Power semiconductor module comprising potting body and production method

Abstract

Presented is a power semiconductor module comprising a potting body and a method of production, the power semiconductor module comprising a substrate having an insulating body and substrate conductor traces arranged thereon, a power semiconductor component arranged on the substrate, a connection device, a potting body, a pressure device, an external terminal element and a prefabricated housing, the semiconductor component is arranged on and electrically conductively connected to one of the base conductor traces, the connection device being implemented as a film stack comprising a first conductive film, a second conductive film and an electrically insulating film arranged between the first conductive film and the second conductive film, according to the invention, the entire connection device is covered by the potting body, the pressure device is designed to apply pressure directly on the potting body by means of the spring element, and the external terminal elements are arranged on or connected to the prefabricated housing in a form-locked manner and each have a contact device in contact with the associated base conductor trace.

Description

Technical Field

[0001] The invention describes a production method and a power semiconductor module comprising a substrate, comprising a power semiconductor component arranged on the substrate, comprising a connection device, comprising a potting body, comprising a pressure device, comprising an external terminal element and comprising a prefabricated plastic housing. Background Art

[0002] DE 10 2013 104 949 B3 discloses a switching device, which comprises a substrate, a power semiconductor component, a connecting device, a load terminal device and a pressure device. In this case, the substrate has an electrically insulating conductor track, and the power semiconductor component is arranged on one of the conductor tracks. The connecting device is implemented as a film composite comprising an electrically conductive film and an electrically insulating film and having a first main surface and a second main surface. The switching device is thus connected internally in a circuit-compatible manner. The pressure device has a pressure body, which has a first cutout, and the first cutout is arranged with a pressure element protruding from it, wherein the pressure element is pressed onto a part of the second main surface of the film composite, and in this case, the part is arranged within the surface of the power semiconductor component in a projection along the normal direction relative to the power semiconductor component.

[0003] DE 10 2017 125 052 A1 relates to a power semiconductor module, comprising a switching device having a substrate, a power semiconductor component and a membrane stack, and comprising a pressure device implemented to be movable in a normal direction relative to the substrate, wherein the membrane stack has a first main surface facing the substrate and a second main surface facing away from the substrate, wherein the pressure device has a pressure body and a first metal spring, wherein the pressure body exerts a force on the first metal spring in the direction of the substrate, wherein the first metal spring exerts pressure on a first area of ​​the second main surface in the direction of the power semiconductor component via a pressure transmission surface of the first metal spring, the pressure transmission surface facing the first area of ​​the second main surface, and wherein the first area of ​​the second main surface and the pressure transmission surface of the first metal spring are arranged above a first surface of the power semiconductor component in a normal direction relative to the substrate, the first surface facing away from the substrate, and in a manner aligned with the first surface of the power semiconductor component. Summary of the invention

[0004] Knowing the above, the present invention is based on the object of simplifying and structurally strengthening the construction of a known power semiconductor module and of specifying a method for producing such a power semiconductor module.

[0005] According to the invention, this object is achieved by a power semiconductor module, which comprises a substrate, a power semiconductor component arranged on the substrate, a connecting device, a potting body, a pressure device, an external terminal element and a prefabricated housing, preferably a plastic housing, wherein the substrate has an insulating body and a base conductor track arranged thereon, wherein the power semiconductor component is arranged on one of the base conductor tracks and is electrically conductively connected to the one base conductor track, wherein the connecting device is embodied as a film stack, which comprises a first electrically conductive film, a second electrically conductive film and an electrically insulating film arranged between the first and second electrically conductive films, wherein the entire connecting device is covered by the potting body, preferably completely covered by the potting body, wherein the pressure device is embodied to exert pressure on the potting body directly by means of a spring element or only indirectly by means of a metal plate, wherein the external terminal elements are arranged on or connected to the prefabricated housing in a form-locking manner and each have a contact device for contacting the assigned base conductor track.

[0006] When using a power semiconductor module, the pressure of the pressure device is thus applied to the potting body which is pressed directly on the connection device, thereby directly pressing on the power semiconductor component and thus pressing the substrate onto the cooling device. Thus, the structure is simple and has additional stability by virtue of the potting body.

[0007] Advantageously, the electrically conductive films are each embodied as a plurality of film conductor tracks.

[0008] It may be advantageous if the potting body is embodied as epoxy resin.

