FR3047141A1 - ELECTRONIC COMPACT POWER MODULE - Google Patents

Abstract

The invention relates to an electronic power module comprising a metal plate (8) carrying a lower plate (10) provided with conductive tracks (12a, 12b) and on which semiconductor chips (13) are fixed; an upper plate (20) provided with conductive tracks (22a, 22b) on each of its faces, and on which are fixed capacitors (23) adapted to reduce parasitic inductances of the module, said upper plate (20) being superimposed on said lower plate (10); copper pieces (30) extending integrally between said lower plate (10) and said upper plate (20) so as to provide a triple function of thermal conduction, electrical conduction, and mechanical support of the plate (20) superior, without direct contact with said semiconductor chips; means (40; 41; 42) electrically looping said upper plate (20).

Description

BACKGROUND OF THE INVENTION The invention relates to an electronic power module for connecting an electric power source to a load or an electric actuator. The invention relates in particular to such an electronic power module intended for aeronautical, railway or automotive applications, and generally to all types of applications requiring energy conversion between a source and a load. 2. Technological background

An electronic power module, also referred to as the power converter, aims at converting the electrical energy received at the module input into electrical energy compatible with the electrical load controlled by the electronic power module. To do this, the module includes electronic components that act as switches and that cut the voltage and / or the input current to be able to adapt to the needs of the load controlled by the module.

These electronic components are, for example, transistors, diodes, thyristors, or combinations of these different components. In the following, we will refer to semiconductor chips to designate such electronic components. A semiconductor chip conventionally comprises at least one semiconductor material, and at least two metallizations respectively making it possible to report the chip on an electronic plate, for example of the printed circuit type, and to make the electrical connections. Originally, most semiconductor chips were made of silicon. In recent years, these chips are formed of silicon carbide (SiC) or gallium nitride (GaN). In particular, these materials make it possible to form electronic components having much faster current and voltage switching than with silicon. These fast switches reduce energy losses at each switching. Also, the switching frequency within a power converter can be significantly increased with the use of these materials.

However, the increase of the switching speed and the switching frequency makes such a power converter more sensitive to passive parameters, such as loop inductances and parasitic inductances of the various elements involved in the electrical circuit within of which such a converter is used.

It is known to arrange capacitors in the electrical circuits to reduce these parasitic inductances. In particular, it has already been proposed to integrate capacitors directly into the power module, as close as possible to the semiconductor chips, in order to optimize the treatment of parasitic inductances. To do this, the capacitors are arranged in the vicinity of the semiconductor chips, on the electronic plate that carries the semiconductor chips. If this solution actually makes it possible to limit the parasitic inductance, it increases on the other hand the dimensions and the weight of the converter thus obtained, which is not very compatible with aeronautical applications in particular.

The inventors have therefore sought to propose a new architecture of a power module that can both effectively limit parasitic inductances while having a footprint and weight compatible with aeronautical applications in particular. 3. OBJECTIVES OF THE INVENTION The invention aims to provide an electronic power module that overcomes at least some of the disadvantages of known power electronic modules. The invention aims in particular to provide, in at least one embodiment, a compact power electronic module. The invention also aims to provide, in at least one embodiment, an electronic power module that allows the integration, as close as possible to the semiconductor chips, of capacitors that contribute to reducing loop inductances and parasitic inductances. different elements involved in an electrical circuit. The invention also aims to provide, in at least one embodiment, an electronic power module compatible with high voltage or high temperature applications. The invention aims in particular to provide, in at least one embodiment, an electronic power module compatible with aeronautical applications demanding in terms of compactness and performance. The invention also aims to provide a method of manufacturing an electronic power module. 4. Presentation of the invention

To do this, the invention relates to an electronic power module comprising a metal plate carrying a first plate, said lower plate, comprising a ceramic substrate carrying conductive tracks, and on which are fixed semiconductor chips.

