Method for making at least one electrical connection within a power electronics module and power electronics module

Abstract

Method of making at least one electrical connection within a power electronics module (1), the power electronics module (1) comprising - a metallized ceramic substrate (3) having an upper metallic layer (3b) covering a ceramic layer (3a), said upper metallic layer having component mounting areas and electrical interconnection tracks, and - components having a lower face and an upper face, each mounted by its lower face on a respective mounting area, said components having at least one first component (4) being a power semiconductor component, having on its upper face at least one signal electrode connection area of ​​the first component, method comprising a step (a) of additive manufacturing, by melting metal powder, of at least one connecting wire (5) to connect a connection area (30;30, 31) of signal electrode said first component (4) to an external connection area (32) of an electrical track (7) of the substrate or of another component (6), the upper surface of said signal electrode connection area and an upper surface of said external connection area from which said connecting wire is formed being substantially coplanar, said signal electrode connection area having a metallization thickness of at least one hundred microns. Figure of the abstract: Figure 2;

Description

Title of the invention: Method for producing at least one electrical connection within a power electronics module and power electronics module Technical field

[0001] The present disclosure relates to the field of power electronics modules. It relates more particularly to a method for producing at least one electrical connection within a power electronics module, as well as a power electronics module comprising such an electrical connection. Prior art

[0002] A power electronics module very conventionally comprises power semiconductor components acting as switches. The semiconductors are mounted on an electrically insulating substrate.

[0003] The power electronics module integrates, for example, a function of an inverter intended to control an electric motor of an electromechanical actuator.

[0004] The semiconductor components are, for example, power transistors of the JFET, IGBT or MOSFET type or power diodes.

[0005] The substrate is for example made up of a ceramic layer which has, on each of its faces, a metallization layer. In addition to electrical insulation, the role of the substrate is to transfer the heat flow dissipated by the semiconductor components.

[0006] Such a power electronics module also conventionally comprises a base plate which evacuates the heat flow and which ensures mechanical support of the power electronics module. The base plate is generally made of copper or an alloy of aluminum and silicon carbide, and is usually mounted on a heat sink.

[0007] The wiring for connecting a signal electrode connection pad of a component to an external connection pad of an electrical track of the substrate or of another component is in particular constituted by wire wiring, or by ribbons or clips soldered on the upper surface of the components or of the track, or by a double-sided type assembly.

[0008] The use of aluminum or copper wiring wires is the most widespread method in power electronics. To allow the passage of a high current while reducing the resistance and inductance of the interconnections, the interconnection is made up of several wires positioned in parallel.

[0009] It is known to attach metallic wiring leads to a component such as a chip semiconductor by ultrasonic welding, in particular by a method called “wedge bonding”, also called wedge welding.

[0010] Wedge bonding is performed at room temperature and combines pressure and ultrasonic vibrations to bond the wire to a component pad. This method allows the use of large diameter wires, generally made of aluminum.

[0011] Wire cabling is the most widely used interconnection method in power assemblies.

[0012] However, in the context of power electronic modules used in a so-called harsh environment, whether for aeronautical, automotive or railway applications, or even for wind power, combined thermal cycling reveals, by scanning electron microscope micrography, the appearance of cracks, or even breaks, and detachment of the wiring wires.

[0013] Such problems are known and a representative analysis is notably available in the thesis of Turker Dagdelen entitled “Failure Analysis of Thick Wire Bonds” published in 2013.

[0014] Damage to wiring wires such as cracking, peeling, is one of the major causes of failure of a power electronics module. Indeed, a failure in the wire wiring reduces the performance of a power electronics module, or even prevents its operation. Such damage results from the small dimensions of the wiring wires and their high exposure to thermal and mechanical effects. However, they are still used for reasons of efficiency, ease of integration and cost.

[0015] There is thus a need to benefit from an electrical connection, in particular for power electronic modules used in harsh environments, which is more resistant to cracks and detachment.

[0016] Furthermore, climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft but also to those currently in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0017] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products, the integration and use of which in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

[0018] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0019] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0020] To this end, the present disclosure is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft. Summary

[0021] In the present disclosure, according to one aspect, a method is proposed for producing at least one electrical connection within a power electronics module, the power electronics module comprising - a metallized ceramic substrate comprising an upper metal layer covering a ceramic layer, said upper metal layer comprising component transfer pads and electrical interconnection tracks, and - components having a lower face and an upper face, each attached by their lower face to a respective attachment range, said components comprising at least one first component being a power semiconductor component, comprising on the upper face at least one signal electrode connection pad of the first component, method comprising a step (a) of additive manufacturing, by melting metal powder, of at least one connecting wire for connecting a signal electrode connection pad of said first component to an external connection pad of an electrical track of the substrate or of another component, the upper surface of said signal electrode connection pad and an upper surface of said external connection pad from which said connecting wire is formed being substantially coplanar, said signal electrode connection pad having a metallization thickness at least equal to one hundred microns.

