Power electronic assembly with mountable power module

Abstract

The invention relates to a power electronic assembly with which at least two mountable power modules are in electrical contact, the mountable power modules each comprising a power substrate having a metallization, at least one switchable wafer having power terminals, an interposer, and at least one first and one second contact element, the contact elements respectively provide electrical contact of one of the power terminals of the wafer on the interposer.

Description

Technical Field

[0001] The invention relates to a power electronic assembly having a mountable power module, a converter and an electric vehicle. Background Art

[0002] Such power electronic components can be used in industrial converters or traction converters. Summary of the invention

[0003] The object of the present invention is to provide a low-inductance component having a power module which can be installed in a conventional production line.

[0004] The above technical problem is solved by a power electronic component, which has a component substrate, at least two assembleable power modules are electrically contacted with the component substrate, wherein the power modules respectively include a power substrate with a metallization, at least one switchable wafer with a power terminal, an insert and at least one first and second contact element. The contact element provides an electrical contact of one of the power terminals of the wafer on the insert respectively and is constructed here for the electrical contact of the power terminal of the wafer with the power electronic component. In other words, the contact element provides an electrical contact of the power terminal of the wafer arranged in the power module outside the power module, so that the module can be assembled on the component and can be used. The wafer is a semiconductor device, which can be configured as an IGBT or MOSFET, for example. It is related to an unpackaged semiconductor and is also referred to as a bare core or bare wafer. This bare wafer is usually processed only under clean room conditions, and is therefore rarely processed directly in a traditional SMD production line. The module according to the present invention can be advantageously processed in a traditional electronic production line, and at the same time, it is connected approximately with low inductance, such as it can be connected with low inductance with the wafer itself.

[0005] Here, the power terminals of the chip are usually and according to the semiconductor type are constructed as source and drain or collector and emitter. For a diode, the power terminals are constructed as an anode or a cathode. In addition, the chip is bonded to the metallization of the power substrate and to the interposer, and is arranged between the power substrate and the interposer. The gap formed by the first substrate, the interposer and the chip is closed with an insulating material so that the chip is surrounded by the insulating material, the power substrate and the interposer. This has the advantage that the bare chip is now packaged so that it can be processed in traditional SMD manufacturing. Here, the interposer is designed so that the contact element extends through the interposer and / or the interposer provides the contact element.

[0006] The contact elements are preferably configured so that a low-inductance electrical contact can be established from the power electronics assembly to the wafer. In other words, the first contact element and the second contact element are designed to provide electrical contact of the power terminals of the wafer on the interposer, so that the wafer can be electrically contacted from outside the power module.

[0007] Here, the contact element can be designed as part of the insert and make electrical contact with the electrical conductor in the insert. Such a contact element is available on the market in printed circuit board technology or can be produced as a metallization of the insert.

[0008] According to the invention, a simple, one-sided and automatable contacting of the wafer can be achieved by means of the insert. The mountable power module can then be mounted accordingly on the power electronics assembly. Here, the power module preferably has one or at most two switchable wafers.

[0009] In this case, the insert body can have a greater coefficient of thermal expansion than the power substrate. Thus, the insert body can be composed of a cheaper, more flexible and easier to process material than the power substrate.

[0010] The electrical contacting and handling of the wafer during its installation via the power module is thus significantly simplified, wherein the flexibility of the die with regard to the electrical connection (topology, power scaling) and the arrangement in the component is maintained.

[0011] In this case, the power module and accordingly the contact elements and the wafer are designed for a cutoff voltage of at least 24 V, in particular at least 50 V or 100 V, and a load current of at least 1 A, in particular at least 5 A or 10 A.

[0012] In another embodiment, the power substrate is designed as a metal ceramic substrate. In particular, so-called direct-bonded copper and active metal brazing substrates are mentioned here. Such substrates have the great advantage that there is a thermal expansion coefficient that matches the wafer, which results in a very high stability, especially with respect to thermal alternating stresses. At the same time, a high heat conduction from the wafer in the direction of the thermal interface of the substrate can also be achieved, which is arranged opposite the wafer relative to the substrate.

