Power electronics assembly comprising power modules that can be fitted with components

Abstract

The invention relates to a power electronics assembly with which at least two power modules which can be fitted with components are electrically contacted, wherein the power modules which can be fitted with components each comprise a power substrate with a metallization, at least one switchable die with power connections, an interposer, and at least a first and a second contact element, wherein the contact elements each provide electrical contacting for one of the power connections of the die on the interposer.

Description

[0001] Description

[0002] Power electronic assembly with equippable power modules

[0003] The invention relates to a power electronic assembly with equippable power modules, a converter and an electric vehicle

[0004] Such a power electronic module can be used in industrial converters or in traction converters.

[0005] The object of the invention is to provide a low-inductance assembly with power modules that can be fitted in a conventional production line.

[0006] The object is achieved by a power electronics assembly which has an assembly substrate with which at least two equippable power modules are electrically contacted, wherein the power modules each comprise a power substrate with a metallization, at least one switchable die with power connections, an interposer and at least a first and a second contact element. The contact elements each provide an electrical contact for one of the power connections of the die on the interposer and are designed to electrically contact the power connections of the die with a power electronics assembly. In other words, the contact elements provide an electrical contact for the power connections of the die, which is arranged inside the power module, outside the power module, such that the module can be fitted on an assembly and used.The die is a semiconductor component, which can be embodied, for example, as an IGBT or MOSFET. It is an unpackaged semiconductor and is also referred to as a bare die or naked chip. Such bare chips are normally only processed under clean-room conditions and are therefore rarely processed directly in conventional SMD production lines. The module according to the invention can advantageously be processed in conventional electronics production lines and, at the same time, can be connected with a similarly low inductance as would be possible with the die itself.

[0007] The power connections of the die are usually designed as source and drain or collector and emitter, depending on the semiconductor type. In diodes, the power connections are designed as anode and cathode. Furthermore, the die is joined to the metallization of the power substrate and to the interposer and arranged between the power substrate and the interposer. A gap formed by the first substrate, the interposer and the die is closed with an insulating material so that the die is surrounded by the insulating material, the power substrate and the interposer. This has the advantage that the bare chip is now encapsulated in such a way that it can be processed using conventional SMD production. The interposer is designed so that the contact elements protrude through the interposer and / or the interposer provides the contact elements.

[0008] The contact elements are preferably designed such that a low-inductance electrical contact can be established between the power electronic assembly and the die. In other words, the first and second contact elements are designed to provide electrical contact between power terminals of the die on the interposer, so that the die can be electrically contacted from outside the power module.

[0009] The contact elements can be designed as part of the interposer and can be electrically contacted with electrical conductors in the interposer. Such contact elements are commercially available using printed circuit board technology or can be manufactured as metallization of the interposer. According to the invention, simple, one-sided and automated contacting of the die via the interposer is possible. The equippable power module can then be accordingly mounted on a power electronics assembly. The power module preferably has one or at most two switchable dies.

[0010] The interposer can have a larger thermal expansion coefficient than the power substrate. This allows the interposer to be constructed from materials that are more cost-effective, flexible, and easier to process than the power substrate.

[0011] The electrical contacting and handling of dies are therefore considerably simplified by the power module during its assembly, while the flexibility of the bare die with regard to the electrical interconnection (topologies, power scaling) and the arrangement in the component is retained.

[0012] The power module and accordingly the contact elements and the die are designed for a blocking 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.

[0013] In a further embodiment, the power substrate is designed as a metal-ceramic substrate. In particular, the so-called direct-bonded copper and active metal brazing substrates are worth mentioning here. Such substrates have the great advantage of having a thermal expansion coefficient adapted to the die, thus achieving very high stability, particularly against thermal cycling. At the same time, high heat conduction can be achieved from the die towards a thermal interface of the substrate, which is opposite the die with respect to the substrate. In a further embodiment, the interposer is designed as a multilayer circuit carrier. This has the advantage that the cable routing in the multilayer circuit carrier can be designed much more flexibly than would be possible with a ceramic substrate, for example.

[0014] In a further embodiment, the interposer is designed as a plastic circuit board, in particular a fiber-reinforced plastic circuit board, an FR4 circuit board, a so-called high-Tg PCB (having a glass transition temperature TG of greater than 150 °C), made of polyimide and / or as a pre-molded leadframe. High-temperature interposer materials such as PI, PEEK, or LCP have proven suitable for high-temperature applications.

