Power module for controllably supplying electrical power to an electrical appliance

Abstract

A power module for controllably supplying electric power to an electrical appliance is described. The power module has a plurality of encapsulated power semiconductors, a circuit board, and a cooling body and may additionally have a sealant. The encapsulated power semiconductors have electrically conductive connecting elements and each has a heat dissipation surface on the outer side. The power module is characterized in that each of the encapsulated power semiconductors in the power module is arranged on the cooling surface of the cooling body and is connected to the cooling surface of the cooling body in a heat-conductive manner with its heat dissipation surface, and the circuit board is arranged on the side of the power semiconductor opposite to the cooling body in the orthogonal direction, wherein in the region where the projection of the cooling body along the orthogonal direction towards the circuit board does not cover the connecting elements, for example, laterally beside the edge of the cooling body, the connecting elements of the power semiconductors are in electrical contact with the connecting surfaces on the circuit board.

Description

Field of Technology

[0001] The invention relates to a power module with encapsulated power semiconductors for a controllable power supply to electrical appliances. Background Art

[0002] Power modules are used to supply electrical appliances (such as electric motors) with the electrical power required for their operation in a controllable manner. Such power modules are sometimes also referred to as power supply modules, commutators, converters or inverters.

[0003] These power modules can be used, for example, in vehicles to supply electrical power from a battery to an electric motor used as a drive in a regulated manner. Here, the controllable power supply can range from a few kilowatts to several hundred kilowatts.

[0004] For this purpose, power modules usually have power semiconductor structural elements (hereinafter simply referred to as "power semiconductors"), for example in the form of IGBTs (bipolar transistors with insulated gate electrodes; English: Insulated-Gate Bipolar Transistor), SiC (power modules with silicon carbide - MOSFETs) or power MOSFETs controlled by a control circuit.

[0005] In conventional power modules, IGBT or SiC chips are applied (i.e., for example, brazed or sintered) to a so-called DCB (English: Direct Copper Bonded), that is, a structure that enables a close electrical and thermal connection between an electronic component and a chip through copper. Subsequently, the DCB can be sintered or brazed to a copper plate with a cooling structure, for example. Subsequently, the entire structure can be overmolded in a hermetically sealed manner.

[0006] Alternatively, in conventional power modules, IGBT components are assembled to a cooling body by means of a so-called thermal interface material (such as a foil or a thermally conductive paste). Alternatively, the electrically insulating housing of such a component can be directly brazed or sintered to the cooling body. In this case, for example, the electrical connection is achieved by welding to a punching grid, or the component is brazed to a circuit board by means of through-hole technology.

[0007] Conventional power modules usually have a relatively complex structure and are therefore manufactured at high cost. In addition, power modules are usually designed for specific applications, and their design generally cannot be easily adapted to the requirements of other applications or extended to the requirements of other applications. More easily manufactured and / or purpose-specifically adaptable power modules usually require a larger structural space and / or relatively expensive components. Summary of the Invention

[0008] It can thus be regarded as an object of the present invention to provide a power module which at least overcomes at least some of the aforementioned disadvantages of conventional power modules. In particular, there may be a need for a power module which can be easily and cost-effectively constructed, which can be manufactured with less expense, and / or which requires less structural space.

[0009] Such an object can be achieved by a power module according to the present invention for controllably supplying electric power to an electrical appliance. Other embodiments of the present invention will become apparent from the following description.

[0010] One aspect of the present invention relates to a power module for controllably supplying electric power to an electrical appliance. Here, the power module has a plurality of encapsulated power semiconductors, a circuit board, and a cooling body. The encapsulated power semiconductors have electrically conductive connecting elements and each also has a heat dissipation surface on the outer side. The power module is characterized in that each of the encapsulated power semiconductors is arranged on the cooling surface of the cooling body and is connected to the cooling surface of the cooling body in a heat-conductive manner with its heat dissipation surface; and the circuit board is arranged on the side of the power semiconductor opposite to the cooling body in the orthogonal direction, and in the region where the projection of the cooling body along the orthogonal direction towards the circuit board does not cover the connecting elements, the connecting elements of the power semiconductor are in electrical contact with the connecting surfaces on the circuit board.

[0011] The embodiments of the power module described herein are particularly different from conventional power modules in that separate components are used in the overall structural concept of the power module.

