Printed circuit board device, method for manufacturing a printed circuit board device and transmission system for a vehicle with a printed circuit board device

Abstract

Printed circuit board device (110) having the following features: - a multilayer printed circuit board (120); - a packaged power semiconductor element (115) soldered onto the circuit board (120), which has at least one electrical connection (130); and - at least one busbar (125) electrically contacted with the circuit board (120), wherein the electrical connection (130) of the power semiconductor element (115) is mechanically and electrically contacted with the busbar (125), wherein - the busbar (125) was produced by means of a copper plating process.

Description

[0001] The present approach relates to a printed circuit board device, a method for manufacturing a printed circuit board device, and a transmission system for a vehicle with a printed circuit board device.

[0002] To connect a power module to a printed circuit board (PCB), the power module, as a separately assembled module, is attached to the rest of the electronics and / or the PCB using screws, welding, and / or press-fitting techniques. The separately assembled module is first manufactured by mounting a so-called bare die onto a direct-bonded copper substrate (a structure that enables a tight electrical and / or thermal connection of electronic components and chips via copper). The bare die is then bonded to a stamped grid using bonding techniques, such as cold press welding, and subsequently potted and / or overmolded. To locally increase the current-carrying capacity of an FR4 PCB, a soldered busbar is connected to the PCB, first via a solder pad or trace on the FR4 PCB.

[0003] DE 10 2009 022 110 A1 discloses a printed circuit board arrangement for thermally stressed electronic components. The printed circuit board arrangement comprises a low-current conductor track and an electronic power component requiring cooling.

[0004] DE 600 36 932 T2 discloses an electronic power module and a manufacturing method for such a module.

[0005] In DE 10 2014 006 346 A1 a high-current switch with a first busbar and a second busbar is disclosed.

[0006] DE 10 2016 217 554 A1 shows an electronic assembly comprising a printed circuit board and a heat-generating component, wherein the component is covered with a cover material.

[0007] Against this background, the present approach provides an improved printed circuit board device, a method for manufacturing an improved printed circuit board device, and a transmission system for a vehicle with an improved printed circuit board device according to the main claims. Advantageous embodiments are described in the dependent claims and the following description.

[0008] The advantages achievable with the presented approach are that a printed circuit board device with a power semiconductor element and a busbar is created, in which ideal current conductivity is ensured even at high currents and thermal conductivity between the power semiconductor element and the busbar.

[0009] A printed circuit board device comprises a multilayer printed circuit board, a packaged power semiconductor element, and a busbar. The power semiconductor element is soldered to the printed circuit board and has at least one electrical connection. The busbar is electrically connected to the printed circuit board. The electrical connection of the power semiconductor element is mechanically and electrically connected to the busbar.

[0010] The electrical connection of the power semiconductor element is made directly, without an intervening solder pad or conductor track, to the busbar. The power semiconductor element can be understood as a semiconductor device used in power electronics for controlling and switching high electrical currents and voltages, for example, currents exceeding one ampere and / or voltages exceeding 24 volts. The power semiconductor element can be a thyristor. However, it can also be a transistor, which, due to its atomic semiconductor structure, exhibits special switching and performance characteristics. For example, the power semiconductor element could be an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET).The printed circuit board (PCB) can have an electrically non-conductive substrate material or be made entirely of such a material. For example, the PCB could be a so-called "FR4 PCB," which consists of flame-retardant composite materials made of epoxy resin and, additionally or alternatively, fiberglass fabric. The thermal conductivity of such an FR4 PCB can be 0.3 W / mK within a tolerance range of 1 to 20 percent deviation, for example, from a top surface to an opposite bottom surface of the FR4 PCB. The top surface can be understood as the main surface, i.e., the largest area, of the PCB, which is essentially parallel to the bottom surface, which forms another main surface.The power semiconductor element and the busbar can be arranged on or at the top of the circuit board, or at least facing the top.

[0011] The printed circuit board device presented here advantageously achieves a compact design and, thanks to the direct mechanical contact, enables effective electrical and thermal conductivity without bottlenecks during operation of the printed circuit board device.