The electronic power module according to the invention is characterized in that it further comprises: a second plate, called the upper plate, superimposed on said lower plate, and comprising a ceramic substrate carrying conductive tracks on each of its faces higher and lower, and on which are fixed capacitors adapted to contribute to a reduction of parasitic inductances of said module, - metal parts extending integrally between said lower plate and said upper plate so as to ensure a triple function of thermal conduction between the upper and lower plates, of electrical conduction between the conductive tracks of the lower face of the upper plate and the conductive tracks of the lower plate, and mechanical support of the upper plate above said lower plate which prevents any mechanical contact between the semiconductor chips and said upper plate, means of electrical looping of said upper plate adapted to be able to electrically connect the conductive tracks of said upper face to the conductive tracks of said lower face of said upper plate.

A module according to the invention therefore comprises two plates superimposed on one another and separated by metal parts which provide a triple function of thermal conduction, electrical conduction between the two plates and mechanical support of the upper plate which prevents any contact between the semiconductor chips and the top plate. In addition, the upper plate is metallized on each of its two faces by conductive tracks which are electrically connected by means of electrical looping. The upper and lower plates are preferably parallel to each other.

A module according to the invention is therefore compact and makes it possible to arrange capacitors adapted to contribute to a reduction of parasitic inductances as close as possible to the semiconductor chips, without, however, requiring an extension of the lower plate on which the chips are arranged. According to the invention, all types of capacitors adapted to contribute to a reduction of parasitic inductances can be mounted on the upper plate. They may be capacitors specifically dedicated and calibrated to reduce the parasitic inductances of the circuit to which the module is associated. They may also be capacitors intended mainly to provide another function, such as the filtering of noise internal to the module, but which contribute to the reduction of parasitic inductances. Such capacitors providing auxiliary reduction of parasitic inductances are for example common mode capacitors.

In addition, the module according to the invention comprises two plates formed from a ceramic substrate. These plates therefore have more favorable thermal and dielectric characteristics than the epoxy resin or fiberglass printed circuits of the prior art. In particular, a plate formed from a ceramic substrate allows both good electrical insulation and good thermal conductivity favoring heat flux within the module according to the invention.

The ceramic substrate of the plates is metallized by conductive tracks, for example made of copper. Such a plate formed from a metallized ceramic substrate of copper tracks by high temperature oxidation effect is commonly referred to by the acronym DBC for Direct Bonding Copper in English. A plate formed from a ceramic substrate metallized by copper tracks using the solder of a thin layer of silver and copper alloy is commonly referred to by the acronym AMB for Active Metal Braze in English language. According to the invention, one or the other of these plates can be used. Nevertheless, preferably, the lower and upper plates are DBC plates, i.e. plates having conductive copper tracks.

The superposition of two plates formed from a ceramic substrate, and separated by metal parts which have a triple function whose thermal conduction function ensures heat dissipation of the upper plate as effective as the heat dissipation of the lower plate which is cooled by means of the metal base in contact with a cooling device in normal operation of the module.

The bottom plate is in direct contact with the soleplate and carries the semiconductor chips which are the main sources of heat. The upper plate is in indirect contact with the soleplate via the metal parts and the lower plate, and thus carries the passive components of the module, and in particular the capacitors involved in a reduction of the parasitic inductance. The top plate can also carry other passive components such as fuses or control cards.

In addition, the metal parts are advantageously brazed or sintered between the lower and upper plates, which introduces a thermal resistance within the module which has the effect of creating a temperature differential between the upper plate and the lower plate. This temperature differential is useful to respect the maximum operating temperatures of the various components.

In other words, the metal parts promote thermal conduction and therefore thermal flux between the two plates. However, these heat flows are slightly thwarted by the presence of solder between the metal parts and the plates, which allows to maintain a temperature differential between the two plates. This temperature differential can be parameterized from the solders made.

The metal parts are preferably copper parts. However, according to other variants, the metal parts can be gold, aluminum or silver and generally all types of materials to fulfill the three functions of metal parts: heat conduction, electrical conduction and mechanical support. The particular arrangement of a module according to the invention makes it possible to use semiconductor chips of high voltage rating. The voltage rating of the semiconductor chips is dependent on the distance between the upper plate and the lower plate. In other words, the voltage rating of the semiconductor chips depends on the dimensions of the metal parts.