[0012] For controlling the electric power provided by the power module, encapsulated power semiconductors are used here, that is, components in which power semiconductor components (such as IGBTs, SiC, or power MOSFETs) are surrounded by a housing, for example, made of plastic. Here, the encapsulated power semiconductors have elongated, electrically conductive connecting elements, for example, in the form of legs made of metal, which protrude outwards from the plastic housing surrounding the power semiconductor. By means of these connecting elements, control signals and / or electric power can be supplied to the semiconductor structure elements integrated in the encapsulated power semiconductors. Thus, such encapsulated power semiconductors are different from so-called bare dies without a housing. Encapsulated power semiconductors are robust and can be manufactured, stored, and ultimately processed in large quantities and thus advantageously as standard components.

[0013] Since a part of the electrical power conducted in a power semiconductor always causes the power semiconductor to heat up in the form of losses, the encapsulated power semiconductor has a heat dissipation surface on its outer side. Such a heat dissipation surface is sometimes also referred to as an "exposed pad". The heat dissipation surface can be designed as a layer or plate made of a material that can conduct heat well (such as metal, especially copper), which is integrated into the encapsulated power semiconductor and exposed on the surface.

[0014] In order to be able to control the behavior of the power semiconductor, a control circuit is provided. This control circuit can be formed by means of electrical or electronic structural elements. These structural elements can be held on a circuit board and electrically connected to each other and / or to an interface via the circuit board. The circuit board can be the circuit board integrated in the power module proposed herein. In addition, this circuit board can especially also be used to conduct current to the power semiconductor, that is, it is designed to be able to conduct several hundred amperes. For example, this circuit board can be designed as a thick copper circuit board, where the copper layer can have a thickness of 100 μm or more. Alternatively, the structural elements can be mounted on an independent circuit board.

[0015] In order to be able to conduct heat away from the power circuit board, the power module has a cooling body. This cooling body can be, for example, a metal plate, especially a copper plate. If necessary, the cooling body can have an integrated cooling structure, such as cooling ribs. The cooling body can be passively cooled, for example, by radiative exchange and / or heat exchange with the surrounding medium. Alternatively, the cooling body can be actively cooled, for example, by a flowing cooling medium.

[0016] In the overall structural solution for the power module described here, each power semiconductor in the encapsulated power semiconductor is thermally connected to the cooling surface of the cooling body. For this purpose, the heat dissipation surface of the power semiconductor contacts the cooling surface of the cooling body in a thermally conductive manner. For example, a metallic heat dissipation surface can preferably be brazed, welded or sintered to a similarly preferably metallic cooling surface. Here, as large an area of contact as possible and thus a large-area heat-conducting connection can be pursued.

[0017] In the solution proposed here, the circuit board of the power module is arranged on the side of the power semiconductor that is opposite in the orthogonal direction to the side where the cooling body is arranged. Put another way, the cooling body can be arranged, for example, below the power semiconductor, while in contrast, the circuit board is arranged above the power semiconductor. Here, the circuit board can cover the entire area of the power semiconductor of the power module, or even extend laterally (i.e., transversely to the orthogonal direction) beyond this area.

[0018] Thus, the connecting elements of the power semiconductor should be in electrical contact with the circuit board so that electrical signals and / or electrical power can be received via the circuit board. For this purpose, on the circuit board, preferably on the surface facing the power semiconductor, there are provided connecting surfaces which are electrically conductive and are formed, for example, of metal.

[0019] Here, with regard to the power module proposed in the text, these connecting surfaces are arranged in a circuit board region of the connecting elements that is not covered by the projection of the cooling body in the orthogonal direction towards the circuit board, and there they are in contact with the connecting elements. Expressed in another way, at the position of the connecting surface where the power semiconductor is electrically connected to the circuit board via its connecting elements, the cooling body does not cover the circuit board, so that the connecting surface and the connecting elements are freely accessible on the side of the circuit board facing the cooling body. Correspondingly, the connecting elements can be electrically connected to the connecting surfaces in a simple manner during the manufacture of the power module, for example by soldering these connecting elements to the connecting surfaces.

[0020] The overall structural solution proposed enables the simple manufacture of the power module, the efficient cooling of the components of the power module, especially the encapsulated power semiconductor, and the possibility of adapting the design of the power module to the requirements of different applications in a relatively simple manner when using standard semiconductor structural elements.

[0021] According to one embodiment, the connecting elements can be in electrical contact with the connecting surfaces on the circuit board in a manner extending parallel to the connecting surfaces. Expressed in another way, the connecting elements should extend at least at the positions where these connecting elements are in contact with the connecting surfaces on the circuit board parallel to these connecting surfaces. Preferably, the connecting elements leave the housing of the encapsulated power semiconductor in a direction extending parallel to the connecting surfaces.