[0015] In a further embodiment, the interposer has metallic inlays. Such inlays can in particular be made of copper, designed as solid metal blocks and lead to both improved current carrying capacity and improved thermal conductivity when connecting the power connections of the die. The inlays are preferably electrically connected to at least one of the power connections of the die and can be connected to the die via vias in multilayer printed circuit boards. Depending on the power requirement, it is conceivable that one or more vias each make electrical contact with a metallic inlay and then accordingly also provide or electrically contact the contact elements from the interposer.In other words, the inlays serve as electrical conductors for the contact elements to enable a connection between the power terminals of the die and a power electronic assembly.

[0016] In a further embodiment, the interposer has a recess for one of the contact elements, wherein the contact element is electrically contacted with the metallization. Since the dies usually have power connections on the top and bottom, the power connection that is in contact with the metallization of the power substrate must be re-contacted to enable one-sided connection of the power module via the interposer. This re-contacting can be achieved, for example, by a contact element that projects through the interposer. Here, for example, a pin can be provided that serves as a connection or contact element of the power module. This pin can be press-in and can also be easily connected mechanically by a connection to the stable power substrate and has low-inductive properties.Solid terminals designed for the required power are preferably used as contact elements. Additionally or alternatively, the pin can also have an electrical intermediate contact on the interposer and therefore does not need to be electrically connected to the metallization of the power substrate. It can be mounted there in a potential-separated or completely insulated manner.

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

[0018] In a further embodiment, at least one of the contact elements is designed for contacting by means of a pressing process, in particular by means of a press-in process. Flat pressing processes or press-in connections are suitable here. Such contacting processes have very low inductance, are easy to control, and can be easily processed.

[0019] In a further embodiment, at least one of the contact elements is designed for contacting the electronic assembly using a joining process. Solder pins, flat sinterable and / or solderable connection pads (similar to a land grid array), or solderable balls (similar to a ball grid array) are particularly suitable here. Such joining surfaces are particularly low-inductance and can be easily joined, particularly due to the flat or planar design of the power module.

[0020] In a further embodiment, at least one of the contact elements is designed for contacting by means of a spring force. This has the advantage of achieving a low-inductance electrical connection while simultaneously allowing the connection to be released.

[0021] In a further embodiment, the interposer has a first metallic inlay that is electrically contacted with a first power terminal of the die and a first contact element. Additionally or alternatively, the interposer has a second metallic inlay that is electrically contacted with a second power terminal of the die and a second contact element. Thus, the power terminals can be led out of the power module via the metallic inlays with a high current-carrying capacity, very good thermal conductivity, and low inductance.

[0022] In a further embodiment, the interposer is designed such that a creepage distance in the gap between a contact connection of the first power terminal and the second power terminal of the die is smaller than an air gap between the first contact element and the second contact element. The contact elements led out of the power module and provided by the interposer thus preferably have a significantly greater distance in the air (i.e. at the contact elements accessible from outside the power module) than the space available in the power module or in the immediate vicinity of the die would allow. Such equalization in turn has a positive effect on the performance and power density of the power module and makes it possible to dispense with additional insulation material outside the power module or enables the use of cheaper insulation materials.The equalization of the creepage and clearance distances can be achieved with or without an inlay.

[0023] In a further embodiment, the interposer has a control terminal that electrically contacts a control terminal of the die. 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 terminals. This allows for a very compact design.

[0024] The assembly substrate can be designed as a conventional (e.g. FR4) printed circuit board due to the inventive structure of the power modules, since heat is dissipated via the power substrates of the power modules, which are arranged facing away from the assembly substrate, and the power density is equalized by the interposer.

[0025] In a further embodiment, the power electronic assembly can be designed such that the interposers of the power modules are arranged facing the assembly substrate. In other words, the interposer, with the contact elements, provides the electrical contact for the assembly substrate.

[0026] In a further embodiment, the power modules are arranged between the assembly substrate and a heat sink. This means that the interposer points in the direction of the assembly substrate and the power substrate of the power module can be connected directly to the heat sink, for example using a thermal interface. The heat sink can also serve to ensure a flat connection with regard to the power substrates and the alignment of the modules to one another. Compared with fully integrated solutions of commercially available power modules with 4 or 6 switchable semiconductor modules (e.g. so-called six-pack modules), the present invention in general and its embodiments in particular offer many advantages. The power module is a modular package with standardizable connections. Changes to the power semiconductor (different power semiconductor technologies such as e.g.IGBTs, MOSFETs, SiC, GaN) affect the power module itself, so the interposer's connection side could remain the same. The power board (i.e., the assembly substrate) does not need to be changed. Adjustments to the power or circuit topology can be implemented using different power modules with correspondingly different power semiconductors or circuits, even with an identical power board.