[0012] According to one embodiment, the electrical connection of the power semiconductor element is metallurgically bonded to the busbar, in particular by means of gap-head soldering and / or a welding process. For example, the power semiconductor element and the busbar can be metallurgically bonded to each other by gap-head welding or laser welding. This ensures a secure and permanent connection.

[0013] The electrical connection of the power semiconductor element can be configured as a pin, in particular where the pin can contact the busbar at its upper surface. The busbar can be contacted with the printed circuit board from a lower surface opposite the busbar's upper surface. For example, the pin can be configured as a connecting leg, such as a Z-shaped bent pin. In this way, the electrical connection can be arranged directly to the busbar, for example, without contacting the printed circuit board.

[0014] According to the invention, the busbar is produced by means of a copper plating process. Thus, the busbar can already be formed during the production of the printed circuit board using the copper plating process. A busbar plating of this kind achieves particularly high thermal and electrical conductivity. An additional process step for attaching the busbar, for example by soldering, can therefore be advantageously omitted during the production of the printed circuit board.

[0015] According to a further advantageous embodiment, the printed circuit board also includes an electrically insulating and, additionally or alternatively, thermally conductive insert, in particular wherein a housing section of the power semiconductor element can be soldered to the printed circuit board such that the housing section thermally contacts the insert. The insert can also be referred to as an "inlay". The thermal conductivity between an insert surface and an opposing bottom surface of the insert can be between 20 and 1000 W / mK within a tolerance range of 1 to 20 percent deviation. For example, the insert can comprise at least partially aluminum oxide ceramic and additionally or alternatively at least partially aluminum nitride ceramic and additionally or alternatively at least partially silicon carbide and additionally or alternatively at least partially diamond.The insert can be cylindrical. According to an advantageous embodiment, the insert is arranged in a through-opening of the printed circuit board (PCB), in particular, the insert can extend from the top surface of the PCB to a bottom surface opposite the top surface. Advantageously, the insert can be arranged in the through-opening such that its surface is flush with the top surface and, additionally or alternatively, its bottom surface is flush with the bottom surface. The insert can also, or alternatively, be arranged to completely fill the through-opening. Such an insert can advantageously dissipate heat from the power semiconductor element located on the top surface through the PCB to the underside during operation of the PCB device.

[0016] The power semiconductor element can have a solder connection that thermally contacts the insert. For example, the solder connection can be at least partially covered, concealed, or enclosed by the housing section. The solder connection can be soldered to a PCB pad or solder joint on the top side of the printed circuit board (PCB) that covers the insert. The solder connection can be an "ePad" (exposed pad), which consists of materials with high thermal conductivity, such as metal and, additionally or alternatively, ceramic. The ePad can be embedded in or attached to the housing section, with one outer surface of the ePad facing the PCB being flush with an outer surface of the housing section facing the PCB. The ePad can protrude to one side or be exposed.Such an ePad, thermally contacted with the insert, can improve heat dissipation from the power semiconductor element. This creates a close and therefore effective thermal connection between the solder terminal and the insert, which also advantageously allows for a compact design.

[0017] It is also advantageous if at least the power semiconductor element, and additionally or alternatively the busbar, is protected, stabilized, and encapsulated by a plastic material. For example, the plastic material can be positioned at least partially between the electrical connection and the circuit board. Alternatively, the plastic material can be applied, for example, by injection molding, using a molding or overmolding process, and additionally or alternatively as a potting compound or coating. The plastic material can consist of an EP molding compound (a polyurethane molding compound) and additionally or alternatively as a casting resin such as epoxy resin.The plastic material can also be applied as a coating system, for example, a two-component system. Additionally, other components on the circuit board can be protected and further stabilized, or alternatively encapsulated, by the plastic material. Such an application of the plastic material can increase the mechanical resistance of the circuit board components, particularly their resistance to power and temperature cycles. The plastic material can also provide protection against dirt.

