Method for establishing a signal connection between at least one power module and a control board

Abstract

The invention relates to a method for producing a signal connection (49) between at least one power module (10, 94, 96, 98) and a control board (40) comprising the following method steps: According to a), a wiring level (26) is provided on at least one power module (10, 94, 96, 98) with metallic connection surfaces (64) for architectural elements (18, 20, 38, 50) of the signal connection (49). After process step b), the architectural elements (18, 20, 38, 50), in particular pin feet (58), and the metallic connection surfaces (64) are joined by a material bond, followed by joining a head area (60) of the architectural elements (18, 20, 38, 50) of the signal connection (49) to the control board (40) by pressing or selectively soldering (56, 108) into it.

Description

Technical field

[0001] The invention relates to a method for establishing a signal connection between at least one power module and a control board. Furthermore, the invention relates to the use of the method for establishing a signal connection between a control board and at least one power module, as well as to the use of the method in battery-electric inverters of electrically powered vehicles. State of the art

[0002] DE 10 2014 219 998 B4 relates to a power module, in particular for providing a phase current for an electric machine, for example, an electric motor. The power module comprises a circuit carrier with a surface, at least two first contact surfaces on the surface, and at least two first power transistors, each having a ground contact surface. One of the at least two first power transistors is directly arranged on each of the first contact surfaces and is electrically connected directly to the respective first contact surface via its ground contact surface. The power module also comprises a second contact surface on the surface and at least two second power transistors, each having a ground contact surface.The at least two second power transistors are arranged directly on the second contact surface and are electrically connected to the second contact surface via their respective base contact surfaces. Furthermore, the power module comprises at least two third contact surfaces on its surface, wherein the at least two second power transistors have an additional contact surface on their sides facing away from the surface of the circuit carrier, and each second power transistor of the at least two second power transistors is electrically connected to one of the at least two third contact surfaces via its additional contact surface.The at least two first contact surfaces and the at least two third contact surfaces are arranged alternately in a longitudinal direction of the power module, and the second contact surface is arranged next to the at least two first contact surfaces and the at least two third contact surfaces, the second contact surface having at least two contact areas, each of which is located next to one of the at least two first power transistors. The at least two first power transistors each have an additional contact surface on their sides facing away from the surface of the circuit carrier, and each first power transistor of the at least two first power transistors is electrically connected via its additional contact surface to the adjacent contact area of ​​the at least two contact areas of the second contact surface.In this arrangement, at least two contact areas of the second contact surface and at least two second power transistors are arranged alternately one after the other in the longitudinal direction.

[0003] EP 2 418 925 B1 relates to an electrical contact between a flexible film having at least one conductor track and at least one electrical contact of a sensor or control unit. In this case, an end section of the flexible film is electrically contacted at a contact point by means of heat input, wherein the end section of the flexible film at the contact point is aligned with the electrical contacts formed above. The end section of the flexible film is designed as a corrugation, in particular as a deflection.

[0004] DE 10 2022 206 265 A1 relates to a power module with a first circuit carrier having an electrically insulating layer on which at least one first conductor structure, at least one second conductor structure, and at least one third conductor structure are formed. At least one first semiconductor switch is electrically connected between the at least one first conductor structure and the at least one third conductor structure, and at least one second semiconductor switch is electrically connected between the at least one third conductor structure and the at least one second conductor structure. At least one second circuit carrier is arranged spatially parallel to the first circuit carrier and has at least one internal contact area and at least one external contact area.The layout of the first circuit carrier is mirror-symmetrical about a central longitudinal axis, wherein the second circuit carrier is designed as a rectangular and in particular flexible printed circuit board, which is arranged symmetrically about the central longitudinal axis and is connected to the first circuit carrier via soldered connections, welded connections, adhesive connections or sintered connections. Disclosure of the invention

[0005] According to the invention, a method for establishing a signal connection between at least one power module and a control board is proposed, comprising the following method steps: a) Providing a wiring level with metallic connection surfaces for architectural elements of the signal connection, b) material-bonded joining of the architectural elements, in particular a pin base with the metallic bonding surfaces and c) Joining a head area of ​​the architectural elements of the signal connection to the control board by pressing in or selective soldering or selective wave soldering with / in it.

