CERAMIC SUBSTRATE WITH CAPACITOR FUNCTION AND CORRESPONDING POWER MODULE

Abstract

The present invention relates to a ceramic substrate (11) for a power module (10) comprising at least one substrate portion (23.1, 23.1') made of an insulating ceramic material, referred to as the "insulating substrate portion", and at least one substrate portion (23.2, 23.2') made of a capacitive ceramic material, referred to as the "capacitive substrate portion", to perform at least one capacitor function. Figure 2

Description

Title of the invention: CERAMIC SUBSTRATE HAVING A CAPACITOR FUNCTION AND CORRESPONDING POWER MODULE

[0001] The present invention relates to a metallized ceramic substrate having a capacitor function, in particular a decoupling capacitor function, and to the corresponding power module. The invention finds application in the field of power electronics, particularly with power modules having an electrical signal conversion function, such as inverters for rotating electrical machines.

[0002] Figure 1 shows a standard inverter 1 used to control a rotating electrical machine 2. The inverter comprises six switching elements S1 to S6 and a decoupling capacitor Cdc. Three switching arms, B1-B3, are distinguished, each associated with a phase a, b, c of the rotating electrical machine. Each switching arm B1-B3 comprises two switching elements, namely an upper switching element and a lower switching element, connected respectively to a positive voltage terminal +Vdc and a negative voltage terminal -Vdc of a voltage source Vin and having a common terminal connected to the phase of the electrical machine. Thus, the upper switching element and the lower switching element can selectively connect, at high frequency, the phase corresponding to the positive supply potential +Vdc and the negative supply potential -Vdc.

[0003] A switching element may, for example, take the form of a transistor (IGBT Insulated Gate Bipolar Transistor, HEMT High Electron Mobility Transistor, MOSFET Metal Oxide Semiconductor Field Effect Transistor, or other) with or without a freewheeling diode in parallel. The switching elements are controlled in an on / off manner by signals supplied by control circuits.

[0004] During switching operation, a switching arm B1-B3 exhibits a voltage and current with strong oscillations whose amplitudes diminish until they disappear, thus generating transient phases of overvoltage or overcurrent. The overvoltage phenomenon arises from the presence of parasitic inductances related to the inherent connections between the different components. These inductances cause overvoltages and can lead to the destruction of the semiconductors forming the switching elements if the voltage margin is insufficient. Inductance values ​​on the order of a few nanohenries to a few tens of nanohenries significantly impact the performance of electronic components, particularly for functions requiring large current variations. depending on the time when they are ordered in an on / off mode.

[0005] To prevent these overvoltages, taking them into account implies oversizing the elements of the electrical circuit in order to ensure on the one hand the correct operation of the switching arm B1-B3, and on the other hand that the transient voltage value obtained does not cause the destruction of the electronic components constituting the switching arm B1-B3.

[0006] Adding a so-called "decoupling" capacitor (Cdc) in parallel with the switching arms B1-B3 helps to dampen these oscillations and thus to optimize the sizing of the electrical circuit components. However, these decoupling capacitors are additional components that must be added to the circuit, increasing the volume and weight of the system as well as the length of the current paths.

[0007] The invention aims to effectively remedy the aforementioned drawbacks by proposing a ceramic substrate for a power module comprising at least one portion of insulating substrate made of an insulating ceramic material, and at least one portion of capacitive substrate made of a capacitive ceramic material, to ensure at least one capacitor function.

[0008] The invention thus makes it possible, through the integration of the capacitor function into the ceramic substrate, to limit oscillations due to switching by reducing the lengths of the current paths, and thereby reduce the impact on electromagnetic compatibility (EMC) and the sizing of the filter at the converter output. The invention facilitates integration and improves the compactness and conversion efficiency of the power module.

[0009] According to one embodiment of the invention, the insulating substrate portion and the capacitive substrate position extend into a thickness of the substrate.

[0010] According to one embodiment of the invention, the insulating substrate portion and the capacitive substrate portion are co-sintered so as to form a single-piece element.

[0011] According to one embodiment of the invention, the insulating substrate portion carries at least one conductive track for connection with an electronic component and / or an interconnection and the capacitive substrate portion carries at least one conductive track for connection with an electrical component and / or an interconnection.

[0012] According to one embodiment of the invention, said ceramic substrate comprises at least one pellet consisting of the insulating substrate portion and the capacitive substrate portion.

[0013] According to one embodiment of the invention, the insulating substrate portion is constituted by a first pellet and the capacitive substrate portion is constituted by a second pellet, the first pellet and the second pellet being assembled together one above the other.