[0022] In a conventional structural solution for a power module, the connecting elements usually extend orthogonally to the circuit board of the control circuit. When assembling such a conventional power module, this type of connecting element has to be electrically connected to the electrically conductive structure on the circuit board. For this purpose, in the field of so-called through-hole technology, the connecting elements are usually introduced into through-holes in the circuit board and soldered there, for example. However, especially for the case where a very large number of connecting elements have to be connected to the circuit board, fitting the connecting elements into the through-holes can be highly time-consuming and / or error-prone.

[0023] Therefore, in the described embodiment, the connecting elements should not extend orthogonally to the circuit board, but should extend parallel to the circuit board. With such a design solution, the connecting elements can be simply and reliably connected to the electrically conductive structure on the circuit board. In particular, the highly time-consuming fitting of the connecting elements into through-holes in the circuit board can be dispensed with.

[0024] For example, the connecting element can be electrically connected to the connecting surface on the side of the circuit board facing the cooling body. Here, the connecting elements extending parallel to the circuit board can be accumulated on the connecting surfaces of the circuit board and then electrically connected to these connecting surfaces, for example, by brazing or welding. In particular, for this purpose, a method called seam welding can be used, in which the connecting element is pressed onto the connecting surface and then a current is passed through, and the heat for melting the solder is generated by means of this current.

[0025] According to one embodiment, the connecting element is in electrical contact with the connecting surface on the circuit board laterally beside the edge of the cooling body.

[0026] Alternatively expressed, the cooling body can be geometrically formed and dimensioned such that the side edges of the cooling body do not cover the connecting surfaces on the circuit board and thus expose these connecting surfaces. Thus, beside this edge of the cooling body, the connecting elements can be mechanically contacted easily from the side facing the cooling body during the manufacturing process, and for example, these connecting elements can be pressed against the connecting surfaces on the circuit board to electrically connect these connecting elements to this connecting surface by means of brazing or sintering. Therefore, the electrical connection of the connecting elements to the connecting surface can be carried out particularly simply.

[0027] Alternatively, according to one embodiment, the cooling body can have a through-opening, and in the region adjacent to the opening of the cooling body in the orthogonal direction, the connecting element can be in electrical contact with the connecting surface on the circuit board.

[0028] In other words, although the cooling body can be geometrically formed and dimensioned such that the cooling body (if the cooling body is continuous) may cover the connecting surfaces on the circuit board. However, in such a configuration, openings can be provided in the cooling body, and these openings extend through the cooling body at positions adjacent to the connecting surfaces on the circuit board in the orthogonal direction. Thus, in the regions of these openings, the connecting surfaces on the circuit board can be exposed, and in these regions, the connecting elements can be easily accessible from the side facing the cooling body during the manufacturing of the power module so that these connecting elements can be electrically connected to the connecting surface.

[0029] According to one embodiment, the power module can also have a sealant that covers at least a sub-region of the encapsulated power semiconductor and the circuit board with respect to the surrounding environment.

[0030] Depending on the conditions of use, it may be necessary to encapsulate the power module components relative to the surrounding environment to protect them, for example, from contact with surrounding fluid media or contaminants (e.g., metal shavings). For example, contact between liquids (e.g., water) and power module components should be avoided to prevent, for example, electrical shorts and / or corrosion. In particular, in applications where the power module is placed in highly aggressive media (e.g., inside a transmission through which aggressive oil flows), the power module components should be hermetically packaged or encapsulated.

[0031] For this purpose, the power module may also include an encapsulant that covers the encapsulated power semiconductor and at least a subregion of the circuit board relative to the surrounding environment. The encapsulant may, for example, be formed from a material that allows for liquid or viscous processing and can subsequently be cured. For example, the encapsulant may be formed from a plastic (in particular a thermosetting plastic, a thermoplastic, a polymer, and / or an elastomer). The encapsulant may, for example, be processed by injection molding, molding, casting, or other processes.

[0032] According to one embodiment, the circuit board is arranged to be spaced apart from the packaged power semiconductor in the orthogonal direction.

