Power electronics module and method for producing a power electronics module

Abstract

Power electronics module (1), comprising - a number of power semiconductor components which are electrically connected to at least one external terminal (4) via at least one power connection rail (14), - a plastic housing (2) made of a plastic housing compound, in which the power semiconductor components and the at least one power connection rail (14) are embedded, - a control board (7) with at least one current sensor (11) arranged thereon, wherein the current sensor (11) is arranged on a sensor board area (10) which is inclined or perpendicular to a main plane E P the control board (7) and is connected to the control board (7) and projects through the plastic housing mass into a slot-shaped recess (18) in the at least one power connection rail (14).

Description

[0001] The present invention relates to a power electronics module comprising a number of power semiconductor components mounted on a power substrate within a plastic housing. It further relates to a method for manufacturing such a power electronics module.

[0002] Such power electronics modules, which can be designed, for example, as inverters for an electric motor, have current sensors for measuring the currents flowing from the power semiconductor components via busbars to the external terminals. Suitable current sensors can, for example, comprise a ferromagnetic core and a Hall sensor that detects the magnetic flux in the core. The ferromagnetic core can, in particular, be part of a frame into which the power electronics module is inserted and which also serves as a support for the busbars.

[0003] The document DE 10 2019 122 369 A1 describes a power semiconductor module comprising a power semiconductor chip and an external contact, wherein the external contact is electrically coupled to the power semiconductor chip and has an opening in which a current sensor arrangement is arranged.

[0004] Document DE 10 2020 101 585 A1 describes a semiconductor module comprising a semiconductor chip and a potting compound enclosing the semiconductor chip. The potting compound has a recess in which a coreless magnetic field sensor for current measurement is arranged.

[0005] The publication DE 102022 111 406 A1 describes a power semiconductor module in which a contactless current sensor is integrated. The current sensor is mounted on a rigid-flex circuit board of the module.

[0006] There is a need to provide power electronics modules with more compact dimensions. This could be achieved by eliminating the frame, but this would eliminate a common option for mounting the core. Reducing the module height also leaves too little space for a core. An alternative would be coreless current sensors, which are cost- and space-saving, but for which no practical way of integrating them into a power electronics module is currently known.

[0007] It is an object of the present invention to provide a power electronics module that has particularly compact dimensions and is simultaneously cost-effective. Furthermore, a method for producing such a power electronics module is to be provided.

[0008] This problem is solved by the subject matter of the independent patent claims. Advantageous embodiments and further developments are the subject matter of the subclaims.

[0009] According to one aspect of the invention, a power electronics module is specified, comprising a number of power semiconductor components which are electrically connected to at least one external terminal via at least one power connection rail, and a plastic housing made of a plastic housing compound, into which the power semiconductor components and the at least one power connection rail are embedded. Furthermore, the power electronics module has a control board with at least one current sensor arranged thereon, wherein the current sensor is arranged on a sensor board region which is arranged obliquely or perpendicularly to a main plane of the control board and is connected to the control board and projects through the plastic housing compound into a slot-shaped recess in the at least one power connection rail.

[0010] The sensor board area is flexibly connected to the control board.

[0011] There are various concepts for connecting circuit board sections to each other in a mechanically flexible manner. So-called semi-flexible circuit boards are known, which are manufactured using suitable FR-4 materials and can be bent once during assembly to achieve the desired geometry. So-called rigid-flex circuit boards are also known, which combine flexible and rigid areas.

[0012] The power electronics module has the advantage of eliminating the need for a frame. The current sensor is designed without a core and, thanks to the arrangement of the sensor board area at an angle or perpendicular to the main plane of the control board, can protrude into the recess in the power connection rail to measure the current flowing there. The sensor board area extends through the plastic housing dimensions and protrudes into the recess in the power connection rail, designed as a through-hole, thereby positioning the sensor element in the advantageous position for precise current measurement. The power electronics module can be designed particularly compactly and, by eliminating the frame, is also particularly cost-effective.

[0013] Typically, a current sensor is provided for each of the external connections of the power electronics module, for example, for each of three external or phase connections. In particular, it can be provided that the control board has several sensor board areas that are arranged diagonally or perpendicularly to the main plane of the control board and each protrude through the plastic housing compound into the slot-shaped recess of the respective power connection rail at the position of the corresponding external connection. In this arrangement, the current sensors are arranged on a common control board and can thus be inserted into the power electronics module together in a single step.

[0014] The external connection can, for example, be formed as part of the at least one power connection rail.

[0015] According to one embodiment, the at least one current connection rail has a recess into which the sensor board area with the current sensor projects, wherein plastic housing compound is arranged in the recess between the sensor board area and the current rail.

[0016] In this embodiment, a type of pocket for the sensor board area is formed in the plastic housing compound. This pocket can be kept free, particularly during the encapsulation of the power electronics module, particularly with a thermoset. The pocket is kept free in such a way that plastic housing compound can penetrate into the slot-shaped recess in the edge area of ​​the power connection rail, which subsequently forms electrical insulation between the power connection rail and the sensor board area.

[0017] The power electronics module has the advantage of being particularly easy to manufacture, as the prefabricated cavities for each power connection rail can be produced simultaneously during overmolding without any additional effort.