In addition, as indicated above, the metal parts (preferably copper) provide three functions: thermal conduction function between the stages of the module (that is to say between the upper stage defined by the upper plate, and the lower floor defined by the lower plate); electrical conduction function between the two stages of the module; and supporting function of the upper plate while preventing mechanical contact between the upper plate and the semiconductor chips. Also, the same element is used for three different functions, which allows a gain of space and weight compared to a solution where these different functions would be separated.

Finally, a module according to the invention advantageously implements the same materials on the different stages, which eliminates the risks of heterogeneous thermal and electrical behavior of the different stages.

Advantageously and according to the invention, said means for electrically looping said upper plate are formed by a plurality of conductive half-rings, a first end of which is in contact with a conductive track of said upper face of said upper plate and of which a second end is in contact with a conducting track of said lower face of said upper plate.

According to this variant, the electrical connection between the conductive tracks of the upper face of the upper plate and the conductive tracks of the lower face of the upper plate is formed by means of conductive half-rings, which advantageously come to grip the upper plate. , on both sides of the upper plate.

In the case where the upper plate is made of DBC, the half-rings are preferably copper to ensure good electrical conduction.

According to another advantageous variant of the invention, the means of electrical looping of said upper plate are formed by vias formed through said upper plate and which open on either side of said plate on the conductive tracks.

A via is a hole in the upper plate, and metallized to allow to establish an electrical connection between the conductive tracks of the upper face of the upper plate and the conductive tracks of the lower face of the upper plate. This variant provides an electronic power module that has very good electrical and electromagnetic performance. On the other hand, according to this variant, the upper ceramic plate is subjected to significant mechanical stresses during the machining of the vias. Also, preferably, and according to this variant, the upper plate is a plate formed from a metallized silicon nitride substrate on each of its upper and lower faces by copper layers forming said conductive tracks. A silicon nitride substrate of formula Si3N4 has a very high mechanical strength. In particular, its breaking stress is greater than 700 MPa. Therefore, its structure and mechanical performance are well suited to this embodiment.

Advantageously and according to the invention, the lower plate is a plate formed from an aluminum nitride substrate metallized on each of its upper and lower faces by copper layers forming said conductive tracks.

The bottom plate, whatever the embodiment of the loopback means does not require the use of a plate having a very high mechanical strength. Also, a plate formed from an aluminum nitride substrate of formula AIN is adapted to the lower stage of the electronic power module according to the invention. In addition, such an aluminum nitride substrate has a good thermal conduction, of the order of 260 W / m.K, well adapted to the lower plate which receives the semiconductor chips, the main sources of heat.

Advantageously and according to the invention, said metal parts are soldered or sintered copper balls between said upper and lower plates.

A copper ball minimizes the size of the copper part while optimizing the three functions involved: thermal conduction, electrical conduction and mechanical resistance. In other embodiments, the copper balls may be replaced by copper pads or other equivalent means.

Advantageously, a module according to the invention further comprises control component control connectors of said semiconductor chips arranged on said lower plate, said control connectors being connected to said lower plate.

Advantageously, a module according to the invention further comprises power connectors connected to said upper plate. In the case of a module for supplying a three-phase motor, the module comprises for example three power connectors for supplying the three phases of the motor, and two power connectors intended to be powered by a power source, and forming input connectors. Of course, other configurations of the power connectors are possible depending on the intended applications.

Advantageously, a module according to the invention further comprises metal son, for example copper, so-called bonding son, connecting said semiconductor chips and the conductive tracks of said lower plate.