[0033] In other words, there can be a gap between the surface of the encapsulated power semiconductor facing the circuit board and the surface of the circuit board facing the power semiconductor, so that the power semiconductor does not directly rest against the circuit board. The gap can, for example, have a thickness between 0.05 mm and 5 mm, preferably between 0.1 mm and 2 mm. By preventing the power semiconductor from directly resting against the circuit board, cracks or delamination in the encapsulant can be avoided, particularly when both components are encapsulated together in an encapsulant. These cracks or delamination can otherwise occur, in particular, due to the plastic of the encapsulant shrinking significantly after overmolding the component, thereby generating mechanical stresses therein.

[0034] According to one embodiment, the heat sink is designed and the printed circuit board is arranged in such a way that a subregion of the heat sink lies directly against a surface of the printed circuit board.

[0035] Expressed another way, the heat sink does not necessarily need to be flat on its surface facing the circuit board. Instead, it can, for example, have protrusions that mechanically contact the circuit board. Where the heat sink directly abuts the circuit board surface, a highly heat-conducting contact can be established between the two components. Consequently, heat that may be generated in the circuit board, for example due to high currents conducted through it and the resulting losses, can be efficiently dissipated from the circuit board to the heat sink.

[0036] Alternatively, according to one embodiment, the power module may also have a thermally conductive layer on the surface of the circuit board, and the cooling body may be formed and the circuit board may be arranged in such a way that a sub-region of the cooling body abuts against the surface of the thermally conductive layer opposite to the circuit board.

[0037] In other words, the cooling body may have protrusions on its surface facing the circuit board similarly to the previous embodiment. However, in this case, the cooling body does not directly abut against the surface of the circuit board with its protrusions. Instead, a thermally conductive layer is located on the surface of the circuit board, i.e., between the circuit board and the protrusions of the cooling body. This thermally conductive layer may have a higher heat conductivity than the sealant. Therefore, this thermally conductive layer can provide an efficient heat transfer between the circuit board and the cooling body. This thermally conductive layer can, for example, provide a certain mechanical compensation during the plastic shrinkage process (where the sealant loses a certain volume after its treatment) and thus prevent crack formation or delamination if necessary.

[0038] According to one embodiment, the encapsulated power semiconductor is formed in such a way that the electrical power supply to each power semiconductor in the power semiconductor is only achieved by means of the connecting elements.

[0039] In other words, the electrical power conduction to be controlled by the encapsulated power semiconductor should preferably only be achieved by means of the connecting elements of the encapsulated power semiconductor. Since the connecting elements extend in a region of the circuit board not covered by the cooling body and are thus easily accessible from the outside, these connecting elements can be connected to the connection surface of the circuit board in a simple manner during the manufacture of the power module.

[0040] In contrast, there are encapsulated power semiconductors in which a heat dissipation surface formed of metal is simultaneously used as an electrical interface. Then, a metallic cooling body (against which the heat dissipation surface abuts) can also be used as an electrical interface. However, in this case, the heat dissipation surface generally cannot be easily accessed from the outside, so the electrical connection to the cooling body may be highly costly.

[0041] According to one embodiment, the encapsulated power semiconductor and / or the connection of the encapsulated power semiconductor to the cooling body may be designed in such a way that the conductive structures for controlling power in the encapsulated power semiconductor are electrically insulated from the cooling body.

[0042] In other words, for example, the IGBT, SiC or power MOSFET that controls power in the encapsulated power semiconductor, together with all its interfaces, can be electrically insulated from the heat dissipation surface of the encapsulated power semiconductor, so that even when the heat dissipation surface is conductively abutted against the cooling body, there is no electrical connection between these power control structures and the cooling body. Alternatively or additionally, an electrical insulation layer can be provided between the heat dissipation surface of the encapsulated power semiconductor and the cooling surface of the cooling body.

[0043] In this case, the cooling body can be simply formed, for example, formed as a continuous metallic structure, especially a metal plate. Here, the cooling body can be used as the heat dissipation component for multiple encapsulated power semiconductors, and although in thermal contact with these power semiconductors, it does not necessarily have to be in electrical contact with them. Therefore, the structured design of the power module can be relatively simple because there is no need to equip the cooling body as a complex structural element to make different power semiconductors contact electrically separated.

[0044] According to one embodiment, the power module can also have an intermediate circuit capacitor.

[0045] Put another way, the intermediate circuit capacitor can be integrated into the power module, which can provide the mutual coupling of the energies of multiple power grids on a common DC voltage level. Thereby, the functionality of the power module can be improved and / or the structure of the entire power module can be simplified. The intermediate circuit capacitor can be designed as a thin-film capacitor with one or more coils.

