Method for producing a cooled power electronics module

Abstract

The present invention relates to a method for manufacturing a cooled power electronic module, the method comprising the following steps: providing a prefabricated module (14), the prefabricated module comprising a plate-shaped cooling channel cover (12) and at least one electronic component (10) connected in a material-bonded manner and in thermal contact with the lower side of the cooling channel cover (12), 3D printing a metal vortex finder structure (16) in a region of the upper side of the cooling channel cover (12) opposite the electronic component (10), and encapsulating the vortex finder structure (16) in a fluid guiding housing, the fluid guiding housing being provided with a fluid input end (181) and a fluid output end and being connected to the upper side of the cooling channel cover (12) in a fluid-tight manner.

Description

Technical Field

[0001] The invention relates to a method for producing a power electronics module, in particular for cooling a traction electric machine in a motor vehicle. Background Art

[0002] Such a cooled power electronics module is known from document DE 10 2016 222 909 A1.

[0003] The term “cooled” is not limited here to the currently cooled state; rather, it should mean that the module in question has means which allow cooling of the electronic components contained in the module to occur when a cooling fluid line system is conventionally connected.

[0004] The document mentioned describes the manufacture of a cooling body consisting of an electrically insulating outer shell and a highly thermally conductive core by means of 3D printing. The term "3D printing" in the context of the present invention is to be understood as an extension and synonym of the term "additive manufacturing method"; the term includes in particular methods such as laser sintering, laser beam melting, stereolithography, electron beam melting, multi-jet modeling or polyjet modeling. In the known method, a conductive layer is applied to the cooling body produced in this way, also by means of 3D printing, and then the electronic components, such as switching elements, are fixed to the conductive layer in a material connection in a thermal contact manner. This is disadvantageous because when fixing the electronic components (which is usually carried out by sintering under the application of large mechanical forces), there may be a risk of damaging the sensitive vortex finder structure, which is used for the thermal and flow-mechanical interaction of the cooling body with the cooling fluid flowing around the cooling body. Although this risk can be suppressed by a correspondingly stable shaping of the vortex finder structure; however, in order to optimize the cooling efficiency, it is more advantageous to select a very fine structure to interact with the cooling fluid flowing around the very fine structure.

[0005] Thus, for example, document ES 2 584 429 B1 discloses the design of a heat sink or vortex finder for electronic components as a three-dimensional Voronoi grid, without specifying how the heat sink or vortex finder and the electronic components can be brought into thermal and permanent mechanical contact with one another.

[0006] Document DE 10 2014 118 177 A1 discloses another example of a fine vortex finder structure, which is usually used for heat exchangers. Here, a metal foam produced by 3D printing is used, wherein the actual vortex finder and its base plate are produced in the same 3D printing process, and the base plate is then also used for the thermal and mechanical connection to the component to be cooled. In the case of power electronic modules that can theoretically be used for cooling, the problem arises that the vortex finder can be damaged during the sintering of the electronic components to be cooled. Summary of the invention

[0007] The object of the present invention is to provide a method which allows the production of cooled power electronics modules having a fine eddy finder structure while minimizing rejects.

[0008] This object is achieved according to the invention by a method for producing a cooled power electronics module, the method comprising the following steps:

[0009] - providing a prefabricated module comprising a plate-shaped cooling channel cover and at least one electronic component connected in a materially bonded manner and in thermal contact with the underside of the cooling channel cover,

[0010] - 3D printing a metallic vortex finder structure in the region of the upper side of the cooling channel cover opposite the electronic components, and

[0011] The vortex finder structure is encapsulated in a fluid-conducting housing, which is provided with a fluid inlet and a fluid outlet and is connected to the upper side of the cooling channel cover in a fluid-tight manner.

[0012] The core of the invention is a new sequence of method steps or a novel combination of individual components into several assemblies, for which the individual method steps are used. The core of the invention is to provide a component assembly, which is referred to here as a prefabricated module, which comprises, on the one hand, an electronic component to be cooled and, on the other hand, a part of a cooling device, i.e., in particular a plate-shaped cooling channel cover. The cooling channel cover is a component of a cooling channel contained in a finished power electronic module, through which a cooling fluid can flow in a suitable conventional connection with a cooling fluid line system and can indirectly interact thermally with the electronic component to be cooled. The thermal interaction takes place through the aforementioned cooling channel cover. The electronic component to be cooled is fixed on the lower side of the cooling channel cover; the vortex finder structure is arranged on the upper side of the cooling channel cover in order to improve the efficiency of the thermal interaction in the finished power electronic module, in particular fixed in thermal contact on the mentioned upper side. A person skilled in the art will understand that the terms "upper" side and "lower" side are used here only to distinguish between the two main surfaces of the cooling channel cover, without any restriction on a particular spatial orientation.

