Method for manufacturing a power module and power module

Abstract

The invention relates to a method for manufacturing a power module (100), wherein the power module (100) comprises several components (3), wherein at least one component (3) is a substrate (5) with at least one power semiconductor (10), wherein the components (3) are fixed on a carrier (1) and electrical connections are made between the components (3), wherein the power module (100) is then at least partially enclosed with an insulating material (13) and the carrier (1) is then removed, and a power module (100).

Description

[0001] The invention relates to a method for manufacturing a power module and a power module.

[0002] Power modules typically feature a substrate on which at least one power semiconductor is mounted. The substrate includes at least one insulating layer and a structured metallization onto which the power semiconductor is deposited. Depending on the power class of the semiconductor, the substrate is either a printed circuit board or a ceramic with metallization (e.g., DCB, AMB, IMS). The power module also features load connections, which are, for example, designed as leadframes. These load connections are also located on the substrate. The electrical connection between the load connections and the power semiconductors can be established via the structured metallization, bond wires, bond tapes, and / or leadframes. Often, the substrate has an additional metallization on its underside, allowing the power module to be thermally coupled to a heat sink.

[0003] Substrates with a ceramic insulating layer are particularly expensive. Another problem is that the ceramic is relatively brittle, making the production of larger ceramic surfaces complex.

[0004] From US patent 2019 / 0189553 A1, it is known to pot several power modules simultaneously with a potting compound, whereby these are arranged on a common carrier which is removed after potting.

[0005] Methods for manufacturing a power module are known from US 2023 / 0 170 287 A1, US 2015 / 0 076 672 A1 and US 2021 / 0 005 557 A1, wherein the power module has several components, wherein at least one component is a substrate with at least one power semiconductor, wherein the components are fixed onto a support and electrical connections are made between the components, wherein the power module is then at least partially encased with an insulating material and the support is then removed.

[0006] The invention is based on the technical problem of providing a method for manufacturing a power module, by means of which a power module can be manufactured cost-effectively, and of creating a corresponding power module.

[0007] The solution to the technical problem is achieved by a method having the features of claim 1 and a power module having the features of claim 7. Further advantageous embodiments of the invention are set forth in the dependent claims.

[0008] A method for manufacturing a power module is proposed, wherein the power module comprises several components, at least one of which is a substrate with at least one power semiconductor. The components are fixed to a substrate, and electrical connections are established between them. This means that at least one component is not located on the substrate of the at least one other component. Subsequently, the power module is at least partially encased with an insulating material (using a potting compound or a transfer mold), and then the substrate is removed. The substrate can be removed in such a way that it is not damaged and can be reused. However, it is also possible for the substrate to be destroyed during removal. The proposed method has several advantages.By using individual components, the substrate area is reduced and used only for the components that require such insulation. This allows for the use of several smaller substrates, which together are less expensive and more reliable than a single large substrate. The individual components can be tested separately and assembled modularly into various power modules. Another advantage is the ability to achieve a more compact design, as the distances between different structures on the metallization are typically quite large (dictated by design rules). This will be explained in more detail later.

[0009] Furthermore, at least one auxiliary support is arranged on the carrier, with at least one component being arranged on the auxiliary support. The auxiliary support allows the component to be positioned higher, thus shortening contact paths, for example. Additionally, the auxiliary support can also serve as insulation material.

[0010] In this process, the auxiliary support is removed along with the carrier, allowing cavities to be created in the insulating material in a targeted manner, for example to connect the power module to other components.

[0011] The components can be fixed to the carrier in various ways.

[0012] In one embodiment, the components are clamped onto the carrier. For example, they are pressed against the carrier from above by a punch.

[0013] In an alternative embodiment, the components are glued to the carrier. For this purpose, the carrier is designed, for example, as an adhesive film.

[0014] In one embodiment, at least one additional auxiliary support remains in the power module after the support has been removed.

[0015] In one embodiment, the power module has at least two substrates, each with at least one power semiconductor arranged on it. Preferably, the substrates have a ceramic as an insulating layer.

[0016] In another embodiment, at least one component is a printed circuit board, wherein, for example, sensors or gate drivers are arranged on the printed circuit board.

[0017] The power module comprises several components, wherein at least one component is a substrate with at least one power semiconductor and the power module is at least partially enclosed with an insulating material, wherein the several components are each individually arranged in the insulating material, wherein there is at least one cavity in the insulating material.

[0018] Regarding further details, reference is made to the preceding explanations.

[0019] The invention is explained in more detail below with reference to a preferred embodiment. The figures show: Fig. 1 a schematic representation of a support with an auxiliary support, Fig. 2 a schematic representation of the carrier with first components without power semiconductors, Fig. 3 a schematic representation of the carrier with first components with power semiconductors, Fig. 4 a schematic representation of the carrier with electrical connections, Fig. 5 a schematic representation of the support with load connections, Fig. 6 a schematic representation of the cast power module on the carrier and Fig. 7 A schematic representation of the power module after removal of the carrier.