[0018] According to one embodiment, the plastic housing compound has at least one prefabricated cavity in which the at least one sensor board region is arranged.

[0019] In this embodiment, the plastic housing, including the at least one prefabricated cavity, is first manufactured before the control board is placed on top and the at least one sensor board area is inserted into the cavity. Alternatively, it is also conceivable to manufacture the plastic housing only after the control board has already been placed on top. However, this approach may require a significant modification of the molding process.

[0020] According to one embodiment, an air gap is arranged in the cavity between the sensor board area and the power connection rail embedded in the plastic housing compound. This allows the control board with the sensor board areas to be placed on top after the power electronics module has been encapsulated, with the sensor board areas and the components arranged thereon sliding into the cavity.

[0021] The at least one cavity can be at least partially filled with a casting compound.

[0022] The potting compound is applied after the sensor board section has been inserted into the cavity to secure the sensor board section in the cavity, particularly against the effects of vibration. Alternatively, the potting compound is applied before the sensor board section is inserted into the cavity, and the sensor board section is inserted into the still-soft potting compound. The potting compound secures the sensor board section in the cavity.

[0023] The cavity can have an end stop that ensures precise positioning of the sensor board area in the longitudinal direction of the cavity. Furthermore, the cavity can have a guide geometry in its cross-section to laterally guide the board of the sensor board area and thus precisely position it in two directions. This is particularly advantageous since the flexible area could otherwise lead to positional deviations.

[0024] For example, the cross-section can have a larger width in a central region to accommodate the sensor board area there, and a narrower width outside the central region, which is smaller than the width of the sensor board areas. This has the advantage that the position of the sensor board areas is fixed to the central area of ​​the cross-section.

[0025] However, the sensor board area can also be formed as part of the control board in the same manufacturing process, such as lamination, as the control board. In this case, the sensor board area can be physically connected to the control board via one or more insulation layers of the control board and electrically connected to the control board via one or more conductive trace layers.

[0026] The variants mentioned allow the control board area to be aligned diagonally or perpendicularly to the control board.

[0027] According to one embodiment, the control board is arranged on an upper side of the power electronics module, in particular on the upper side of a plastic housing of the power electronics module.

[0028] The power electronics module can be designed, in particular, as an inverter module for an electric motor. However, the power electronics module is also suitable for other applications where high currents must be measured with electrical isolation and a similar arrangement of a control board to a power connection rail exists, such as charging stations, solar inverters, or DC / DC converters.

[0029] According to a further aspect of the invention, a method for producing a power electronics module is specified, comprising providing a number of power semiconductor components which are electrically connected to at least one external terminal via at least one power connection rail, wherein the power semiconductor components are embedded in a plastic housing compound which has at least one prefabricated cavity which extends into a recess in the at least one power connection rail. Furthermore, a control board is provided with at least one current sensor arranged thereon, wherein the current sensor is arranged on a sensor board region which is arranged obliquely or perpendicularly to a main plane of the control board and is connected to the control board.The control board is combined with the power semiconductor components embedded in the plastic housing compound, with the at least one sensor board area arranged in the at least one prefabricated cavity. The sensor board area is flexibly connected to the control board.

[0030] Embodiments of the invention are described below by way of example with reference to schematic drawings. Fig. 1 shows a perspective view of a power electronics module according to an embodiment of the invention, Fig. 2 shows a cross-sectional view of a control board for the power electronics module according to Fig. 1, Fig. 3 shows a perspective view of a section of the control board according to Fig. 2, Fig. 4 shows a cross-sectional view of a further power electronics module and a further control board connected to it and Fig. 5 shows a top view of a section of the power electronics module according to Fig. 4.

[0031] Fig. 1 shows a power electronics module 1, which can be designed in particular as an inverter module for an electric motor. The power electronics module 1 has a plurality of power semiconductor components, which are Fig. 1 are not shown and which are arranged on a power substrate which is also not shown.

[0032] The power semiconductor components are connected to external terminals of the power electronics module 1 via power connection rails. Fig. 1 shows external terminals designed as supply terminals 3 and external terminals designed as phase terminals 4. The power semiconductor components, the power substrate, and the power connection rails are embedded in a plastic housing 2.

[0033] In order to be able to measure currents flowing through the phase connections 4, for example for the control and regulation of the electric motor, the power electronics module 1 has a current sensor system that measures the current flow in the power connection rails leading to the phase connections 4. For this purpose, cavities 6 are arranged in the plastic housing 2. The cavities 6 are designed to accommodate sensor elements that measure the current flow through the power connection rails. The sensor elements are designed as Hall sensors and are located in recesses in the power connection rails for current measurement.

[0034] Fig. 2 shows a control board 7 with a first side 8 and a second side 9 opposite this for the power electronics module 1. For each of the Fig. Within the cavities 6 shown in Figure 1, the control board 7 has a sensor board area 10 with at least one sensor element 11 arranged thereon. The sensor element 11 is designed as a Hall sensor for measuring the current flow through the power connection rail. Additionally, further sensor elements, such as temperature sensors, can also be arranged on the sensor board area 10.

