Semiconductor package, semiconductor module, power converter, electric axle drive and motor vehicle
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- ZF FRIEDRICHSHAFEN AG
- Filing Date
- 2021-11-30
- Publication Date
- 2026-07-09
AI Technical Summary
Existing semiconductor packages are not suitable for high-current applications and are only available as individual switch packages, lacking the capability to efficiently integrate power semiconductor elements and connections for high-power applications.
The power semiconductor elements are embedded in the printed circuit board with all power contacts arranged on one side, utilizing busbars connected via inlays and vias, and optionally enclosed by a casting compound, allowing for efficient current distribution and heat management.
This configuration enables high-current applications with reduced stray inductance, symmetrical layout, and effective heat dissipation, facilitating compact and efficient power conversion.
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Abstract
Description
[0001] The invention relates to a semiconductor package for a power converter comprising at least one printed circuit board and at least two power semiconductor elements.
[0002] Power converters are devices used to change the type or intensity of current. Examples include inverters, rectifiers, and DC / DC converters.
[0003] These devices typically contain power semiconductor elements, also called semiconductor chips or simply chips. These power semiconductor elements are applied to printed circuit boards (PCBs) for electrical contact. The PCBs may have current-carrying layers to which the power semiconductor elements can be connected. In this way, electrical circuits can be created using power semiconductor elements.
[0004] These power semiconductor elements are embedded in so-called packages. This simplifies the assembly of the power semiconductor elements, since a semiconductor package can contain not only the bare semiconductor, but also power connectors and other components.
[0005] Known packages, for example in the 400 V range, are only available as single-switch packages. Furthermore, they are not suitable for high-current applications.
[0006] Based on this, the object of the present invention is to provide a semiconductor package that is improved in comparison.
[0007] To solve this problem, it is proposed for a semiconductor package of the type mentioned above that the power semiconductor elements are embedded in the printed circuit board and that all power contacts of a power semiconductor element are arranged on one side.
[0008] The printed circuit board (PCB) may or may not contain conductive layers. It consists of a substrate material with predefined properties. Common materials include FR-4, Teflon, and PTFE. Furthermore, the PCB substrate can be organic or ceramic, such as a PCB, an embedded PCB, or an IMS substrate.
[0009] Embedding a power semiconductor element in the printed circuit board means that the power semiconductor element is at least partially embedded in the printed circuit board.
[0010] The power semiconductor elements are essentially cuboidal in shape and therefore have six sides. Two of these surfaces are significantly larger than the other four, as the cuboids are planar. The power contacts are located on one of these six surfaces. Preferably, they are located on one of the two larger surfaces.
[0011] If the power semiconductor elements are not rectangular in cross-section, the above also applies analogously to other shapes. Typically, there are two essentially parallel, larger surfaces, which can also be referred to as the top and bottom surfaces. The side surface(s) are narrower in comparison. Even with a non-rectangular cross-section, the power semiconductor elements are located on one side, and preferably on one of the larger surfaces.
[0012] The fact that all power contacts of a power semiconductor element are arranged on one side can mean that, in the case of two or more power semiconductor elements in a semiconductor package, all power contacts are preferably arranged on one side, i.e., pointing upwards in the installed position. Alternatively, it is also possible that the power contacts of the first power semiconductor element are located on one side, the power contacts of the second power semiconductor element on a second side, different from the first, and for further power semiconductor elements, one of the first two sides or additional sides may be present. However, for a single power semiconductor element, all power contacts are always located on one side.
[0013] Advantageously, the power semiconductor elements can be contacted with the current-carrying busbars via inlays. This means that inlays are arranged between the busbars and the power semiconductor elements. These are advantageously made of copper.
[0014] In another embodiment, the inlays can also be arranged to be at least partially embedded in the printed circuit board. Preferably, they are completely embedded in the printed circuit board.
[0015] Advantageously, the power semiconductor elements can be contacted with the current-carrying busbars via vias. In particular, both inlays and vias can be present, with the power semiconductor elements being connected to the inlays via the vias. In this case, the connection runs from the busbar to the power semiconductor elements via inlays and vias.
[0016] Preferably, the vias can be prefabricated in the printed circuit board. They are the first component to be inserted into the substrate material. They are created, for example, by drilling holes in the circuit board or substrate material and then electroplating them.
[0017] This design can also be used for the current-carrying busbars. In this case, the current flows from the power semiconductor elements via vias and inlays to the busbars.