[0020] Based on the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. Section 7 will now explain the procedure for manufacturing a power module. This involves... Fig. Figure 1 shows a support 1 on which an auxiliary support 2 is arranged. The auxiliary support 2 can be made of the same material as the support 1 or of a different material, which will be explained in more detail later. For example, the support 1 may have an adhesive surface so that the auxiliary support 2 sticks to the support 1. In the Fig. Figure 2 shows how components 3, or parts of components, are mounted on the carrier 1 or the auxiliary carrier 2. The components 3 are leadframes 4, substrates 5, and a printed circuit board 6. One leadframe 4 is arranged on the auxiliary carrier 2. Preferably, the other leadframe 4 is also arranged on an auxiliary carrier 2, which will be explained later. The substrates 5 have an insulating layer 7, which is made of ceramic. A structured metallization 8 is arranged on the upper side of the insulating layer 7, and another metallization 9 is arranged on the lower side of the insulating layer 7. The substrates 5 and also the left leadframe 4 can be considered subcomponents, since elements are still mounted on them. For example, power semiconductors 10 are mounted on the metallizations 8 of the substrates 5 (see Figure 2). Fig. 3) However, the power semiconductors 10 can also be applied to the substrates 5 beforehand, so that the substrates 5 with power semiconductors 10 are placed on the carrier 1.

[0021] In the Fig. Figure 4 now shows how electrical connections between the components 3 are made using bond wires 11, whereby load terminals 12 are subsequently connected to one leadframe 4 and one metallization 8 of the substrate 3. The load terminals 12 can also be designed as leadframes. The application of the load terminals can also be reversed in the sequence of making the electrical connection using the bond wires 11. Likewise, the load terminal 12 with the leadframe 4 can be applied to the carrier 1 as a prefabricated component 3. Now, let's consider... Fig. 5, thus one can recognize four separate components 3, namely the leadframe 4 with the load connection 12, the two substrates 5 with the power semiconductors 10 as well as the load connection 12 and the leadframe 4 on the sub-carrier 2.

[0022] In a next step, the power module 100 with its individual components 3 is partially encased with an insulating material 13 (e.g., potted using a potting compound or molded using a transfer mold). For example, the insulating material 13 is a silicone gel as a potting compound, or the transfer mold is an epoxy resin with which the power module 100 is overmolded, which in Fig. Figure 6 is shown. After the insulating material 13 has hardened, the support 1 is removed, leaving the auxiliary support 2 in the performance module 100, which is shown in Fig.Figure 7 shows that the metallizations 9 are once again freely accessible and can be used for thermal connection to a heat sink. In the example shown, the left leadframe 4 is uninsulated, so an auxiliary support 2 can preferably be provided here to ensure insulation. Furthermore, the auxiliary supports 2 allow the respective connection height of the leadframes 4 to be adjusted, thus optimizing connection paths, for example, for the bond wires 11. The power module 100 does not require a large substrate 5 but can be built modularly from several smaller substrates 5. The material of the auxiliary support 2 can be selected so that it melts at the potting process temperatures and thus forms a strong bond with the insulating material 13, so that it remains in the power module 100 when the support 1 is removed.For example, the auxiliary support 2 is made of the material of the insulation material 13. Reference symbol list 1 carrier 2 auxiliary carriers 3 components 4 Leadframe 5 Substrat 6 circuit board 7 Insulation layer 8 Metallization 9 Metallization 10 Power semiconductors 11 Bond wire 12 Load connection 13 Insulation material 100 power module

Claims

Method for manufacturing a power module (100), wherein the power module (100) comprises several components (3), wherein at least one component (3) is a substrate (5) with at least one power semiconductor (10), wherein the components (3) are fixed on a carrier (1) and electrical connections are made between the components (3), wherein the power module (100) is then at least partially encased with an insulating material (13) and the carrier (1) is subsequently removed, wherein at least one auxiliary carrier (2) is arranged on the carrier (1), wherein at least one component (3) is arranged on the at least one auxiliary carrier (2), wherein the at least one auxiliary carrier (2) is removed along with the carrier (1). Method according to claim 1, characterized in that the components (3) are clamped onto the carrier (1). Method according to claim 1, characterized in that the components (3) are glued onto the carrier (1). Method according to one of the preceding claims, characterized in that at least one further auxiliary carrier (2) remains in the power module (100) when the carrier (1) is removed. Method according to one of the preceding claims, characterized in that the power module (100) has several substrates (5) on which at least one power semiconductor (10) is arranged. Method according to one of the preceding claims, characterized in that at least one component (3) is a printed circuit board (6). Power module (100) comprising several components (3), wherein at least one component (3) is a substrate (5) with at least one power semiconductor (10) and the power module (100) is at least partially enclosed with an insulating material (13), wherein the several components (3) are each individually arranged in the insulating material (13), wherein the insulating material (13) has at least one cavity.

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