[0046] In particular, the intermediate circuit capacitor can be arranged adjacent to the side of the circuit board facing away from the cooling body.

[0047] In other words, the intermediate circuit capacitor can be arranged above the circuit board located on the cooling body and thus next to the encapsulated power semiconductor. Thereby, a structure with very low inductance can be achieved. This can in turn enable very fast switching of the power semiconductor.

[0048] In addition, the intermediate circuit capacitor can be electrically connected to the circuit board.

[0049] Put another way, the intermediate circuit capacitor can be connected to the electrical interface of the circuit board in a simply implementable manner, for example, by brazing, welding, bonding or similar techniques.

[0050] Additionally, the intermediate circuit capacitor can be at least partially embedded in the sealant, which also covers the power semiconductor and a sub-region of the circuit board.

[0051] Particularly advantageously, the sealant can be designed or applied during the manufacture of the power module in such a way that the sealant covers and thus encapsulates the entire intermediate circuit capacitor and the encapsulated power semiconductor and at least part of the circuit board against dirt and / or in a medium-tight manner. Here, during the manufacture of the power module, it may be sufficient to subject a previously formed unit consisting of the cooling body, the circuit board, and the power semiconductor together with the intermediate circuit capacitor to a common molding process in which all of the mentioned components are overmolded with the sealant. Description of the Drawings

[0052] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0053] Figure 1 and Figure 3 Each shows a top view of a respective power module according to an embodiment of the present invention.

[0054] Figure 2 and Figures 4 to 8 Show cross-sectional views through power modules according to different embodiments of the present invention.

[0055] The reference signs used in the drawings and their meanings are explained in summary form in the list of reference signs. In principle, the same or similar components are provided with the same reference signs. The drawings are only schematic and not to scale. Detailed Description of the Embodiments

[0056] Figure 1 and Figure 3 Each shows a top view of a power module 1 for controllably supplying electrical power to an (undisplayed) electrical appliance, such as an electric motor in an electrically powered vehicle. Figure 2 Shows a cross-sectional view through Figure 1 the power module 1. Figure 4 Shows a cross-sectional view through Figure 3 the power module 1. Figure 5 Shows a cross-sectional view through Figure 4 a slightly modified variant of the power module 1.

[0057] The power module 1 includes a plurality of encapsulated power semiconductors 3, a circuit board 5, a cooling body 7, and a sealant 9. The cooling body 7 can be designed as a cooling plate made of metal (such as copper) and optionally has a cooling structure 21. Electrical and / or electronic structural elements 11 are provided on the circuit board 5, and these structural elements form a control circuit 13 for controlling the power semiconductors 3. Electrical power can be fed in, for example, from a battery via an external interface 49 and then, in a manner controlled by the power module 1, be supplied to the motor phases of an electric motor via other external interfaces 49.

[0058] Each power semiconductor in the power semiconductor 3 has a heat dissipation surface 15 on its outer side facing the cooling body 7. At this heat dissipation surface 15, a metal surface or a metal plate is provided on the encapsulated power semiconductor 3, and heat generated inside the encapsulated power semiconductor 3, for example, by semiconductor structure elements (such as IGBT, SiC or power MOSFET) that control power located therein, can be dissipated through this metal surface or metal plate.

[0059] Here, each of the encapsulated power semiconductors 3 has a conductive connecting element 23. In the example shown, three connecting elements 23 are provided on each power semiconductor 3, but there can also be more than three connecting elements 23. The connecting element 23 is used to electrically connect the power control structures (such as in the form of semiconductor structure elements) inside the encapsulated power semiconductor 3 in order to supply control signals and / or the electric power to be controlled to these power control structures.

[0060] Each power semiconductor in the encapsulated power semiconductor 3 is arranged on the cooling surface 17 of the cooling body 7. Here, the heat dissipation surface 15 of the encapsulated power semiconductor 3 is connected to the cooling surface 17 of the cooling body 7 in a heat-conductive manner.

[0061] The circuit board 5 is arranged on the side of the power semiconductor 3 opposite to the side where the cooling body 7 is arranged in the orthogonal direction. In other words, the power semiconductor 3 is located between the cooling body 7 and the circuit board 5.

[0062] Here, the cooling body 7 is designed in such a way and the connecting element 23 of the power semiconductor 3 is arranged in such a way that the connecting element 23 is in electrical contact with the connecting surface 25 on the circuit board 5 in the region where the projection of the cooling body 7 in the orthogonal direction towards the circuit board does not cover the area of the connecting element 23.