[0022] The features set out in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0023] The additive manufacturing step can be implemented so as to simul- tangently: - a first portion of the connecting wire from the upper surface of the signal electrode connection pad of said first component, and - a second portion of the connecting wire from the upper surface of the external connection pad, - until said first and second portions are joined at a junction point at a predetermined height above a surface plane of said signal and external electrode connection pads.

[0024] The additive manufacturing step is for example such that said first and second portions of the connecting wire form an angle at their junction point of between 70° and 120°.

[0025] The method may comprise a step prior to step a) of additive manufacturing, the first component having on the upper surface of the semiconductor substrate, a set of metallizations, also called pads, for interconnecting said signal electrode comprising at least one metallization, said preliminary step comprising: - a formation of a metal part which is a metal strip having a thickness of the order of at least a hundred microns, and of planar shape adapted so as to cover said set of interconnection metallizations of said signal electrode, - a transfer of said metal part onto said set of metallizations, said metal part and the set of metallizations forming the connection area of ​​said signal electrode.

[0026] In this case, the first component is for example a transistor, said first component may comprise a set of metallizations of a power signal electrode and a control signal electrode metallization, the prior step consisting in particular of producing and then transferring a first metal part onto the set of power signal electrode metallizations and a second metal part onto the control signal electrode metallization.

[0027] The additive manufacturing step can be configured to produce at least two connection wires per power signal electrode having the same first cross-section dimensioned for the power current density to be transported.

[0028] The additive manufacturing step may be configured to produce at least one additional connection wire per power signal electrode connecting the power signal electrode connection pad to an external connection pad consisting of a connection pad for a measurement or an electrical track, said additional connection wire having a second cross-section smaller than the first cross-section.

[0029] The additive manufacturing step may be configured to produce at least one additional connecting wire for the control signal electrode having a third cross-section smaller than the first cross-section.

[0030] The method may comprise, prior to said additive manufacturing step, at least one step from among the following steps b) and c): - b) producing a flat-bottomed cavity in the thickness of the upper metal layer of the substrate, and transferring, in particular by brazing or sintering, said first component onto a corresponding transfer area of ​​the flat cavity bottom, - c) forming and transferring, in particular by brazing or sintering, a third metal part onto the external connection pad, the cavity depth and / or the thickness of the third metal part may be such that the upper surfaces of the signal electrode connection pad and the external connection pad are substantially coplanar.

[0031] Said other component is for example a power semiconductor component.

[0032] The additive manufacturing step may be such that each of the first and second portions of connecting wire comprises a first foot-forming section extending over a predetermined height from a first end on the upper surface of the respective signal or external electrode connection pad in a direction orthogonal to this surface to a second end from which a first branch-forming section extends in an oblique direction towards a junction point between said first and second portions.

[0033] The additive manufacturing step is for example such that at least each first and second portion of connecting wire comprises - a second foot section of the same height as the first foot section, the first and second foot sections forming a first pair of feet, and - a second branch section extending from the second foot section in an oblique direction to converge towards said first branch section, with said first and second branch sections forming an angle substantially equal to the angle at the junction point between the first and second portions of the connecting wire.

[0034] In this case, the additive manufacturing step may be such that at least the first portion of connecting wire comprises at least a second pair of feet comprising a first and a second foot-forming section, each continuing with a first, respectively a second, branch-forming section, said first and second branch-forming sections converging towards each other at the same junction point on the first branch-forming section, and forming between they have an angle substantially equal to the angle at the junction point between the first and second portions of the connecting wire.

[0035] The first and second foot sections of the pairs of feet preferably have the same height.

[0036] The first section forming a branch of said first and / or second portion may comprise a part common to said at least two connecting wires, having a cross-section whose width is greater than the sum of the widths of said at least two connecting wires.

[0037] Step a) of additive manufacturing may include the concomitant printing of at least one additive manufacturing support pillar for each first and second portion of connecting wire to be produced.

[0038] The additive manufacturing step implemented is advantageously chosen from the group consisting of selective laser melting (SLM), laser melting of a powder projection, electron beam melting (EBM) technology and directed energy deposition, preferably selective laser melting.

[0039] The method can be applied for the collective production of at least all of the power signal electrode connection wires of the power semiconductor components of the power electronics module.

[0040] According to another aspect, in combination with the above, there is provided a power electronics module comprising: - a metallized ceramic substrate comprising an upper metal layer covering a ceramic layer, said upper metal layer comprising component transfer pads and electrical interconnection tracks, and - components having a lower face and an upper face, each attached by their lower face to a respective attachment range, said components comprising at least one first component being a power semiconductor component, comprising on the upper face at least one signal electrode connection pad of the first component, - a connecting wire for connecting a signal electrode connection pad of said first component to an external connection pad of an electrical track of the substrate or of another component, the upper surface of said signal electrode connection pad and an upper surface of said external connection pad from which said connecting wire is formed being substantially coplanar, said signal electrode connection pad having a metallization thickness at least equal to a hundred microns, the connecting wire being produced by implementing the method as defined above.