[0006] In a particularly advantageous way, the method proposed according to the invention can create a flat topography of the upper surface of a power module, which advantageously promotes further processing, for example by sintering.

[0007] In an advantageous further development of the method proposed according to the invention, the wiring plane according to process step a) is formed by a DBC substrate or another ceramic substrate, for example DPC (Direct Plated Copper), AMB (Active Metal Brazed) or a stamped grid or a printed circuit board or a surface section of a metallic material embedded in a mold body.

[0008] Advantageously, the method proposed according to the invention provides that solder pins or press-fit pins are used as architectural elements, either applied directly to the wiring plane or subsequently inserted sleeves made of metallic material, for example Cu- or Al-based sleeves.

[0009] In the method proposed according to the invention, it is advantageously provided that, according to process step b), the material-joining of the architectural elements is carried out by ultrasonic welding.

[0010] In the method proposed according to the invention, it is further provided that the material-bonded joining of the architectural element is carried out with a positional tolerance of + / - 0.1 mm to + / - 0.025 mm relative to a reference point on the power module. The more precisely the positional tolerance can be maintained, the more cost-effective and smoother series production can be.

[0011] In the method proposed according to the invention, it is further provided that the architectural elements in the head region or, alternatively, openings of the control board are provided with a metallic lamination, in particular a copper lamination. This pretreatment step of either the architectural elements in the head region or the openings of the control board enables the creation of a very good electrical connection that can be produced on a mass production scale.

[0012] Furthermore, the method proposed according to the invention is characterized in that, according to process step c), the head regions of the architectural elements of the signal connection are soldered in an overhead position of the control board relative to a soldering system. By maintaining the overhead position during the bonding process, solder beads can ideally be avoided or at least significantly reduced.

[0013] In the method proposed according to the invention, the joining of the head regions of the architectural elements to the control board is further provided for by selective wave soldering. Alternatively, other soldering methods are also possible, such as robotic or laser soldering.

[0014] In an advantageous further development of the method proposed according to the invention, when joining the head regions of the architectural elements to the control board, either the soldering system is moved relative to the control board, or alternatively, the control board arranged on the power modules is moved relative to the soldering system. Travel paths are possible in both horizontal and vertical directions.

[0015] In the method proposed according to the invention, as an alternative to forming a solder connection between the head regions of the architectural elements of the signal connection and the control board, the head regions of the architectural elements of the signal connection can be pressed into openings in the control board that are covered with metallic material. This creates a force-fit or form-fit press-fit connection, which also provides an electrical contacting option that can be implemented on a mass production scale.

[0016] Finally, the invention relates to the use of the method for producing a signal connection between a control board and at least one power module, as well as to the use of the method in battery-electric inverters of electrically powered vehicles. Advantages of the invention

[0017] The method proposed according to the invention advantageously allows direct and short-path contacting via ultrasonically welded architectural elements directly on the power module. For this purpose, exposed copper surfaces of a molded substrate of the power module can be used, as well as other copper surfaces of a wiring plane of a power module. In particular, the architectural elements, in the form of solder pins or copper sleeves or the like, can be metallurgically bonded to a stamped grid integrated into the power module by ultrasonic welding.

[0018] The method proposed according to the invention enables a flat top surface topography of the power modules, which facilitates good further processing, for example in subsequent sintering processes. Short distances between the power module and the control board can be advantageously achieved. Furthermore, flexible variation of the materials and geometries of the architectural elements, as well as tight tolerances between the architectural elements, is possible. Thus, robust manufacturing processes can be implemented on a large scale while maintaining positional tolerances of + / - 0.1 mm.