[0018] Preferably, the power connections can be arranged in the order DC-, DC+, and AC. The connection for the positive battery terminal, DC+, is therefore closer to the AC connection than the connection for the negative battery terminal, DC-. The busbars for the DC- and DC+ connections can be flat and overlapping, meaning they are partially stacked parallel to the circuit board.
[0019] Advantageously, the power connections of the power semiconductor elements can be welded to the busbars. This is possible if the power semiconductor elements are contacted via inlays.
[0020] Preferably, the power semiconductor elements can be partially encapsulated by a potting compound. This serves to protect that part of the power semiconductor elements which are not embedded in the printed circuit board.
[0021] Advantageously, at least one inlay can be arranged on a power semiconductor element and on the side opposite the power contacts. Preferably, the inlay can be made of copper. These inlays serve to spread heat away from a cooling device.
[0022] Preferably, an inlay for heat spreading can be provided for each power semiconductor of the semiconductor package.
[0023] Preferably, the power semiconductor elements can be configured as lateral power semiconductors. In this case, the current flows in a lateral direction.
[0024] Preferably, the semiconductor material in at least some of the power semiconductor elements can consist of gallium nitride (GaN). Preferably, the semiconductor material in all power semiconductor elements can consist of gallium nitride.
[0025] Preferably, the power semiconductor element can be designed as a GaN-HEMT, i.e., as a gallium nitride high electron mobility transistor.
[0026] Alternatively, the power semiconductor elements can be configured as vertical power semiconductors. In this case, the current flows in a vertical direction. The semiconductor material of at least some of the power semiconductor elements can consist of silicon (Si) or silicon carbide (SiC).
[0027] Then a SiC MOSFET or a Si IGBT can be used as the power semiconductor element.
[0028] The semiconductor package comprises at least two power semiconductor elements, at least one of which is connectable to or connected to the positive terminal of a battery, and at least one of which is connected to the negative terminal of the battery. To enable current scaling, multiple power semiconductor elements can be arranged in parallel. Thus, several power semiconductor elements can be connected to the negative terminal of the battery. These are also called low-side switches (LSS), and the power semiconductors connected to the positive terminal of the battery are called high-side switches (HSS).
[0029] With more than one power semiconductor element per battery terminal, i.e., at least two power semiconductor elements connected in parallel, it can be provided that at least one of the parallel-connected power semiconductor elements comprises a first semiconductor material and at least one other power semiconductor element comprises a second semiconductor material. In this configuration, the power semiconductor element on the "low side" (i.e., the power semiconductor element connected to the negative battery terminal) and the switch on the "high side" (i.e., the power semiconductor element connected to the positive battery terminal), which are arranged in series, comprise the same material.
[0030] One package can then be used to generate one phase of the alternating current.
[0031] The described design allows for short signal contacts for good gate control, maximum creepage distances with minimal stray inductance, and a symmetrical layout.
[0032] Preferably, the driver output stages can be arranged in or on the printed circuit board.
[0033] Signal contact can also be made via press-fit or solder pins.
[0034] Furthermore, the invention relates to a semiconductor module comprising a semiconductor package and a cooling device. The semiconductor module is characterized by the fact that the semiconductor package is configured as described.
[0035] In particular, a copper layer may be provided for contact between the package and the cooling device. Specifically, the back side of the semiconductor package may be metallurgically bonded to the cooling device. This metallurgical bond can be achieved, for example, by sintering, soldering, or compression with an organic insulator. A thermally conductive insulator may be arranged between the semiconductor package and the cooling device. This prevents an electrical connection between the semiconductor package and the cooling device.
[0036] Furthermore, the invention relates to a power converter with at least one semiconductor package and / or one semiconductor module. The power converter is characterized in that the semiconductor package and / or the semiconductor module are configured as described. Power converters are devices for converting an electric current. This can involve changing the type of current or a characteristic parameter. Inverters, for example, convert direct current (DC) to alternating current (AC), and DC-DC converters convert an input voltage to an output voltage. Inverters and DC-DC converters are particularly common in motor vehicles. Inverters convert the direct current from a battery into alternating current for an electric motor, while DC-DC converters enable charging from power supplies whose voltage differs from that of the battery.Of course, other types of power converters can also benefit from the described semiconductor package. These are merely mentioned as examples.