[0041] The connecting wire may comprise a first portion of the connecting wire from the upper surface of the signal electrode connection pad of said first component, and a second portion of the connecting wire from the upper surface of the external connection pad, and a junction point of said first and second portions at a predetermined height above a surface plane of said signal and external electrode connection pads.

[0042] Said first and second portions may form an angle at their junction point of between 70° and 120°.

[0043] The first component may have on the upper face, a set of metallizations - or pads - for interconnecting said signal electrode comprising at least one metallization, the power electronics module comprising a metal part which is a metal strip having a thickness of the order of at least a hundred microns, and of planar shape covering said set of metallizations for interconnecting said signal electrode, said metal part and the set of metallizations forming the connection pad of said signal electrode.

[0044] The first component is for example a power transistor. In this case, said first component may comprise a set of metallizations, or pads of a power signal electrode and a control signal electrode metallization, the power electronics module comprising a first metal part on the set of power signal electrode metallizations and a second metal part on the control signal electrode metallization.

[0045] The module may comprise at least two connecting wires per power signal electrode having the same first cross-section dimensioned for the power current density to be transported. Such connecting wires may be arranged substantially parallel to each other, close to each other.

[0046] The module may comprise at least one additional connection wire per power signal electrode connecting the power signal electrode connection pad to an external connection pad consisting of a connection pad for a measurement or an electrical track, said additional connection wire having a second cross-section smaller than the first cross-section.

[0047] The module may comprise at least one additional connection wire connecting the connection pad of the control signal electrode to an external connection pad, said additional connection wire having a third cross-section smaller than the first section.

[0048] The module may comprise at least one of: - a flat-bottomed cavity in the upper metal layer thickness of the substrate, in which said first component is transferred onto a corresponding transfer area of ​​the flat cavity bottom, and - a third metal part on the external connection pad, the cavity depth and / or the thickness of the third metal part being able to be such that the upper surfaces of the signal electrode connection pad and the external connection pad are substantially coplanar.

[0049] Said other component is for example a power semiconductor component.

[0050] Each of the first and second connecting wire portions may comprise a first foot section extending over a predetermined height from a first end on the upper surface of the respective signal or external electrode connection pad in a direction orthogonal to this surface to a second end from which a first branch section extends in an oblique direction towards a junction point between said first and second portions.

[0051] In this case, at least each first and second portion of connecting wire may comprise - a second foot section of the same height as the first foot section, the first and second foot sections forming a first pair of feet, and - a second branch section extending from the second foot section in an oblique direction to converge towards said first branch section, with said first and second branch sections forming an angle substantially equal to the angle at the junction point between the first and second portions of the connecting wire.

[0052] At least the first portion of connecting wire may comprise at least a second pair of feet comprising a first and a second section forming a foot, each continuing with a first, respectively a second, section forming a branch, said first and second section forming a branch converging towards each other at the same junction point on the first section forming a branch, and forming between them an angle substantially equal to the angle at the junction point between the first and second portions of the connecting wire.

[0053] The first and second foot sections of the pairs of feet may have the same height.

[0054] The first section forming a branch of said first and / or second portion may comprise a part common to said at least two connecting wires, having a cross-section whose width is greater than the sum of the widths of said at least two connecting wires. Brief description of the drawings

[0055] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0056] [Fig.l] shows schematically and partially, in cross-section, an interconnection on the upper face of the power semiconductor components of a power electronics module according to an example after implementation of the method according to an example.

[0057] [Fig.2] shows schematically and partially, in cross-section, a interconnection on the upper face of the power semiconductor components of a power electronics module according to another example after implementing the method according to another example.

[0058] [Fig.3] shows schematically and partially, in top view, an example interconnection on the upper side of the power semiconductor components of the power electronics module.

[0059] [Fig.4] shows schematically and partially, in top view, according to an example interconnection on the upper side of the power semiconductor components of the power electronics module.

[0060] [Fig.5] shows schematically and partially, in top view, an example interconnection on the upper side of the power semiconductor components of the power electronics module.

[0061] [Fig.6] shows schematically and partially, in top view, an example interconnection on the upper side of the power semiconductor components of the power electronics module.

[0062] [Fig.7] is a schematic and partial view, in cross-section, of an example of the connectors on power electronics module.

[0063] [Fig.8] is a view similar to [Fig.7] of another example of the connection on a power electronics module.

[0064] [Fig.9] is a top view, schematic, partial and in perspective of another example of a power electronics module and its connections.

[0065] [Fig. 10] is a top view, schematic, partial and in perspective, of another example of a power electronics module and its connections.

[0066] [Fig. 11] is a view similar to [Fig.7] of another example of the connection on a power electronics module.