[0027] Layout changes (e.g., shifting the assembly positions) on the power board can be easily implemented thanks to the standardized connection structures of the power module according to the invention. With regard to the design of a power electronics assembly, the power module according to the invention has the advantage that it can be viewed as a discrete component in the circuit design and can therefore be planned directly during layout planning. Each individual power module is and remains fully electrically testable. In contrast to multiple semiconductors on a circuit carrier, which can only be tested as a complete structure, the yield can be increased considerably as a result.

[0028] For thermal decoupling between the power module and the power board, the required area for potentially costly high-temperature interposer material is kept to a minimum. Cost-effective standard material can preferably be used for the power board.

[0029] A particularly advantageous feature is that the individual power modules can be elegantly leveled relative to one another and to the heat sink by pressing or soldering them with retaining clips or by compensating connecting elements. In the power electronics assembly, the individual thermal interfaces of the power modules can thus be aligned with one another in a plane within a specified tolerance.

[0030] The problem is further solved by a converter having at least one power electronics module, as well as an electric vehicle having such a converter. Furthermore, the power electronics module can also be configured as a DC / DC converter.

[0031] The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the figures. They show schematically:

[0032] FIG 1 a power module in cross section

[0033] FIG 2 another power module in cross section with contact elements,

[0034] FIG 3 another power module in cross section with additional contact elements,

[0035] FIG 4 shows a supplementary embodiment of the power module with a pin extending through the interposer,

[0036] FIG 5 an embodiment with two pins projecting through the interposer,

[0037] FIG 6 shows a representation of air and creepage distances on a power module,

[0038] FIG 7 a power module with an interposer having inlays,

[0039] FIG 8 a power module with an interposer having inlays, in an embodiment with a control terminal,

[0040] FIG 9 shows a single-sided power electronic module and FIG 10 shows a double-sided power electronic module.

[0041] FIG 1 shows a power module 100 having a power substrate 10 with a core 12, in particular a ceramic core, a first metallization 14 and a second metallization 16. A die 40, in this case a switchable die 40, is attached, for example joined, to the first metallization 14. The die 40 is attached with its first power connection 42 to the first metallization 14 and electrically contacted, so that an electrical connection can be established between the first power connection of the die 42 and an interposer 50 via one or more recontacts 18. The interposer 50 has contact elements 62, 64 which electrically provide the first power connection of the die 42 with the first contact element 62, here divided into two pads, a second power connection of the die 44 through the second contact element 64 and a control connection 46 through a control connection 66 of the interposer 50.All connections of the die 40 are thus provided on the interposer by contact elements 62, 64 and the control connection 66.

[0042] The interposer 50 is shown only schematically in this case. Below the interposer 50 there is an insulating material 20 which fills a gap 22 between the interposer 50, the power substrate 10 and the die 40. The contact points 18 are also surrounded by the insulating material 20. An underfill material or molding can be used here, for example. It is advantageous if only a single IGBT with the associated freewheeling diode or only a small number of MOSFETs connected in parallel is mounted on one of the power substrates 10 in order to achieve the greatest possible flexibility.

[0043] FIG. 2 shows a power module 100, as shown in FIG. 1, wherein the contact elements 62, 64 and the control connection 66 already have press-in pins. Alternatively, solder pins or rivets could be provided here. Such contact elements are easy to process and can be used in standard processes. FIG. 3 shows an alternative embodiment of a power module, wherein on the interposer 50, in addition to the press-in or solder pin, a solder pad or a solder ball is also provided as contact elements 62, 64. Solder connections of this type are known, for example, from ball grid arrays, wherein in the present case a power connection is created by a corresponding number of balls / the size of the pads. Flat pads and / or spring connections are also conceivable. The connecting elements can be combined, but usually one type of connecting element is used for all connections on the respective power module.

