Power electronics module and assembly method

Abstract

Power electronics module (100), comprising - a first printed circuit board (1) with a top layer (10) of electrically conductive material, a middle layer (11) of electrically non-conductive material and a bottom layer (12) of electrically conductive material, and a second printed circuit board (2) with a top layer (20) of electrically conductive material, a middle layer (21) of electrically non-conductive material and a bottom layer (22) of electrically conductive material, and - a high-side string with at least one power semiconductor formed as a high-side switch (3.1) and a low-side string with at least one power semiconductor formed as a low-side switch (3.2), wherein - the first printed circuit board (1) is arranged opposite the second printed circuit board (2) such that the top layers (10, 20) face each other, and wherein the top layer (10) of the first printed circuit board (1) serves as the AC phase connection (AC), and wherein the top layer (20) of the second printed circuit board (2) is structured such that it serves as the DC negative and DC positive connection (DC), and - the power semiconductors (3.1) formed as high-side switches and the power semiconductors (3.2) formed as low-side switches are arranged such that their AC terminals point towards and are contacted with the top layer (10) of the first printed circuit board (1), and DC terminals of the power semiconductors (3.1, 3.2) to the top layer (20) of the second printed circuit board (2) and are thus contacted, wherein the top layer (20) of the second printed circuit board (2) is structured such that a first sub-area thereof serves as a contact area for an AC rail (AC-S) to be contacted therewith, and wherein an AC spacer (9) is provided on the contact area and arranged such that it serves as an AC connecting element to the top layer (10) of the first printed circuit board (1), wherein the top layer (20) of the second printed circuit board (2) is structured such that a second sub-area thereof serves as a signal / control connection (7), and wherein a spacer (70) is provided on the signal / control connection (7) and arranged such that it serves as a connecting element to the signal / control connection (7) on the top layer (10) of the first printed circuit board (1).

Description

[0001] The present invention relates to the field of electromobility, in particular electronic modules.

[0002] The use of electronic modules, such as power electronic modules, in motor vehicles has increased significantly in recent decades. This is due, on the one hand, to the need to improve fuel efficiency and vehicle performance, and on the other hand, to advances in semiconductor technology. To provide the necessary energy, a variety of electronic components are required, which are used, for example, to implement bridge circuits (such as half-bridges), such as semiconductor power switches, also known as power semiconductors. Power semiconductors can be integrated into complete power electronic modules (also called power modules) or as discrete components. Power electronic modules consist of a printed circuit board (PCB) with power semiconductors mounted on it, which are electrically connected to each other on the PCB for power and control purposes.

[0003] The switching power semiconductors of the electronic modules require active cooling to dissipate switching and conduction losses. For simplified connection of the power semiconductors, they are arranged in a 2D plane, with the phase tap (AC) located centrally between the power semiconductors. This arrangement allows for simple, single-plane manufacturing, but results in a less than optimal commutation cell.

[0004] To increase cooling performance, concepts have already been designed in which cooling is also established via a heat sink 5, 6 on the top side of the power semiconductors 3.1, 3.2, as shown in Fig. Figure 1 schematically indicates this. The usual 2D layout in the chip arrangement is retained, and a thermal connection of the upper-side structure of the power semiconductors 3.1 and 3.2 is provided, thereby achieving improved cooling. For this purpose (in the case of using MOSFETs), a load connection must be established between the source S of the high-side power semiconductor 3.1 and the drain D of the low-side power semiconductor 3.2. This can be implemented using wire bonds, as shown in Fig. The curved lines indicate the design. However, this configuration requires space on the high-side power semiconductor 3.1 (which restricts the upward heat transfer) and on the portion of the circuit board, typically DBC 1, that serves as the AC phase (AC tap). Alternatively, the load path can be partially routed through the upper DBC 2, but this requires additional components to connect it to the lower DBC 1. An example of such double-sided cooled electronic modules can be found in US 10,211,133 B2.

[0005] Likewise, other double-sided cooled electronic modules are known from DE 10 2017 203 846 A1, EP 4 075 497 A2 and US 2013 / 0 020 694 A1.