[0067] [Fig. 12] is a view similar to [Fig.7], during the making of an electrical connection, by means of the method according to an example, within a power electronics module according to an example.

[0068] [Fig. 13] illustrates schematically and in isolation, partially and in perspective an example of connection wires produced using the method according to an example of implementation. Description of the embodiments

[0069] In the various figures, the same references designate identical or similar elements. For the sake of brevity, only the elements which are useful for understanding the embodiment described are shown in the figures and are described in detail below. The drawings are schematic.

[0070] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures and of the power electronics module.

[0071] By "connection wire" is meant a wire having an electrical function of transporting an electrical signal between two ends of the wire, each of the ends being connected to a connection pad, to an electrical track or to a component. Such a wire may have a circular, square, rectangular, or other cross-sectional shape. It may have a ribbon appearance.

[0072] Reference is now made to [Fig. 1]. This illustrates the implementation of an example of a method for producing at least one electrical connection within a power electronics module 1. The power electronics module 1 comprises a metallized ceramic substrate 3 comprising an upper metal layer 3b, generally made of copper or aluminum, covering a ceramic layer 3a, in particular made of aluminum nitride (AIN), alumina (A12O3) or silicon nitride (Si3N4). In this example, the support 3 also comprises a lower metal layer 3c, generally made of copper or aluminum, covering the ceramic layer 3a on a face which is opposite the face covered by the upper metal layer 3b.

[0073] The upper metal layer 3b comprises component transfer pads 16, one of which is visible in [Fig.l], and electrical interconnection tracks 7, one of which is visible in [Fig.l]. The power electronics module 1 also comprises components, a first component 4 of which is visible in [Fig.l], having a lower face 2 and an upper face 9, each attached by their lower face 2 to a respective transfer pad 16. The first component 4 is a power semiconductor component, comprising on the upper face at least one signal electrode connection pad 30 of the first component 4.

[0074] The method comprises a step of additive manufacturing, in this example by melting metal powder, of at least one connection wire 5 to connect one or the signal electrode connection pad 30, which consists of a metallization, of the first component 4 to an external connection pad 32 of an electrical track 7 of the substrate 3 in this example but the external connection pad 32 could be that of another component. The upper surface 9 of the signal electrode connection pad 30 and an upper surface 11 of the external connection pad 32 from which the connecting wire 5 is formed are substantially coplanar, as visible in [Fig.l], in a surface plane P. In the present disclosure, it is thus a planar structure or interconnection, that is to say in two dimensions. In addition, the signal electrode connection pad 30 has a metallization thickness e at least equal to a hundred microns. The connecting wire 5 can be made of aluminum.

[0075] The additive manufacturing step is implemented so as to simultaneously form, as visible using the two arrows in [Fig.l], in a vertical direction Z, a first portion 8 of the connecting wire 5 from the upper surface 9 of the signal electrode connection pad 30 of the first component 4, and a second portion 10 of the connecting wire 5 from the upper surface 11 of the external connection pad 32 until the first and second portions 8, 10 join at a junction point 19 at a predetermined height Hc above the surface plane P of the upper surfaces 9 and 11 of the signal and external electrode connection pads 30 32. In the example illustrated, the additive manufacturing is carried out symmetrically, the first and second portions 8 and 10 being substantially symmetrical with respect to a vertical plane passing through the junction point 19.

[0076] In this example, the additive manufacturing step is implemented such that the first and second portions 8 and 10 make an angle y at their junction point 19 of between 70° and 120°, in this example 110°. The angle α between the upper surface 9 of the signal electrode connection pad 30 and the first portion 8 is preferably equal to the angle [3 between the upper surface 11 of the external connection pad 32 and the second portion 10, each being equal to (90°- y / 2), in this example 35°.

[0077] It should be noted that, in this example, the method comprises, prior to the additive manufacturing step, the step of producing a cavity 15 with a flat bottom in the thickness of the upper metal layer 3b of the substrate 3, and transferring the first component 4 onto a corresponding transfer area 16 of the flat bottom of the cavity 15, by brazing or by sintering. The depth of the cavity 15 is such that the upper surfaces 9 and 11 of the signal electrode connection area 30 and of the external connection area 32 are substantially coplanar.

[0078] In the example illustrated in [Fig.2], the method comprises a step prior to the additive manufacturing step. Indeed, in this example, the first component 4 has on the upper face, a set of interconnection metallizations 20 of the signal electrode comprising at least one metallization generally called a pad. In this example, the preliminary step comprises a formation of a metal part 33 which is a metal strip, in particular made of aluminum or copper, having a determined thickness el, and a planar shape adapted so as to cover said set of interconnection metallizations (or pads) 20 of said signal electrode, then a transfer, in this example by brazing, of said metal part 33 on said set of metallizations 20, said metal part 33, the brazing layer 25 and the set of metallizations 20 forming the connection pad 30 of said signal electrode. In general, transfer is understood to mean a direct transfer by brazing or sintering, known as such. The metal strip has a thickness el such that the connection pad 30 thus formed has a determined thickness, of the order of at least a hundred microns. The metal strip makes it possible to protect the active zone of the first component 4 during additive manufacturing, in particular against the effects of the laser during the powder melting step.