[0018] The power semiconductor element can be configured as a high-voltage circuit designed to switch voltages of at least 300 volts. For example, the power semiconductor element can be configured to switch voltages between 300 and 1200 volts within a tolerance range of 1 to 20 percent deviation. This enables the switching of very high voltages. The power semiconductor element can be configured, for example, to drive an electric motor, particularly an electric motor in a powertrain and, additionally or alternatively, a vehicle's steering system.

[0019] A transmission system for a vehicle comprises a transmission and a printed circuit board device, which is configured in one of the variants described above, in particular where the printed circuit board device can be arranged in the transmission oil. This allows for particularly effective heat dissipation.

[0020] A method for manufacturing a printed circuit board (PCB) fixture comprises a provisioning step and an assembly step. In the provisioning step, a multilayer PCB with a packaged power semiconductor element, having at least one electrical connection, soldered to the PCB, and a busbar electrically contacted with the PCB are provided. In the contacting step, the electrical connection of the power semiconductor element is mechanically and electrically contacted with the busbar to manufacture the PCB fixture.

[0021] This method can be implemented, for example, in software or hardware, or in a hybrid form of both, such as in a control unit. This implementation variant of the approach, in the form of a method, also allows the underlying problem to be solved quickly and efficiently.

[0022] The approach presented here also creates a device designed to carry out, control, and implement the steps of a variant of the method presented here in appropriate facilities. This device-based implementation of the approach also allows the underlying problem to be solved quickly and efficiently.

[0023] It is also advantageous to have a computer program product with program code that can be stored on a machine-readable medium such as semiconductor memory, hard disk memory or optical memory and is used to carry out the method according to one of the embodiments described above when the program is executed on a computer or device.

[0024] Examples of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows: Fig. 1 A schematic side cross-sectional view of a vehicle with a transmission system and a printed circuit board device according to an exemplary embodiment; and Fig. 2 a flowchart of a method for manufacturing a printed circuit board device according to an exemplary embodiment.

[0025] In the following description of preferred embodiments of the present approach, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, without repeating these elements.

[0026] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

[0027] Fig. Figure 1 shows a schematic lateral cross-sectional view of a vehicle 100 with a transmission system 105 and a printed circuit board device 110 according to an exemplary embodiment.

[0028] For illustrative purposes only, the printed circuit board device 110 is part of the transmission system 105 according to this embodiment and is also, for illustrative purposes only, immersed in the oil of a gearbox of the transmission system 105. According to this embodiment, the transmission system 105 is, for illustrative purposes only, arranged in or on the vehicle 100.

[0029] The printed circuit board device 110 comprises a housed power semiconductor element 115, a multilayer printed circuit board 120, and a busbar 125. The power semiconductor element 115 is soldered to the printed circuit board 120 and has at least one electrical connection 130. The busbar 125 is electrically connected to the printed circuit board 120. The electrical connection 130 of the power semiconductor element 115 is mechanically and electrically connected to the busbar 125.

[0030] In this embodiment, the power semiconductor element 115 and the busbar 125 are arranged on a top surface 135 of the printed circuit board 120 and / or adjacent to each other. The printed circuit board 120 has a bottom surface 140 on a side opposite the top surface 135. In this embodiment, the electrical connection 130 of the power semiconductor element 115 is metallurgically connected to the busbar 125, in this embodiment by means of gap soldering and / or a welding process. In this embodiment, the electrical connection 130 is designed as a pin. In this embodiment, the pin is contacted by means of a terminal leg on a top surface 145 of the busbar 125. The busbar 125 is mechanically contacted with the printed circuit board 120 from a bottom surface opposite the top surface 145.According to this embodiment, the connecting leg is essentially Z-shaped. Three sections forming the overall Z-shaped connecting leg are each oriented at right angles to one another. A first section of the connecting leg extends from the power semiconductor element 115 directly to the busbar 125. This first section does not make mechanical contact with the busbar 125 and / or the circuit board 120. A second section of the connecting leg, extending at right angles to the first section and / or located centrally, also does not make mechanical contact with the busbar 125 and / or the circuit board 120.In this embodiment, a free end of a third section of the connecting leg, which extends perpendicularly to the second section, lies flat on the top surface of the busbar 145. In this embodiment, the third section is arranged above the first section, i.e., further away from the circuit board 120 than the first section. In this embodiment, the entire electrical connection 130 is not mechanically contacted with the circuit board 120 and / or a solder pad.