[0014] According to one embodiment of the invention, one of the substrate portions selected from the The insulating substrate portion and the capacitive substrate portion have a cylindrical shape, and the other substrate portion chosen from the insulating substrate portion and the capacitive substrate portion has an annular shape extending around the cylindrical substrate portion.

[0015] According to one embodiment of the invention, the cylindrical-shaped portion of the substrate and the annular-shaped portion of the substrate are coaxial with respect to each other.

[0016] The invention also relates to a power module comprising: - a ceramic substrate as previously defined, and - at least one electronic component mounted on the ceramic substrate.

[0017] According to one embodiment of the invention, the insulating substrate portion and the capacitive substrate portion are electrically connected to a common reference potential.

[0018] According to one embodiment of the invention, the common reference potential is a heat sink.

[0019] According to one embodiment of the invention, the power module takes the form of a switching arm of an inverter comprising two switching elements and the ceramic substrate comprises two capacitive substrate portions each having a decoupling capacitor function associated with one of the switching elements.

[0020] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0021] [Fig-1] The [Fig.1], already described, is an electrical diagram of a three-phase inverter classic for a rotating electrical machine;

[0022] [Fig.2] Fig.2 is a schematic cross-sectional representation of a module of equivalent power to arms Bl, B2 or B3 of [Fig.l] according to the invention comprising a metallized ceramic substrate having a capacitor function;

[0023] [Fig.3a][Fig.3b][Fig.3c] Figures 3a, 3b and 3c are respectively perspective, cross-section and top views of a first embodiment of a switching arm according to the invention;

[0024] [Fig.4a][Fig.4b][Fig.4c] Figures 4a, 4b and 4c are respectively perspective, cross-section and top views of a second embodiment of a switching arm according to the invention;

[0025] [Fig.5a][Fig.5b][Fig.5c] Figures 5a, 5b and 5c are respectively perspective, cross-section and top views of a third embodiment of a switching arm according to the invention.

[0026] [Fig.6] Fig.6 is an equivalent electrical diagram of the switching arms of the different embodiments according to the invention;

[0027] [Fig.7a][Fig.7b] Figures 7a and 7b are graphical representations of the voltage and current signals of a top switching element of a switching arm respectively without and with a decoupling capacitor integrated into the ceramic substrate according to the invention.

[0028] It should be noted that the structural and / or functional elements common to the different embodiments have the same reference numerals. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0029] Fig. 2 is a schematic cross-sectional view of a power module 10 comprising a substrate 11 providing various functions, in particular a mechanical holding function for semiconductor chips or other electronic components 13, an electrical connection function, a function for housing a protective cover and / or a function for housing an encapsulation solution, as well as a heat exchange function with a cooling device.

[0030] The substrate 11 can be assembled onto a base 12 constituting a heat sink, particularly in the case of a metallized ceramic substrate. For this purpose, the substrate 11 comprises a metallization layer 15 fixed to the base 12 by brazing or sintering.

[0031] The electronic components 13 are made, for example, of chips made of power semiconductor material, such as switching elements. The electronic components 13 are mounted on the substrate 11. The electronic components 13 can be soldered onto the substrate 11.

[0032] Electrical interconnections 14 are made, in particular, between the electronic components 13 and conductive tracks of the substrate 11 and between the electronic components 13 and power terminals 16. The power terminals 16 can be brazed onto the substrate 11. In [Fig.2], the brazing areas are referenced 17.

[0033] The electrical interconnections 14 are preferably made using a wire bonding process. According to this technology, an electrical wire, also called a bridge, is welded, for example by ultrasound, between two elements to be electrically connected. The electrical interconnections 14 can also be made using clips attached by sintering.

[0034] An electronic control board 18 carrying electronic components 9 can be fixed in a raised position relative to the substrate 11 by means of mechanical supports 19. The electronic control board 18 has control terminals 20.

[0035] The assembly thus formed is embedded in an encapsulation material 21 allowing to protect the electronic components 9, 13 against aggressions caused by an environment in which the power module 10 is located.

[0036] Classically, the encapsulation material 21 can take the form of a gel, an epoxy resin and / or a coating of an insulating material suitable for application to the electronic components 9, 13. The encapsulation material 21 is also known by the Anglo-Saxon term "coating".

[0037] A housing 22 closes the assembly thus formed. The housing 22 may carry some of the power terminals 16 and / or the control terminals 20.