The shape and arrangement of said bonding wires determines the minimum size of the copper balls that can be used to carry out the invention. Indeed, said bonding wires are soldered on the semiconductor chips and connected to the conductive tracks of the lower plate, forming, due to their structure, a curvature which extends into the space delimited by the lower and upper plates. . The dimension, in the vertical direction, of this space is defined by the dimensions along the same vertical direction of the copper balls. This vertical dimension is the direction perpendicular to the planes in which the upper and lower plates extend. The invention also relates to a method of manufacturing an electronic power module comprising the following steps: - conditioning a first plate, said lower plate, from a metallized ceramic substrate of conductive tracks, on which one comes fixing semiconductor chips, - conditioning a second plate, said upper plate, from a metallized ceramic substrate of conductive tracks on each of its upper and lower faces, and intended to receive capacitors adapted to compete in a reduction of parasitic inductances, - soldering or sintering of metal parts on said lower plate and said upper plate intended to ensure, once the final power electronic module, a triple function of thermal conduction of the module, of electrical conduction between the conductive tracks of the underside of said upper plate and the conductive tracks of said lower plate, and mechanical support of said upper plate which prevents any mechanical contact between the semiconductor chips and the upper plate, - electrical looping of said upper face of said upper plate with said lower face of said plate upper, - superposition of said upper plate to said lower plate, - mounting capacitors adapted to contribute to a reduction of parasitic inductances - brazing of the assembly and assembly on a metal sole.

The different steps are not necessarily performed in the order in which they are listed. The method implements all of these steps, but the order of execution of the steps can vary without changing the electronic module obtained by the method.

In particular, the capacitors can be mounted during the conditioning of the upper plate or when the upper and lower plates are assembled together.

Similarly, the electrical looping of the upper and lower faces of the upper plate can be achieved during the conditioning of the upper plate or later.

Advantageously, a method according to the invention further comprises one or more steps of placing the module in the oven at different stages of its manufacture at temperatures of, for example, between 245 ° C. and 310 ° C., depending on the operation.

Advantageously, a method according to the invention implements a plurality of soldering steps, each step using a specific brazing paste.

For example, the brazing steps are advantageously the following: a brazing step at a very high temperature for the semiconductor chips and the copper half-rings forming the means of electrical looping of the top plate (in the case where this looping is performed by such half-rings). This brazing is for example carried out at a temperature of 310 ° C, using a solder paste formed of 80% gold and 20% tin. - An intermediate temperature soldering step for copper balls, control connectors and power connectors. This brazing is for example carried out at a temperature of 280 ° C, using a solder paste formed of 90% tin and 10% antimony. - A low temperature soldering step for the sole and for capacitors adapted to reduce parasitic inductances. This brazing is for example carried out at a temperature of 240 ° C, using a solder paste formed of 96.5% tin, 3% silver, and 0.5% copper.

A method according to the invention advantageously makes it possible to manufacture an electronic power module according to the invention.

In addition, a module according to the invention is advantageously manufactured by a method according to the invention. The invention also relates to an electronic power module and a method of manufacturing an electronic power module characterized in combination by all or some of the characteristics mentioned above or below. 5. List of Figures Other objects, features and advantages of the invention will appear on reading the following description given solely by way of non-limiting example and which refers to the appended figures in which: - Figure 1 is a schematic view of principle of an electronic power module according to the invention, - Figure 2 is a schematic side view of an electronic power module according to one embodiment of the invention, - Figure 3 is a schematic side view. of an electronic power module according to another embodiment of the invention, - Figures 4a and 4b are schematic perspective views, respectively from above and below, of a top plate of an electronic power module according to one embodiment of the invention, - Figures 5a and 5b are schematic perspective views, respectively from above and below, of a lower plate of a modu the power electronics according to one embodiment of the invention, - Figure 6 is a schematic perspective view of an electronic power module according to one embodiment of the invention obtained by the assembly of the upper and lower plates represented in FIGS. 4a, 4b, 5a, and 5b. 6. Detailed Description of the Embodiments of the Invention

Figures, scales and proportions are not strictly adhered to for the purpose of illustration and clarity. Throughout the following detailed description with reference to the figures, unless otherwise indicated, each element of an electronic power module is described as arranged when the module is horizontal. This arrangement is shown in particular in FIGS. 2 and 3. In addition, identical, similar or similar elements are designated by the same references in the various figures.

A three-phase electronic power module according to the invention comprises, as shown in FIGS. 1, 2 and 3, a metal plate 8, a lower plate 10 and a top plate 20 superimposed on the bottom plate 10.

