Power semiconductor module comprising potting body and production method

Abstract

The invention provides 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 a substrate conductor trace arranged thereon, a power semiconductor component arranged on the substrate, a connecting device, an external terminal element, a potting body and a pressure device, the power semiconductor component is arranged on one of the base conductor traces, the connection device is 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, the external terminal elements each have a contact device in contact with an assigned substrate conductor trace, and the potting body completely covers the entire connection device and encloses the substrate and also the external terminal elements, in addition to the external contact portion, the pressure device is designed to exert pressure directly on the potting body by means of a spring element.

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 connection means, comprising external terminal elements, comprising a potting body and comprising pressure means. Background Art

[0002] DE 10 2013 104 949 B3 discloses a switch device, which comprises a substrate, a power semiconductor component, a connection 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 the conductor track. The connection 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 switch 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 known power semiconductor modules and of specifying a method for producing such a power semiconductor module.

[0005] According to the present 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, an external terminal element, a potting body and a pressure device, 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 conductively connected to the one base conductor track, wherein the connecting device is implemented as a film stack, the film stack comprises a first conductive film, a second conductive film and an electrically insulating film arranged between the first conductive film and the second conductive film, wherein the external terminal elements each have a contact device for contacting the assigned base conductor track, wherein the potting body completely covers the entire connecting device and encapsulates the substrate and also the external terminal elements, except for the external contact parts, and wherein the pressure device is implemented to apply pressure on the potting body directly by a spring element or only indirectly by a metal plate.

[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 preferably has an elastic modulus which is at least 10% lower, advantageously at least 20% lower.

[0011] It can 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, it can also be advantageous if the finger contact region is aligned in the normal direction with the power semiconductor component or with the midpoint 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 abcd or abdc: 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 external terminal elements and connecting the contact means of these external terminal elements to the assigned base conductor tracks; d. Covering and encapsulating the entire connection device, the substrate and also the external terminal elements, except for the external contact portions, with a potting compound which, when cured, embodies 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 mentioned in the singular (eg power semiconductor components) may appear multiple times, unless explicitly excluded or inherently excluded or contradict the concept of the present invention.

[0018] It goes without saying that the various configurations of the invention, whether they are mentioned in conjunction with a power semiconductor module or with the method, 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 invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further explanation, advantageous details and features of the present invention will be described below. Figures 1 to 6 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] Figure 2 A cross section through a first configuration of a power semiconductor module according to the invention is shown.

[0022] Figure 3 A second configuration of a power semiconductor module according to the invention is shown.

[0023] Figure 4 and Figure 5 A three-dimensional view of a power semiconductor module according to the invention is shown.

[0024] Figure 6 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. The 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 in a materially bonded and electrically conductive manner on one of these base conductor tracks 22.

[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 external terminal elements 70, 72, here two DC voltage terminal elements thereof, 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 that can be contacted from the normal direction N; see also Figure 4 and Figure 5 .

[0028] Prior to the method step shown here, the external terminal elements 70, 72, more precisely their contact elements, were connected to the assigned base conductor track 22. The illustration now shows the beginning of covering the power semiconductor component 3, the connection device 4 and parts of the external terminal elements with a potting compound 500, see Figure 2 .

[0029] Figure 2 A cross section of a first configuration of a power semiconductor module 1 according to the invention arranged on a cooling device 9 (here a liquid cooling device) is shown. The original potting compound 500 in the solidified state is now embodied as a potting body 5 composed of epoxy resin, which has an elastic modulus of 3500 MPa and a CTE value of 5 ppm / K.

[0030] The illustration also shows a pressure device 6 comprising a spring element 60 which exerts pressure directly (i.e. immediately adjacent) on the potting body 5, here more precisely on two pimple-shaped profile elements 50 which protrude in the normal direction N and are implemented integrally with the rest of the potting body, and thus establishes a thermally conductive connection between the power semiconductor component 3 and the cooling device 9. As a simplification, a metal base plate can also be provided here instead of a specific cooling device 9.

[0031] Figure 3 A second configuration of a power semiconductor module 1 according to the invention is shown, wherein the potting body 5 here additionally has a metal plate 54, which faces the spring element 62 of the pressure device 6. The metal plate 54 serves to better distribute the pressure on the potting body 5, which originally has the same specifications as above.

[0032] The potting body 5 and also the pressure device have two cutouts, each aligned in a normal direction N, through which a screw extends as a pressure introduction body 68, respectively. The screw 68 further extends through two connecting elements 700, 740 and through two external terminal elements 72, 76 therein, more precisely through external load terminal elements, and finds an abutment 90 in the cooling device 9. In this case, a further molded insulating body 78 is arranged for electrically insulating the screw 68. As an example, the connecting elements 700, 720, 760 are connected to an electric motor or a battery.

[0033] Figure 4 and Figure 5 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.

[0034] Compared to the potting body 5 of the first construction, the potting body 5 of this construction has an intermediate potting body 52, which directly covers the connecting device 4 and therefore also covers the power semiconductor component, and the intermediate potting body 52 has an elastic modulus that is 20% lower than the elastic modulus of the rest of the potting body 5 and, in addition, is also implemented as epoxy resin.

[0035] Figure 4 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.

[0036] Figure 5 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.

[0037] The corresponding accessible contact areas of the external terminal elements 70 , 72 , 74 , 76 are shown in a shaded manner.

[0038] Figure 6 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.

[0039] The spring element 66 of the pressure device 6 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 the group of power semiconductor components.

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 external terminal elements (70, 72, 74, 76), comprising a potting body (5) and comprising a pressure device (6), 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). wherein the external terminal elements (70, 72, 74, 76) each have contact means for contacting the assigned base conductor track (22), wherein the potting body (5) completely covers the entire connecting device (4) and encapsulates the substrate (2) and also the external terminal elements (70, 72, 74, 76), except for the external contact portions, and The pressure device (6) is designed to exert pressure on the potting body (5) directly via spring elements (60, 62, 64, 66), or to exert pressure on the potting body (5) only indirectly via a metal plate (54).

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

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 preferably, the intermediate potting body (52) 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) and the connecting device (4), and if present, also 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 abcd or abdc: 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. Arranging the connecting device (4); c. arranging the external terminal elements (70, 72, 74, 76) and connecting the contact means of these external terminal elements (70, 72, 74, 76) to the assigned base conductor tracks (22); d. Covering and encapsulating the entire connection device (4), the substrate (2) and the external terminal elements (70, 72, 74, 76) with a potting compound (500), except for the external contact parts, the potting compound (500) is embodied as the potting body (5) when cured.

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

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