[0038] The ceramic substrate 11 comprises at least one portion of substrate 23.1 made of an insulating ceramic material referred to as "insulating portion of substrate" and at least one portion 23.2 made of a capacitive ceramic material referred to as "capacitive portion of substrate" ensuring at least one capacitor function, in particular a decoupling capacitor function associated with an electronic component.

[0039] The insulating substrate portion 23.1 and the capacitive substrate portion 23.2 extend within a thickness E of the substrate 11. The thickness E is defined by all the layers of the ceramic substrate 11 made of a ceramic material. No mechanical housing-type element is interposed between the insulating substrate portion 23.1 and the capacitive substrate portion 23.2.

[0040] The capacitive substrate portion 23.2 has a capacitance between InF and 1 pF, in particular between lOnF and 500nF. The capacitive ceramic material can, for example, be a perovskite-structured ceramic material, in particular titanates, especially a material of the BaTiO3, SrTiO3 type, a solid solution of these two materials or composites having a matrix based on these materials.

[0041] Preferably, the insulating substrate portion 23.1 has a capacitance of less than 100pF. The insulating ceramic material can, for example, be alumina, aluminum nitride, silicon nitride, or a composite having a matrix based on these materials.

[0042] The capacitive substrate portion 23.2 and the insulating substrate portion 23.1 are preferably co-sintered to form a single-piece element. The sintering technique is preferably the SPS (Spark Plasma Sintering) technique. Alternatively, any other sintering technique suitable for the application may be used.

[0043] Thus, the two substrate portions 23.1, 23.2 can be produced together by hot compaction of different types of ceramic powders. Alternatively, the insulating substrate portion 23.1 and the capacitive substrate portion 23.2 can be produced independently of each other and joined together by bonding or brazing.

[0044] Alternatively, a layer of metal, in particular intended to form a conductive track, can be co-sintered with the insulating substrate portion 23.1 and / or the capacitive substrate portion 23.2.

[0045] In the embodiment of figures 3a, 3b and 3c, the power module 10 takes the form of a switching arm B1-B3 comprising two switching elements, namely a high switching element 13.1 intended to be electrically connected to the positive potential +Vdc of a voltage source and a low switching element 13.2 intended to be electrically connected to the negative potential -Vdc of the voltage source.

[0046] A first pad 24.1 associated with the upper switching element 13.1 comprises an insulating ceramic portion 23.1 and a capacitive ceramic portion 23.2, having a decoupling capacitor function.

[0047] A second pad 24.2 associated with the lower switching element 13.2 comprises an insulating ceramic portion 23.1' and a capacitive ceramic portion 23.2' having a decoupling capacitor function.

[0048] The two portions 23.1 and 23.2 or 23.1' and 23.2' of the same pellet 24.1, 24.2 constitute a single piece. The two portions 23.1 and 23.2 or 23.1' and 23.2' of the same pellet 24.1, 24.2 are arranged adjacent to each other and have substantially the same thickness E. Each pellet 24.1, 24.2 can be made by sintering two anisotropic ceramic materials. A pellet 24.1, 24.2 has a round shape, in particular the shape of a flat cylinder, that is to say, a cylinder having a thickness at least twice less than its diameter. Each portion of substrate 23.1, 23.2, 23.1' and 23.2' has a flat, semi-cylindrical shape. Alternatively, the pellets 24.1 and 24.2 may have a square shape or any other shape suitable for the application.

[0049] As can be seen in [Fig.3b], a terminal 25.1 connected to the positive electrical potential +Vdc of the voltage source and one end of an interconnection 14.1 are electrically connected to a conductive track 26.1 carried by an upper face of the capacitive substrate portion 23.2 of the first pad 24.1.

[0050] The other end of the interconnection 14.1 and a drain of the upper switching element 13.1 are electrically connected to a conductive track 26.2 carried by an upper face of the insulating substrate portion 23.1 of the first pad 24.1.

[0051] An interconnection 14.2 is electrically connected on one side to the source of the upper switching element 13.1 and on the other side to a conductive track 26.3 carried by an upper face of the insulating substrate portion 23.1' of the second pad 24.2. The drain of the lower switching element 13.2 is also electrically connected to the conductive track 26.3 of the insulating substrate portion 23.1' of the second pad 24.2.

[0052] An interconnection 14.3 is electrically connected on one side to the source of the low switching element 13.2 and on the other side to a conductive track 26.4 carried by an upper face of the capacitive substrate portion 23.2' of the second pad 24.2. A terminal 25.2 connected to the negative electrical potential -Vdc of the voltage source is also electrically connected to the conductive track 26.4. The phase PH is taken from the electrical potential of the conductive track 26.3.