[0013] In another embodiment, the interposer is designed as a multilayer circuit carrier. This has the advantage that the line routing in the multilayer circuit carrier can be designed much more flexibly than is possible, for example, with a ceramic substrate.

[0014] In another embodiment, the interposer is designed as a plastic circuit board made of polyimide, in particular a fiber-reinforced plastic circuit board, an FR4 circuit board, a so-called high-Tg-PCB (with a glass transition temperature TG of more than 150° C.) and / or as a pre-molded lead frame. For high-temperature applications, high-temperature interposer materials such as PI, PEEK or LCP have proven to be suitable.

[0015] In another embodiment, the insert has a metal inlay. Such an inlay can consist in particular of copper, be designed as a solid metal block and, when connecting the power terminals of the chip, lead not only to improved current carrying capacity but also to improved thermal conductivity. In this case, the inlay is preferably electrically connected to at least one of the power terminals of the chip and can be connected to the chip via a through hole in the multilayer printed circuit board. It is therefore conceivable, depending on the power requirements, that one or more through holes are respectively electrically contacted to the metal inlay and then correspondingly also provide contact elements from the insert or electrically contact to the contact elements. In other words, the inlay serves as an electrical conductor for the contact element in order to enable a connection between the power terminals of the chip and the power electronics component.

[0016] In another embodiment, the insert has a recess for one of the contact elements, wherein the contact element is electrically contacted with the metallization. Because the wafer usually has power terminals on the upper side and the lower side, it is necessary to surround the power terminals that are in contact with the metallization of the power substrate so that the power module can be connected unilaterally via the insert. This surrounding contact can be achieved, for example, by a contact element extending through the insert. Here, for example, a pin can be provided, which is used as a terminal or contact element of the power module. The pin can be press-fit, and can also be mechanically well connected by connection with a stable power substrate, and has low inductance characteristics. Solid terminals are preferably used as contact elements, which are designed according to the power generated. In addition or alternatively, the pin can also have an electrical intermediate contact on the insert, and accordingly, it is not necessary to electrically contact on the metallization of the power substrate, and can be placed there in a potential-separated or fully insulated manner.

[0017] In another embodiment, the interposer is designed such that the power and control connections of all the wafers are provided on a common side of the interposer facing away from the power substrate. This enables simple assembly and, in the process, a particularly low-inductance connection of the power module.

[0018] In another embodiment, at least one of the contact elements is designed for contacting by means of a pressing method, in particular by means of a press-in method. Planar pressing methods or also press-in connections are conceivable here. Such contact methods are very low-inductive, well controllable and can be easily processed.

[0019] In another embodiment, at least one of the contact elements is designed to make contact with the electronic component by means of a bonding method. In particular, solder pins, planar sinterable and / or solderable connection pads (similar to a land grid array) or solderable balls (similar to a ball grid array) are suitable here. Such bonding surfaces are particularly low-inductance and can be easily bonded, in particular, even with a flat or planar structure of the power module.

[0020] In another embodiment, at least one of the contact elements is designed to make contact by means of a spring force. This has the advantage that a low-inductance electrical connection can be achieved while being releasable.

[0021] In another embodiment, the interposer has a first metal inlay, which is in electrical contact with the first power terminal and the first contact element of the wafer. In addition or alternatively, the interposer has a second metal inlay, which is in electrical contact with the second power terminal and the second contact element of the wafer. Thus, the power terminal can be led out of the power module through a metal inlay with a high current carrying capacity, very good thermal conductivity and low inductance.

[0022] In another embodiment, the insert is designed such that the creepage distance in the gap between the enclosing contacts of the first power terminal and the second power terminal of the chip is smaller than the air distance between the first contact element and the second contact element. The contact elements that are led out of the power module and provided by the insert therefore preferably have a significantly larger spacing in the air (i.e. at the contact elements that can be reached from outside the power module) than the spatial conditions in the power module or in the direct surroundings of the chip allow. This balance in turn has a positive effect on the efficiency and power density of the power module and allows additional insulating materials outside the power module to be abandoned or enables the use of cheaper insulating materials. Here, the balance of creepage distance and air distance can be achieved with or without an inlay.