[0031] According to this embodiment, the busbar 125 is contacted onto the circuit board 120 as a separate metal part. According to this embodiment, the busbar 125 is soldered onto the circuit board 120. According to an alternative embodiment, the busbar 125 has been produced on the circuit board 120 by means of a copper plating process.

[0032] According to this embodiment, the printed circuit board 120 comprises at least one electrically insulating and / or thermally conductive insert 150, wherein, according to this embodiment, a housing section 155 of the power semiconductor element 115 is soldered to the printed circuit board 120 such that the housing section 155 thermally contacts the insert 150. According to this embodiment, the insert 150 is cylindrical in shape. According to this embodiment, the power semiconductor element 115 is arranged adjacent to the insert 150. The power semiconductor element 115 at least partially covers the insert 150 on its upper surface 135, and according to this embodiment, completely covers it. According to this embodiment, the power semiconductor element 115 has a solder terminal 160 that thermally contacts the insert 150.According to this embodiment, the solder terminal 160 is covered, concealed, or enclosed by the housing section 155. The insert 150 is arranged in a through-hole of the printed circuit board 120, extending from the top 135 to the bottom 140, and / or completely filling the through-hole. In this embodiment, one surface of the insert 150 is flush with the top 135, and / or a bottom surface of the insert 150 opposite the surface is flush with the bottom 140.

[0033] According to this embodiment, the printed circuit board device 110 also comprises a plastic material 180 that protects, stabilizes, and / or encapsulates at least the power semiconductor element 115 and / or the busbar 125 on the printed circuit board 120. According to an alternative embodiment, at least one control electronic component and / or all components arranged on the top surface 135 of the printed circuit board 120 are also encapsulated in the plastic material 180. According to this embodiment, the electrical connection 130 is substantially completely stabilized and / or encapsulated by the plastic material 180, with the exception of a contact surface on the busbar 125.

[0034] According to this embodiment, the power semiconductor element 115 is configured as a high-voltage circuit designed to switch a voltage of at least 300 volts. According to this embodiment, the power semiconductor element 115 is designed to control an electric motor, specifically an electric motor in a drive train and / or steering system of the vehicle 100.

[0035] According to this embodiment, the printed circuit board 120 also has at least one via 185. According to this embodiment, the via 185 is electrically and / or thermally contacted with the busbar 125. According to this embodiment, a plurality of conductor tracks extend from the via 185 in several planes within the printed circuit board 120 parallel to an axis of extension of the top surface 135.

[0036] The following are examples of the printed circuit board device 110 presented here, described again in other words: The current rail 125 soldered on according to this embodiment is advantageously directly electrically contacted by a surface-mount device (SMD), in this embodiment in the form of the power semiconductor element 115. In other words, according to this embodiment, at least one IGBT solderable component is soldered onto the printed circuit board 120 (PCB) and directly contacted with the soldered current rail 125. An additional solder pad on the PCB 120 is therefore advantageously unnecessary. This allows for an increase in current-carrying capacity.

[0037] According to this embodiment, the printed circuit board device 110 implements a design concept for a power circuit based on an FR4 printed circuit board with thermally highly conductive and electrically insulating inserts 150 in the form of inlays.

[0038] A busbar 125 and, according to this embodiment, an ePad of the MOSFET / IGBT component are soldered to the PCB. According to this embodiment, at least one or more leads of the IGBT component are subsequently bonded to the busbar 125 for electrical contact. According to this embodiment, the leads are bent upwards and not soldered directly to the circuit board 120. According to this embodiment, the entire electronic assembly, and in particular this connection point in the form of the leads, is mechanically supported and / or protected from media by a plastic encapsulation in the form of potting and / or thermoset overmolding.