[0006] Besides optimizing the thermal path, optimizing the electrical properties within a power electronics module is also of great importance. However, the well-known approach of double-sided cooled electronic modules does not adequately address this electrical optimization.

[0007] The invention is therefore based on the objective of providing a power electronics module through which improved cooling, in particular double-sided cooling, of the power semiconductors and electrical optimization can be achieved.

[0008] This task is solved by the features of independent claims. Advantageous embodiments are the subject of dependent claims.

[0009] A power electronics module is proposed, comprising a first printed circuit board with a top layer of electrically conductive material, a middle layer of electrically non-conductive material, and a bottom layer of electrically conductive material, and a second printed circuit board with a top layer of electrically conductive material, a middle layer of electrically non-conductive material, and a bottom layer of electrically conductive material, and a high-side strand with at least one power semiconductor configured as a high-side switch and a low-side strand with at least one power semiconductor configured as a low-side switch, wherein the first printed circuit board is arranged opposite the second printed circuit board such that the top layers face each other, and wherein the top layer of the first printed circuit board serves as an AC phase connection, and wherein the top layer of the second printed circuit board is structured such thatthat it serves as the DC negative and DC positive terminals, and the power semiconductors formed as high-side switches and the power semiconductors formed as low-side switches are arranged such that their AC terminals point towards and are thus contacted with the top layer of the first circuit board, and the DC terminals of the power semiconductors point towards and are thus contacted with the top layer of the second circuit board.

[0010] The top layer of the second printed circuit board is structured in such a way that a first sub-area of ​​it serves as a contact area for an AC rail to be contacted, and an AC spacer is provided on the contact area and arranged in such a way that it serves as an AC connecting element to the top layer of the first printed circuit board.

[0011] Furthermore, the top layer of the second printed circuit board is structured in such a way that a second sub-area of ​​it serves as a signal / control connection, and a spacer is provided on the signal / control connection and arranged in such a way that it serves as a connecting element to a signal / control connection on the top layer of the first printed circuit board.

[0012] In one embodiment, a spacer element is provided for each power semiconductor, wherein the spacers of the power semiconductors formed as high-side switches are arranged between the top layer of the first printed circuit board and the power semiconductor and are electrically and thermally contacted with the first printed circuit board and the power semiconductor, and wherein the spacers of the power semiconductors formed as low-side switches are arranged between the top layer of the second printed circuit board and the power semiconductor and are electrically and thermally contacted with the second printed circuit board and the power semiconductor, or wherein the spacers of the power semiconductors formed as low-side switches are arranged between the top layer of the first printed circuit board and the power semiconductor and are electrically and thermally contacted with the first printed circuit board and the power semiconductor.

[0013] In one embodiment, the power electronics module further comprises at least one signal / control rail per power semiconductor, wherein at least one signal / control connection is provided on the side of each power semiconductor to be contacted with one of the DC terminals, which is contacted with the associated signal / control rail by means of connecting elements.

[0014] In one version, the top layer of the first circuit board is fully covered by the power semiconductors.

[0015] In one version, a heat sink is arranged on the bottom layer of each circuit board and thus thermally coupled.

[0016] In one version, the printed circuit board is a DBC printed circuit board, an AMB printed circuit board, or an IMS printed circuit board.

[0017] Furthermore, an assembly method for the power electronics module is provided, wherein in a first step the power semiconductors are applied to the associated printed circuit board, and in a further, third step connections of the load terminals and the signal / control terminals with associated rails are made by means of one or two leadframes, and in a fourth step the printed circuit boards are joined together by placing the two upper layers of the printed circuit boards with the power semiconductors arranged on them on top of each other and connecting them at designated areas.

[0018] In one embodiment, in a fifth step the power electronics module is surrounded with a potting compound, and in a sixth step the leadframe(s) are removed, so that only the rails and contact elements connected to the signal / control connections protrude from the potting compound.

[0019] In one embodiment, spacer elements are applied to the power semiconductors and / or to the top layer of the printed circuit boards in a second step provided between the first and third steps or after the third step.

