Injection molded support plate providing mechanical and electrical connection between a HV PCB and LV PCB

Abstract

An electronic circuit board assembly includes a support plate having opposite first and second sides, a first printed circuit board mounted to the first side, and a second printed circuit board mounted to the second side. The support plate includes first mounting features for the first printed circuit board, second mounting features for the second circuit board, and third mounting features configured to connect the support plate to an invertor housing enclosure. A connector pin is over-molded in the support plate and extends the through the support plate, projecting in opposite directions outwardly from the first side and the second side. The connector pin is electrically connected to both the first and second printed circuit boards, and electrically connects at least one first electronic component attached to the first circuit board to at least one second electronic component attached to the second circuit board.

Description

Attorney Docket No. 25065-2241 (713643PCT)INJECTION MOLDED SUPPORT PLATE PROVIDING MECHANICAL AND ELECTRICAL CONNECTION BETWEEN A HV PCB AND LV PCBFIELD

[0001] The present disclosure is generally related to a support structure utilized within an inverter to support at least a pair of printed circuit boards. The support structure provides a support plate between a first and second printed circuit boards and further mounts to the enclosure of the inverter. An electrically conducting pin is integrated within the support plate to provide an electrical connection between the first printed circuit board and the second printed circuit board.BACKGROUND

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] An inverter for an electric machine, such as those used in electric vehicles, converts direct current (DC) from the battery into alternating current (AC) to drive the electric motor. An inverter allows precise control over the motor's speed and torque by adjusting the output frequency optimizing motor performance and energy efficiency in applications requiring variable speed operation. Inverters include electrical components which are exposed to mechanical and thermal environmental conditions dependent on the application. The main components within an inverter can be categorized into low voltage and high voltage components and they are typically mounted on a printed circuit board (PCB). High voltage components may include DC link capacitors, filters, and power semiconductor devices such as either IGBT or MOSFET switches. The low voltage components may include a microcontroller, gate driver, current sensor, and low voltage connectors. A gate driver receives control signals from the microcontroller and outputs a highAttorney Docket No. 25065-2241 (713643PCT) voltage to drive the gates of a semiconductor device to control current applied to a motor. Bus bars are utilized in the inverter to complete electrical connections to receive and deliver power to and from the inverter.

[0004] Electrical connections between the low voltage and high voltage components are provided by conductive traces within the PCB. Environmental conditions may include high levels of vibration and mechanical stresses which may be detrimental to the internal electrical components of the inverter if not properly designed. The printed circuit boards are mounted within an inverter enclosure with other additional components providing further electrical functionality or thermal controlling operations. The sum and arrangement of these various components in the inverter enclosure provides an inverter assembly. Typically, PCBs are mounted directly to the inverter enclosure. A PCB layout is designed to optimize the electrical connections, functionality, and mounting of the low voltage and high voltage components.

[0005] If the PCB is directly mounted to the inverter enclosure and the mounting interfaces are remote from the components attached to the PCB, the preferred optimized PCB footprint may need to be extended to reach the mounting interface locations, resulting in the need to span the distance with expensive PCB material and the associated processing costs. In addition, such a design may result in negative structural implications. In automotive applications, inverters are often used in electrically driven powertrain arrangements in primary, secondary, or hybrid arrangements. Packaging within the automotive environment is always very difficult and the overall size of the electric drive module and the inverter assembly is important to minimize. One possibility to reduce the overall inverter assembly footprint is to utilize more than one PCB, where high voltage components are located on a first PCB while low voltage components are mounted on a second PCB. A challenge to this arrangement is that electrical communication must spanAttorney Docket No. 25065-2241 (713643PCT) between the first and second PCBs. This electrical communication includes the electrical connection between the power semiconductor devices and the microcontroller. This high voltage connection must be made in a reliable way considering the environmental operational conditions. High voltage connections must also include significant insulation between the connections and should be symmetrical to improve switching performance.

[0006] In view of the above, improvements can be made to the PCB arrangement to achieve an optimized inverter design by separating the low voltage and high voltage components on separate PCBs.SUMMARY

[0007] It is an aspect of the present disclosure to provide a board assembly including a supportive plate structure and at least a pair of printed circuit boards mounted to the support plate to be utilized within an inverter.