[0039] According to an alternative embodiment, the busbar 125 is not soldered on as a separate metal part, but is manufactured directly in a PCB manufacturing process via a copper plating process. According to this embodiment, the metallurgical bond is created by gap soldering or a welding process, or, according to another embodiment, by gap and / or laser welding. According to this embodiment, the power section is designed as a high-voltage circuit capable of switching voltages in the range of 400 to 1000 volts. According to this embodiment, the power semiconductor(s) control an electric motor in the drivetrain or steering system. According to this embodiment, and according to an alternative embodiment also together with a DC link capacitor, the entire electronics assembly, including the transmission, is installed in the vehicle 100 in the oil.

[0040] Advantageously, the printed circuit board (PCB) fixture 110 presented here enables the conduction of high currents on the PCB 120, thereby increasing the integration density of the electronics. This creates a cost-optimized approach, as the costs for the PCB 120 or PCB fixture 110 remain unchanged. Furthermore, the compact arrangement of the elements on the PCB 120 advantageously reduces the number of interfaces required. This allows for shorter cable lengths and thus has a positive impact on the control behavior and losses.

[0041] Fig. Figure 2 shows a flowchart of a method 200 for manufacturing a printed circuit board device according to an exemplary embodiment. This can be the one described in Fig. 1. The described printed circuit board device is involved.

[0042] Method 200 comprises a provisioning step 205 and an arrangement step 210. Optionally, method 200 according to this embodiment also comprises an insertion step 215, a soldering step 220, a further production step 225, and / or a stabilizing step 230.

[0043] In step 205 of the provisioning process, a multilayer printed circuit board (PCB) with a packaged power semiconductor element soldered to the PCB, which has at least one electrical connection, and a busbar electrically contacted to the PCB are provided. In step 210 of the contacting process, the electrical connection of the power semiconductor element is mechanically and electrically contacted to the busbar to manufacture the PCB fixture.

[0044] According to this embodiment, in step 210 of the contacting process, the electrical connection of the power semiconductor element is metallurgically connected to the busbar, according to one embodiment by means of gap-head soldering and / or a welding process. According to this embodiment, in step 210 of the contacting process, the electrical connection of the power semiconductor element, which is configured as a pin, or according to one embodiment as a connecting leg, is contacted on the top surface of the busbar.

[0045] In step 215 of the insertion process, an insert that is more thermally conductive than the printed circuit board (PCB) is arranged in a through-hole in the PCB, in particular wherein the insert is arranged in the through-hole from a top side of the PCB to a bottom side of the PCB opposite the top side. According to this embodiment, step 215 of the insertion process is performed before step 205 of the provisioning process. According to one embodiment, the method 200 also includes a creation step before step 215 of the insertion process, in which the through-hole is created. In step 220 of the soldering process, according to this embodiment, a housing section of the power semiconductor element and / or the busbar are soldered to the PCB, wherein the power semiconductor element is soldered to the PCB such that the housing section thermally contacts the insert.In step 220 of the soldering process, according to one embodiment, at least one control electronic component is soldered to the printed circuit board (PCB). This component is configured to control the power semiconductor element, in particular the power semiconductor element, which is configured to control an electric motor. According to this embodiment, soldering step 220 is performed before step 205 of the provisioning process and / or after step 215 of the insertion process. According to an alternative embodiment, no busbar is soldered to the PCB in soldering step 220. In this alternative embodiment, a PCB is provided in step 205 of the provisioning process that has a busbar already generated in a PCB manufacturing process. In this alternative embodiment, a PCB is provided in step 205 of the provisioning process that has a busbar generated by a copper plating process.According to one embodiment, the method includes a further production step 225 prior to the provisioning step 205, in which the busbar is produced on the printed circuit board, in particular by copper plating. In stabilization step 230, at least the power semiconductor element and / or the busbar is protected and / or stabilized and / or encapsulated on the printed circuit board by means of a plastic material, in particular wherein, in stabilization step 230, the plastic material is at least partially injected between the printed circuit board and the electrical connection. In stabilization step 230, according to one embodiment, at least one control electronic component and / or all components arranged on at least one side of the printed circuit board are also protected and / or stabilized and / or encapsulated on the printed circuit board by means of the plastic material.According to this embodiment, step 230 of stabilizing is performed after step 210 of contacting.