[0053] Furthermore, the insulating substrate portion 23.1 and the capacitive substrate portion 23.2 of the first pellet 24.1 are electrically connected to a common reference potential 30. The insulating substrate portion 23.1' and the capacitive substrate portion 23.2' of the second pellet 24.2 are electrically connected to the common reference potential 30.

[0054] The common reference potential 30 is preferably constituted by a heat sink 12. The connection is preferably made via a conductive track 26.5, 26.6, 26.7, 26.8 deposited on a lower face of a corresponding portion of substrate 23.1, 23.2, 23.1', 23.2' which is brazed or welded onto the heat sink 12. The first pad 24.1 and the second pad 24.2 are thus electrically connected to the common reference potential 30.

[0055] In the embodiment of figures 4a, 4b and 4c, the power module 10 takes the form of a switching arm B1-B3 comprising two switching elements 13.1, 13.2, namely a high switching element 13.1 intended to be electrically connected to the positive potential +Vdc of a voltage source and a low switching element 13.2 intended to be electrically connected to the negative potential -Vdc of the voltage source.

[0056] A first set of pads 31.1 associated with the upper switching element 13.1 comprises a pad 23.1 made of an insulating ceramic material (constituting the insulating substrate portion) called the "insulating pad" and a pad 23.2 made of a capacitive ceramic material (constituting the capacitive substrate portion) having a decoupling capacitor function called the "capacitive pad".

[0057] A second set of pads 31.2 associated with the lower switching element 13.2 comprises a pad 23.1' made of an insulating ceramic material (constituting the insulating substrate portion) called "insulating pad" and a pad 23.2' made of a capacitive ceramic material (constituting the capacitive substrate portion) having a decoupling capacitor function called "capacitive pad".

[0058] The pellets 23.1, 23.1', 23.2, 23.2' are round, in particular flat cylindrical, but could alternatively have another shape. The pellets 23.1, 23.1', 23.2, 23.2' of the same set of pellets 31.1, 31.2 may have different diameters. One of the pellets, in this case the upper pellet, has a smaller diameter than the lower mounted pellet. against the heat sink 12, so that the conductive track arranged on the upper face of the lower pad can be made around the upper pad. The thickness E of the substrate 11 then corresponds to the sum of the thicknesses E of two pads from a given set of pads 31.1, 31.2.

[0059] As can be seen in [Fig.4b], a terminal 25.1 connected to the positive electrical potential +Vdc of the voltage source and one end of an interconnection 14.1 are electrically connected to a conductive track 26.1 carried by an upper face of the capacitive pad 23.2 of the first set of pads 31.1.

[0060] The other end of the interconnection 14.1 and a drain of the upper switching element 13.1 are electrically connected to a conductive track 26.2 carried by an upper face of the insulating pad 23.1 of the first set of pads 31.1. The conductive tracks 26.1, 26.2 can be co-sintered respectively with the conductive substrate portion and the insulating substrate portion.

[0061] An interconnection 14.2 is electrically connected on one side to the source of the upper switching element 13.1 and on the other side to a conductive track 26.3 carried by an upper face of the insulating pad 23.1' of the second set of pads 31.2. The drain of the lower switching element 13.2 is also electrically connected to the conductive track 26.3 of the insulating pad 23.1' of the second set of pads 31.2.

[0062] An interconnection 14.3 is electrically connected on one side to the source of the lower switching element 13.2 and on the other side to a conductive track 26.4 carried by an upper face of the capacitive pad 23.2' of the second set of pads 31.2. A terminal 25.2 is connected to the negative electrical potential -Vdc of the voltage source is also electrically connected to the conductive track 26.4. The phase PH is taken from the electrical potential of the conductive track 26.3.

[0063] The capacitive pad 23.2 of the first set of pads 31.1 is electrically connected to a common reference potential 30. The capacitive pad 23.2' of the second set of pads 31.2 is electrically connected to the common reference potential 30.

[0064] The common reference potential 30 is preferably constituted by a heat sink 12. The connection is preferably made via a conductive track 26.5, 26.6 disposed on an underside face of the pads 23.2, 23.2' which is brazed or preferably sintered on the heat sink 12. The first set of pads 31.1 and the second set of pads 31.2 are thus electrically connected to the common reference potential 30.

