Power semiconductor module, Inverter

Abstract

Power semiconductor module (1) comprising at least one substrate (3) with a lower side (7) and an upper side (8) and a plurality of power semiconductor components (2) arranged on the upper side (8) of the substrate (3), wherein the plurality of power semiconductor components (2) and at least a part of the upper side (8) of the substrate (3) are embedded in a plastic housing (9), wherein the power semiconductor module (2) further comprises a stiffening structure (12, 13, 14) which extends in or on the plastic housing (9) in a main plane (20) which is parallel to the substrate (3) and extends over the cross-sectional area of ​​the plastic housing (9).

Description

[0001] The present invention relates to a power semiconductor module comprising at least one substrate with a lower side and an upper side and a plurality of power semiconductor components arranged on the upper side of the substrate, wherein the power semiconductor module has a plastic housing. Furthermore, the invention relates to an inverter comprising the aforementioned module.

[0002] Power semiconductor modules are subject to significant temperature fluctuations both during manufacturing and during operation. During normal operation, semiconductor components in a power semiconductor module, such as an inverter module, experience high losses. The heat generated during operation is primarily dissipated via the substrate and adjacent cooling structures, such as a liquid cooler.

[0003] As a result, different parts of the power semiconductor module heat up differently. Due to different materials and therefore different thermal expansion coefficients, different parts of the power semiconductor module also react differently to a temperature increase. As a result, warping and distortion can occur. Warping of the module can damage electrical contacts and can also compromise the sealing of the plastic housing against external influences, especially moisture.

[0004] In addition, warpage can disrupt the close thermal contact between the substrate of a power semiconductor module and a cooling structure, thereby reducing cooling efficiency.

[0005] It is therefore an object of the present invention to provide a power semiconductor module with a reduced risk of warpage during manufacture and operation.

[0006] This object is achieved by means of the power semiconductor module according to claim 1.

[0007] Advantageous embodiments and further developments are the subject of the dependent claims.

[0008] According to one aspect of the invention, a power semiconductor module is provided, comprising at least one substrate having a lower side and an upper side, and a plurality of power semiconductor components arranged on the upper side of the substrate. The plurality of power semiconductor components and at least a portion of the upper side of the substrate are embedded in a plastic housing. The power semiconductor module further comprises a stiffening structure extending in or on the plastic housing in a main plane parallel to the substrate and extending across the cross-sectional area of ​​the plastic housing.

[0009] The stiffening structure provides the plastic housing with sufficient rigidity to withstand thermal stresses and substantially prevent warpage of the package. To achieve this, the stiffening structure extends in or on the plastic housing in a principal plane parallel to the substrate. This means that the stiffening structure extends substantially in one plane, and that this plane is parallel to the plane of the substrate. Elements of the stiffening structure may protrude from the plane. The stiffening structure is not necessarily planar; it may have curved sections or a bent edge region.

[0010] The stiffening structure extending across the cross-sectional area of ​​the plastic housing is understood to mean that the stiffening structure extends substantially across the entire cross-sectional area, i.e., a major portion of approximately at least 70 percent, preferably at least 80 percent, of the plastic housing, which may be substantially identical to the footprint of the substrate. Therefore, the stiffening structure extends across the entire area relevant to the occurrence of warpage and is capable of preventing warpage.

[0011] The plastic housing can be solid and completely covers the upper side of the substrate and the power semiconductor components arranged on the upper side of the substrate.

[0012] According to one aspect of the invention, the power semiconductor module is an inverter module, and the plurality of power semiconductor components comprises at least one high-side semiconductor switch and at least one low-side semiconductor switch. The semiconductor switches can, in particular, be SiC MOSFETs. This semiconductor module can be suitable for use in an electrically powered vehicle, in particular for supplying voltage to the electric motor.

[0013] This type of power semiconductor module is subject to particularly high thermal stresses due to high losses. The risk of warping is therefore relatively high. At the same time, warping has a particularly detrimental effect, as it prevents effective cooling of the module. The power semiconductor module according to the invention has the advantage that warping can be prevented or significantly reduced by the stiffening structure.

[0014] The stiffening structure can be made of metal, for example, copper. Alternatively, or in combination, it can be made of fiberglass and / or carbon. A stiffening structure formed essentially of metal has the advantage of being able to provide both electromagnetic shielding and stiffening. This can be important for applications where electromagnetic interference due to fast-switching components should be minimized.

[0015] In particular, the stiffening structure can be a copper grid or a mesh made of fiberglass or carbon. The stiffening structure can, in particular, have a thickness of a fraction of a millimeter, e.g., 0.1 or 0.2 millimeters.