[0020] Furthermore, an electric drive for a vehicle is provided, comprising a power electronics component which includes at least the described power electronics module.

[0021] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing which shows details according to the invention, and from the claims.

[0022] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawing. Fig. Figure 1 shows a sectional view of a basic structure of a power electronics module with double-sided cooling according to the state of the art. Fig. Figure 2 shows a sectional view of a basic structure of a power electronics module with double-sided cooling according to an embodiment of the present invention. Fig. Figure 3 shows a sectional view of a basic structure of a power electronics module with double-sided cooling according to an alternative embodiment of the present invention. Fig. Figure 4 shows a view of a basic structure of a power electronics module with double-sided cooling according to an embodiment of the present invention. Fig. Figure 5 shows a view of a basic structure of an upper printed circuit board with leadframe according to an embodiment of the present invention. Fig. Figure 6 shows a view of a basic structure of an upper printed circuit board without a leadframe according to an embodiment of the present invention. Fig. Figure 7 shows a view of a basic structure of a lower printed circuit board with leadframe according to an embodiment of the present invention. Fig. Figure 8 shows a view of a basic structure of a lower printed circuit board without a leadframe according to an embodiment of the present invention. Fig. Figure 9 shows a view of a basic structure of a power electronics module with double-sided cooling and leadframe according to an embodiment of the present invention. Fig. Figure 10 shows a view of a basic structure of an upper circuit board according to a further embodiment of the present invention. Fig. Figure 11 shows a view of a basic structure of a lower printed circuit board without a leadframe and with (AC / DC / signal / control) rails according to the further embodiment of the present invention. Fig. Figure 12 shows a view of a basic structure of a lower printed circuit board with leadframe according to the further embodiment of the present invention. Fig. Figure 13 shows a view of a basic structure of a power electronics module with double-sided cooling and leadframe according to a further embodiment of the present invention. Fig. Figure 14 shows a view of a basic structure of a power electronics module with double-sided cooling without a leadframe according to a further embodiment of the present invention. Fig. Figure 15 shows a process flow for manufacturing a power electronics module with double-sided cooling according to an embodiment of the present invention.

[0023] In the following figure descriptions, identical elements or functions are designated with the same reference numerals. According to the invention, a double-sided cooling system for power electronics modules 100 is provided for use in power electronics components, e.g., inverters (DC / AC inverters), in the automotive sector, which improves electrical commutation, optimizes thermal interfaces, and provides a simple design for the power electronics module 100.

[0024] A power electronics module 100 typically provides one phase (with AC phase tap) of an inverter. To obtain a three-phase inverter, three of the described power electronics modules 100 are connected in series. Various methods for this are known, which will not be described further here. Since usually identical power electronics modules 100 are connected in series, the description is limited to a single power electronics module 100.

[0025] Based on the Fig. The double-sided cooled power electronics module 100 described below comprises two printed circuit boards 1, 2, each with at least three layers. The top layer 10, 20 is made of electrically conductive material, the middle layer 11, 21 of electrically non-conductive material (e.g., ceramic), and the bottom layer 12, 22 of electrically conductive material. One such printed circuit board is, for example, a DBC board. DBC stands for direct bonded copper, although the abbreviation DCB (direct copper bonded) can also be used. However, an AMB (active metal brazing) or an IMS (insulated metal substrate) printed circuit board can also be used, as long as it has at least the three described layers.

[0026] According to the invention, the top layer 10 of the first circuit board 1 serves as an AC contact (AC). The top layer 20 of the second circuit board 2 serves as a DC phase contact (DC- and DC+). Furthermore, after final assembly, the two circuit boards 1, 2 face each other with their two top layers 10, 20.

[0027] Furthermore, the power electronics module 100 has at least one half-bridge, i.e., at least one power semiconductor 3.1 arranged in a high-side strand and formed as a high-side switch, hereinafter referred to as high-side switch 3.1, and one power semiconductor 3.2 arranged in a low-side strand and formed as a low-side switch, hereinafter referred to as low-side switch 3.2.

