Housings for power electronics and methods for manufacturing such housings

Abstract

Method for manufacturing a housing (1) for power electronics consisting of at least one circuit board (2) and electronic or electrical components (3) comprising the following steps: - Incorporation of structures (6, 5, 4) for the production of cooling channels, - Overmolding the circuit board (2) with a material (11) of a lost layer, - Overmolding the structures (6, 5, 4) with plastic

Description

[0001] The invention relates to a method for producing a housing for power electronics comprising at least one circuit board and electronic or electrical components, comprising the following steps: introducing structures for producing cooling channels and overmolding the structures with plastic.

[0002] Furthermore, the invention relates to a housing which is produced according to the method. State of the art

[0003] Power electronics is one of the three central components of every electric drivetrain in hybrid and electric vehicles. Its function in the vehicle is to control the electric motor, communicate with the vehicle control system, and diagnose the drive system.

[0004] Typically, the power electronics system consists of an electronic control unit, an inverter, and a DC / DC converter. The control unit is in constant contact with the vehicle's control system and receives the driver's instructions to be implemented, as well as a wealth of other important information from other control units. During operation, the inverter converts the battery's DC voltage into an AC voltage, which is used to control the electric motor. This process is reversed to charge the battery. The DC / DC converter can transform the DC voltage from the high-voltage storage system into a lower DC voltage, thus supplying the entire system.

[0005] Depending on the vehicle structure, housings are provided for the power electronics, which are designed as individual housings or as integrated housings.

[0006] DE 10 2015 214 788 A1 discloses a cooling structure for an electric compressor that has two cooling channel feedthroughs in the area of ​​the control unit. These serve to cool the rear side of the control unit, the side of the control unit facing away from the electric motor. This cools other highly stressed electronic components of the control unit.

[0007] The cooling structure is supplied with cooling fluid via a cooling fluid inlet and a cooling fluid outlet.

[0008] The method for producing the described electric compressor comprises producing the housing by means of a potting process, wherein the potting process is carried out in such a way that the cooling structure in the form of cooling channels is formed integrally with the housing in the housing.

[0009] The cooling structure is created by inserting molded bodies. The molded bodies for the cooling channels and the opening molded bodies are mechanically removed after the casting process.

[0010] JP H11-166 500 A describes an electric pump whose stator and electronic control system are completely encapsulated. Cooling channels are provided along the electronics.

[0011] DE 10 2017 003 854 A1 discloses a method for overmolding cooling channels. In this process, metallic tubes are attached to a shielding plate, and the entire metallic structure is then overmolded with plastic.

[0012] The object of the invention is to produce a housing for power electronics that allows optimal cooling with a simple structure. Description of the invention

[0013] The problem is solved by a method for producing a housing for power electronics consisting of at least one circuit board and electronic or electrical components with the following steps: - Insertion of structures for the production of cooling channels, - Overmolding the board with a lost layer material, - Overmolding the structures with plastic.

[0014] In an advantageous embodiment, the structures consist of webs that are overmolded with a material of a lost layer.

[0015] In this way, very large cooling volumes can be produced.

[0016] Advantageously, the design is such that the webs are not removable while the material of the lost layer is removed after overmolding.

[0017] In an alternative embodiment, the structures are selected such that the structures consist of cooling channel inserts made of a soluble material.

[0018] In a further alternative embodiment, it is advantageous that the structures consist of cooling channel inserts that represent finished channels.

[0019] In order to protect the circuit board from moisture, it is advantageous to insulate the circuit board before inserting the structures.

[0020] In order to expose the cooling channels, it is necessary that the material of the lost layer or the soluble material is released from the housing after the completion of the housing with a solvent or by introducing energy.

[0021] The object is further achieved by a housing for power electronics produced according to the method according to the invention. Description of the characters Fig. 1 shows a manufacturing state of the housing with webs, Fig. 2 shows a section through the embodiment according to Fig. 1, Fig. 3 shows an initial structure, Fig. 4 shows a cooling channel structure.

[0022] In Fig. 1 schematically shows a housing 1, which, in this embodiment, contains a single circuit board 2. However, the invention can also be applied to multiple circuit boards, which are jointly overmolded with a material to produce the housing 1. In this example, the circuit board 2 carries several components 3, which represent electronic or electrical components 3. The components 3 are parts of a power electronics system, such as those used for an inverter.

[0023] The circuit board has a top side 16 and a bottom side 17. Depending on the board's manufacturing process, the bottom side of the board may already be completely covered with an insulating plastic and does not necessarily need to be overmolded with a plastic to create the housing. Instead, the bottom side of the board forms the housing base.

