembly of the modular elements, in this case the top-to-bottom assembly of the modular elements 1.sub.A and 1.sub.B. The openings in the lower conductive plate PB.sub.A, PB.sub.B have the same pitch P, although the opening OG1.sub.A, OG1.sub.B is absent in this plate, in this embodiment.

(28) The two modular elements 1.sub.A and 1.sub.B are assembled by bringing them together (along arrows F). The three pins 2.sub.1, 2.sub.2, and 2.sub.3 are engaged in the openings OD1.sub.A and OA1.sub.B, OB1.sub.A, and OG1.sub.B, and OA1.sub.A and OC1.sub.B, respectively. The pins 2.sub.1, 2.sub.2 and 2.sub.3 ensure the mechanical assembly and the electrical connections. Thus, the grid electrodes G of the transistor chips CP.sub.A and CP.sub.B are accessible on the upper face of the upper plate PH.sub.A, in the region of the openings OG1.sub.A and OB1.sub.A, respectively.

(29) With reference to FIGS. 4, 5 and 6, a second particular embodiment 2 of a power switching modular element according to the invention, as well as a first assembly of two modular elements of this kind, will now be described.

(30) As shown in FIG. 4, the power switching modular element 2 differs from the modular element 1 essentially by the fact that it comprises two transistor chips CP1 and CP2, also of the vertical type, but having a different connection configuration, and by the grid connection opening OG2.

(31) In a manner analogous to the modular element 1, the transistor chips CP1 and CP2 are buried, in a sandwich manner, between the two upper PH2 and lower PB2 conductive plates, which are typically made of copper. The intermediate dielectric layer CD2 separates the upper PH2 and lower PB2 conductive plates, which plates are thus electrically isolated from one another. The transistor chips CP1 and CP2 are contained in respective recesses which are arranged in the intermediate dielectric layer CD2.

(32) In this embodiment, the transistor chips CP1 and CP2 are mounted in parallel, which indicates that the source, drain and grid electrodes thereof are contacted together, in pairs.

(33) As shown in FIG. 5, the chip CP1, CP2 comprises the source electrode S1, S2 on the upper face thereof, and the grid electrode G1, G2 and the drain electrode (not shown) being located on the lower face of the chip. In the chip CP1, CP2, the grid electrode G1, G2 is not implanted centrally, as in the case of the modular element 1, but on an edge of the chip. The chips CP1 and CP2 are arranged side-by-side, having the grid electrodes G1 and G2 thereof facing each other. The source electrodes S1, S2 and the drain electrodes (not shown) are electrically connected to the upper PH and lower P.sub.B conductive plates, respectively. In this case, the opening OG2 makes it possible to connect all the grid electrodes G1 and G2 and to take the electrical connection as far as the upper face of the upper conductive plate PH2.

(34) As can be seen in FIG. 4, in this case the opening OG2 is a through-opening, passing through the upper PH2 and lower PB2 conductive plates, and the intermediate dielectric layer CD2. A dielectric layer DE2 and a conductive layer CI2 are present in the opening OG2, and cover the opening in the upper conductive plate PH2. As can be seen in FIG. 5, the internal conductive layer CI2 is in electrical contact with the grid electrodes G1 and G2 of the chips CP1 and CP2.

(35) By way of the internal conductive layer CI2 thereof, the opening OG2 thus makes it possible to take the electrical connection of the grid electrodes G1 and G2 as far as the upper face of the upper conductive plate PH2. It will be noted that the metallization of the dielectric layer DE2, which produces the internal conductive layer CI2, does not extend, in the opening OG2, beyond the contact with the grid electrodes G1 and G2, such that there is no short-circuit between the electrodes and the lower conductive plate PB2 to which the drain electrodes are electrically connected. It will be noted that the presence of the opening OG2 in the lower conductive plate PB2 makes it possible, with respect to the modular element 1, to have, in this case, an additional conductive assembly pin, and a regular spacing (pitch P) between the pins.

(36) The other openings OA2, OB2, OC2 and OD2 of the modular element 2 are analogous to the openings OA1, OB1, OC1 and OD1 of the modular element, and will not be described here.

(37) An assembly of two modular elements 2.sub.A and 2.sub.B having four conductive assembly pins 2.sub.4 to 2.sub.7 is shown in FIG. 6. The conductive assembly pins 2.sub.4 to 2.sub.7 are longer than the assembly pins 2.sub.1 to 2.sub.3 used for the assembly of FIG. 2. In this case, the greater length of the conductive assembly pins 2.sub.4 to 2.sub.7 makes it possible to form a fluid circulation channel CAL, while maintaining a spacing between the modular elements 2.sub.A and 2.sub.B. A circulation of a heat-transfer fluid can thus be established through the channel CAL in order to cool the modular elements 2.sub.A, 2.sub.B.

(38) As shown in FIGS. 7 and 8, standard assembly and interconnection elements BI are provided in the invention, and can be used for achieving assemblies AS comprising a large number of modular elements 4.sub.A, 4.sub.B, 4.sub.C, etc. According to the invention, the modular elements 4.sub.A, 4.sub.B, 4.sub.C, etc. can be arranged in three dimensions in order to form assemblies AS. A plurality of assembly and interconnection elements BI.sub.A, BI.sub.B, etc. can be used for creating the assemblies AS.

(39) As can be seen more clearly in FIG. 7, the assembly and interconnection elements BI are typically in the form of conductive bars or small plates provided with conductive assembly pins. In the embodiment of FIG. 7, the conductive bar 3 is typically made of copper and comprises a plurality of upper 2.sub.8H to 2.sub.11H and lower 2.sub.8B to 2.sub.11B conductive assembly pins. The conductive assembly pins are mounted, by means of clamping, in the openings OE of the conductive bar 3. The openings OE have a spacing therebetween that is equal to the pitch P. In this case, the pins are mounted in pairs in the openings OE, an upper pin and a lower pin being inserted into the same opening OE. It will be noted that a pin having a greater length can be used in other embodiments in order to replace the pair of upper and lower pins in one opening OE.

(40) Other assembly and interconnection elements BI.sub.F, such as that shown in FIG. 9, can be used in the assemblies AS in order to provide channels CAN that are typically intended for circulation of a heat-transfer or fire-retardant fluid, or for heat pipes.

(41) In the embodiment of FIG. 9, three conductive bars 4 are stacked and assembled mechanically by means of the pins OF. A spacing is retained between the bars 4, so as to obtain the channels CAN.

(42) The claimed invention is not limited to the particular embodiments that have been described here by way of example. Depending on the applications, a person skilled in the art could make various amendments and variants which are within the scope of the invention.