[0028] The low-side branch, i.e., the low-side switch(es) 3.2, is arranged on the top layer 10 of the first circuit board 1 such that its AC phase contact (in the case of MOSFETs, the drain D; in the case of IGBTs, the collector corresponding to the drain) is electrically connected to the top layer 10. Thus, its DC contact (in the case of MOSFETs, the source; in the case of IGBTs, the emitter corresponding to the source) points towards the top layer 20 of the second circuit board 2.

[0029] In a preferred embodiment, a spacer element 4 is arranged on the DC contact (here S) of the lowside switch 3.2 and is electrically and thermally contacted with both the DC contact (here S) and the top layer 20 of the second circuit board 2.

[0030] In an alternative version (in Fig. (as shown in Figure 3) in the low-side strand, the DC contact (in the case of MOSFETs, the source S; in the case of IGBTs, the emitter corresponding to the source) is directly (over its entire surface) contacted with the top layer 20 of the second circuit board 2, and the spacer element 4 is arranged over its entire surface on the AC phase contact (in the case of MOSFETs, the drain D; in the case of IGBTs, the collector corresponding to the drain) and contacted with the top layer 10 of the first circuit board 1. This design is less advantageous because it is more difficult from a manufacturing perspective to provide contact for the signal / control connections 7 described below.

[0031] The high-side strand, i.e., the high-side switch(es) 3.1, is arranged on the top layer 20 of the second printed circuit board 2 such that its DC contact (in the case of MOSFETs, the drain D; in the case of IGBTs, the collector corresponding to the drain) is electrically connected to the top layer 20. Thus, its AC phase contact (in the case of MOSFETs, the source S; in the case of IGBTs, the emitter corresponding to the source) points towards the top layer 10 of the first printed circuit board 1. In one embodiment, a spacer element 4 is arranged on the AC phase contact of the high-side switch(es) 3.1 (here S) and is electrically and thermally connected to both the AC phase contact (here S) and the top layer 10 of the first printed circuit board 1.

[0032] In the illustrated versions, the lowside strand is arranged on the first circuit board 1 before final assembly, and the highside strand is arranged on the second circuit board 2 before final assembly.

[0033] The spacers 4 of both strands (highside and lowside) are made of an electrically and thermally conductive material such as copper. Highside switch 3.1 and lowside switch 3.2 generally have the same external dimensions, and the spacers 4 advantageously have the same height, so that the two circuit boards 1 and 2 can be connected with minimal tolerance. Tolerance compensation can also be achieved when joining the two circuit boards 1 and 2, for example, by applying solder.

[0034] Signal / control connections 7 are provided on the AC phase contact side of each power semiconductor 3.1, 3.2, so that the entire area of ​​the power semiconductor 3.1, 3.2 is not occupied by the AC phase contact (load connection for AC). Therefore, the spacers 4 are designed such that they do not occupy the entire area of ​​the respective power semiconductor 3.1, 3.2, but leave an area free on which signal / control connections 7 are provided instead of load connections. These signal / control connections 7 can be a gate connection or a Kelvin source connection. Thus, at least at the height of the spacers 4, there is space for contacting the signal / control connections 7 using contact elements such as wire bonds. A cooling element (not shown) can also be provided as an intermediate element in this free space, enabling additional heat dissipation (heat spreading).

[0035] Depending on the design and assembly method, the signal / control connections 7 can be provided as part of the printed circuit board 1, 2 or as external connections, as described below with reference to the assembly or manufacturing process. The circuit boards 1, 2 not only act as electrical contacts, but also as thermal conductors to dissipate heat to a heat sink 5, 6 arranged on the lowest layer 12, 22, and thus to cool the power semiconductors 3.1 and 3.2.