Each of the two plates 10, 20 comprises a ceramic substrate 11, 21 and copper tracks 12a, 12b, 22a, 22b formed on each of the two upper and lower faces of each plate. Figure 1 shows schematically the plates 10, 20 lower and upper and their constitutions. In practice and preferably, the lower and upper plates are plates known to those skilled in the art under the acronym DCB or DBC for Direct Copper Bonded. These plates are formed from a metallized ceramic of copper tracks.

The lower plate carries chips 13 semiconductors. These chips can be of all types and depend on the application targeted by the electronic power module.

The upper plate 20 also carries capacitors 23 adapted to contribute to a reduction of spurious inductances generated by the various elements involved in the electrical circuit.

These capacitors 23 may be specifically dedicated and calibrated to reduce parasitic inductances of the circuit with which the module is associated. These capacitors may also, alternatively or in combination, comprise common-mode capacitors, whose main function is to filter the noise internal to the module, but which contribute to the reduction of parasitic inductances. These capacitors adapted to contribute to a reduction of parasitic inductances (either mainly or in an auxiliary manner) are also referred to throughout the text by the terms parasitic inductance compensation capacitors, it being understood that these capacitors do not suppress the capacitors. parasitic inductances, but contribute to reduce them.

The upper plate is carried by copper balls which extend completely between the lower plate and the upper plate. According to other embodiments, the copper balls may be replaced by gold, aluminum or silver balls.

These balls 30 provide a triple function. The first function provided is the conduction of heat flows between the upper plate and the lower plate. This function results from the thermal properties of the material used to form the balls (in this case, copper in the embodiment of the figures), the arrangement of the balls between the two plates and the thermal properties of the ceramic substrates of the plates. lower and upper.

The second function provided is the electrical conduction between the copper tracks 22a of the lower face of the upper plate and the copper tracks 12b of the upper face of the lower plate. This function results from the conductive properties of the material used (in this case copper) to form the balls, and from the arrangement of the balls which are in contact with the conductive tracks of the upper and lower plates.

The third function provided is the mechanical support of the upper plate. This function results from the mechanical properties of the material used to form the balls (in this case copper) and the shape of the balls.

These copper balls 30 have for example a diameter of the order of 1.6 mm and are, according to one embodiment, brazed at a temperature of the order of 280 ° C. on the lower and upper plates using a paste. solder formed of 90% tin and 10% antimony. In another embodiment, the copper balls are sintered on the upper and lower plates.

According to other embodiments, the copper balls may be replaced by other types of copper parts, for example by copper pads or any equivalent structures sufficiently strong to be able to support the top plate while ensuring thermal conduction and electrical conduction between the two stages of the module.

A module according to the invention further comprises electrical looping means 40 arranged between the upper tracks 22b of the upper plate 20 and the lower tracks 22a of the upper plate 20. These looping means 40 thus make it possible to close the electrical circuit between the upper and lower faces of the upper plate.

We will describe hereinafter with reference to FIGS. 2 and 3 two distinct embodiments of these means 40 of loopback.

Figure 2 shows a first embodiment of the means 40 loopback. According to this embodiment, the looping means 40 comprise half-rings 41 of copper which are arranged laterally on either side of the upper plate so as to sandwich the upper plate and form an electrical connection between them. copper tracks of the upper face of the upper plate and the copper tracks of the lower face of the plate 20. These half-rings 41 thus provide electrical continuity between the two faces of the upper plate, and therefore form a part module electrical circuit that electrically connects the components of the upper plate to the components of the lower plate. These half-rings 41 of copper are for example brazed at high temperature (of the order of 310 ° C.) on the upper plate 20 using a solder paste formed of 80% gold and 20% tin. According to this embodiment, preferably, the lower and upper plates are formed from an aluminum nitride substrate of formula AIN, which has thermal and dielectric characteristics compatible with the intended result.