[0019] Furthermore, the application of the method proposed according to the invention is expected to result in a significant reduction in manufacturing costs compared to solutions used today. Brief description of the drawings

[0020] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0021] They show: Fig. 1 a schematic diagram of a power module with a DBC substrate, Fig. 2 the perspective view of a power module with a wiring sleeve formed by a punched grid and architectural elements of the signal connection arranged on it, Fig. 3 and Fig. 3.1 Copper sleeves bonded to a power module as architectural elements, Fig. 4 a schematically represented control board with openings that have a copper lamination, Fig. 5 a mold body arranged on a heat sink with metallic attachment surfaces embedded on its upper side, Fig. 6 and Fig. 7 solder heads, with which the head areas of the architectural elements of the signal connection are joined in a material-bonded manner in the concealed openings of the control board, Fig. 8 the illustration of a housing with three power modules shown in an overhead position, which are contacted via a common control board and Fig. 9 a plumb line system arranged overhead according to Fig. 8 opposite and with the help of which the head areas of the signal connections in the control board are formed as material-bonded joining connections by architectural elements. Embodiments of the invention

[0022] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0023] Fig. Figure 1 shows a power module 10, housed in a housing 12 shown here in perspective. Several DBC substrates 14 are arranged side by side and have free copper surfaces 16 on their upper side. The housing 12 of the in Fig. The power module 10 shown in perspective view further comprises a housing tray 34 and is bounded all around by a housing wall 36. The free copper surfaces 16 according to the perspective view in Fig. 1 form metallic bonding surfaces 64, as described in more detail below.

[0024] According to the perspective representation Fig. Figure 2 shows a power module 10, which has punched grids 28 forming a wiring level 26. The individual punched grids 28 contact a top surface of a circuit substrate. Furthermore, the perspective view shows Fig. 2 shows that on the punched grids 28 forming the wiring level 26 there are architectural elements 18 for forming a signal connection 49, which are shown in the illustration according to Fig. 2 are designed as sleeves 20. The sleeves 20, as architectural elements 18 that form part of a signal connection 49, are preferably attached by means of an ultrasonic welding connection 24 in the wiring plane 26 on the top of the stamped grids 28. Fig. Figure 2 further shows that within the power substrate [circuit substrate?] a number of bond connections 30 are formed, which are formed by individual bond wires 32. The punched grids 28, which form the wiring plane 26, are essentially located within the housing tray 34 of the housing 12, as shown in the perspective view in Figure 2. Fig. 2 included. The housing 12 comprises said housing wall 36, which encloses the installation components of the power module 10. By means of the in Fig. The architectural elements 18 shown in Figure 2, arranged on the punched grid 28 forming the wiring plane 26, are arranged in a Fig. 2 control board 40 not shown (see Fig. 4) contacted.

[0025] The Fig. 3 and Fig. Figure 3.1 shows an example of a power module 10, on whose free copper surfaces 16, for example a pair of architectural elements 18 designed as Cu sleeves 38, is arranged. According to the illustration in Fig. 3.1 These copper sleeves 38 are metallurgically connected to the free copper surfaces 16 of the power module 10 via metallurgical connections 22, designed as ultrasonic welds 24. However, pins, either single-piece or multi-piece, can also be used. Regarding positional tolerance, it should be noted that the tolerance for the arrangement of the copper sleeves 38, which serve as architectural elements 18, in the XY plane relative to a reference point on the power module 10 is ±0.1 mm to ±0.025 mm. The more reliably this positional tolerance can be maintained, the smoother the subsequent contacting processes will be, especially in high-volume production on pick-and-place machines.

[0026] According to the representation Fig. Figure 4 shows an exemplary side view of a control board 40. The control board 40 comprises a number of openings 42. A top side of the control board 40 is designated by reference numeral 44, while a bottom side is designated by reference numeral 46. The individual openings 42 are preferably provided with a lining of metallic material, in particular a copper lamination 48.

[0027] From the representation according to Fig. Figure 5 shows that a mold body 68 is arranged on a heat sink 78 by means of a bonding layer 80. On a top surface 70 of the mold body 68, there are individual connection surfaces 64 embedded in the molding material of the mold body 68 within an embedding 66, which are made, for example, of a contacting material, preferably copper. The top surface 70 of the mold body 68 is designed as a flat surface and can be provided with a first power connection 74 and a second power connection 76.

[0028] From the representation according to Fig. 5 shows that aligned with the openings 42 in the control board 40 according to Fig. 4. Architectural elements 18 in the form of solder pins 50 or signal pins 50 are connected to the bonding surfaces 64 by means of a pin base 58 in a material-bonded manner. The material-bonded connection is preferably carried out as an ultrasonic welding connection.