[0008] The PCBs may be arranged in a stacked manner attached to a structural mounting plate which will include integration of electrical connections to connect the first and second PCBs together. The structural mounting plate may be mounted to the inverter enclosure and ensure isolation and positioning of related components as required for improved and robust functionality. Electrical connections due to the stacked proximity of the PCBs results in the shorter connection between the low voltage and high voltage electrical components, improving switching performance.

[0009] It is a aspect of the present disclosure to provide a board assembly with a support plate located between first and second printed circuit boards with mounting features to attach the support plate to the enclosure of the inverter.Attorney Docket No. 25065-2241 (713643PCT)

[0010] It is a further aspect of the present disclosure to provide an electrically conducting pin integrated within the support plate that provides an electrical connection between the first printed circuit board and the second printed circuit board.

[0011] In a further aspect of the present disclosure, the first printed circuit board includes low voltage electrical components, and the second printed circuit board includes high voltage electrical components, and an electrical connection is over-molded within the support plate and connects the low voltage component to the high voltage component.

[0012] In a further aspect of the present disclosure, the over-molded electric pin integrated into the support plate connects a gate driver to a semiconductor switch

[0013] These and other features and advantages of the present disclosure will become more readily appreciated when considered in connection with the following detailed description and appending drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings wherein:

[0015] FIG. 1 is cross-sectional view of an inverter with a board assembly;

[0016] FIG. 2 is a perspective view of the support plate of the board assembly;

[0017] FIG. 3 is a detailed cross-sectional view of an over-molded pin utilized in the board assembly.Attorney Docket No. 25065-2241 (713643PCT)DETAILED DESCRIPTION

[0018] Referring to FIG. 1, a cross-sectional view of an inverter 10 is provided. In this view a board assembly 12 is shown mounted within and to an inverter enclosure 14. Board assembly 12 includes a first 16 and second 18 printed circuit board (PCBs) connected to a structural plate 20. The PCB is a flat, typically rectangular board that mechanically supports and electrically connects electronic components using conductive pathways, tracks, or signal traces etched from copper sheets laminated onto a non-conductive substrate. The PCB may include a substrate, copper layer, a protective solder mask, and a silkscreen layer with printed information. The substrate or base material of the PCB is made of fiberglass, composite epoxy, or other laminate materials, provides the structural support. To produce a PCB, a thin layer of copper is laminated onto the substrate and then etched away to leave the desired circuit pattern to connect the various electronic components provided on the PCB. PCBs may include more than one copper layer or include multiple layers of substrate and copper stacked together.

[0019] Inverter enclosure 14 includes an enclosure mount 22 provided internally to enclosure 14 to provide features for board assembly 12 to be fixed to via an arrangement of fasteners 24A, 24B, 24C, etc. In the illustrated arrangement, a structural plate 20 is located between first 16 and second 18 PCBs. Structural plate 20 provides support and locating for mounting and joining of PCBs 16 and 18 together in a stacked arrangement, and is utilized to provide structure for attachment to enclosure 14. First PCB 16 and second PCB 18 may have a similar or smaller size or footprint relative to structural plate 20. Structural plate 20 is able to span across enclosure 14 between mount locations instead of utilizing a PCB structure for this purpose, reducing the material required for the PCB and utilizing a lower cost material for structural board 12. The designAttorney Docket No. 25065-2241 (713643PCT) and material utilized for structural board 12 may also be optimized for strength and rigidity in ways a PCB itself cannot.

[0020] First PCB 16 may include at least one low voltage electrical component 26. The electrical component 26 is physically and electrically connected to first PCB 16. Known arrangements of attachment include through-hole technology (THT) and surface-mount technology (SMT) where electrical component leads 28 are soldered to the copper pads of the PCB. Alternatively, a press-fit connection may be used which involves inserting lead 28 into a plated through-hole (PTH) on the PCB with an interference fit, creating a reliable electrical and mechanical connection without the need for solder. One of the electric components 26 which may be attached to first PCB board 16 includes a gate driver. The gate driver is electrically connected to a microcontroller.

[0021] Second PCB 18 may include at least one high voltage electrical component 30. Electrical component 30 is physically and electrically connected to second PCB 18 in a similar manner as previously described for the first PCB 16. Electrical component 30 may include a semiconductor switch. An electrical connection between first PCB 16 and second PCB 18 is provided and will be described in more detail later in the specification.