[0037] Furthermore, the invention relates to an electric axle drive for a motor vehicle comprising at least one electric motor, a transmission unit, and a power converter. The electric axle drive is characterized by the power converter being configured as described. The transmission unit can include a gearbox for reducing the speed of the electric motor. It can also include a differential, which can also be combined as a so-called integrated differential.
[0038] Furthermore, the invention relates to a motor vehicle comprising an electric axle drive as described and / or a power converter as described and / or a semiconductor package as described and / or a semiconductor module as described.
[0039] Further features, characteristics and details of the invention will become apparent from the following description of figures and exemplary embodiments. These show: Fig. 1 A motor vehicle, Fig. 2 a semiconductor module in cross-section, Fig. 3 a circuit arrangement, Fig. 4 a semiconductor power element, Fig. 5 a circuit diagram of the power semiconductor element, Fig. 6 a semiconductor module in a second embodiment, Fig. 7 a semiconductor module in a third configuration, Fig. 8 a semiconductor module in a fourth embodiment, Fig. 9 a semiconductor module in a fifth configuration, Fig. 10 the semiconductor module after Fig. 5 in the top view, Fig. 11 the semiconductor module after Fig. 6 in the top view, Fig. 12 the semiconductor module after Fig. 7 in the top view, Fig. 13 the semiconductor module after Fig. 5 in an exploded view, Fig. 14 the semiconductor module after Fig. 7 in an exploded view, Fig. 15 the semiconductor module after Fig. 8 in an exploded view, Fig. 16 a part of a power converter in an exploded view and Fig. 17 a part of a power converter.
[0040] Fig. Figure 1 shows a motor vehicle 1 with an electric axle drive 2 comprising an electric motor 3, a transmission 4, and an inverter 5. The motor vehicle may also include a battery 6 and a DC / DC converter 7. The proximity to the inverter 5 indicates that the DC / DC converter 7 may be integrated into the inverter 5. However, it can also be designed as a completely separate component and positioned anywhere within the motor vehicle.
[0041] The electrical connection between battery 6 and inverter 5 is not shown. The inverter 5 can, in particular, comprise at least one semiconductor module 8 with a semiconductor package 9. These are described in more detail in the following figures.
[0042] Fig. Figure 2 shows a cross-sectional view of a semiconductor module 8 in a first embodiment. The semiconductor module 8 comprises a semiconductor package 9 and a cooling device 10. The semiconductor package 9 includes at least one first and one second power semiconductor element. These are referred to below as LSS chip 12 and HSS chip 14. The LSS chip 12 is the power semiconductor element that is electrically connected to the negative battery terminal, and the HSS chip 14 is connected to the positive battery terminal. For contacting the LSS chip 12 and the HSS chip 14 with the current rail 16 and 18, respectively, the semiconductor package 9 has inlays 20 and 22. These can be made of copper. The inlays 20 and 22 are each connected to the LSS chip 12 and the HSS chip 14, respectively, via vias 24 and 26. Vias are metallized holes in the substrate material of the printed circuit board. The busbars 16 and 18 can be welded to the respective inlay 20 or 22.This results in particularly good power transmission. A driver board 28 is located above the power rail 18.
[0043] On the side facing away from the vias and thus the power contacts, inlays 13 and 15 are located for heat dissipation. Inlays 13 and 15 are also preferably made of copper.
[0044] The power semiconductor elements, i.e., the LSS chip 12 and the HSS chip 14, are embedded in a printed circuit board 30. The inlays 13, 15, 20 and 22 are also embedded in the printed circuit board 30. In the configuration according to Fig. 2. Both the power semiconductor elements and the inlays are completely embedded in the circuit board 30. All power contacts 32 and 34 of the power semiconductor elements, i.e., of the LSS chip 12 and the HSS chip 14, point to a single side. In Fig. 2 is the top side. However, this position only refers to the installation position of the chips in the inverter 2; the inverter 5 itself can, in principle, be positioned anywhere in the vehicle 1.
[0045] The HSS chip 14 is connected to the power rail 40 via further vias 36 and an inlay 38. The alternating current generated by the semiconductor package 9, or more precisely one phase thereof, is transported to the electric motor 3 via the power rail 40.
[0046] The LSS chip 12 and the HSS chip 14 are connected to each other via an electrical contact 42, which in turn is contacted with the chips 12 and 14 via vias 44.
[0047] Accordingly, the circuit diagram is derived from Fig. 3. This is based on Fig. 2 is basically self-explanatory.
[0048] The power connections 48, 50, and 52 are arranged in the order DC-, DC+, and AC. These power connections are also the power connections.