[0023] In another embodiment, the interposer has a control terminal which electrically contacts the control terminal of the wafer. In this case, the control terminal of the interposer can be arranged between the first and second contact elements. This not only saves space, but also does not change the insulation requirements, since the control terminal is at a different potential than the power terminal. It can thus be constructed very compactly.

[0024] The assembly substrate can be designed as a conventional (eg FR4) printed circuit board by the design according to the invention of the power module, since heat dissipation is carried out via the power substrate of the power module arranged facing away from the assembly substrate and the power density is equalized via the interposer.

[0025] In another embodiment, the power electronics component can be designed such that the interposer of the power module is arranged toward the component substrate. In other words, the interposer with the contact element provides electrical contact for the component substrate.

[0026] In another embodiment, the power module is arranged between the component substrate and the cooling body. That is, the insert body points in the direction of the component substrate, and the power substrate of the power module can be directly connected to the cooling body, for example, by means of a thermal interface. In this case, the cooling body can also be used to ensure a planar connection between the power substrate and the module with respect to their orientation.

[0027] Compared to fully integrated solutions of commercially available power modules with 4 or 6 switchable semiconductor modules (e.g. so-called Sixpack modules), the present invention in general and in its specific embodiments offers numerous advantages. The power module is a modular package with standardized connectors. The variation of the power semiconductors (different power semiconductor technologies, e.g. IGBT, MOSFET, SiC, GaN) concerns the power module itself, so that the insert can remain the same on the connection side. There is no need to change the power board (i.e. the component substrate). The matching of the power or circuit topology can be achieved with the same power board by different power modules with correspondingly different power semiconductors or connections.

[0028] Layout changes on the power board (e.g., movement of the assembly position) can be easily realized by the standardized connection structure of the power module according to the present invention. In terms of the design of power electronic components, the power module according to the present invention has the following advantages: it is regarded as a discrete device in the circuit design and can be directly planned together in the layout accordingly. Each individual power module is and remains fully electrically testable. Compared with multiple semiconductors on the circuit carrier (which can only be tested as a whole), the yield can be significantly increased.

[0029] For thermal decoupling between the power module and the power board, the area required for potentially high-cost high-temperature interposer material is limited to a minimum. Preferably, low-cost standard materials can be used for the power board.

[0030] It is particularly advantageous that the individual power modules can be aligned in a simple manner relative to one another or above one another and relative to the heat sink by pressing in or soldering with a clamp or by means of compensating connecting elements. Thus, in a power electronics assembly, the individual thermal interfaces of the power modules can be aligned relative to one another in a plane within predeterminable tolerances.

[0031] Furthermore, the above technical problem is solved by a converter having at least one power electronic component and an electric vehicle having such a converter. Furthermore, the power electronic component can also be designed as a DC / DC converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be described and explained in detail below with reference to the embodiments shown in the accompanying drawings. In the accompanying drawings, respectively:

[0033] Figure 1 shows a cross section of a power module;

[0034] Figure 2 shows a cross section of another power module with contact elements,

[0035] Figure 3 shows a cross section through another power module with further contact elements,

[0036] Figure 4 A supplementary embodiment of a power module having pins extending through an interposer is shown,

[0037] Figure 5 An embodiment is shown with two pins extending through the interposer,

[0038] Figure 6 Diagram showing air and creepage distances on a power module,

[0039] Figure 7 shows a power module having an interposer with an inlay,

[0040] Figure 8 shows a power module with an interposer having an inlay in an embodiment with control terminals,

[0041] Fig. 9 shows a single-sided power electronics assembly, and

[0042] Fig.10 The power electronics components are shown mounted on both sides. DETAILED DESCRIPTION

[0043] Figure 1A power module 100 is shown, which has a power substrate 10 with a core 12, in particular a ceramic, a first metallization 14 and a second metallization 16. A wafer 40, in this case a switchable wafer 40, is mounted, for example bonded, on the first metallization 14. Here, the wafer 40 is placed with its first power terminal 42 on the first metallization 14 and electrically contacted, so that an electrical connection between the first power terminal of the wafer 42 and an interposer 50 can be established via one or more surrounding contacts 18. Here, the interposer 50 has contact elements 62, 64, which electrically provide a first power terminal of the wafer 42 (here divided into two pads) by means of the first contact element 62, a second power terminal of the wafer 44 by means of the second contact element 64 and a control terminal 46 by means of a control terminal 66 of the interposer 50. Thus, all terminals of the wafer 40 are provided on the interposer via the contact elements 62, 64 and the control terminal 66.