[0065] This solution has the advantage of being easily implemented by a sintering technique using a single material per pellet, but limits the final integration taking into account the size of the sets of pellets 31.1, 31.2.

[0066] In the embodiment of figures 5a, 5b and 5c, the power module 10 takes the form of a switching arm B1-B3 comprising two switching elements 13.1, 13.2, namely a high switching element 13.1 intended to be electrically connected to the positive potential +Vdc of a voltage source and a low switching element 13.2 intended to be electrically connected to the negative potential -Vdc of the voltage source.

[0067] A first pad 24.1 associated with the upper switching element 13.1 comprises an insulating substrate portion 23.1 and a capacitive substrate portion 23.2, having a decoupling capacitor function.

[0068] A second pad 24.2 associated with the low switching element 13.2 comprises an insulating substrate portion 23.1' and a capacitive substrate portion 23.2'. having a decoupling capacitor function.

[0069] The pellets 24.1, 24.2 are round but could alternatively be square or any other shape suitable for the application. In this case, one of the substrate portions selected from the insulating substrate portion 23.1 and the capacitive substrate portion 23.2 is cylindrical, in particular a flat cylinder, i.e., thin compared to its diameter. The other substrate portion selected from the insulating substrate portion 23.1 and the capacitive substrate portion 23.2 is annular so as to extend around the cylindrical substrate portion.

[0070] To this end, the annular substrate portion has an internal diameter equal to the external diameter of the flat cylindrical substrate portion. An external periphery of the flat cylindrical substrate portion is in contact with an internal periphery of the annular substrate portion. The two substrate portions 23.1, 23.2 are coaxial with respect to each other. The flat cylindrical substrate portion and the annular substrate portion have substantially the same thickness E. By "substantially," it is meant that the difference between the two thicknesses is less than 10% of the greater thickness.

[0071] A pellet 24.1, 24.2 can be obtained by simultaneous sintering of the insulating substrate portion 23.1 and the capacitive substrate portion 23.2. This solution allows for optimal integration of a capacitor within a power module.

[0072] As can be seen in [Fig.5b], a terminal 25.1 connected to the positive electrical potential +Vdc of the voltage source and one end of an interconnection 14.1 are electrically connected to a conductive track 26.1 carried by an upper face of the annular insulating substrate portion 23.1 of the first pad 24.1.

[0073] The other end of the interconnection 14.1 and a drain of the upper switching element 13.1 are electrically connected to a conductive track 26.2 carried by an upper face of the cylindrical capacitive substrate portion 23.2 of the first pad 24.1.

[0074] An interconnection 14.2 is electrically connected on one side to the source of the upper switching element 13.1 and on the other side to a conductive track 26.3 carried by an upper face of the cylindrical insulating substrate portion 23.1' of the second pad 24.2. The drain of the lower switching element 13.2 is also electrically connected to the conductive track 26.3 of the insulating substrate portion 23.1' of the second pad 24.2.

[0075] An interconnection 14.3 is electrically connected on one side to the source of the low switching element 13.2 and on the other side to a conductive track 26.4 carried by an upper face of the annular capacitive substrate portion 23.2' of the second pad 24.2. A terminal 25.2 connected to the negative electrical potential -Vdc of the voltage source is also electrically connected to the conductive track 26.4. The phase PH is taken from the electrical potential of the conductive track 26.3.

[0076] The conductive tracks 26.1, 26.4 have an annular shape but could alternatively have any other geometry as long as the conductive tracks are electrically insulated from each other.

[0077] Furthermore, the insulating substrate portion 23.1 and the capacitive substrate portion 23.2 of the first pellet 24.1 are electrically connected to a common reference potential 30. The insulating substrate portion 23.1' and the capacitive substrate portion 23.2' of the second pellet 24.2 are electrically connected to a common reference potential 30.

[0078] The common reference potential 30 is preferably constituted by a heat sink 12. The connection can be made via a single conductive track 26.5 deposited on an underside of the substrate portions 23.1, 23.2, 23.1', 23.2' which is brazed or preferably sintered onto the heat sink 12. The first pad 24.1 and the second pad 24.2 are thus electrically connected to the common reference potential 30.