[0079] In the above, the steps of transferring a component onto a transfer pad or a metal strip onto a set of pads are typically steps of direct transfer by soldering or sintering. The thickness of the metallizations or pads 20 is not shown in the figures, for simplification and is negligible compared to the respective thicknesses of solder or sintered joint and of the metal strip.

[0080] In the example of [Fig.3], an example of a power electronics module 1 is shown in which the first component 4 is a power transistor, for example a JFET, IGBT or MOSFET type transistor,.... The first component 4 comprises in this example, on the upper face, a metallization (a pad) 22 of a control signal electrode substantially positioned centrally, and a set of metallizations (pads) 21 of a power signal electrode, six in number in the illustrated example, shown in dotted lines, distributed around this metallization 22.In implementing the method, the preliminary step is carried out consisting of producing and then transferring a first metal part 33a onto the set of metallizations 21 of the power signal electrode forming a connection pad 30i of the power signal electrode and a second metal part 33b onto the metallization of the control signal electrode 22, forming a connection pad 302 of the control signal electrode.

[0081] In this example also, the additive manufacturing step is implemented to produce at least two connection wires 5, in this example three, connecting the connection pad 30i of the power signal electrode and an external connection pad 32 (of a track or another component), the two wires having the same first cross-section Stl sized for the power current density to be transported. This makes it possible to increase the reliability of the power connection.

[0082] In the example of [Fig.4], one of the external connection pads 32 consists of a connection pad for a measurement or an electrical track. Such measurements make it possible to collect health data from the transistor. This makes it possible to carry out by example a measurement of electrical voltage on the surface of the component, in particular to have a reference voltage.

[0083] The additive manufacturing step was, still in the example of [Fig.4], implemented to further produce at least one additional connection wire 5 connecting the connection pad 30i of the power signal electrode to this external connection pad 32 for measurement. In this case and as can be seen, the additional connection wire 5 being a measurement wire and not a power transfer wire, it has a second cross-section St2 smaller than the first cross-section Stl.

[0084] Still in the example of [Fig.4], the additive manufacturing step was implemented to produce at least one connection wire 5 for the connection pad 302 of the control signal electrode having a third cross-section St3 smaller than the first cross-section St1.

[0085] In [Fig.4], it is also noted that the additive manufacturing step was implemented to produce four connection wires 5 for the metallic connection pad 30i of the power signal electrode connected to two separate external connection pads 32 located laterally on either side of the support 3, with two connection wires 5 connecting each external connection pad 32 to the connection pad 30i, as visible.

[0086] The metal part 33a may also have, in addition to the function of protecting the active zone with a barrier effect preventing the penetration of laser radiation during the step of melting the metal powder, a function of thermal diffusion of the power density transmitted by the signal electrode, cooperating with the connecting wires 5 in additive manufacturing which also have a larger cross-section compared to the known wire technology. Finally, this metal part 33a may have a function of mechanical attachment of the connecting wires 5 in additive manufacturing.

[0087] [Fig.5] illustrates a variant of [Fig.4], in which only two connection wires 5 are produced to connect the metallic connection pad 30i of the power signal electrode to the same external connection pad 32. Still in this example, we see that the metallization (a pad) 22 of the control signal electrode is positioned on a corner of the first component 4.

[0088] [Fig.6] illustrates an application to a diode, the first component 4 then comprising a single metal connection pad 303 for the connection of a power signal electrode. The additive manufacturing step was implemented to produce two connection wires 5 connecting this metal connection pad 303 to an external connection pad 32.

[0089] The or each connecting wire 5 may comprise a first portion 8 and a second portion 10 which are simple and form a straight line segment, as illustrated in Figures 1 to 6. In variants illustrated in Figures 7 to 11, connecting wires 5 made in such a way as to present different configurations as will be described below.

[0090] In [Fig.7], the additive manufacturing step has been implemented in such a way that each of the first and second portions 8, 10 of connecting wire 5 comprises a first foot section 40 extending over a predetermined height h, preferably less than or equal to 5 mm, from a first end 41 on the upper surface 9, 11 of the respective signal electrode 30 or external electrode 32 connection pad in a direction orthogonal to this surface 9 or 11 to a second end 42 from which a first branch section 43 extends in an oblique direction towards the junction point 19 between said first and second portions 8, 10. The first foot section 40 creates a wire support, the base of the wire in additive manufacturing. Instead of mounting with an angle directly on the component, it is preferred to create a wire support in additive manufacturing.