[0044] FIG 4 shows a further embodiment of a power module 100, in which a first contact element 62 projects through the interposer 50. The contact pin or the contact element 62 is designed such that it is applied to a metallization 14, which is connected to a first power connection 42 of the die 40, on a power substrate 10. In this way, no re-contacting is necessary and a very low-inductance connection to the metallization 14 or the chip underside and the first power connection 42 arranged there is created. In this case too, the die 40 is surrounded by an underfill or a molding, which acts as an insulating material 20. Such contact pins can be attached directly during the manufacture of the metallization of the DGB or AMB substrates. A second contact element 64 can be designed as described and is indicated here as a surface.The second power connection 44 is connected to a second contact element 64 by an electrical conductor in the interposer 50. The second contact element 64 can be designed differently than the contact elements in the embodiments and can be configured depending on the application. The die 40 is joined with its power connections 42, 44 to the substrate or to the interposer 50. The die 40 can also have a control connection, which is not shown here. FIG. 5 shows an embodiment similar to FIG. 4, wherein the first and second contact elements 62, 64 are each designed as a pin, the first contact element 62 being designed as in FIG. 4 and being in electrical contact with the first power connection 42 of the die 40. The second contact element 64 is also designed as a pin, which is in contact with a second power connection 44 of the die 40 via the interposer 50.The second contact element 64 can be arranged directly on the core of the substrate 10, as shown, but can also be mounted on an electrically isolated island of the metallization 14. The die 40 can also have a control terminal, which is not shown here.

[0045] 6 shows a further embodiment of a power module 100, wherein an air gap xl and a creepage distance x2 are shown here. The air gap xl is located outside the power module 100 between a first contact element 62 and a second contact element 64. The air gap xl is the distance that is provided as insulation in the air or in the fluid in which the power module 100 is used, between the two power-conducting contact elements 62, 64. This distance must be large enough to meet insulation requirements in the respective power class. In this particularly advantageous embodiment, the air gap xl is greater than a creepage distance x2 that is located within an insulation material 20. The spreading of the air gap xl with respect to the creepage distance x2 is determined by the interposer 50 or the contact elements 64, 62 arranged thereby.The contact element 62 connects a recontact 18, which is connected to the first power connection 42 of the semiconductor 40 via a metallization of the power substrate 10, and a second contact element 64, which is also connected to a second power connection 44 of the semiconductor or of the die 40 via the interposer 50. The underside and the top side of the interposer are connected via vias 56 in such a way that the air gap xl is considerably greater than the creepage distance x2. The interposer serves as a flexibly designed intermediate layer which spreads the power connections 62 and 64 accordingly. Control connections of the die 40 are not shown, but can also be led out via the interposer.

[0046] FIG. 7 shows an embodiment similar to FIG. 6, wherein a multi-layer interposer 50 is used which has metallic inlays 55 which simultaneously serve to provide better and very low-inductance electrical contact and enable a spreading between the air and creepage distances x1, x2. The inlays are preferably designed as a thick copper layer in the center, which is contacted with the two outer layers via vias. The inlays offer very good thermal connection and also excellent low-resistance vertical current feedthrough. The vias can in particular be designed as laser-drilled vias which are filled with copper. The resulting equalization of the load currents directly at the semiconductor or directly at the die 40 enables an optimized concept and the use of standard multilayer PCBs.

[0047] FIG 8 shows a further embodiment of a power module 100 with an interposer 50 having inlays 55, similar to FIG 6. Here it can be seen how a die 40 having a control connection 46 can be contacted by the interposer 50. A control connection 66 of the interposer 50 is connected to the control connection 46 of the die 40 via a via through the multilayer interposer 50. Such an arrangement is further advantageous because the control connection 66 does not impair the distribution of the air and creepage distances x1, x2 (not shown here), since the control connection 66 is accordingly at a different potential. The arrangement of the control connection 66 is independent of the inlays 55.

[0048] FIG. 9 schematically shows a power electronic assembly 200 comprising two power modules 100, a heat sink 210, and an assembly substrate 220 with a metallization 224. The assembly substrate 220 can be made of materials known for printed circuit board technology, since the power-intensive components are located on the power modules 100. Thus, assemblies 200 can be designed very flexibly for a wide variety of applications and can also be heat-dissipated for high-performance applications.

[0049] FIG 10 schematically shows a power electronics assembly 200, as in FIG 9, wherein the assembly substrate 220 is populated and contacted on both sides with two power modules 100. In this way, a very high power density can be achieved because the connection of the power modules 100 to the assembly substrate 220, e.g. via a double-sided metallization 224, can still be realized with very low inductance and at the same time the heat dissipation is effectively realized via the heat sinks arranged on both sides. In general, the power electronics assembly 200 and the assembly substrate 220 are designed such that the contact elements 62, 64 of the power modules 100 each find joining partners on the assembly substrate 220. These can be corresponding sockets or counterparts to the corresponding contact elements 62, 64.