[0049] The semiconductor module 8 according to the Fig. 2 and Fig. 3 is optimized for lateral power semiconductor elements. Such a power semiconductor element is shown in the following two figures.
[0050] Fig. Figure 4 shows an embodiment of an LSS chip 12 or HSS chip 14 in a gallium nitride HEMT (GaN HEMT) configuration. In addition to the power contacts Source 54 and Drain 56, this chip also has two gate power contacts 58. The chip 12, 14 is cuboid in shape. All power contacts are located on the top surface.
[0051] Fig. Figure 5 shows a corresponding circuit diagram of the chip. Fig. 4.
[0052] Fig. Figure 6 shows an alternative design of a semiconductor module 8. The description of [missing information] can be largely applied here. Fig. 2 are referred to. Differences to Fig. The two features consist of the LSS chip 12 and the HSS chip 14, as well as the inlays 20, 22, and 38, being embedded in a printed circuit board 60, but only partially. To prevent these components from protruding, they, along with the printed circuit board 60, are embedded in a potting compound 62. For the sake of clarity, the reference numerals have been largely omitted, as no further information is provided in this regard. Fig. 2 can be referred to.
[0053] Fig. Figure 7 shows a semiconductor module 8 in a third embodiment. In this embodiment, an organic insulator 46 and a copper plate 64 are located between the semiconductor package 9 and the cooling device 10. Furthermore, a bonding layer 66 is located between the copper plate 64 and the cooling device 10, by means of which the cooling device 10 and the semiconductor package 9 are metallurgically connected.
[0054] Before the semiconductor package 9 and the cooling device 10 are assembled, the insulation 46, the copper plate 64, and the interconnect layer 66 are all part of the semiconductor package 9. The interconnect layer 66 can be a solder or a suitable material for sintering the semiconductor package 9. These components are then bonded to the cooling device 10 by a soldering or sintering process, or, as described above, alternatively by compression.
[0055] Also with regard to Fig. 7 refers to the further description on Fig. 2 or 6 were referred to.
[0056] Fig. Figure 8 shows a further embodiment of a semiconductor module. This module differs from the embodiments according to the Fig. 2 to Fig. Seven vertical power semiconductor elements, for example SiC MOSFETs or Si IGBTs, are mounted. Accordingly, the semiconductor package receives the reference number 68, the LSS chip 70, and the HSS chip 72. The inlays and vias, as well as the power rails, correspond in structure and function to what is described in Fig. 2 was described, which is why reference is made to... Fig. 2 is referred to.
[0057] Embedding in a substrate is carried out analogously to Fig. 6, which is why we also refer to this in this regard Fig. 6 is referred to.
[0058] One difference lies in the arrangement of the inlays, as inlays 22 and 38 are no longer spatially separated. Inlay 74 is instead connected to power rail 18 and thus also to power rail 40. Furthermore, inlay 74 also connects LSS chip 70 and HSS chip 72.
[0059] Fig. Figure 9 shows a semiconductor module 8 in a further embodiment. Here too, vertical power semiconductor elements are used, as already mentioned in Figure 9. Fig. Figure 8 describes the following. In contrast to the figures described so far, the power contacts 32 of the LSS chip 70 and the power contacts 34 of the HSS chip 72 are no longer on the same side, even though all power contacts 32 of the LSS chip 70 and all power contacts 34 of the HSS chip 72 are on the same side of the HSS chip 72. This means that while the power contacts for each chip are still on one side, this is no longer the case for the entire package 68. The HSS chips 72 are mounted upside down.
[0060] Fig. Figure 10 shows the semiconductor module 8 after the Fig. 6 and Fig. Figure 7 in perspective view. Besides the power rails 16, 18, and 40, the potting compound 62 is also visible on the top. Furthermore, four signal pins 76 are located on the top. For a further description of the semiconductor module 8, see [reference to be added]. Fig. 10 refers to the description of Fig. 6 and Fig. 7 and the Fig. 2 referred.
[0061] Fig. 11 shows the semiconductor module 8 after Fig. 8 in the top view. It can be seen that the arrangement of the busbars is opposite Fig. 10 is changed. The busbars 18 for connection to the positive battery terminal are arranged on both sides of an arm of the busbar 40.
[0062] Fig. 12 shows the semiconductor module 8 after Fig. 9 in perspective view. Compared to the Fig. In 10, a spatial approximation of the busbars 16 and 18 is possible, and module 8 is more compact overall.