[0044] The interposer 50 is only schematically shown in this case. Below the interposer 50 is an insulating material 20 which fills the gap 22 between the interposer 50, the power substrate 10 and the wafer 40. The surrounding contact 18 is also surrounded by the insulating material 20. Here, for example, an underfill material or a molding can be used. It is advantageous to mount only a single IGBT with an associated freewheeling diode or only a small number of MOSFETs connected in parallel on one of the power substrates 10 in order to achieve the highest possible flexibility.

[0045] Figure 2 Shown as Figure 1 The power module 100 shown in this embodiment already has press-fit pins for the contact elements 62 , 64 and the control terminal 66 . Alternatively, solder pins or rivets can be provided here. Such contact elements can be easily processed and can be used in standard processes.

[0046] Figure 3 An alternative embodiment of a power module is shown, in which solder pads or solder balls are now provided as contact elements 62, 64 on the insert 50 in addition to press-in pins or solder pins. Such solder connections are known, for example, from ball grid arrays, in which the power connection is achieved in the present case by a corresponding number of balls / size of the pads. In addition, planar pads and / or spring connections are conceivable. The connecting elements are combinable here, but usually one type of connecting element is used for all connections on the corresponding power module.

[0047] Figure 4Another embodiment of the power module 100 is shown, in which the first contact element 62 extends through the insert 50. Here, the contact pin or contact element 62 is constructed so that it is applied on the metallization 14 on the power substrate 10, which is connected to the first power terminal 42 of the chip 40. In this way, there is no need to surround the contact, and a very low inductance connection with the metallization 14 or the lower side of the chip and the first power terminal 42 arranged there is achieved. In this case, the chip 40 is also surrounded by a bottom filler or molding that acts as an insulating material 20. Such contact pins can be directly installed in the metallization manufacturing process of the DCB or AMB substrate. The second contact element 64 can be designed as described and is represented as a surface here. The second power terminal 44 is connected to the second contact element 64 by an electrical conductor in the insert 50. Here, the second contact element 64 can be designed differently from the contact element as in the embodiment and according to the application. Here, the chip 40 is bonded to the substrate or the insert 50 with its power terminals 42, 44. In this case, the wafer 40 can also have control connections which are not shown here.

[0048] Figure 5 Shows something like Figure 4 Embodiment, wherein the first and second contact elements 62, 64 are each configured as pins, wherein the first contact element 62 is configured as a pin. Figure 4 The second contact element 64 is also designed as a pin, which contacts the second power terminal 44 of the wafer 40 via the interposer 50. In this case, the second contact element 64 can be arranged directly on the core of the substrate 10 as shown, but can also be placed on an electrically insulating island of the metallization 14. In this case, the wafer 40 can also have a control terminal, which is not shown here.

[0049] Figure 6Another embodiment of a power module 100 is shown, wherein an air distance x1 and a creepage distance x2 are plotted here. The air distance x1 is located between a first contact element 62 and a second contact element 64 outside the power module 100. Here, the air distance x1 is the distance between two power-conducting contact elements 62, 64, which is set as insulation in the air or in the fluid in which the power module 100 is used. This distance must be large enough to meet the insulation requirements in the corresponding power class. In this particularly advantageous embodiment, the air distance x1 is greater than the creepage distance x2 located in the insulating material 20. The expansion of the air distance x1 relative to the creepage distance x2 is achieved here by the insert 50 or the contact elements 64, 62 arranged thereby. Here, the contact element 62 connects the surrounding contact 18, which is connected to the first power terminal 42 of the semiconductor 40 via the metallization of the power substrate 10, and the second contact element 64 is also connected to the second power terminal 44 of the semiconductor or wafer 40 via the insert 50. Here, the lower side and the upper side of the interposer are connected by through-holes 56 in such a way that the air distance x1 is significantly greater than the creepage distance x2. Here, the interposer serves as a flexibly designed intermediate layer, which correspondingly expands the power terminals 62 and 64. The control terminals of the wafer 40 are not shown, but they can also be led out through the interposer.