[0091] In the example of [Fig. 8], the additive manufacturing step was implemented such that each first and second portion 8, 10 of connecting wire 5 comprises a second foot section 44 of the same height as the first foot section 40, the first and second foot sections 40 and 44 forming a first pair of feet 45, and a second branch section 46 extending from the second foot section 44 in an oblique direction to converge towards said first branch section 43, with the first and second branch sections 43, 46 forming an angle substantially equal to the angle y at the junction point 19 between the first and second portions 8, 10 of the connecting wire 5. This constitutes at least two contact points per electrode, whether it is a power signal, control or measurement electrode. This brings flexibility to the metal attachment.Thus, in the step of shrinking the connecting wire material 5 at the end of the additive manufacturing process, this will distribute the force on the component and makes it possible to avoid or reduce a risk of tearing the component from the surface of the substrate. Preferably, two contact points are used, which is simpler and sufficiently efficient. The connecting wire 5 preferably has the same topology for the same power electronics module to simplify the process.

[0092] Figures 9 and 10 illustrate examples of power electronics modules 1 comprising connection wires 5 as described with reference to Figures 7 and 8, for first components 4 similar to that described with reference to [Fig.5].

[0093] In the example of [Fig.9], there is a first component 4 whose connection pad 30 of the power signal electrode is connected to an external connection pad 32 of an electrical track 7 using three connection wires 5 of the type illustrated in [Fig.8] and of cross section Stl. The connection pad 30 for the control signal electrode is connected to an external connection pad 32 of an electrical track 7 using a connection wire 5 of the type illustrated in [Fig.7] and of cross section St3. In this example, the first component 4 is not arranged in a cavity. Leveling pads 35 formed on the substrate 3 are made on the external connection pads 32 of the electrical tracks 7 so as to level the upper surfaces 9 and 11. On the electrical tracks 7, a strip 35 is transferred by brazing or sintering which has the function of a leveling pad - in other words, of leveling - to allow coplanar interconnection. The first component 4 comprises, under the metal part 33a, a solder and a metallization 34 or a set of metallizations (pads) of power signal electrode, source / emitter (for transistor) or cathode (for diode), itself on an active zone 37 (Si, GaN, SiC, etc.).The cumulative thickness of the metal part 33a, the solder (or sintered joint) and the metallization 34 is greater than or equal to 100 μm. Under the metal part 33b, there is a solder (or sintered joint) and a metallization 36 of the grid of the first component 4.

[0094] In the example of [Fig. 10], the power electronics module 1 comprises a first component 4 and another component 6 which, in this example, is a power semiconductor component. In this case, the method has included the step, prior to the additive manufacturing of the connection wires 5, consisting of forming and transferring a third metal part 33c, onto the external connection pad 32, of the type of the metal part 33a in this example, the thickness of the third metal part 33c being such that the upper surfaces 9 and 11 of the signal electrode connection pad 30 and of the external connection pad 32 are substantially coplanar. In addition, the first and other components 4 and 6 are each in a cavity 15 made in the thickness of the upper metal layer 3b of the substrate 3.The depth of each cavity 15 depends on the component, for the manufacture of the connection wires 5 from the same level for the two ends of the first and second portions 8 and 10. Furthermore, the external connection pads 32 of the electrical tracks 7, to which the connection pads of the signal electrodes of the first and other components 4 and 6 are connected, are arranged on leveling pads 35 to level the starting surface of the connection wires 5. The metal parts 33a (or 33c) allow laser protection in additive manufacturing and diffusion of the power in operation. The metal parts 33b allow laser protection in additive manufacturing. The metal parts 33a, 33b and 33c can have the same thickness, such that the thickness of the cumulative metallization (metallization, solder or sintered joint, and metal part), above the active surface of the component, is greater than or equal to 100 μm.

[0095] In the example of [Fig. 11], the additive manufacturing step was implemented in such that at least the first portion 8 of connecting wire 5 comprises at least one second pair of feet 47 comprising a first and a second foot-forming section 48 and 49, each continuing with a first 50, respectively a second 51, branch-forming section, said first and second branch-forming sections 50 and 51 converging towards each other at the same junction point 52 on the first branch-forming section 50, and forming between them an angle substantially equal to the angle y at the junction point 19 between the first and second portions 8, 10 of the connecting wire 5. It is noted that the first and second foot-forming sections 40, 44, 48, 49 of the pairs of feet 45 and 47 have the same height.

[0096] In the embodiment of [Fig. 12], an example of implementation of the additive manufacturing step is shown, including the concomitant printing of at least one additive manufacturing support pillar 55 for each first and second portion 8, 10 of connecting wire 5 to be produced. This makes it possible to have a larger angle y, as illustrated in this [Fig. 12], which makes it possible to widen the angular range, which has the advantage of allowing more adaptability depending on the connection distance and the height of the connecting wire 5. It should be noted that it is necessary to have sufficient height hp to be able to cut the additive manufacturing support pillars 55. These pillars can be manufactured by metallic additive manufacturing, in the same printing material as the connecting wire 5. They are removed by carrying out a mechanical cutting operation, for example by pliers, saw or other.