[0016] According to one embodiment of the invention, the stiffening structure is attached to the upper side of the plastic housing, for example, using an adhesive layer. According to this embodiment, the stiffening structure can be a metal plate or a metal grid arranged on the upper side of the housing after the molding process. This has the advantage that the arrangement of the stiffening structure is particularly simple.

[0017] According to one embodiment of the invention, the stiffening structure is attached to the upper side of the substrate. According to this embodiment, the stiffening structure has an edge portion that protrudes from the main plane and extends toward the substrate. The stiffening structure can be attached to the upper side of the substrate using a fastening structure. Alternatively, the stiffening structure can be attached to the upper side of the substrate using an adhesive.

[0018] If the stiffening structure is formed from a metal, an electrically insulating layer may be arranged between the upper side of the substrate and the stiffening structure.

[0019] According to an alternative embodiment of the invention, the stiffening structure is arranged in a floating manner within the plastic housing. According to this embodiment, the stiffening structure is not attached to the substrate or the semiconductor components, but is completely embedded in and surrounded by the plastic material. During the molding process, the stiffening structure is held in position by the mold.

[0020] The substrate can, in particular, be a ceramic substrate, for example, a DCB (Direct Copper Bonded) substrate. A ceramic substrate is particularly well suited for applications where significant heat is generated and needs to be dissipated. Typically, heat is dissipated from the semiconductor components into the layers of the substrate and absorbed by a cooling structure arranged in thermal contact with the underside of the substrate.

[0021] According to one embodiment of the invention, the plastic housing can be formed by molding or overmolding plastic on the upper side of the substrate.

[0022] According to a further aspect of the invention, an inverter is provided, comprising: - at least one power semiconductor module as described above, wherein the power semiconductor components are designed as semiconductor switching elements, and - a control circuit for controlling the at least one power semiconductor module, wherein the control circuit is connected to the power semiconductor components by signal connections.

[0023] Further advantages, advantageous embodiments and the further development of the power semiconductor module will be apparent from the embodiments described below in conjunction with the schematic figures. Fig. 1 shows a cross-sectional view of a power semiconductor module according to a first embodiment of the invention, Fig. 2 shows a cross-sectional view of a power semiconductor module according to a second embodiment of the invention, Fig. 3 shows a cross-sectional view of a power semiconductor module according to a third embodiment of the invention, Fig. 4 shows a perspective view of the power semiconductor module according to Fig. 1, and Fig. 5 shows a detail of the power semiconductor module according to the first embodiment.

[0024] Fig. 1 shows a power semiconductor module 1 comprising a plurality of power semiconductor components 2. The power semiconductor components 2 can, in particular, be SiC MOSFETs arranged to function as high-side and low-side switches of an inverter.

[0025] The power semiconductor components 2 are arranged on a substrate 3. The substrate 3 is a DCB substrate and has at least one layer 4 made of copper, a ceramic layer 5, and a second layer 6 made of copper, wherein the ceramic layer 5 is arranged between the two layers 4, 6 made of copper.

[0026] The substrate 3 has a lower side 7, which largely forms the lower side 10 of the power semiconductor module 1, and an upper side 8, on which the power semiconductor components 2 are arranged.

[0027] A plastic housing 9 is arranged on the upper side 8 of the substrate 3, into which the power semiconductor components 2 and the upper side 8, and even an edge portion of the substrate 3, are embedded. The lower side 7 of the substrate 3 is exposed and not covered by the plastic housing 9. Therefore, the lower side 7 of the substrate 3 can be brought into contact with a cooling structure. The plastic housing 9 has an upper side 11, which forms an upper side of the power semiconductor module 1.

[0028] A stiffening structure 12 is arranged within the plastic housing 9. The stiffening structure 12 according to this embodiment is formed from a metal grid and arranged on the upper side 8 of the substrate 3 above the semiconductor components 2. The stiffening structure 12 thus extends largely in a plane 20 that is parallel to the substrate 3 and is bent at the edges to come into contact with the upper side 8 of the substrate 3.

[0029] The stiffening structure 12 is arranged on the substrate 3 prior to the molding process and is embedded in the plastic material. The stiffening structure 12 prevents warping of the power semiconductor module 1. It also provides electromagnetic shielding for the power semiconductor components 2.