[0063] The Fig. 13 to Fig. Figure 15 shows possible manufacturing steps for the different semiconductor modules. It is shown that, regardless of the actual design, the printed circuit board 30 or 60, including the vias, is prefabricated. The chips 12 and 14, the inlays 13 and 15, and optionally the insulation 46 can be bonded together by sintering or soldering.
[0064] Fig. Figure 16 shows a possible implementation of part of an inverter 5, focusing primarily on the module 8. Several packages 9 or 68 are connected in parallel to scale up the amount of current that can be processed. The busbars 16 and 18, as well as several busbars 40 for the individual phases, are also visible. Two semiconductor packages are provided per phase. The cooling device 10 is connected to the semiconductor packages by means of a thermally conductive insulator 46.
[0065] Fig. 17 shows the arrangement according to Fig. 16 after assembly. In this case, the busbars 16, 18 and 40 may be welded to the packages 9 in particular. Reference symbol list 1 motor vehicle 2 electric axle drives 3 Electric motor 4 Gearbox unit 5 inverters 6 batteries 7 DC-DC converters 8 Semiconductor module 9 semiconductor package 10 Cooling device 12 LSS Chip 13 Inlay 14 HSS Chip 15 Inlay 16 busbar 18 busbar 20 Inlay 22 Inlay 24 Via 26 Via 28 driver board 30 circuit boards 32 Performance Contact 34 Performance Contact 36 Via 38 Inlay 40 busbar 42 connection 44 Via 46 Insulator 48 Power connection 50 power connection 52 Power connection 54 Source 56 Drain 58 Gate 60 circuit boards 62 Potting compound 64 copper plates 66 Compound layer 68 semiconductor package 70 LSS Chip 72 HSS Chip 74 Inlay 76 Signal pin
Claims
[1] Semiconductor package (9, 68) for a power converter (5) comprising at least one printed circuit board (30, 60) and at least two power semiconductor elements (12, 14, 70, 72), characterized by , that the power semiconductor elements (12, 14, 70, 72) are embedded in the circuit board (30, 60) and all power contacts (32, 34) of a power semiconductor element (12, 14, 70, 72) are arranged on one side. [2] Semiconductor package according to claim 1, characterized by , that the power semiconductor elements (12, 14, 70, 72) are contacted with the current-supplying busbars (16, 18) via inlays (20, 22). [3] Semiconductor package according to claim 1 or 2, characterized by , that the power semiconductor elements (12, 14, 70, 72) are contacted with the current-supplying busbars (20, 22) via vias (24, 26). [4] Semiconductor package according to any of the preceding claims, characterized by, that the power connections (48, 50, 52) are arranged in the order DC-, DC+ and AC. [5] Semiconductor package according to any one of the preceding claims, characterized by , that the power connections of the power semiconductor elements (12, 14, 70, 72) are welded to the busbars (48, 50, 52). [6] Semiconductor package according to any one of the preceding claims, characterized by , that the power semiconductor elements (12, 14, 70, 72) are partially enclosed by a potting compound (62). [7] Semiconductor package according to any one of the preceding claims, characterized by , that in at least some of the, in particular all, power semiconductor elements (12, 14) the semiconductor material consists of gallium nitride (GaN). [8] Semiconductor module (8) with a semiconductor package (9, 68) and a cooling device (10), characterized by , that the semiconductor package (9, 68) is configured according to one of the preceding claims. [9] Semiconductor module according to claim 8, characterized by , that copper inlays (13, 15) are arranged between the semiconductor package (9, 68) and the cooling device (10) for heat spreading. [10] Power converter (5) comprising at least one semiconductor package (9, 68) and / or one semiconductor module (8), characterized by , that the semiconductor package (9, 68) is configured according to one of claims 1 to 7 and / or the semiconductor module (8) according to one of claims 8 to 9. [11] Power converter according to claim 10, characterized by , that the power converter is designed as an inverter (5). [12] Electric axle drive (2) for a motor vehicle comprising at least one electric machine (3), a transmission device (4) and a power converter (5), characterized by that the power converter is configured according to claim 10 or 11. [13] Motor vehicle (1) comprising an electric axle drive (2) according to claim 12 and / or a power converter (5) according to claim 10 or 11 and / or a semiconductor package (9, 68) according to any one of claims 1 to 7 and / or a semiconductor module (8) according to any one of claims 8 to 9.