[0036] According to the invention, the low-side switch 3.2 is arranged rotated 180 degrees (horizontally mirrored) relative to the high-side switch 3.1, so that the AC terminals of both power semiconductors 3.1 and 3.2 point in the same direction, i.e., towards the top layer 10 of the first circuit board 1, and are thus electrically and thermally contacted (depending on the embodiment, also via spacers 4). Furthermore, the DC terminals of both power semiconductors 3.1 and 3.2 point in the same direction, i.e., towards the top layer 20 of the second circuit board 2, and are thus electrically and thermally contacted (depending on the embodiment, also via spacers 4). This arrangement enables an optimized commutation cell compared to the prior art through the three-dimensional arrangement of DC+, phase AC, and DC-. In addition, the design allows for optimized double-sided cooling of all power semiconductors 3.1, 3.2, and 3.2.2, since the connecting spacer elements 4 allow not only power flow but also thermal flow to the second circuit board 2.

[0037] The direct (full-surface) connection of the drain D (in the case of MOSFETs) of the individual power semiconductors 3.1 and 3.2 with the top layer 10, 20 of the respective printed circuit board 1, 2 leads to a simplified manufacturing of the power electronics module 100 compared to the state of the art, since, among other things, wire bonds or connecting elements can be saved.

[0038] As already indicated, depending on the assembly or manufacturing process, the signal / control connections 7, as well as the load connections (DC and AC), can be arranged slightly differently, as described below. The sequence of the assembly or manufacturing process according to one design is shown in Fig. 15 schematically represented.

[0039] In a first iteration of the assembly or manufacturing process, a power electronics module 100 results, as shown in Fig. 4 shown. The first version according to the Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. Figure 9 does not correspond to the invention. In a first step, S1, the power semiconductors 3.1 and 3.2 are applied to the corresponding printed circuit boards 1 and 2 (lowside to the first printed circuit board 1 and highside to the second printed circuit board 2). Advantageously, the power semiconductors 3.1 and 3.2 are sintered (not soldered). Thus, the DC contacts of the high-side switches 3.1 (drain D in the case of MOSFETs) are applied to the top layer 20 of the printed circuit board 2, and the AC phase contacts of the low-side switches 3.2 (drain D in the case of MOSFETs) are applied to the top layer 10 of the printed circuit board 1 and thermally and electrically connected there. The top layer 10 of the printed circuit board 1 remains completely intact and is therefore not structured, as in Figure 9. Fig. 5 and Fig. 6 is clearly visible. The top layer 20 of the circuit board 2 is structured to electrically separate DC positive and DC negative from each other, as shown in Fig. 7 and Fig. 8 is clearly visible.

[0040] In a second step S2, the spacers 4 are applied either to the power semiconductors 3.1 and 3.2 or to the circuit board 1, 2. Alternatively, the spacers 4 can also be applied only after or in the third step S3, advantageously after the signal / control connections 7 have been contacted with the associated rails (signal / control rail 8) using connecting elements. The sequence depends on the connecting elements used.

[0041] In a third step S3, the connections between the load terminals DC, AC, and the signal / control terminals 7 are established with the corresponding rails (DC rail DC-S, AC rail AC-S, signal / control rail 8). This is done using so-called leadframes LF1, LF2. The described assembly and manufacturing process of the first version requires two leadframes LF1, LF2, resulting in two partial circuit boards 1, 2 with corresponding connections. As in Fig. As shown in Figure 5, the first leadframe LF1 carries the AC rail AC-S and the signal / control rails 8 of the lowside switches 3.2, and therefore belongs to the first circuit board 1. Fig. Figure 6 shows the first circuit board 1 with the AC rail AC-S and the signal / control rails 8 after removing the unnecessary sections of the leadframe LF1 to illustrate the assembly. As shown in Fig. As shown in Figure 7, the second leadframe LF2 carries the DC rails DC-S of DC-Plus (DC+) and DC-Minus (DC-) and the signal / control rails 8 of the highside switches 3.1, and thus belongs to the second circuit board 2. Fig. Figure 8 shows the first circuit board 2 with the DC rails DC-S and the signal / control rails 8 after removing the unneeded sections of the leadframe LF2 to show the assembly.