[0009] Preferably, the modulus of elasticity of the potting body is between 2000 MPa and 6000 MPa, preferably between 3000 MPa and 4200 MPa. Alternatively or in addition, it may be preferred that the coefficient of linear expansion CTE of the potting body is between 1 ppm / K and 200 ppm / K, preferably between 2 ppm / K and 50 ppm / K, and more particularly preferably between 3 ppm / K and 20 ppm / K.

[0010] It may be advantageous if the potting body has an intermediate potting body which directly covers the connection device and which advantageously has an elastic modulus which is at least 10% lower, advantageously at least 20% lower.

[0011] It may be preferred that the substrate, the connecting device and the potting body and, if present, also the metal plate are each aligned with one another and each have a continuous cutout through which the pressure introduction element projects.

[0012] It may also be preferred if the surface of the potting body facing away from the substrate has contour elements, for example pimple-like protrusions.

[0013] In the case of a power semiconductor module having a metal plate, it is preferred that the surface of the metal plate facing away from the substrate has contour elements, for example pimple-like protrusions.

[0014] It can be particularly advantageous if the spring element has a finger with a finger contact region. In this case, the finger contact region can be aligned in the normal direction with the power semiconductor component or with the center point of a group of two or three power semiconductor components.

[0015] The present invention also achieves the above-mentioned object by a method for producing such a power semiconductor module, the method comprising the following working steps, in particular in the order of abcdef or abdcef: a. Implementing a substrate having a power semiconductor component, the power semiconductor component being arranged on one of the base conductor traces and connected to the one base conductor trace; b. Arrange the connecting device; c. Arranging the external terminal element in a shape-locking manner on the prefabricated housing or connecting the terminal element to the prefabricated housing in a shape-locking manner; d. The base comprising a connecting means is arranged in the prefabricated housing; e. The contact means of the external terminal element is connected to the assigned base conductor trace; f. Covering the entire connection device with a potting compound which, when cured, forms a potting body.

[0016] Preferably, the spring device is arranged after the last method step.

[0017] Of course, in the power semiconductor module according to the present invention, features or feature groups (eg power semiconductor components) mentioned in the singular may appear multiple times, unless explicitly excluded or inherently excluded or contradict the concept of the present invention.

[0018] It goes without saying that, regardless of whether the various configurations of the present invention are mentioned in conjunction with a power semiconductor module or with the method, the various configurations of the present invention can be implemented individually or in any combination in order to achieve improvements. In particular, the features mentioned and explained above and below can be used not only in the indicated combination, but also in other combinations or by themselves without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further explanation, advantageous details and features of the present invention will be described below.Figures 1 to 8 It will become apparent from the description of exemplary embodiments of the invention or corresponding parts thereof schematically shown in the accompanying drawings.

[0020] Figure 1 A step of the method according to the invention for producing a power semiconductor module according to the invention is shown.

[0021] Figures 2 to 4 The figures show cross sections through different configurations of power semiconductor modules according to the invention.

[0022] Figure 5 A fourth configuration of a power semiconductor module according to the invention is shown.

[0023] Figure 6 and Figure 7 A three-dimensional view of a power semiconductor module according to the invention is shown.

[0024] Figure 8 A plan view of a power semiconductor module according to the invention is shown. DETAILED DESCRIPTION

[0025] Figure 1 A method step of the method according to the invention for producing a power semiconductor module according to the invention is shown, more precisely method step d). The starting point is a substrate 2 which defines a normal direction N. This substrate 2 is implemented here merely as an example as a ceramic substrate 20 conventional in the art, which has a plurality of base conductor tracks 22 made of copper. A power semiconductor component 3 (here merely as an example, a silicon carbide MOS-FET) is arranged on one of these base conductor tracks 22 in a materially bonded and electrically conductive manner.

[0026] The power semiconductor component 3 is connected to another base conductor track 22 in a circuit-compatible manner via a module-internal connection device 4. The connection device 4 is implemented as a film stack consisting of two conductive films 40 and 44, wherein an electrically insulating film 42 is arranged between the conductive films. The conductive films 40 and 44 are structured and thus form mutually insulated film conductor tracks.

[0027] The illustration also shows a prefabricated plastic housing 8 comprising injection-molded external terminal elements 70 and 72, here two DC voltage terminal elements of which are shown, which are embodied in some parts as stacked in order to minimize parasitic inductances. These DC voltage terminal elements 70, 72 have respective contact areas which can be contacted from a normal direction N; see also Figure 6 and Figure 7 .

[0028] Prior to the method step shown here, the substrate 2 is arranged relative to the prefabricated housing 8 and the external terminal elements 70, 72 are connected to the assigned substrate conductor tracks 22. The illustration now shows the beginning of covering the power semiconductor components 3 and the connecting means 4 with the potting compound 500, see Figure 2 .