[0046] The embodiments described and shown in the figures are only examples. Different embodiments can be combined completely or with respect to individual features. An embodiment can also be supplemented by features from another embodiment.

[0047] Furthermore, the procedural steps presented here can be repeated and carried out in a different order than described. Reference sign 100 vehicles 105 transmission system 110 Printed circuit board device 115 Power semiconductor element 120 circuit boards 125 busbar 130 electrical connection 135 Top 140 bottom 145 Top of busbars 150 insert 155 Housing section 160 solder terminals 180 plastic material 185 Through-hole plating 200 methods for manufacturing a printed circuit board device Step 205 of deployment Step 210 of contacting Step 215 of the insertion process 220th step of soldering 225 Step of further generation 230th step of stabilization

Claims

[1] Printed circuit board device (110) having the following features: - a multilayer printed circuit board (120); - a packaged power semiconductor element (115) soldered onto the circuit board (120), which has at least one electrical connection (130); and - at least one busbar (125) electrically contacted with the circuit board (120), wherein the electrical connection (130) of the power semiconductor element (115) is mechanically and electrically contacted with the busbar (125), wherein - the busbar (125) was produced by means of a copper plating process. [2] Printed circuit board device (110) according to claim 1, wherein the electrical connection (130) of the power semiconductor element (115) is contacted with the busbar (125) by means of a material connection, in particular by means of gap soldering and / or a welding process. [3] Printed circuit board device (110) according to one of the preceding claims, wherein the electrical connection (130) of the power semiconductor element (115) is formed as a pin, in particular wherein the pin contacts the busbar (125) on a busbar top surface (145). [4] Printed circuit board device (110) according to one of the preceding claims, wherein the printed circuit board (120) comprises at least one electrically insulating and / or thermally conductive insert (150) compared to the printed circuit board (120), in particular wherein a housing section (155) of the power semiconductor element (115) is soldered to the printed circuit board (120) such that the housing section (155) thermally contacts the insert (150). [5] Printed circuit board device (110) according to one of the preceding claims, wherein at least the power semiconductor element (115) and / or the busbar (125) is protected and / or stabilized and / or encapsulated on the printed circuit board (120) by means of a plastic material (180). [6] Printed circuit board device (110) according to one of the preceding claims, wherein the power semiconductor element (115) is configured as a high-voltage circuit designed to switch a voltage of at least 300 volts. [7] Printed circuit board device (110) according to one of the preceding claims, wherein the power semiconductor element (115) is configured to control an electric motor, in particular an electric motor in a drive train and / or steering system of a vehicle (100). [8] Transmission system (105) for a vehicle (100), wherein the transmission system (105) comprises a transmission and a printed circuit board device (110) according to one of the preceding claims, in particular wherein the printed circuit board device (110) is arranged in the oil of the transmission. [9] Method (200) for manufacturing a printed circuit board device (110) according to claim 1, wherein the method (200) comprises the following steps: Providing (205) a multilayer printed circuit board (120) with a packaged power semiconductor element (115) soldered onto the printed circuit board (120), the element having at least one electrical connection (130) and a busbar (125) electrically contacted with the printed circuit board (120); and Contacting (210) the electrical connection (130) of the power semiconductor element (115) with the busbar (125), wherein the electrical connection (130) is mechanically and electrically contacted with the busbar (125) to produce the printed circuit board device (110). [10] Device configured to perform and / or control steps of a method (200) according to claim 9 in corresponding units. [11] Computer program configured to execute and / or control a method (200) according to claim 9. [12] Machine-readable storage medium on which a computer program according to claim 11 is stored.

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