[0042] In a fourth step S4, the two leadframes LF1, LF2 with the attached (populated) circuit boards 1, 2 are then joined by depositing the two upper layers 10, 20 of the circuit boards 1, 2 with the power semiconductors 3.1, 3.2 and the spacers 4 arranged on them onto one another and connecting them at designated areas, e.g. by sintering. These areas are either the (free) sides of the spacers 4 opposite the power semiconductors 3.1, 3.2 (in the preferred embodiment, as in Fig. 2 shown), or a (free) side of the spacer elements 4 opposite the power semiconductors 3.1 and the DC contacts of the power semiconductors 3.2 (in the preferred embodiment, as shown in Fig. 3 shown). In Fig. Figure 9 shows an oblique view of the combined circuit boards 1, 2 with leadframes LF1, LF2. The resulting power electronics module 100 (with the outwardly facing load rails DC-S, AC-S and signal / control rails 8) after removing the unnecessary parts of the leadframes LF1, LF2 is shown in Fig. 4 shown in an oblique view.

[0043] In a fifth step, S5, the power electronics module 100 is encased in a potting compound (not shown) to provide protection against environmental influences. This potting compound also serves to hold the signal / control rails 8 in position, as they would otherwise hang freely from the connections (e.g., wire bonds) after the leadframes LF1 and LF2 are removed. After potting, the leadframes LF1 and LF2 are then removed in a final step, S6. The potting compound surrounds the power electronics module 100 in such a way that only parts of the load rails DC-S and AC-S and the signal / control rails 8 protrude outside the potting compound after the leadframes LF1 and LF2 are removed.

[0044] As in Fig. As can be clearly seen in Figure 4, there is a gap between the DC rails DC-S and the circuit board 1 and between the AC rail AC-S and the circuit board 2 after joining, so that no contact occurs here. A second iteration of the assembly or manufacturing process results in a power electronics module 100, as shown in Fig. Figure 14 shows that the power semiconductors 3.1 and 3.2 are applied to the corresponding circuit board 1, 2, preferably sintered on, as in the first embodiment.

[0045] As in Fig. As can be clearly seen, the uppermost layer 10 of the upper circuit board 1 remains fully covered in the area of ​​the power semiconductors 3.1, 3.2, but is / will be structured at an edge area to provide islands 101 for the (electrical) contacting of the signal / control connections 7 of the power semiconductors 3.2 arranged on the uppermost layer 10 of the first circuit board 1 with the signal / control rails 8 provided in a later step. Spacers 4 are also applied to the power semiconductors 3.1 and 3.2 or to the circuit board 1, 2, as in the first embodiment.

[0046] As in Fig. As can be clearly seen in Figure 11, the top layer 20 of the lower circuit board 2 is structured to provide the load connections (DC and AC) and all signal / control connections 7.

[0047] In this embodiment, additional spacer elements 4 are applied to the uppermost layer 20 of the lower circuit board 2, to which the AC phase tap AC (island area as part of the uppermost layer 20, as in Fig. 11 (clearly visible) and the signal / control connections are located at 7.

[0048] Alternatively, all spacers 4 of the two circuit boards 1, 2 can also be attached only after the signal / control connections 7 have been connected to the corresponding rails (signal / control rail 8). The order depends on the connecting elements used.

[0049] Due to the spacers 4 on the lower circuit board 2, only one leadframe LF1 is required in this assembly or manufacturing process, since all load rails (DC-S and AC-S) as well as all signal / control rails 8 are connected on the lower circuit board 2, as shown in Fig. 12 are easy to see. Fig. Figure 12 shows the lower circuit board 2 with the leadframe LF1 attached to it, Fig. Figure 11 shows the circuit board 2 with the leadframe LF1 removed, i.e. with load rails (DC-S and AC-S), as well as all signal / control rails 8, but without the upper circuit board 1. Fig. Figure 13 shows the combined circuit boards 1, 2, which, as in all versions, point towards each other with their top layers 10, 20 and the power semiconductors 3.1, 3.2 arranged on them, with the leadframe LF1 still present. Fig. Figure 14 shows the combined circuit boards 1, 2 without leadframe LF1. As in the previous version, the potting compound surrounding the power electronics module 100 is not shown here, so that only parts of the load rails DC-S, AC-S and the signal / control rails 8 protrude outside the potting compound.