[0029] This causes the solder pins or signal pins 50, which for example have an elastically formed arc 62, to protrude from the top surface 70 of the mold body 68. Advantageously, the solder pins or signal pins 50, which represent architectural elements 18, are arranged such that their head regions 60 are aligned with the openings 42, which are preferably provided with a copper cladding 48 in the control board 40.

[0030] When the control board 40 is joined, i.e., when the underside 46 of the control board 40 is brought close to the vertical 54 in the joining direction 52, the pin-shaped solder pins or signal pins 50 engage in the openings 42 of the control board 40 which are provided with the copper laminations 48. An enlarged connection is formed between the architectural elements 18, designed as solder pins or signal pins 50, and the copper lamination 48. This connection is formed, for example, by means of a material-bonded joining process such as selective soldering 56, creating an electrically conductive connection.

[0031] A signal connection 49 between the control board 40 and the power module 10, which is embedded in the mold body 68, for example, is now made from the Cu cladding 48 in the head area 60 of the solder pins or signal pins 50 via the pin base 58 into the connection surfaces 64, which are preferably made of metallic material and are embedded on the top side 70 of the mold body 68.

[0032] In relation to Fig. 5. It should be mentioned that the mold body 68, according to the illustration in Fig. 5 is connected to the top of the heat sink 78 by means of the bonding layer 80. The bonding layer 80 is preferably produced by vapor phase soldering.

[0033] The Fig. 6 and Fig. Figure 7 shows that after a reversal movement to an overhead position 90, the control board 40 is now opposite a soldering head of a soldering system. This is explained in Fig. In the soldering head shown in Figure 7, selective soldering 56 is performed. Using selective soldering 56, a metallurgical bond is created between the head areas of the signal pins or solder pins 50 of the copper lamination 48 and the solder material as part of the signal connection 49. The illustrations of the Fig. 8 and Fig. Figure 9 shows that the heat sink 78, with its two opposing connection ports 92 for supplying a cooling medium, is rotated into an upside-down position 90. Accordingly, the first, second, and third power modules 94, 96, 98, attached to the heat sink 78, are also rotated into the upside-down position 90. The control board 40 is connected to the individual power modules 94, 96, 98 via the aforementioned architectural elements 18, which form the signal connection 49. In the embodiment according to Fig. The three power modules 94, 96, and 98 shown here share a common control board. This control board, used jointly for the three power modules 94, 96, and 98, is designated here by reference numeral 100. In the overhead position 90, the control board 100 is connected to these modules via the aforementioned signal connections 49, so that in this case the soldering system 110 opposite the ends of the signal connection 49 is as shown in the illustration. Fig. 9 said signal connections 49 are able to form a material-bonded connection by ultrasonic welding.

[0034] For this purpose, the in Fig.9. The soldering system 110, shown schematically, executes travel paths 112, which can be directed both horizontally 114 and vertically 116. The individual soldering heads, which are used in selective wave soldering 108, are located exactly opposite the architectural elements 18, i.e., the head areas 60 of the solder pins or signal pins 50, which are formed here in groups of three signal connections 49.

[0035] It is now possible to move the housing 12 with power modules 94, 96, 98 formed on the heat sink 78 and a common control board 100 arranged therein relative to the soldering heads that perform the selective wave soldering 108, or alternatively, to move the individual soldering heads of the soldering system 110 relative to a stationary housing 12. Both embodiments are possible within the scope of the solution proposed according to the invention.

[0036] The solution proposed according to the invention advantageously results in direct and short contacts between the power modules 94, 96, 98 embedded in the mold bodies 68 and the control board 40 or the common control board 100. The described solution enables a flat module side topography, which facilitates excellent further processing, for example, in sintering processes. Furthermore, very short distances between the respective power modules 10, 94, 96, 98 and the control boards 40 or the common control board 100 can be advantageously achieved. In addition, a flexible variation of the pin materials and geometries used is possible, as are tight tolerances with regard to the arrangement of the solder pins or signal pins 50, sleeves 20, or copper sleeves 38, which represent the architectural elements 18 of the signal connection 49, to name just a few of the architectural elements 18.

[0037] Furthermore, lower manufacturing costs can be expected by applying the method proposed according to the invention compared to solutions used today.

[0038] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 219 998 B4

[0002] EP 2 418 925 B1

[0003] DE 10 2022 206 265 A1

[0004]

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