[0024] Depending on the design, however, it may be necessary to cover the top or bottom, or both, with an insulating layer 9 before the plastic housing 1 can be formed. This insulating layer 9 can be applied, for example, using a dipping process and then covers the entire circuit board 2 and all components 3 installed thereon.

[0025] In the Fig. Figure 1 shows a first embodiment of the method according to the invention for producing the housing 1. Webs 6 are applied to the circuit board 2 and to the circuit board 2. In this exemplary embodiment, small cylindrical webs 6 can be seen along the x- and y-axes, which serve as spacers between the circuit board and the overmolding to be applied. Furthermore, an elongated web 6 is arranged along the x-axis in the center of the circuit board 2, which bridges a larger distance between the components 3. Furthermore, components 5 can be seen, which are hollow and serve as connections for a cooling fluid. The webs 6 and components 5 are made of a material that is stable and cannot be removed in the subsequent process. In a next process step, the circuit board is overmolded with the applied webs made of a material 11 as a lost layer. The material 11 surrounds all electronic components 3 as well as the webs 6 and components 5.The height of the webs in the z-direction is selected such that the material of the lost layer 11 does not completely surround the webs 6 in terms of height, so that the webs 6 can bond with the next layer, the material 12 of the overmolding. The material 12 of the overmolding is applied over the material of the lost layer 11. This material 12 of the overmolding bonds with the material 10 of the webs to form a solid housing. The material of the lost layer 11 is then removed. Removal is carried out either with a solvent or by introducing heat energy so that the material 11, the lost layer, melts out. In this embodiment, the small volume of the webs 6 with their material 10 creates large areas around the components 3 in which cooling liquid can be distributed along the surface 16 of the circuit board. This results in very efficient cooling of the electronic components 3.

[0026] The webs for producing the large cooling surfaces above the circuit board 2 can consist of individual components as shown in this embodiment or of prefabricated overall structures that are applied to the circuit board.

[0027] The aim is to keep the assembly effort as low as possible and not to have to install individual webs one by one.

[0028] While in this embodiment a structure of webs 6 is applied, which remain non-releasably between the circuit board 2 and the housing 1, in the embodiment according to the Fig. 3 and Fig. 4 shows an alternative solution.

[0029] In the alternative embodiment, a cooling channel insert 4 is manufactured separately. In a first variant, this is a plastic component that is completely formed as a lost mold. This component is mounted on the circuit board 2 and then overmolded with the overmold material 12. The cooling channel insert 4 is then completely removed with a solvent or melted out using heat.

[0030] In a second variant, the cooling channel insert 4 is manufactured as a hollow mold with cavities 15. The manufacturing process can be an injection molding process or a 3D printing process. Again, the cooling channel insert 4 is applied to the circuit board 2 and overmolded with the material 12 together with the circuit board 2. The cooling channels are then already present after overmolding, and no further step involving the release of lost material is necessary. List of reference symbols 1 housing 2 circuit boards 3 electronic, electrical components 4 cooling channel insert 5 Connection 6 bridges 9 insulating layer 10 material bars 11 Material lost layer 12 Material overmolding 15 cavity 16 Top 17 Subpage

Claims

[1] Method for producing a housing (1) for power electronics comprising at least one circuit board (2) and electronic or electrical components (3) with the following steps: - introducing structures (6, 5, 4) for producing cooling channels, - Overmolding the circuit board (2) with a material (11) of a lost layer, - Overmolding the structures (6, 5, 4) with plastic [2] Method for producing a housing (1) according to claim 1, characterized by that the structures consist of webs (6) which are overmolded with the material (11) of a lost layer. [3] Method for producing a housing (1) according to claim 2, characterized by that the webs (6) are not removable, while the material (11) of the lost layer is removed after overmolding with a material (12). [4] Method for producing a housing (1) according to claim 1, characterized bythat the structures consist of cooling channel inserts (4) made of a soluble material (11). [5] Method for producing a housing (1) according to claim 1, characterized by that the structures consist of cooling channel inserts (4) which represent finished channels. [6] Method for producing a housing (1) according to one of the preceding claims, characterized by that the circuit board (2) is provided with an insulating layer (9) before the structures are introduced. [7] Method for producing a housing (1) according to one of the preceding claims, characterized by that the material (11) of the lost layer or the soluble material is released from the housing (1) after completion of the housing (1) with a solvent or by introducing energy. [8] Housing (1) for power electronics, manufactured according to one of the preceding claims.

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