[0063] In Figure 1 and Figure 2 In the embodiment shown, for this purpose, the elongated connecting element 23 is arranged laterally beside the edge 18 of the cooling body 7 and contacts the connecting surface 25 there.

[0064] In Figure 3 and Figure 4 In the embodiment shown, a through-opening 19 is provided in the cooling body 7. The opening 19 is located beside the edge of the cooling body 7. In this case, in the region adjacent to the opening 19 of the cooling body 7 in the orthogonal direction, that is, at the position where the cooling body 7 does not cover the circuit board 5 due to the opening 19 provided therein, the connecting element 23 contacts the connecting surface 25 on the circuit board 5.

[0065] In Figure 5In the embodiment shown, instead of the two elongated openings 19 provided near the edge of the cooling body 7 in the foregoing embodiment, a central, elongated opening 19 is provided.

[0066] In the Figures 1 to 5 embodiment mentioned, the cooling body 7 does not cover the connecting element 23 which is implemented as a leg of the power semiconductor 3 in such a way that it locally adjoins the connecting surface 25, and thus it is possible to achieve that the connecting element 23 is freely accessible and can be brazed, for example by butt seam welding, to the connecting surface 25.

[0067] In the described embodiment, the power semiconductor 3 can directly contact the circuit board 5 by means of its side facing the circuit board 5, or alternatively be spaced apart from the circuit board by means of a gap.

[0068] In Figure 4 the embodiment shown, the cooling body 7 is designed and the circuit board 5 is arranged in such a way that a protruding sub-region 26 of the cooling body 7 directly abuts the surface of the circuit board 5. In this way, the circuit board 5 can efficiently conduct heat to the cooling body 7.

[0069] The sealant 9 covers both the encapsulated power semiconductor 3 and a sub-region of the circuit board 5. Here, the molded sealant 9, for example formed from a thermosetting plastic, preferably fluid-tightly encapsulates the components mentioned.

[0070] To manufacture the power module 1, for example, the circuit board 5 can be loaded with the structural elements 11 such that these structural elements are electrically interconnected with the control circuit by means of SMD soldering. In this way, a first component can be formed. Independently thereof, a second component can be formed by, for example, soldering, sintering or gluing the power semiconductor 3 to the cooling body 7. Subsequently, the two components can be connected to each other by, for example, soldering the connecting element 23 of the power semiconductor 3 to the connecting surface 25 on the circuit board 5 by butt seam welding. Finally, the entire component formed in this way can be overmolded or cast with the sealant 9.

[0071] In Figure 6 the embodiment shown, a thermally conductive layer 37 is provided on the surface of the circuit board 5 facing the cooling body 7. Here, the cooling body 7 is designed in such a way that it abuts this thermally conductive layer 37 in the protruding sub-region 26. Correspondingly, heat can be efficiently conducted from the circuit board 5 to the cooling body 7. Here, the thermally conductive layer 37 can be used as a compensating element in order to prevent the formation of cracks or delamination during the shrinkage process of the sealant 9. Here, the thermally conductive layer 37 can also extend between the power semiconductor 3 and the circuit board 5, where this region may alternatively also be filled with the sealant 9.

[0072] exist Figure 7 shows an embodiment of a power module 1 that additionally has an intermediate circuit capacitor 33. The intermediate circuit capacitor 33 can have one or more coils 35. Here, the intermediate circuit capacitor 33 is arranged adjacent to the side of the printed circuit board 5 facing away from the heat sink 7 and is electrically connected to the printed circuit board 5 via a capacitor connection 45. To protect the intermediate circuit capacitor 33, it is partially or completely embedded in a sealing compound 9, which also covers the power semiconductor 3 and a subregion of the printed circuit board 5.

[0073] Figure 8 An alternative embodiment of a power module 1 is shown. Here, the heat sink 7 is constructed in two parts and has an upper cooling plate 27, which is separated from a lower cooling structure 31 by an intermediate electrically insulating layer 29. The electrically insulating layer 29 can be a thermally conductive foil.

[0074] In such a design, the heat sink 7, and in particular the cooling plate 27 thereon, can be used as a busbar. Such a busbar can be used to supply electrical power to the power semiconductor 3. In such a design, the heat sink 15 connected to the heat sink 7 is preferably electrically connected to the interface of the power control structure within the power semiconductor 3. For example, the electrical interface of an IGBT or SiC can be electrically connected to the metallic heat sink 15.