[0029] Figures 2 to 4 The sections show different configurations of power semiconductor modules 1 according to the invention, each arranged on a cooling device 9 , here a liquid cooling device. For simplification, a metal base plate which does not protrude laterally beyond the housing can also be provided here instead of an explicit cooling device.

[0030] In the first construction, according to Figure 2 , the power semiconductor component 3 and the connection device 4 have been covered circumferentially by a potting compound 500, wherein in the cured state the potting compound now embodies a potting body 5 consisting of an epoxy resin having an elastic modulus of 3500 MPa and a CTE value of 5 ppm / K. In this configuration, the contact areas of the external terminal elements 70, 72 with the allocated portions of the base conductor track 22 are not covered by the potting body 5.

[0031] Figure 3 A second configuration of the power semiconductor module 1 according to the invention is shown, in which the adjacent parts with the assigned base conductor tracks 22 and the external terminal elements 70 , 72 , more precisely the adjacent parts of the load terminal elements, are here additionally covered by a potting body 5 .

[0032] The illustration also shows a pressure device 6 comprising a spring element 60 which exerts pressure directly (ie immediately adjacent) on the potting body 5 and thus establishes a thermally conductive connection between the power semiconductor component 3 and the cooling device 9 .

[0033] Figure 4 A third configuration of a power semiconductor module 1 according to the invention is shown, in which the entire substrate 2 and therefore also parts of the external terminal elements 70 and 72 , more precisely parts of the load terminal elements, are here additionally covered by a potting body 5 .

[0034] The illustration also shows a pressure device 6 , which here again comprises a spring element 60 , which exerts pressure directly (i.e. immediately adjacent) on a contour element 50 of the potting body 5 , which is embodied as two pimple-like elevations, and thus establishes a thermally conductive connection between the power semiconductor component 3 and the cooling device 9 .

[0035] Compared to the potting body 5 of the aforementioned construction, the potting body 5 of this construction comprises an intermediate potting body 52 which directly covers the connection device 4 and therefore also covers the power semiconductor component and has an elastic modulus 20% lower than the rest of the potting body 5 and is also implemented as epoxy resin.

[0036] Figure 5 A fourth configuration of a power semiconductor module 1 according to the invention is shown, wherein here the potting body 5 is implemented in a manner similar to that according to the second configuration and additionally has a metal plate 54 facing the spring element 62 of the pressure device 6. This metal plate 54 serves for a better pressure distribution on the potting body 5, which originally has the same specifications as described above. The potting body 5 here extends laterally to the housing 8 and can be connected to the housing 8, in particular in a form-locking manner, in particular by toothing.

[0037] The pressure device 6 itself has two cutouts through which screws extend respectively as pressure introduction elements 68. These screws also extend through two connection elements 700, 760, two external terminal elements 72, 76 therein, more precisely, external load terminal elements, and through two cutouts 82 on the edge 80 of the prefabricated plastic housing 8 and find an abutment 90 in the cooling device 9. In this case, a further molded insulating body 78 is arranged for electrically insulating the screws 68. As an example, the connection elements 700, 720, 760 are connected to an electric motor or a battery.

[0038] Figure 6 and Figure 7 A three-dimensional view of a power semiconductor module 1 according to the invention is shown, with Figure 4 Both designs have a central cutout through which a screw as a pressure introduction element 68 extends directly into the cooling device. The spring element 66 of the pressure device 6 itself is implemented here as a spiral spring.

[0039] Figure 6 Shown is a power semiconductor module 1 comprising two external DC voltage terminal elements 70, 72 and one external AC voltage terminal element 76. The circuit implemented in this power semiconductor module 1 is a two-stage half-bridge circuit.

[0040] Figure 7 Shown is a power semiconductor module 1 comprising three external DC voltage terminal elements 70, 72, 74 and one external AC voltage terminal element 76. The circuit implemented in the power semiconductor module 1 is a three-level half-bridge circuit.

[0041] The corresponding accessible contact areas of the external terminal elements 70 , 72 , 74 , 76 are shown in a shaded manner.

[0042] Figure 8 A plan view of a power semiconductor module 1 according to the invention is shown. In this case, the two external DC voltage terminal elements 70 , 72 are configured adjacent to one another when viewed from the normal direction N, ie not in such a way as to form a stack.