[0022] Structural plate 20 includes several mounting, supporting, and locating features integrated into the plate for the attachment of first PCB 16 and second PCB 18 boards to the plate 20, as well as mounting features that allow attachment of the plate 20 to the enclosure mount 22 of inverter enclosure 14. Structural plate 20 uses an arrangement of fasteners 24A, 24B, 24C, etc. and mounting bosses 32 in various ways to connect the PCBs 16 and 18 to the plate 20 as well as to connect the plate 20 to enclosure mount 22. Structural plate 20 may provide a specific distanceAttorney Docket No. 25065-2241 (713643PCT) of separation Y between PCBs 16 and 18 to provide the required electrical isolation and improved EMF performance, as defined by the height or thickness of mounting features of plate 20.

[0023] Three different attachment arrangements / options are shown for structural plate 20. Two attachment options provide for connection of PCBs 16 and 18 to plate 20, while a third attachment option is provided for the mounting of plate 20 to enclosure 14. The first arrangement for attachment of either PCB to plate 20 utilizes fastener 24A that engages a threaded hole 34. Threaded hole 34 may be provided by an over-molded insert 36 into boss 32A of structural plate 20, or a tapped hole directly formed into a similar thicker portion formed into a non-inj ection molded plate 20. The purpose of fastener 24A is to attach either PCB 16 or 18 to structural plate 20.

[0024] A second arrangement utilizes fastener 24B in combination with either a nonthreaded compressive insert 38 integrated and over molded into an injection molded plastic structural plate 20 within boss 32B, or a through hole provided to plate 20. In either arrangement fastener 24B passes through first PCB 16, the boss 32B, and further through second PCB 18. Fastener 24B is received into threaded bore 40, disposed below and beyond the second PCB 18 in FIG. 1, where tightening of fastener 24B results in connecting PCBs 16 and 18 tightly to plate 20 and boss 32B. Threaded bore 40 may be included in enclosure mount 22 or may be a separate component requiring attachment to board assembly 12. The bore in the form of a separate component (illustrated in FIG. 1) may include heat sink structure located in thermal contact with high voltage electrical component 30 to provide a cooling or heat dissipation means.

[0025] The third mounting arrangement provided in plate 20 is utilized to fix board assembly 12 to inverter enclosure mount 22 utilizing plate fasteners 24C. A plurality of fasteners 24C are inserted into a through hole 48 in one of the mounting bosses 32C and are threaded directlyAttorney Docket No. 25065-2241 (713643PCT) into a threaded bore 50 that is provided in inverter enclosure mount 22. The through hole 48 may be defined by a non-threaded insert, similar to mounting boss 32B. It will be appreciated that various layouts, spacing, and arrangements of the enclosure mount may be provided.

[0026] The arrangement of the three mounting arrangements accordingly fasten PCBs 16 and 18 to support plate 20, forming board assembly 12, without connection of the PCBs directly to inverter enclosure 14. This arrangement provides the ability to optimize the design and layout of PCBs and assembly simplification by providing PCB support via support plate 20 and assembly fixturing / tooling alignment within plate 20. Board assembly 12, having plate 20 with the PCBS mounted thereto, is mounted to inverter enclosure 14 utilizing only fasteners 24C inserted into the threaded bores 50 of enclosure mount 22.

[0027] The different fasteners 24A, 24B, 24C are associated with the different types of mounting bosses 32A, 32B, 32C. Mounting boss 32A is illustrate to attach the first PCB 16 to the plate 20. Mounting boss 32B has a through bore and is used to attach both PCBs 16 and 18 to each other as well as to the plate. Mounting boss 32C is used to attach the plate 20 to the enclosure mount 22 locations. The plate 20 may include multiple ones of each type of mounting boss.