[0097] The additive manufacturing step implemented is preferably chosen from the group consisting of selective laser melting (SLM), laser melting of a powder projection, electron beam melting (EBM) technology and directed energy deposition, preferably selective laser melting.

[0098] As can be seen for example in Figures 9 and 10, the method as described above is applied for the collective production of all the signal electrode connection wires 5 of the power semiconductor components of the power electronics module 1.

[0099] Of course, the invention is not limited to the examples which have just been described. In particular, the shape and dimensions of the connecting wire(s) 5 may vary without departing from the scope of the invention. In particular, it is possible to envisage producing the connecting wires in a curved and / or non-symmetrical form.

[0100] The shape of the connecting wire 5 at the junction point 19 may be pointed, flattened, rounded or have another shape.

[0101] [Fig. 13] shows another example in which at least two connecting wires 5 are produced, in this example three, and in which the first section forming branch 43 of said first and second portions 8, 10, of which only the second portion 10 has been shown in this figure, comprises a common part 60 to said at least two connecting wires 5, having a cross-section whose width is greater than the sum of the widths of said at least two connecting wires 5. At the first and second foot sections 40 and 44 and at a section around the junction point 19, the connecting wires 5 are distinct, as visible. An advantage of forming the common part 60 is thermal, in that it allows more calories to be evacuated than in its absence. The current density does not increase because the foot sections remain unchanged. These foot sections 40 are not joined to avoid increasing the shear stresses at the end of the additive manufacturing.

[0102] The power electronics module may comprise connection wires 5 produced by additive manufacturing according to the present disclosure and other connection wires produced otherwise, for example by "wire bonding", i.e. by wire welding. For example, the connection wires of diameter St2 and St3 may be produced otherwise, in particular by "wire bonding", while the connection wires of diameter St1 are produced by additive manufacturing according to the present disclosure.

Claims

Claims

1. Method for producing at least one electrical connection within a power electronics module (1), the power electronics module (1) comprising - a metallized ceramic substrate (3) comprising an upper metal layer (3b) covering a ceramic layer (3a), said upper metal layer (3b) comprising component transfer pads and electrical interconnection tracks, and - components having a lower face and an upper face, each attached by their lower face to a respective transfer pad, said components comprising at least one first component (4) being a power semiconductor component, comprising on the upper face at least one signal electrode connection pad (30) of the first component (4), method comprising - a step (a) of additive manufacturing, by melting metal powder,of at least one connecting wire (5) for connecting a signal electrode connection pad (30) of said first component (4) to an external connection pad (32) of an electrical track (7) of the substrate or of another component (6), the upper surface (9) of said signal electrode connection pad (30) and an upper surface (11) of said external connection pad (32) from which said connecting wire (5) is formed being substantially coplanar, said signal electrode connection pad (30) having a metallization thickness at least equal to one hundred microns.,

2. Method according to claim 1, in which the additive manufacturing step is implemented so as to simultaneously form: - a first portion (8) of the connecting wire (5) from the upper surface (9) of the connection pad (30) of the signal electrode of said first component (4), and - a second portion (10) of the connecting wire (5) from the upper surface (11) of the external connection pad (32), until said first and second portions (8, 10) are joined at a junction point (19) at a predetermined height (Hc) above a surface plane (P) of said signal and external electrode connection pads (30, 32).

3.

4.

5.

6. The method of claim 2, wherein the manufacturing step additive is such that said first and second portions (8, 10) make an angle (y) at their junction point (19) of between 70° and 120°. A method according to any one of claims 1 to 3, comprising a step prior to step a) of additive manufacturing, the first component (4) having on the upper surface of the semiconductor substrate, a set of interconnection metallizations (pads) (20, 34) of said signal electrode comprising at least one metallization, said preliminary step comprising: a formation of a metal part (33) which is a metal strip having a thickness of the order of at least a hundred microns, and of planar shape adapted so as to cover said set of interconnection metallizations of said signal electrode, a transfer of said metal part (33) onto said set of metallizations, said metal part and the set of metallizations forming the connection pad (30) of said signal electrode. A method according to claim 4, wherein the first component (4) is a transistor, said first component (4) comprising a set of metallizations of a power signal electrode and a control signal electrode metallization, the prior step consisting of producing and then transferring a first metal part (33a) onto the set of power signal electrode metallizations and a second metal part (33b) onto the control signal electrode metallization. A method according to any one of claims 1 to 5, wherein the additive manufacturing step is configured to achieve at least two connecting wires (5) per power signal electrode having a same first cross-section (Stl) dimensioned for the power current density to be carried.