[0079] Figure 6 shows an equivalent electrical diagram of the different embodiments of the switching arms B1-B3 of the preceding figures. This diagram highlights that the first decoupling capacitor C1 formed by the capacitive substrate portion 23.2 is connected on one side to the positive terminal +Vdc of the voltage source and to the drain of the upper switching element 13.1, and on the other side to the common reference potential 30. The second decoupling capacitor C2 formed by the capacitive substrate portion 23.2' is connected on one side to the negative terminal -Vdc of the voltage source and to the source of the lower switching element 13.2, and on the other side at common reference potential 30. The first capacitor Cl and the second capacitor C2 each have a capacitance of 50nF for a total decoupling capacitance of 100nF.

[0080] Furthermore, a freewheeling diode D1, D2 is integrated or reported with respect to each switching element 13.1, 13.2.

[0081] Figures 7a and 7b are graphical representations of the voltage Vh and current Ih signals of the upper switching element 13.1 (see [Fig.6]) of a switching arm B1-B3 respectively without and with a decoupling capacitor integrated into the ceramic substrate 11 according to the invention.

[0082] Fig. 7a shows that the absence of a decoupling capacitor generates a voltage signal Vh across the terminals of transistor 13.1 and diode Dl with a high overvoltage and high-frequency oscillations, as well as a current signal Ih through transistor 13.1 (diode Dl is blocked) with high-frequency oscillations.

[0083] Fig. 7b shows that the integration of the decoupling capacitors 23.2 (Cl) and 23.2' (C2) in the substrate 11 according to the invention generates a voltage signal Vh across the transistor 13.1 and Disans overvoltage diode having low frequency oscillations as well as a current signal Ih through the transistor 13.1 (the diode Dl is blocked) having very low oscillations.

[0084] Of course, the capacitive substrate portion 23.2, 23.2' can have a function other than a decoupling capacitor function, such as an electrical energy storage function, a smoothing function or any other function that a capacitor can have in an electrical circuit.

[0085] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0086] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Claims

1. Ceramic substrate (11) for a power module (10) characterized in that said ceramic substrate (11) comprises at least one insulating substrate portion (23.1, 23.1') made of an insulating ceramic material, and at least one capacitive substrate portion (23.2, 23.2') made of a capacitive ceramic material, to ensure at least one capacitor function.

2. Ceramic substrate according to claim 1, characterized in that the insulating substrate portion (23.1, 23.1') and the capacitive substrate position (23.2, 23.2') extend in a thickness (E) of the substrate (11).

3. Ceramic substrate according to claim 1 or 2, characterized in that the insulating substrate portion (23.1, 23.1') and the capacitive substrate portion (23.2, 23.2') are co-sintered so as to form a single-piece element.

4. Ceramic substrate according to any one of claims 1 to 3, characterized in that the insulating substrate portion (23.1, 23.1') carries at least one conductive track (26) for connection with an electronic component and / or an interconnection (14) and the capacitive substrate portion (23.2, 23.2') carries at least one conductive track (26) for connection with an electrical component and / or an interconnection (14).

5. Ceramic substrate according to any one of claims 1 to 4, characterized in that it comprises at least one pellet constituted by the insulating substrate portion (23.1) and the capacitive substrate portion (23.2).

6. Ceramic substrate according to any one of claims 1 to 4, characterized in that the insulating substrate portion (23.1) is constituted by a first pad (24.1) and the capacitive substrate portion is constituted by a second pad (24.2), the first pad (24.1) and the second pad (24.2) being assembled together one above the other.

7. Ceramic substrate according to any one of claims 1 to 4, characterized in that one of the substrate portions chosen from the insulating substrate portion (23.1) and the capacitive substrate portion (23.2) has a cylindrical shape and the other substrate portion chosen from the insulating substrate portion (23.1) and the capacitive substrate portion (23.2) has an annular shape extending around the cylindrical substrate portion.

8. Ceramic substrate according to claim 7, characterized in that the cylindrical substrate portion (23.1, 23.2) and the annular substrate portion (23.1, 23.2) are coaxial with each other.

9. Power module (10) comprising: - a ceramic substrate (11) defined according to any one of the preceding claims, and - at least one electronic component (13) mounted on the ceramic substrate (11).

10. Power module according to claim 9, characterized in that the insulating substrate portion (23.1) and the capacitive substrate portion (23.2) are electrically connected to a common reference potential (30).

11. Power module according to claim 10, characterized in that the common reference potential (30) is a heat sink (12).

12. Power module according to any one of claims 9 to 11, characterized in that it takes the form of a switching arm (B1-B3) of an inverter comprising two switching elements (13.1, 13.2) and in that the ceramic substrate (11) comprises two capacitive substrate portions (23.2, 23.2') each having a decoupling capacitor function associated with one of the switching elements (13.1, 13.2).

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