Figure 3 shows a second embodiment of the means 40 loopback. According to this embodiment, the looping means 40 comprise through orifices formed in the upper plate 20 and forming vias 42 metallized. The plate may comprise several vias 42. Only a few are referenced in FIG. 2 for the sake of clarity. These vias 42 thus provide electrical continuity between the two faces of the upper plate, and thus the electrical continuity between the upper plate and the lower plate of the module. Preferably, in this embodiment, the substrate used to form the upper plate is silicon nitride, of formula Si 3 N 4 which has a very high mechanical strength and can thus support the machining of orifices to form the vias 42.

A module according to the embodiments of the figures also comprises connectors 16 for controlling the control components of the semiconductor chips 13. These control connectors 16 are connected to the lower plate 10 to be able to control control components of the semiconductor chips 13. The control components are not shown in the figures for the sake of clarity.

The module also comprises power connectors 26 connected to the upper plate 20 and intended to pass the power supplied / received by the electronic power module. The module also includes power connectors for receiving power and forming input connectors. These input connectors are not shown in the figures so as not to overload the figures. These connectors are connected to the upper plate by any appropriate means and known to those skilled in the art.

The number and arrangement of the control and power connectors depend on the intended application and are not described here in detail.

A module according to the embodiment of Figures 2 and 3 also comprises copper son 17, so-called bonding son, which provide the electrical connection between the semiconductor chips 13 and the conductive tracks 12b of the lower plate. These son have for example a section of the order of 150 pm and are, for example, ultrasonically welded at room temperature. These bonding wires may be gold, silver or aluminum according to other embodiments.

Figures 4a and 4b show schematically the upper plate 20 according to the embodiment of Figure 2, that is to say the embodiment in which the means 40 of looping are formed by half-rings 41 of copper. Figure 4a is a perspective view from above showing the top of the upper plate. In this view, the capacitors 23 for compensating the parasitic inductance are not shown for the sake of clarity. Only the layer 22b of copper is represented, with the connectors 26 of power. Figure 4b is a perspective view from below showing the underside of the upper plate. In this view, the copper balls 30 and the location of the semiconductor chips 13 have been shown for clarity, it being understood that the chips 13 are attached directly to the bottom plate 10 and not to the upper plate. Only a few balls 30 are referenced in FIG. 4b. The number of copper balls and their location depends on the intended applications and does not limit the scope of protection contemplated by this application. The balls are positioned to have a maximum of temperature differential between the chips that are soldered on the bottom plate and the top plate.

FIGS. 5a and 5b schematically represent the bottom plate 10 according to one embodiment of the invention, compatible for example with the embodiment of FIG. 2. FIG. 5a is a perspective view from above showing the top of the lower plate. This view shows the copper tracks 12b, the semiconductor chips 13, the bonding wires 14, the copper balls 30 and the control connectors 16. In this view, six semiconductor chips are shown. The number of chips 13 and their type depends on the intended application. It can be diodes, transistors, thyristors and generally all types of components to adapt the current and / or voltage of an input signal to suit the intended application. Figure 5b is a bottom view in perspective of the lower plate 10 revealing a layer of copper to be fixed by brazing at low temperature (of the order of 240 ° C) on the sole 8 metal.

Figure 6 is a perspective view of the lower and upper plates joined to each other. In this view, the compensation capacitors 26 are not shown for clarity. The invention also relates to a method of manufacturing an electronic power module.

Such a manufacturing method comprises the following steps: - conditioning of the lower plate 10 and removal of the semiconductor chips 13 - conditioning of the upper plate 20 for receiving the compensation capacitors 23 - electric looping of the faces of the plate 20, for example by brazing half-rings 41, brazing or sintering of metal parts on said lower plate intended to ensure, once the final power electronic module, a triple function of thermal conduction of the module, electrical conduction between the conductive tracks of the lower face of said upper plate and the conductive tracks of the upper face of said lower plate, and of mechanical support of said upper plate, - brazing of the bonding wires, - superposition of said upper plate to said plate lower - assembly of capacitors that contribute to a reduction of induct parasitic ances on the upper plate, - final assembly of the module. The step of conditioning the lower plate and depositing the semiconductor chips 13 may for example be carried out by the succession of the following substeps: cleaning of each face of the plate by dipping the plate in a bath ultrasonication, activation of the surfaces by plasma, placement of a tool for masking the positioning of semiconductor chips, placement of solder preforms, for example an Au80-Sn20 paste as described above, with the aid of a suction cup pen, - places semiconductor chips with a suction cup pen, - puts weight on the chips to fix them during the soldering operation using a pair of pliers, - removal of the mask - baking at a temperature of 310 ° C.