[0013] According to the invention, firstly a prefabricated module is provided with a cooling channel cover and electronic components already fixed thereto. Such a prefabricated module can be produced, for example, by sintering the electronic components, without having to take into account any elaborate structures. Accordingly, the production process can be carried out quickly, inexpensively and in a stable production environment; only the temperature and force limit values ​​predetermined by the properties of the electronic components must be observed.

[0014] The fine vortex finder structure is then produced on site by means of 3D printing. The vortex finder structure can be designed as finely as desired, since due to the sequence of method steps according to the invention there is no longer any threat of mechanical damage.

[0015] Finally, the vortex finder structure is encapsulated in a fluid guide housing, which together with the cooling channel cover forms a cooling channel, which itself can be connected to a cooling fluid guide system. To this end, the fluid guide housing must obviously have at least one cooling fluid input and at least one cooling fluid output, but their position, shape and number are freely designed by the skilled person according to the requirements of the individual case.

[0016] The method according to the invention thus provides a cooled power electronics module in which, despite the possibility of producing the finest eddy finder structures, the incidence of rejects is particularly low, since the sensitive structures are only created after all method steps that subject the structures to mechanical stress have been carried out. The method according to the invention therefore has clear economic advantages over known methods.

[0017] Two preferred variants are particularly suitable for the step of encapsulating the vortex finder structure. In the first variant, it is provided that the encapsulation of the vortex finder structure is achieved by connecting the housing, which is constructed as a sheet metal forming part and provides a dome for the vortex finder structure, to the upper side of the cooling channel cover by material bonding. For example, the material bonding connection can be achieved by laser welding or laser brazing. In this variant, the fluid guiding housing and thus the fluid channel are formed by the mentioned housing and the aforementioned cooling channel cover. Both can be constructed as sheet metal forming parts, which allows fast, cheap and stable manufacturing or connection. However, it should be noted that when connecting the housing and the cooling channel cover, the thermal tolerance limit of the electronic components cannot be exceeded. Here, laser welding and laser brazing, which only introduce heat very locally, are just the preferred technologies. On the contrary, due to the associated thermal load of the electronic components, the brazing in the brazing furnace, which is also conceivable in principle, is less attractive.

[0018] According to the second variant which is also preferred, the encapsulation of the vortex finder structure is achieved by 3D printing an outer cover layer, which is closed except for the fluid input end and the fluid output end. This can be carried out in particular and preferably in the same working process as the 3D printing vortex finder structure itself. In other words, in this variant, the internal vortex finder structure and the external outer cover layer are jointly established on the upper side of the cooling channel cover by means of 3D printing. Although this variant is more time-consuming than the first method variant mentioned above. For this reason, compared with the effect that can be achieved by placing a preformed shell, a better fit between the vortex finder structure and the outer cover layer can be achieved, so that the module is generally built smaller.

[0019] Preferably, the cooling channel cover is configured as a flat sheet metal part. Accordingly, the housing or outer cover layer that provides a dome for the vortex finder structure must be designed in the shape of a basin. However, the opposite arrangement is also conceivable, in which the cooling channel cover is configured as a molded sheet metal part, having a basin-shaped depression on the upper side of the sheet metal part and a corresponding protrusion on the lower side of the sheet metal part, wherein the vortex finder structure is printed on the bottom of the basin-shaped depression. In the case of appropriate relative dimensioning of the basin and the vortex finder structure, the housing or outer cover layer can be designed in the form of a flat sheet metal part. However, it is obviously also possible to design the upper side of the cooling channel cover and the housing or outer cover layer (on the contrary) in a basin-shaped manner.

[0020] Regarding the specific design of the vortex finder structure, it is preferably provided that the vortex finder structure is constructed as a three-dimensional Voronoi grid formed by metal tabs. In this case, a bionic structure is also discussed, which imitates the nodules (Taberkel) in the bone tissue of vertebrates. The structure provides a particularly favorable relationship between a large total pore volume, a high stability and a large surface, thereby forming a stable structure, through which the cooling fluid can flow with particularly low flow resistance but with effective heat exchange. The tabs of this Voronoi grid are preferably widened in the direction of their ends in order to avoid sharp corners that increase the flow resistance. For the same reason, the tabs are preferably rounded and / or arc-shaped. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further details and advantages of the present invention are obtained from the following detailed description and the accompanying drawings. In the drawings:

[0022] Figure 1 A first method step for producing a prefabricated module according to the invention is shown;

[0023] Figure 2 Showing a prefabricated module according to the present invention;

[0024] Figure 3 Shown for Figure 2 A second method step of printing a vortex finder structure on a prefabricated module;

[0025] Figure 4 showing a third method step of placing a housing that domes the vortex finder structure; and

[0026] Figure 5 Shown is a method for connecting the housing to Figure 4 In a fourth method step, the prefabricated modules are connected by laser welding or laser brazing.