[0050] Figure 7 Shows something like Figure 6 Embodiment in which a multilayer interposer 50 is used which has a metal inlay 55 which simultaneously serves for better and very low-inductance electrical contact and enables expansion between the air distance and the creepage distance x1, x2. In this case, the inlay is preferably constructed as a central thick copper layer which contacts the two outer layers via through-holes. The inlay provides a very good thermal connection and an excellent low-resistance vertical current feedthrough. The through-hole can in particular be designed as a laser-drilled through-hole which is filled with copper. The resulting equalization of the load current directly on the semiconductor or directly on the wafer 40 enables an optimized solution and the use of a standard multilayer PCB.

[0051] Figure 8 Another embodiment of a power module 100 having an interposer 50 is shown, the interposer having an inlay 55, similar to Figure 6 Here it can be seen how the wafer 40 with the control terminal 46 is in contact with the interposer 50. The control terminal 66 of the interposer 50 is connected to the control terminal 46 of the wafer 40 via a via that passes through the multilayer interposer 50. This arrangement is also advantageous because the control terminal 66 does not influence the division of the air distance and the creepage distance x1, x2 (not shown here) because the control terminal 66 is at a different potential accordingly. The arrangement of the control terminal 66 is independent of the inlay 55.

[0052] Fig. 9 A power electronics assembly 200 is schematically shown, which has two power modules 100, a heat sink 210 and an assembly substrate 220 with a metallization 224. In this case, the assembly substrate 220 can be produced from materials known for circuit board technology, since power-intensive components are transferred to the power modules 100. The assembly 200 can thus be designed very flexibly for different applications and can also dissipate heat for high-power applications.

[0053] Fig.10 The power electronic assembly 200 is schematically shown, as shown in FIG. Fig. 9 As in the example, the component substrate 220 is equipped with two power modules 100 on both sides and contacts them. Therefore, a very high power density can be achieved, because the connection of the power module 100 to the component substrate 220, for example, via the metallization 224 on both sides, can also be achieved with very low inductance, and at the same time, heat dissipation can be effectively achieved via the heat sinks arranged on both sides. It is generally applicable that the power electronic component 200 and the component substrate 220 are designed so that the contact elements 62, 64 of the power module 100 each find a mating counterpart on the component substrate 220. Here, they can be corresponding sockets or matching parts with corresponding contact elements 62, 64.

[0054] In summary, the present invention relates to an assembleable power module 100, which comprises a power substrate 10 having metallization parts 14, 16, at least one switchable chip 40 having power terminals 42, 44, an interposer 50 and at least one first and second contact element 62, 64, wherein the contact elements 62, 64 respectively provide electrical contact to one of the power terminals 42, 44 of the chip 40 on the interposer 50. In order to illustrate a power module 100 that can be assembled in a conventional production line and can be connected to a component 200 with low inductance without clean room conditions, for example in an SMD assembly line, it is proposed that: the wafer 40 is bonded to the first metallization 14 of the power substrate 10 and to the interposer 50 and is arranged between the power substrate 10 and the interposer 50; the gap formed by the first substrate 10, the interposer 50 and the wafer 40 is closed by the insulating material 20, so that the wafer 30 is surrounded by the insulating material 20, the power substrate 10 and the interposer 50; and the interposer 50 is designed so that one or more of the contact elements 62, 64 protrude through the interposer 50 and / or the interposer 50 provides one or more of the contact elements 62, 64. The present invention also relates to a power electronic component 200, a converter and an electric vehicle.