[0050] To provide contact between the AC rails AC-S and the signal / control rails 8 and the upper circuit board 1, spacers 70 are arranged in this embodiment in the area of ​​the islands 201 (part of the top layer 20) on the lower circuit board 2, on which the signal / control rails 8 are placed. An AC spacer 9 is also provided in the area of ​​the AC contact of the AC rails AC-S (top layer 20). These spacers 70, 9 are made of an electrically and thermally conductive material such as copper and serve to establish contact (especially electrical contact) between components of the first and second circuit boards 1, 2. They thus serve as connecting elements. Advantageously, the spacers 4 (of the power semiconductors 3.1 and 3.2) are made of the same material as the spacers 70, 9.

[0051] The spacers 70, 9 can be attached to the circuit boards 1, 2 in a separate process step, or together with other components, e.g. together with the spacer elements 4.

[0052] The additional spacers 70, 9 on the lower circuit board 2 (of which there are 20 on the top layer) make it possible to use only a single leadframe LF1. These spacers 70, 9 allow the AC phase AC and the signal / control contacts 7 of circuit board 1 to be electrically (and thermally) connected by joining the two circuit boards 1 and 2, as shown in Fig. 13 and Fig. 14 shown. As in Fig. As can be clearly seen on page 14, there is a gap between the DC rails DC-S and the circuit board 1 after joining, so that no contact is made here.

[0053] In all versions, the connections (electrical / thermal contacts) are made by sintering. This eliminates the need for solders requiring different melting temperatures. However, it may be possible to use a solder for a final connection to compensate for tolerances. Alternatively, metallurgical bonds can be achieved using technologies such as hook and loop welding.

[0054] In all versions, heat sinks 5, 6 are provided on the lowest layer 12, 22 of the circuit board 1, 2 to dissipate the waste heat outside the power electronics module 100.

[0055] A power electronics module 100 within the scope of this invention serves to operate a motor vehicle powered by an electric motor (with accumulator). The motor vehicle is, in particular, a commercial vehicle such as a truck or bus, or a passenger car. The power electronics module comprises a DC / AC inverter. It may also include an AC / DC rectifier, a DC / DC converter, a transformer, and / or another electrical converter, or a part thereof. In particular, the power electronics module 100 serves to supply power to an electric machine, for example, an electric motor and / or a generator. A DC / AC inverter preferably serves to generate a multiphase alternating current from a direct current generated by a DC voltage from an energy source, such as a battery. Reference symbol list 100 Power Electronics Module 1 first circuit board 10 top layer 101 Island / Contact Area 11 medium position 12 bottom layer 2 second circuit board 20 top layer 201 Island / Contact Area 21 medium position 22 bottom layer 3.1 High-side power semiconductors 3.2 Low-side power semiconductors S Source (Emitter) D Drain (collector) 4 spacer elements 5, 6 heat sinks 7 Signal / control connection (gate / Kelvin source connection) 70 spacers 8 Signal / control rail 9 AC spacers AC rail AC AC connection AC-S AC rail DC DC connection (DC negative or DC positive) DC-S DC rail LF1 Leadframe 1 LF2 Leadframe 2