[0050] In summary, the invention relates to a power module 100 that can be populated, comprising a power substrate 10 with a metallization 14, 16, at least one switchable die 40 with power connections 42, 44, an interposer 50 and at least a first and a second contact element 62, 64, wherein the contact elements 62, 64 each provide an electrical contact between one of the power connections 42, 44 of the die 40 and the interposer 50. In order to specify a power module 100 that can be populated in a conventional production line and without clean room conditions, e.g.in an SMD assembly line, can be connected to an assembly 200 with low inductance, it is proposed that the die 40 is joined 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, a gap formed by the first substrate 10, the interposer 50 and the die 40 is closed with an insulating material 20, so that the die 30 is surrounded by the insulating material 20, the power substrate 10 and the interposer 50 and that the interposer 50 is designed such 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 invention further relates to a power electronic assembly 200, a converter and an electric vehicle.

[0051] Reference sign

[0052] 100 equippable power modules

[0053] 10 Power substrate

[0054] 12 core

[0055] 14 first metallization of the power substrate

[0056] 16 Second metallization of the power substrate and thermal interface

[0057] 18 Recontacting

[0058] 20 I insulation material

[0059] 22 gap

[0060] 40 switchable

[0061] 42 first power connection of the die

[0062] 44 second power connection of the die

[0063] 46 Control connection of the die

[0064] 50 interposers

[0065] 55 metallic inlay

[0066] 56 Via

[0067] 62 first contact element

[0068] 64 second contact element

[0069] 66 Interposer control connection

[0070] 200 power electronic modules

[0071] 210 heat sink

[0072] 220 assembly substrate

[0073] 224 Metallization of the assembly substrate

Claims

Patent claims 1. Power electronic assembly (200) comprising an assembly substrate (220) with which at least two equippable power modules (100) are electrically contacted, wherein the equippable power modules (100) each comprise: - a power substrate (10) with at least one first metallization (14), - at least one switchable die (40) with power connections (42,44), - an interposer (50) and - at least one first and one second contact element (62, 64), each of which provides electrical contact with one of the power terminals (42, 44) of the die (40) on the interposer (50), wherein the die (40) is joined 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 die (40) is closed with an insulating material (20), so that the die (30) is surrounded by the insulating material (20), the power substrate (10) and the interposer (50), wherein the interposer (50) is designed such 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).

2. Power electronic assembly (200) according to claim 1, wherein the power modules (100) are arranged with their interposers (50) facing the assembly substrate (220).

3. Power electronic assembly (200) according to claim 1 or 2, wherein the power modules (100) are arranged between the assembly substrate (220) and a heat sink (210).

4. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) is designed as a multilayer circuit carrier.

5. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) has a recess for one of the contact elements (62, 64) which is electrically contacted with the first metallization (14).

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

7. Power electronic assembly (200) according to one of the preceding claims, wherein at least one of the contact elements (62, 64) is designed for contacting by means of a pressing process, in particular a press-in process.

8. Power electronic assembly (200) according to one of the preceding claims, wherein at least one of the contact elements (62, 64) is designed for contacting by means of a joining process.

9. Power electronic assembly (200) according to one of the preceding claims, wherein at least one of the contact elements (62, 64) is designed for contacting by means of a spring force.

10. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) has a first metallic inlay (55) which is electrically contacted with a first power terminal (42) of the die (40) and a first contact element (62).

11. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) has a second metallic inlay (55) which is electrically contacted with a second power terminal (44) of the die (40) and a second contact element (64).

12. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) is designed such that a creepage distance (x2) in the gap (22) between a contacting (18) of the electrical contacting of the first power terminal (42) and the second power terminal (44) of the die (40) is smaller than an air gap (xl) between the first contact element and the second contact element (44) which are led out of the interposer (50).

13. Power electronic assembly (200) according to one of the preceding claims, wherein the interposer (50) has a control terminal (66) which electrically contacts a control terminal (46) of the die, wherein the control terminal (66) of the interposer (50) is preferably arranged between the first and the second contact element (62, 64).

14. Converter comprising at least one power electronic assembly (200) according to one of the preceding claims, which is designed to convert direct voltage into alternating voltage and / or vice versa.

15. Electric vehicle comprising a converter according to claim 14 as part of an electric drive.

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