The steps of conditioning the upper plate and electric looping of the plate can for example be carried out by the following succession of sub-steps: cleaning of each face of the plate by dipping the plate in an ultrasound bath; activation of the surfaces by plasma, - installation of positioning masking tooling of the half-rings forming the means of electrical looping of the upper plate, - fitting of the half-rings to the locations provided in the tooling with the aid of a clamp, - deposition of a solder paste for the half-rings, for example an Au80-SN20 paste as described above, - passage in the oven at a temperature of 310 ° C.

The baking of the lower and upper plates is preferably carried out at the same time and in the same oven.

The soldering steps of the copper balls and the bonding wires may for example be carried out by the succession of the following sub-steps: depositing and connecting the bonding wires to the semiconductor chips, depositing a solder paste , for example an Sn90-SblO paste, - placement of the copper balls using a clamp, - deposition of a solder paste, for example the Sn90-SblO paste on the copper balls, - deposit of solder paste, for example Sn90-Sbl0 paste for control connectors. The plate superposition step may for example be performed by the following succession of steps: - deposition of the lower plate on the basis of an assembly tool, - arrangement of a mechanical guide device around the lower plate - placing the upper plate on the lower plate with the aid of the guiding device, - depositing a solder paste, for example an Sn90-Sbl0 paste on the top plate, - placement of the control connectors and connectors of power on solder pastes, - attachment of a connector mask on the basis of assembly tools, - placing the assembly at a temperature of 280 ° C. The assembly step comprises, for example, the succession of the following substeps: deposition of a solder paste on the soleplate, establishment of a soleplate in a tooling, setting up of the formed assembly two plates on the sole, - placement and fixing of a connector mask, - placement of fasteners, - deposition of solder paste for connectors and capacitors for compensation of parasitic inductances, - placement of connectors, - placement and soldering of the capacitors with a soldering iron, - placing the assembly in the oven, for example at a temperature of 245 ° C. The invention may also comprise a last step of encapsulation in a housing which may comprise the succession of the following steps: - preparation of the surfaces of the housing, - gluing of the lower housing on the sole, - injection and crosslinking of a gel, - nesting and gluing of the case.

According to a variant of the invention, a housing can be configured to receive a plurality of modules according to the invention.

The method described is only a way of obtaining an electronic power module according to the invention. Other methods implementing other sub-steps may also lead to an electronic module according to the invention.

Claims (10)