Claims

[1] Power electronics module (100), comprising - a first printed circuit board (1) with a top layer (10) of electrically conductive material, a middle layer (11) of electrically non-conductive material and a bottom layer (12) of electrically conductive material, and a second printed circuit board (2) with a top layer (20) of electrically conductive material, a middle layer (21) of electrically non-conductive material and a bottom layer (22) of electrically conductive material, and - a high-side string with at least one power semiconductor formed as a high-side switch (3.1) and a low-side string with at least one power semiconductor formed as a low-side switch (3.2), wherein - the first printed circuit board (1) is arranged opposite the second printed circuit board (2) such that the top layers (10, 20) face each other, and wherein the top layer (10) of the first printed circuit board (1) serves as the AC phase connection (AC), and wherein the top layer (20) of the second printed circuit board (2) is structured such that it serves as the DC negative and DC positive connection (DC), and - the power semiconductors (3.1) formed as high-side switches and the power semiconductors (3.2) formed as low-side switches are arranged such that their AC terminals point towards and are contacted with the top layer (10) of the first printed circuit board (1), and DC terminals of the power semiconductors (3.1, 3.2) to the top layer (20) of the second printed circuit board (2) and are thus contacted, wherein the top layer (20) of the second printed circuit board (2) is structured such that a first sub-area thereof serves as a contact area for an AC rail (AC-S) to be contacted therewith, and wherein an AC spacer (9) is provided on the contact area and arranged such that it serves as an AC connecting element to the top layer (10) of the first printed circuit board (1), wherein the top layer (20) of the second printed circuit board (2) is structured such that a second sub-area thereof serves as a signal / control connection (7), and wherein a spacer (70) is provided on the signal / control connection (7) and arranged such that it serves as a connecting element to the signal / control connection (7) on the top layer (10) of the first printed circuit board (1). [2] Power electronics module (100) according to claim 1, wherein a spacer element (4) is provided for each power semiconductor (3.1, 3.2), and wherein - the spacer elements (4) of the power semiconductors (3.1) formed as high-side switches are arranged between the top layer (10) of the first printed circuit board (1) and the power semiconductor (3.1) and are electrically and thermally contacted with the first printed circuit board (1) and the power semiconductor (3.1), and wherein - the spacer elements (4) of the power semiconductors (3.2) formed as low-side switches are arranged between the top layer (20) of the second printed circuit board (2) and the power semiconductor (3.2) and are electrically and thermally contacted with the second printed circuit board (2) and the power semiconductor (3.2), or wherein the spacer elements (4) of the power semiconductors (3.2) formed as low-side switches are arranged between the top layer (10) of the first printed circuit board (1) and the power semiconductor (3.2) and are electrically and thermally contacted with the first printed circuit board (1) and the power semiconductor (3.2). [3] Power electronics module (100) according to one of the preceding claims, further comprising at least one signal / control rail (8) per power semiconductor (3.1, 3.2), wherein on the side of each power semiconductor (3.1, 3.2) to be contacted with one of the DC terminals the signal / control terminal (7) is arranged, which is contacted with the associated signal / control rail (8) by means of connecting elements. [4] Power electronics module (100) according to one of the preceding claims, wherein the uppermost layer (10) of the first printed circuit board (1) is fully guided over the power semiconductors (3.1, 3.2). [5] Power electronics module (100) according to one of the preceding claims, wherein a heat sink (5, 6) is arranged on the lowest layer (12, 22) of each printed circuit board (1, 2) and is thus thermally coupled. [6] Power electronics module (100) according to any one of the preceding claims, wherein the printed circuit board (1, 2) is a DBC printed circuit board or an AMB printed circuit board or an IMS printed circuit board. [7] Assembly method for a power electronics module according to any one of claims 1 to 6, wherein in - in a first step (S1) the power semiconductors (3.1, 3.2) are applied to the associated circuit board (1, 2), and - in a further, third step (S3) connections of the load terminals (DC, AC) and the signal / control terminals (7) with associated rails (AC-S, DC-S, 8) are made by means of one or two leadframes (LF1, LF2), and - in a fourth step (S4) the printed circuit boards (1, 2) are joined together by placing the two upper layers (10, 20) of the printed circuit boards (1, 2) with the power semiconductors (3.1, 3.2) arranged on them on top of each other and connecting them at designated areas. [8] Assembly method according to claim 7, wherein in a fifth step (S5) the power electronics module (100) is surrounded with a potting compound and in a sixth step (S6) the leadframe(s) (LF1, LF2) are removed, so that only the rails (AC-S, DC-S, 8) and contact elements connected to the signal / control terminals (7) protrude from the potting compound. [9] Assembly method according to claim 7 or 8, wherein in a second step (S2) provided between the first and third step (S1, S3) or after the third step (S3) spacer elements (4) are applied to the power semiconductors (3.1, 3.2) and / or to the top layer (10, 20) of the printed circuit boards (1, 2). [10] Electric drive of a vehicle comprising a power electronics component comprising at least one power electronics module (100) according to any one of claims 1 to 6.

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