[0075] Finally, in summary and with slightly different wording, the details of possible designs and implementations of the power module proposed in this article are explained:

[0076] A power module structure is proposed, which includes encapsulated power semiconductors (e.g., IGBTs, SiC, power MOSFETs, etc.) that are sintered, soldered, or adhesively bonded directly via their exposed pads to a cooling body, preferably a copper plate with an integrated cooling structure (although it can also be a simple metal plate). To this end, the exposed pads of the encapsulated component are preferably electrically insulated (within the component), although insulating the metal plate is also conceivable.

[0077] The overall modular design is unique in that it uses separate components:

[0078] Place, screw or otherwise fasten a circuit board (preferably FR4) onto a cooling plate (preferably copper) with discrete power semiconductors brazed, sintered or bonded thereto. The circuit board may have been previously loaded with control electronics for the power semiconductors or other types of electronic devices. In this arrangement, the interfaces of the power semiconductors are parallel to the circuit board. The connection to the circuit board is not achieved by through-hole technology, but preferably by seam welding of joints or other suitable brazing or welding methods, by pressing the interfaces onto the circuit board (serving as tolerance compensation). Here, the cooling body is designed such that it allows free access for seam welding the connection pins to the circuit board. Another possible solution is a window cutout in the cooling body, above the connecting element. Here, current conduction is preferably achieved by means of an integrated circuit board.

[0079] To protect this overall structure from adverse ambient conditions (vibration, dielectric corrosion, etc.), it is conceivable to overmold or cast the overall structure with a suitable material. However, it is also conceivable to use a standard housing as a solution.

[0080] As other embodiments that can be envisioned:

[0081] - having a window cutout in the cooling body related to seam welding of joints;

[0082] - having a thermal connection to the circuit board (directly placing the circuit board to cool the loaded components or the conductor circuit of the circuit board that conducts high current);

[0083] - connecting the circuit board by means of a thermally conductive material, additionally serving as compensation for the plastic shrinkage process;

[0084] - Additionally, parts or the whole of the intermediate circuit capacitor can be integrated into the power module. Here, the individual coils of the thin-film capacitor are preferably directly arranged on the power semiconductors (a structure with very low inductance that enables very fast switching), and are connected to the circuit board (methods conceivable here are, for example, brazing, welding, bonding), and are protected from the ambient conditions and resistant to vibration together with the whole module by overmolding.

[0085] - Additionally, the cooling plate is used as a busbar. The power semiconductors are not insulated relative to the exposed pads or are only specific switches.

[0086] Furthermore, the following advantages can be achieved especially with the proposed embodiments of the power module:

[0087] - a simple and robust structure and connection scheme that is well-suited for the overmolding technology of encapsulated structural elements developed by ZF (in the transmission field);

[0088] - Standard components can be connected without through-holes / through-plugging.

[0089] - The control circuit of the power semiconductor can be placed directly on the circuit board and positioned very close to the power switch, which supports fast switching.

[0090] - These two components (the loaded circuit board, the cooling plate with the power switch) can be manufactured independently of each other and only later connected by joint seam welding.

[0091] - By means of the overmolding process, the complete power module can be protected in a media-sealed manner, if necessary including the control device of the intermediate circuit.

[0092] - The simple handleability of the encapsulated power switch compared to the bare solution.

[0093] - By means of the overmolding technology, a smaller insulation distance can be achieved for high voltages.

[0094] - By using standard power switches in standard housings, a high cost-saving potential (better competitiveness) can be achieved.

[0095] - (Achieved by parallel connection of power switches) Better scalability of the module in terms of current requirements.

[0096] - High flexibility regarding the structural space.

[0097] - High value creation in in-house manufacturing.

[0098] - By means of the current guidance in the circuit board, a mechanism with very low inductance can be achieved because the current guidance of the output wire and the return wire cannot be realized side by side, but can be realized slightly overlapping in different layers of the circuit board. Thus, large current loops are avoided.

[0099] - Additionally, the structure can be further optimized regarding the series inductor by integrating the intermediate circuit capacitor or parts thereof, which further facilitates fast switching.

[0100] Complementary, it can be noted that "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it can be noted that the features or steps already described with reference to one of the above embodiments can also be used in combination with other features or steps of the other embodiments described above. The reference signs in the claims should not be regarded as limiting.