metallic, for example copper, so-called bonding son, connecting said semiconductor chips and the conductive tracks of said lower plate. The shape and arrangement of said bonding wires determines the minimum size of the copper balls that can be used to carry out the invention. Indeed, said bonding wires are soldered on the semiconductor chips and connected to the conductive tracks of the lower plate, forming, due to their structure, a curvature which extends into the space delimited by the lower and upper plates. . The dimension, in the vertical direction, of this space is defined by the dimensions along the same vertical direction of the copper balls. This vertical dimension is the direction perpendicular to the planes in which the upper and lower plates extend. The invention also relates to a method of manufacturing an electronic power module comprising the following steps: - conditioning a first plate, said lower plate, from a metallized ceramic substrate of conductive tracks, on which one comes fixing semiconductor chips, - conditioning a second plate, said upper plate, from a metallized ceramic substrate of conductive tracks on each of its upper and lower faces, and intended to receive capacitors adapted to compete in a reduction of parasitic inductances, - soldering or sintering of metal parts on said lower plate and said upper plate intended to ensure, once the final power electronic module, a triple function of thermal conduction of the module, of electrical conduction between the conductive tracks of the underside of said upper plate and the conductive tracks of said lower plate, and mechanical support of said upper plate which prevents any mechanical contact between the semiconductor chips and the upper plate, - electrical looping of said upper face of said upper plate with said lower face of said plate Superior, Claims An electronic power module comprising a metal plate (8) carrying a first plate, said lower plate (10) comprising a ceramic substrate (11) carrying conductive tracks (12a, 12b), and on which chips are fixed ( 13) semiconductor, characterized in that it further comprises: a second plate, said plate (20) upper, comprising a substrate (21) ceramic carrying conductive tracks (22a, 22b) on each of its upper faces and lower, and on which are fixed capacitors (23) adapted to contribute to a reduction of parasitic inductances of said module, said upper plate (20) being superimposed on said lower plate (10), metal parts (30) extending integrally between said lower plate (10) and said upper plate (20) so as to provide a triple thermal conduction function between the upper and lower (10) plates of conductive electrical connection between the conductive tracks (22a) of the lower face of the upper plate (20) and the conductive tracks (12b) of the lower plate (10), and mechanical support of the upper plate (20) above the lower plate which prevents any mechanical contact between the semiconductor chips and said upper plate, means (40; 41; 42) electrically looping said upper plate (20) adapted to electrically connect the conductive tracks (22b) of said upper face to the conductive tracks (22a) of said lower face of said upper plate. 2. Electronic power module according to claim 1, characterized in that said means for electrically looping said upper plate (20) are formed by a plurality of conductive half-rings (41) whose first end is in contact with a track. Conductive (22b) of said upper face of said upper plate (20) and a second end of which is in contact with a track (22a) conductive of said lower face of said upper plate (20). 3. Electronic power module according to claim 1, characterized in that said means of electrical looping of said upper plate are formed by vias (42) formed through said plate (20) upper and which open on both sides of said upper plate (20) on the conductive tracks (22a, 22b). 4. Electronic power module according to one of claims 1 to 3, characterized in that said plate (10) is a lower plate formed from a substrate (11) of aluminum nitride metallized on each of its faces upper and lower by copper layers forming said conductive tracks (12a, 12b). 5. Electronic power module according to one of claims 1 to 4, characterized in that said plate (20) is a top plate formed from a substrate (21) metallized silicon nitride on each of its upper faces. and lower by copper layers forming said conductive tracks (22a, 22b). 6. electronic power module according to one of claims 1 to 5, characterized in that said metal parts are copper balls (30) brazed or sintered between said upper and lower plates. 7. Electronic power module according to one of claims 1 to 6, characterized in that it further comprises control connectors (16) of control components of said chips (13) semiconductor arranged on said plate (10). ), said control connectors (16) being connected to said lower plate (10). 8. electronic power module according to one of claims 1 to 7, characterized in that it comprises power connectors (26) connected to said plate (20) upper. 9. Electronic power module according to one of claims 1 to 8, characterized in that it further comprises metal son, said son (17) bonding, electrically connecting said chips (13) semiconductor and said tracks. (12b) conductive of said lower plate (10). 10. A method of manufacturing an electronic power module comprising the following steps: conditioning a first plate, said plate (10) below, from a metallized ceramic substrate (11) tracks (12a, 12b) conductive, on which one comes to fix chips (13) semiconductors, conditioning a second plate, said plate (20) upper, from a substrate (21) ceramic metallized conductive tracks (22a, 22b) on each of its upper and lower faces, and intended to receive capacitors (23) adapted to contribute to a reduction of parasitic inductances, brazing or sintering of metal parts (30) on said lower plate (10) and said plate (20) higher intended to ensure, once the final power electronic module, a triple thermal conduction function of the module, electrical conduction between the tracks (22a) conductive of the lower face e of said upper plate (20) and conductive tracks (12b) of said lower plate (10), and of mechanical support of said upper plate (20) which prevents any mechanical contact between the semiconductor chips and the upper plate, electrical looping of said upper face of said upper plate (20) with said lower face of said upper plate, superimposition of said upper plate (20) to said lower plate (10), mounting capacitors (23) adapted to contribute to a reduction parasitic inductances on the upper plate (20), brazing of the assembly and assembly on a metal plate (8).