[0055] Reference numerals list

[0056] 100 Assembleable Power Modules

[0057] 10 Power substrate

[0058] 12 cores

[0059] 14 First metallization portion of power substrate

[0060] 16 Second metallization part of power substrate and thermal interface

[0061] 18 surrounding contact part

[0062] 20 Insulation Materials

[0063] 22 Gap

[0064] 40 switchable chips

[0065] 42 The first power supply terminal of the chip

[0066] 44 The second power supply terminal of the chip

[0067] 46 chip control terminals

[0068] 50 insert body

[0069] 55 Metal Inlay

[0070] 56 through holes

[0071] 62 first contact element

[0072] 64 second contact element

[0073] 66 control terminals of the insert

[0074] 200 power electronics components

[0075] 210 heat sink

[0076] 220 component substrate

[0077] 224 Metallization of component substrate

Claims

1. A power electronic component (200), comprising a component substrate (220), at least two mountable power modules (100) being in electrical contact with the component substrate, wherein: The assembleable power modules (100) respectively comprise: - a power substrate (10) having at least one first metallization (14), - at least one switchable chip (40) having power terminals (42, 44), - an insert (50), and - at least one first contact element and a second contact element (62, 64), each of which provides, on the interposer (50), an electrical contact with one of the power terminals (42, 44) of the wafer (40), wherein the wafer (40) is bonded to the metallization (14) of the power substrate (10) and to the interposer (50) and is arranged between the power substrate (10) and the interposer (50), wherein a gap (22) formed by the first substrate (10), the interposer (50) and the wafer (40) is closed by an insulating material (20), so that the wafer (30) is surrounded by the insulating material (20), the power substrate (10) and the interposer (50), The insert body (50) is designed such that one or more of the contact elements (62, 64) protrude through the insert body (50), and / or the insert body (50) provides one or more of the contact elements (62, 64).

2. The power electronic component (200) according to claim 1, wherein: The power module (100) is arranged with its insert (50) facing the component substrate (220).

3. The power electronic component (200) according to claim 1 or 2, wherein: The power module (100) is arranged between the component substrate (220) and the cooling body (210).

4. The power electronic component (200) according to any one of the preceding claims, wherein: The insert (50) is designed as a multi-layer circuit carrier.

5. The power electronic component (200) according to any one of the preceding claims, wherein: The insert (50) has a recess for one of the contact elements (62, 64), which is in electrical contact with the first metallization (14).

6. The power electronic component (200) according to any one of the preceding claims, wherein: The interposer (50) is configured such that the power terminals (42, 44) and the control terminals (46) of all wafers (40) are provided on a common side of the interposer (50) facing away from the power substrate (10).

7. The power electronic component (200) according to any one of the preceding claims, wherein: At least one of the contact elements (62, 64) is designed for contacting by means of a pressing method, in particular a press-in method.

8. The power electronic component (200) according to any one of the preceding claims, wherein: At least one of the contact elements (62, 64) is designed for contacting by means of a joining method.

9. The power electronic component (200) according to any one of the preceding claims, wherein: At least one of the contact elements (62, 64) is designed to make contact by means of a spring force.

10. The power electronic component (200) according to any one of the preceding claims, wherein: The interposer (50) has a first metal inlay (55) which is in electrical contact with a first power terminal (42) and a first contact element (62) of the wafer (40).

11. The power electronic component (200) according to any one of the preceding claims, wherein: The interposer (50) has a second metal inlay (55) which is in electrical contact with a second power terminal (44) and a second contact element (64) of the wafer (40).

12. The power electronic component (200) according to any one of the preceding claims, wherein: The insert (50) is designed so that a creepage distance (x2) in a gap (22) between surrounding contact portions (18) of electrical contacts of the first power terminal (42) and the second power terminal (44) of the chip (40) is smaller than an air distance (x1) between the first contact element and the second contact element (44) led out from the insert (50).

13. The power electronic component (200) according to any one of the preceding claims, wherein: The interposer (50) has a control terminal (66) which electrically contacts a control terminal (46) of the wafer, wherein the control terminal (66) of the interposer (50) is preferably arranged between the first contact element and the second contact element (62, 64). 14 . A converter having at least one power electronic component ( 200 ) according to claim 1 , which is designed to convert a direct voltage into an alternating voltage and / or vice versa.

15. An electric vehicle having the converter according to claim 14 as part of an electric drive device.

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