[0027] The same reference numbers in the drawings identify the same or similar elements. DETAILED DESCRIPTION

[0028] Figure 1 The schematic diagram shows the thermal and mechanical connection of the electronic component 10 to the cooling channel cover 12 which is designed as a flat plate. The details of the electronic component 10 are not important in the context of the present invention. However, it can be a switching element of a power electronics device for the operation of a traction machine of a motor vehicle. Preferably, the electronic component 10 is Figure 1 The upper side shown pointing upward in FIG. 1 has a sinterable coating which is sintered with a corresponding material on the underside of the cooling channel cover 12 in order to thereby produce a tight, material-bonded thermal and mechanical connection. Figure 2 The prefabricated module 14 is schematically shown in FIG.

[0029] Next, in Figure 3 In the method step shown, a vortex finder structure 16 is applied by means of 3D printing to the upper side of the cooling channel cover 12. The vortex finder structure 16 can be, in particular, a bionic structure, in particular a three-dimensional Voronoi grid.

[0030] Next, in Figure 4 In the method step shown, the vortex finder structure 16 is encapsulated. This is achieved in the embodiment shown in that a housing 18 is arranged, which is designed as a sheet metal formed part and which provides a dome for the vortex finder structure 16. The housing 18 has at least one fluid inlet and at least one fluid outlet. In the embodiment shown, the fluid inlet 181 is arranged in the middle of the housing 18. Figure 4 A plurality of fluid outputs, not visible in FIG. 1 , are located in the side walls of the housing 18 .

[0031] like Figure 5 As shown, the encapsulation process of the vortex finder structure 16 also includes a fluid-tight connection between the housing 18 and the upper side of the cooling channel cover 12. This can be carried out, for example, by full-scale laser welding or laser brazing.

[0032] Of course, the embodiments discussed in the specific description and shown in the drawings are only illustrative examples of the present invention, and a person skilled in the art can provide a wide range of variation possibilities based on the content disclosed herein. In particular, it is also possible to encapsulate the vortex finder structure 16 using an outer cover layer provided together with the vortex finder structure 16 by means of 3D printing instead of a separate housing 18.

[0033] List of Reference Numerals

[0034] 10 Electronic components

[0035] 12 Cooling channel cover

[0036] 14 Prefabricated modules

[0037] 16 Vortex Finder Structure

[0038] 18 Housing

[0039] 181 Cooling fluid input

Claims

1. A method for manufacturing a cooled power electronic module, the method comprising the following steps: - providing a prefabricated module (14) comprising a plate-shaped cooling channel cover (12) and at least one electronic component (10) connected in a materially bonded manner and in thermal contact with the underside of the cooling channel cover (12), wherein the cooling channel cover (12) is a component of a cooling channel contained in the finished power electronic module and through which a cooling fluid can flow, - 3D printing a metallic vortex finder structure (16) in a region of the upper side of the cooling channel cover (12) opposite the electronic component (10), and Finally, the vortex finder structure (16) is encapsulated in a fluid-conducting housing, which is provided with a fluid inlet (181) and a fluid outlet and is connected to the upper side of the cooling channel cover (12) in a fluid-tight manner.

2. The method according to claim 1, characterized in that The encapsulation of the turbulator structure (16) is achieved by connecting a housing (18) designed as a sheet metal formed part and framing the turbulator structure (16) to the upper side of the cooling channel cover (12) by material bonding.

3. The method according to claim 2, characterized in that The material-joining connection is achieved by laser welding or laser brazing.

4. The method according to claim 1, characterized in that: The packaging of the vortex finder structure is achieved by 3D printing an outer cover layer, and the outer cover layer is closed except for a fluid input end and a fluid output end.

5. The method according to claim 1, characterized in that: The vortex finder structure (16) is constructed as a three-dimensional Voronoi grid formed by metal webs.

6. The method according to claim 5, characterized in that The web widens toward its end.

7. The method according to claim 5, characterized in that The webs are rounded and / or arc-shaped.

8. The method according to claim 1, characterized in that The cooling channel cover (12) is configured as a flat plate.

9. The method according to claim 1, characterized in that: The cooling channel cover is designed as a formed sheet metal part having a pot-shaped depression on the upper side of the sheet metal part and a corresponding protrusion on the lower side of the sheet metal part, wherein the vortex finder structure is printed on the bottom of the pot-shaped depression.

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