[0043] The spring element 66 of the pressure device is of a spider-like design with a plurality of (here four) fingers, whose finger contact areas (for introducing pressure onto the encapsulation body 5) are each assigned to a group of power semiconductor components 3 and, when viewed in the normal direction N, are aligned with the midpoint of this group of power semiconductor components 3.

Claims

1. A power semiconductor module (1), comprising a substrate (2), comprising a power semiconductor component (3) arranged on the substrate (2), comprising a connection device (4), comprising a potting body (5), comprising a pressure device (6), comprising external terminal elements (70, 72, 74, 76) and comprising a prefabricated housing (8), preferably a plastic housing, in, The substrate (2) has an insulating body (20) and substrate conductor tracks (22) arranged on the insulating body (20), wherein the power semiconductor component (3) is arranged on one of the substrate conductor tracks (22) and is electrically conductively connected to the one substrate conductor track. The connecting device (4) is implemented as a film stack, the film stack comprises a first conductive film (40), a second conductive film (44) and an electrically insulating film (42), the electrically insulating film (42) being arranged between the first conductive film (40) and the second conductive film (44). The entire connecting device (4) is covered by the potting body (5), preferably completely covered by the potting body (5). The pressure device (6) is designed to exert pressure on the potting body (5) directly via spring elements (60, 62, 64, 66) or only indirectly via a metal plate (54). Therein, the external terminal elements (70, 72, 74, 76) are arranged on the prefabricated housing (8) or connected to the prefabricated housing (8) in a form-locking manner and each have a contact device for contacting the assigned base conductor track (22).

2. The power semiconductor module according to claim 1, wherein: The conductive films (40, 44) are each embodied as a film conductor trace.

3. The power semiconductor module according to any one of claims 1 to 2, wherein: The potting body (5) is implemented as epoxy resin.

4. The power semiconductor module according to any one of claims 1 to 2, wherein: The elastic modulus of the potting body (5) is between 2000 MPa and 6000 MPa, preferably between 3000 MPa and 4200 MPa.

5. The power semiconductor module according to any one of claims 1 to 2, wherein: The linear expansion coefficient CTE of the potting body (5) is between 1 ppm / K and 200 ppm / K, preferably between 2 ppm / K and 50 ppm / K, and more preferably between 3 ppm / K and 20 ppm / K.

6. The power semiconductor module according to any one of claims 1 to 2, wherein: The potting body (5) has an intermediate potting body (52), which directly covers the connecting device (4) and advantageously has an elastic modulus that is at least 10% lower, advantageously at least 20% lower.

7. The power semiconductor module according to any one of claims 1 to 2, wherein: The base (2), the connecting device (4) and the potting body (5) and, if present, the metal plate (54) are each aligned with one another and each have a continuous cutout through which the pressure introduction element (68) projects.

8. The power semiconductor module according to any one of claims 1 to 2, wherein: The surface of the potting body (5) facing away from the substrate (2) has a contour element (50).

9. The power semiconductor module according to any one of claims 1 to 2, comprising a metal plate, wherein: The surface of the metal plate (54) facing the substrate (2) has a profile element (50).

10. The power semiconductor module according to claim 8, wherein: One of the profile elements (50) is arranged in a manner aligned with the power semiconductor component (3) in a normal direction (N) relative to the substrate (2).

11. The power semiconductor module according to claim 8, wherein: The contour elements (50) are embodied in a knob-like manner.

12. The power semiconductor module according to any one of claims 1 to 2, wherein: The spring element (66) has a finger with a finger contact area.

13. The power semiconductor module according to claim 12, wherein: The finger contact area is aligned in the normal direction (N) with a midpoint of a power semiconductor component (3) or with a group of two or three power semiconductor components (3).

14. A method for producing a power semiconductor module (1) according to any of the preceding claims, comprising the following working steps, in particular in the order abcdef or abdcef: a. implementing a substrate (2) having a power semiconductor component (3), wherein the power semiconductor component (3) is arranged on one of the substrate conductor tracks (22) and is connected to the one substrate conductor track (22); b. Arrange the connection device (4); c. arranging the external terminal elements (70, 72, 74, 76) on the prefabricated housing (8) or connecting the external terminal elements (70, 72, 74, 76) to the prefabricated housing (8) in a form-locking manner; d. arranging the base (2) including the connecting device (4) in the prefabricated housing (8); e. connecting the contact means of the external terminal elements (70, 72, 74, 76) to the assigned base conductor tracks (22); f. Covering the entire connection device (4) with a potting compound (500), which forms the potting body (5) when solidified.

15. The method according to claim 14, wherein: After the last method step f), the spring device ( 6 ) is arranged.

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