[0035] The sensor board areas 10 are connected to the control board 7 via flexible areas 12. The sensor board areas 10 are connected to their plane E PB perpendicular to plane E P the control board 7.

[0036] Fig. 3 shows a perspective view of the control board 7. In this illustration, it can be seen that the sensor board area 10 with the sensor element 11 is arranged in a cutout 13 from the control board 7 and is connected to it via the flexible area 12.

[0037] At the Fig. 3, the sensor board area 10 is still in plane E P of the control board 7 and is not aligned at right angles to it. Fig. 3 shows the situation of the control board 7, for example, as it exists during the manufacturing process. For mounting the control board 7 on a power electronics module 1, the sensor board area 10 is bent out of plane E of the control board 7.

[0038] Fig. 4 shows another power electronics module 1 with another control board 7 during its placement on the plastic housing 2. The pocket-shaped cavity 6, accessible from the top side 5 of the plastic housing 2, is formed in the plastic housing 2 and projects into a slot-shaped recess 18 in the power connection rail 14. The sensor board area 10 is arranged in the pocket-shaped cavity 6. The control board 7 is aligned parallel to the top side 5 of the plastic housing 2 and faces the top side 5 of the plastic housing 2 with its first side 8. After assembly is complete, the first side 8 can rest directly on the top side 5.

[0039] The sensor board area 10 protrudes into the cavity 6 such that the sensor element 11 lies in the slot-shaped recess 18 in the power connection rail 14 in order to measure the current flow through the power connection rail 14. The recess 18 is designed as a through hole in the power connection rail 14.

[0040] A potting compound 16 is arranged in the recess 18, into which the sensor board area 10 projects. The potting compound 16 fixes the sensor board area 10 in the cavity 6. In the Fig. In the solution shown in Figure 4, the sensor board area 10 is not connected to the control board 7 via a flexible area, but via press-in pins 15, via which an alignment of the sensor board area 10 perpendicular to the control board 7 is also achieved.

[0041] Between the edge of the power connection rail 14 and the cavity 6, plastic housing compound is arranged in the recess 18 in the power connection rail 14 in the area 19, which forms an electrical insulation between the power connection rail 14 and the sensor board area 10 with the sensor element 11.

[0042] Fig. Figure 5 shows a top view of a guide geometry of the cavity 6, in which a central region 17 of the cavity 6 has a greater width than non-central regions. The control board 7 is located in the central region 17, thereby fixing its position in the cavity 6. List of reference symbols 1 power electronics module 2 plastic housings 3 Supply connection 4 phase connection 5 Top 6 Cavity 7 Control board 8 first page 9 first page 10 Sensor board area 11 Sensor element 12 flexible area 13 Excerpt 14 Power connection rail 15 press-in pin 16 Potting compound 17 central area 18 Recess 19 Area

Claims

[1] Power electronics module (1), comprising - a number of power semiconductor components which are electrically connected to at least one external terminal (4) via at least one power connection rail (14), - a plastic housing (2) made of a plastic housing compound, in which the power semiconductor components and the at least one power connection rail (14) are embedded, - a control board (7) with at least one current sensor (11) arranged thereon, wherein the current sensor (11) is arranged on a sensor board area (10) which is inclined or perpendicular to a main plane E P the control board (7) and is connected to the control board (7) and projects through the plastic housing compound into a slot-shaped recess (18) in the at least one power connection rail (14); wherein the sensor board region (10) is flexibly connected to the control board (7). [2] Power electronics module (1) according to claim 1, wherein plastic housing compound is arranged in the recess (18) between the sensor board area (10) and the busbar (14). [3] Power electronics module (1) according to claim 1 or 2, wherein the plastic housing compound has at least one prefabricated cavity (6) in which the at least one sensor board region (10) is arranged. [4] Power electronics module (1) according to claim 3, wherein an air gap is arranged in the cavity between the sensor board area (10) and the power connection rail (14) embedded in the plastic housing compound. [5] Power electronics module (1) according to claim 3 or 4, wherein the at least one cavity (6) is at least partially potted with a potting compound (16). [6] Power electronics module (1) according to one of claims 1 to 5, wherein the control board (7) is arranged on a top side (5) of the power electronics module (1). [7] Power electronics module (1) according to one of claims 1 to 6, wherein the power electronics module (1) is designed as an inverter module. [8] Method for producing a power electronics module (1), comprising - Providing a number of power semiconductor components which are electrically connected to at least one external terminal (4) via at least one power connection rail (14), wherein the power semiconductor components are embedded in a plastic housing (2) made of a plastic housing compound which has at least one prefabricated cavity (6) which extends into a recess (18) in the at least one power connection rail (14); - Providing a control board (7) with at least one current sensor (11) arranged thereon, wherein the current sensor (11) is arranged on a sensor board area (10) which is inclined or perpendicular to a main plane E Pthe control board (7) is arranged and connected to the control board (7); - merging the control board (7) with the power semiconductor components embedded in the plastic housing compound, while arranging the at least one sensor board region (10) in the at least one prefabricated cavity (6); - wherein the sensor board area (10) is flexibly connected to the control board (7).

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