[0101] List of reference numerals

[0102] 1 Power module

[0103] 3 Power semiconductor

[0104] 5 Circuit board

[0105] 7 Cooling body

[0106] 9 Sealing material

[0107] 11 Structural element

[0108] 13 Control circuit

[0109] 15 Heat dissipation surface

[0110] 17 Cooling surface

[0111] 18 Edge of the cooling body

[0112] 19 Opening

[0113] 21 Cooling structure

[0114] 23 Connecting element

[0115] 25 Connecting surface

[0116] 26 Projecting sub-region of the cooling body

[0117] 27 Upper cooling plate

[0118] 29 Electrical insulation layer

[0119] 31 Lower cooling structure

[0120] 33 Intermediate circuit capacitor

[0121] 35 Coil

[0122] 37 Heat-conductive layer

[0123] 45 Capacitor interface

[0124] 49 External interface

Claims

1. A power module (1) for controllably supplying electrical power to an electrical consumer, wherein the power module (1) comprises: A plurality of packaged power semiconductors (3), each of which has a plurality of electrically conductive connecting elements (23) and each of which has a heat dissipation surface (15) on an outer side. a circuit board (5), and cooling body (7), It is characterized in that Each of the packaged power semiconductors (3) is arranged on a cooling surface (17) of the cooling body (7), and is connected to the cooling surface (17) of the cooling body (7) via its heat dissipation surface (15) in a heat-conducting manner, and The circuit board (5) is arranged on a side of the packaged power semiconductor (3) opposite to the cooling body (7) in an orthogonal direction. In an area where the projection of the cooling body (7) toward the circuit board (5) in an orthogonal direction does not cover the connecting element (23), the connecting elements (23) of the plurality of packaged power semiconductors (3) are each electrically contacted with a connecting surface (25) on the circuit board (5).

2. The power module according to claim 1, wherein: The connecting element (23) is in electrical contact with the connecting surface (25) on the circuit board (5) in a manner extending parallel to the connecting surface (25).

3. The power module according to claim 1 , wherein: The connecting element (23) is electrically contacted laterally by the edge (18) of the heat sink (7) with a connecting surface (25) on the printed circuit board (5).

4. The power module according to any one of claims 1 and 2, characterized in that The cooling body (7) has a through opening (19), and in a region adjacent to the opening (19) of the cooling body (7) in the orthogonal direction, the connecting element (23) is in electrical contact with a connecting surface (25) on the circuit board (5).

5. The power module according to claim 1, further comprising a sealing compound (9) which covers the encapsulated power semiconductor (3) and at least a subregion of the printed circuit board (5) relative to the surrounding environment.

6. The power module according to any one of claims 1 and 2, characterized in that The circuit board (5) is loaded with structural elements (11), which form a control circuit (13) for controlling the packaged power semiconductor (3).

7. The power module according to any one of claims 1 and 2, characterized in that The circuit board (5) is arranged to be spaced apart from the packaged power semiconductor (3) in the orthogonal direction.

8. The power module according to any one of claims 1 and 2, characterized in that The heat sink (7) is designed and the printed circuit board (5) is arranged in such a way that a subregion of the heat sink (7) lies directly against the surface of the printed circuit board (5).

9. The power module according to any one of claims 1 and 2, characterized in that The power module (1) also has a heat-conducting layer (37) on the surface of the circuit board (5), and the heat sink (7) is designed and the circuit board (5) is arranged in such a way that a subregion of the heat sink (7) lies against the surface of the heat-conducting layer (37) opposite to the circuit board (5).

10. The power module according to any one of claims 1 and 2, characterized in that The packaged power semiconductors (3) are formed in such a way that the electrical power supply to each packaged power semiconductor (3) is realized only by means of the connecting element (23).

11. The power module according to any one of claims 1 and 2, characterized in that The encapsulated power semiconductor (3) and / or the connection of the encapsulated power semiconductor (3) to the cooling body (7) is designed in such a way that the power-controlling, electrically conductive structures within the encapsulated power semiconductor (3) are electrically insulated from the cooling body (7).

12. The power module according to any one of claims 1 and 2, characterized in that The power module (1) further comprises an intermediate circuit capacitor (33).

13. The power module according to claim 12, wherein: The intermediate circuit capacitor (33) is arranged adjacent to a side of the printed circuit board (5) facing away from the heat sink (7).

14. The power module according to claim 12, wherein: The intermediate circuit capacitor (33) is electrically connected to the circuit board (5).

15. The power module according to claim 12, wherein: The intermediate circuit capacitor (33) is at least partially embedded in a sealing compound (9), which also covers the encapsulated power semiconductor (3) and at least a subregion of the circuit board (5).

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