[0030] Fig. 2 shows a second embodiment of the power semiconductor module 1. This embodiment differs from that shown in Fig. 1 regarding the shape of the stiffening structure 13. According to the second embodiment, the stiffening structure 13 is a planar structure, for example, a planar metal sheet or a planar metal mesh, which is arranged in a floating manner within the material of the plastic housing 9. Therefore, it is not in contact with the substrate 3, but is completely embedded in the plastic material. During manufacturing, the stiffening structure 13 can be held in position by a mold or a support structure that is removed during the molding process.

[0031] According to an embodiment not shown in the figures, the stiffening structure 13 has a planar structure, as in Fig. 2. However, according to this embodiment, the planar structure is not arranged floating in the plastic housing 9, but is supported by plastic pins arranged on the upper side 8 of the substrate 3, which provide mechanical support for the planar structure but at the same time provide electrical insulation from the substrate 3.

[0032] Fig. 3 shows a third embodiment of the power semiconductor module 1, which again differs with respect to the shape and arrangement of the stiffening structure 14. According to the third embodiment, the stiffening structure 14 is a planar structure, for example, a planar metal sheet or a planar metal grid, which is arranged on the upper side 11 of the plastic housing 9 using an adhesive layer 15.

[0033] Fig. 4 shows a perspective view of the power semiconductor module 1 according to Fig. 1. The perspective view shows the lattice structure of the stiffening structure 12. At the edges, sections of the stiffening structure 12 are bent from the plane 20 of the stiffening structure 12 toward the substrate 3. The stiffening structure 12 is attached to the substrate 3 in contact areas 16.

[0034] Fig. 5 shows a detailed view of a contact region 16. In the contact region 16, the stiffening structure 12 is attached to the substrate 3 by means of an insulation layer 17. List of reference symbols 1 power module 2 power semiconductor chips 3 Substrat 4 layer 5 layer 6 layer 7 bottom side 8 upper side 9 plastic housing 10 bottom page 11 top page 12 Stiffening structure 13 Stiffening structure 14 Stiffening structure 15 Adhesive layer 16 Contact area 17 Isolation 20 levels

Claims

[1] Power semiconductor module (1) comprising at least one substrate (3) with a lower side (7) and an upper side (8) and a plurality of power semiconductor components (2) arranged on the upper side (8) of the substrate (3), wherein the plurality of power semiconductor components (2) and at least a part of the upper side (8) of the substrate (3) are embedded in a plastic housing (9), wherein the power semiconductor module (2) further comprises a stiffening structure (12, 13, 14) which extends in or on the plastic housing (9) in a main plane (20) which is parallel to the substrate (3) and extends over the cross-sectional area of the plastic housing (9). [2] Power semiconductor module (1) according to claim 1, wherein the power semiconductor module (1) is an inverter module and the plurality of power semiconductor components (2) comprises at least one high-side semiconductor switch and at least one low-side semiconductor switch. [3] Power semiconductor module (1) according to claim 1 or 2, wherein the stiffening structure (12, 13, 14) is formed from metal. [4] Power semiconductor module (1) according to one of claims 1 to 3, wherein the stiffening structure (12, 13, 14) is formed from glass fiber. [5] Power semiconductor module (1) according to one of claims 1 to 4, wherein the stiffening structure (12, 13, 14) is formed from carbon. [6] Power semiconductor module (1) according to one of claims 1 to 5, wherein the stiffening structure (14) is attached to the upper side (11) of the plastic housing (9). [7] Power semiconductor module (1) according to one of claims 1 to 6, wherein the stiffening structure (12) is attached to the upper side (8) of the substrate (3). [8] Power semiconductor module (1) according to claim 7, wherein an insulation layer (17) is arranged between the upper side (8) of the substrate (3) and the stiffening structure (12). [9] Power semiconductor module (1) according to one of claims 1 to 5, wherein the stiffening structure (13) is arranged floating in the plastic housing (9). [10] Power semiconductor module (1) according to one of claims 1 to 9, wherein the substrate (3) is a ceramic substrate. [11] Power semiconductor module (1) according to one of claims 1 to 10, wherein the plastic housing (9) is formed by molding or overmolding plastic on the upper side (8) of the substrate (3). [12] Power semiconductor module (1) according to one of claims 1 to 11, wherein the lower side (10) of the power semiconductor module (1) is in contact with a cooling structure. [13] Inverter, comprising: - at least one power semiconductor module (1) according to one of claims 1 to 12, wherein the power semiconductor components (2) are designed as semiconductor switching elements, - a control circuit for controlling the at least one power semiconductor module (1), wherein the control circuit is connected to the power semiconductor components (2) by signal connections.

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