7. Method according to any one of claims 1 to 6, comprising, prior to said additive manufacturing step, at least one step from among the following steps b) and c): - b) producing a cavity (15) with a flat bottom in the thickness of the upper metal layer (3b) of the substrate (3), and transferring said first component (4) onto a corresponding transfer area (16) of the flat cavity bottom (15), - c) forming and transferring a third metal part (33c) onto the external connection area (32), the cavity depth (15) and / or the thickness of the third metal part (33c) being such that the upper surfaces (9, 11) of the signal electrode connection area (30) and the external connection area (32) are substantially coplanar.

8. A method according to any one of claims 1 to 7, wherein said further component (6) is a power semiconductor component.

9. A method according to claim 2 in combination with any one of claims 3 to 8, wherein the additive manufacturing step is such that each of the first and second portions (8, 10) of connecting wire (5) comprises a first foot section (40) extending over a predetermined height (h) from a first end (41) on the upper surface of the respective signal or external electrode connection pad in a direction orthogonal to this surface to a second end (42) from which a first branch section (43) extends in an oblique direction towards a junction point between said first and second portions.

10. The method of claim 9, wherein the additive manufacturing step is such that at least each first and second portion (8, 10) of connecting wire (5) comprises - a second foot section (44) of the same height as the first foot section (40), the first and second foot sections (40, 44) forming a first pair of feet (45), and - a second branch section (46) extending from the second foot section (44) in an oblique direction to converge towards said first branch section (43), with said first and second branch sections (43, 46) forming an angle substantially equal to the angle (y) at the junction point between the first and second portions of the connecting wire.

11. The method of claim 10, wherein the additive manufacturing step is such that at least the first portion (8) of connecting wire (5) comprises at least a second pair of feet (47) comprising a first and a second foot section (48, 49), each continuing with a first (50), respectively a second (51), branch section, said first and second branch sections (50, 51) converging towards each other at the same junction point (52) on the first branch section, and forming between them an angle substantially equal to the angle (y) at the junction point between the first and second portions of the connecting wire.

12. A method according to claim 10 or 11, wherein the first and second foot sections of the foot pairs (45, 47) have the same height.

13. Method according to claim 6 and any one of claims 9 to 12, in which the first branch-forming section (43) of said first and / or second portion (8; 10) comprises a part (60) common to said at least two connecting wires (5), having a cross-section whose width is greater than the sum of the widths of said at least two connecting wires (5).

14. Method according to any one of claims 2 to 13, step a) of additive manufacturing including the concomitant printing of at least one additive manufacturing support pillar (55) for each first and second portion (8, 10) of connecting wire (5) to be produced.

15. Method according to any one of claims 1 to 14 applied for the collective production of at least all of the power signal electrode connection wires (5) of the power semiconductor components of the power electronics module.

16. Power electronics module (1) comprising: - a metallized ceramic substrate (3) comprising an upper metal layer (3b) covering a ceramic layer (3a), said upper metal layer comprising component transfer pads and electrical interconnection tracks, and - components having a lower face and an upper face, each attached by their lower face to a respective transfer pad, said components comprising at least one first component (4) being a power semiconductor component, comprising on the upper face at least one signal electrode connection pad (30) of the first component (4), - a connecting wire (5) for connecting a signal electrode connection pad (30) of said first component (4) to an external connection pad (32) of an electrical track (7) of the substrate or of another component (6), the upper surface (9) of said signal electrode connection pad (30) and an upper surface (11) of said external connection pad (32) from which said connecting wire (5) is formed being substantially coplanar, said signal electrode connection pad (30) having a metallization thickness at least equal to a hundred microns, the connecting wire (5) being produced by implementing the method according to any one of claims 1 to 15.

17. Power electronics module (1) according to claim 16, wherein the connecting wire (5) comprises a first portion (8) of the connecting wire (5) from the upper surface (9) of the signal electrode connection pad (30) of said first component (4), and a second portion (10) of the connecting wire (5) from the upper surface (11) of the external connection pad (32), and a junction point (19) of said first and second portions (8, 10) at a predetermined height (Hc) above a surface plane (P) of said signal and external electrode connection pads.

18. Power electronics module according to any one of claims 16 and 17, in which the first component (4) has on its upper face, a set of interconnection metallizations (pads) (20, 34) of said signal electrode comprising at least one metallization, the power electronics module comprising a metal part (33) which is a metal strip having a thickness (el) of the order of at least a hundred microns, and of planar shape covering said set of interconnection metallizations (20, 34) of said signal electrode, said metal part (33) and the set of metallizations (20, 34) forming the connection pad (30) of said signal electrode.

19. Power electronics module according to claim 18, the first component (4) being a power transistor, said first component (4) comprising a set of metallizations (pads) (21) of a power signal electrode and a control signal electrode metallization (22), the power electronics module comprising a first metal part (33a) on the set of power signal electrode metallizations (21) and a second metal part (33b) on the control signal electrode metallization (22).

20. Power electronics module according to any one of claims 16 to 19, comprising at least two connection wires (5) per power signal electrode having the same first cross-section (Stl) dimensioned for the power current density to be transported.

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