[0028] Referring to FIG. 2, a view of the bottom of support plate 20 is shown, which is the side where PCB 18 is mounted. The PCB 16 is mounted on the opposite side in this example. Support plate 20 is shown as one example in a non-limiting design to show a component made as a single piece plastic injection molded component. Examples of the various previously described mounting bosses 32A, 32B, 32C are shown. Mounting bosses 32A are provided with a closed end as seen in the view of FIG. 2, with fastener 24A is provided from the opposite side to attach PCB 16. The closed ends of mounting bosses 32A correspond to the cross-section shown in FIG. 1, in which insert 36 is disposed and fastener 24A does not extend through the boss 32A.Attorney Docket No. 25065-2241 (713643PCT)

[0029] Ribbing and weight saving features (open spaces between strut-like connector structure) may be included to further optimize the design of plate 20. A plurality of pins 42 are shown over-molded into plate 20. Alternatively, plate 20 may be made from a multi material construction. One potential arrangement of the plate 20 includes the use of a stamped metal, cast aluminum, or other material for the majority of the plate 20, while utilizing a smaller nonconductive material in zone 52, where conductive pins 42 are still over-molded in this area. The benefit of a multi-material design is to provide a first material optimized for structural and mounting requirements, while still being able to maintain the benefits of over-molding the pins 42 in a second material to provide electrical isolation and a simplified assembly process. Such an arrangement may still be considered a single piece plate 20. The opposite side of plate 20, which PCB 16 mounts to, is of a similar arrangement. However, the open facing portion of insert 36 disposed in boss 32A, which receives fastener 24A, is accessible and not closed. The through- hole type arrangement of bosses 32B and 32C would appear similarly, because both ends are open from each side of the plate 20.

[0030] Referring to FIG. 3, a more detailed view of board assembly 12 is provided. Because structural plate 20 is proposed to be at least partially non-conductive in zone 52 or fully made of a non-conductive material, at least one electrically conductive connecting pin 42 may be provided and over-molded into this non-conductive portion of plate 20. Pin 42 is utilized to electrically connect electrical component 26 mounted on first PCB 16 to the electrical component 30 of the second PCB 18. Over molding of pin 42 into plate 20 provides the ability to directly correlate PCB location of mounting features of plate 20 to pin 42 to ensure proper alignment when making the electrical connection between the PCBs. Electrical pin 42 is constructed of a single component with a central body portion 54 and bi-directionally extending compressive engagementAttorney Docket No. 25065-2241 (713643PCT) portions 56. Central body portion 54 may include features to be better retained into the over molded portion of plate 20.

[0031] When over molded into plate 20, pin 42 extends perpendicularly from a top surface 44 towards and through first PCB 16 (when PCB 16 is attached) with a length of the pin 42 and engagement portion 56 allowing insertion fully into PCB 16. Pin 42 also extends in the opposite direction from a bottom surface 46 towards and through second PCB 18 at a length also allowing full insertion into the thickness of PCB 18. PCBs 16 and 18 include openings that receive engagement portion 56, with conductive traces 58 extending toward the openings to contact engagement portion 56. Pin 42 is utilized to provide a robust, direct, and easy to assemble electrical connection between first PCB 16 and second PCB 18. The connection method described here is an interference press-fit mechanical and electrical connection between pin 42 and conductive traces 58 provided at PCBs 16 and 18. Because pins 42 are fixed into the support plate 20 in a simplified manner, only requiring the PCB to be installed and pushed onto projecting pins 42, stopping against plate 20, the result is an electrical connection without the need for a soldered connection.

[0032] In one aspect, the pin 42 may be specifically utilized to provide the electrical connection between a gate driver (electrical component 26) and a half bridge circuit configuration for a pair of semiconductors (electrical components 30). The gate, collector / drain, and emitter / source signals of the semiconductor are connected to the gate driver. The arrangement of pin 42 adjacent the attachment location of electrical components 26 and 30 provides a reliable and reduced distance connection, thereby improving switching performance. The arrangement or the present disclosure therefore may reduce costs, because the high voltage power state conductive layer in a high voltage PCB 18 may be excluded. Because electrical pin 42 may transmit highAttorney Docket No. 25065-2241 (713643PCT) voltage potential, integrating the electrical pin 42 into an injection molded portion of structural plate 20 provides sufficient insulation and isolation between an arrangement of multiple pins 42 within plate 20.

[0033] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varies in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of disclosure.

Claims

Attorney Docket No. 25065-2241 (713643PCT)CLAIMS1. An electronic circuit board assembly comprising: a support plate having opposite first and second sides; a first printed circuit board mounted to the first side of the support plate; a second printed circuit board mounted to the second side of the support plate; wherein the support plate includes first mounting features for the first printed circuit board and second mounting features for the second circuit board; wherein the support plate includes third mounting features configured to connect the support plate to an invertor housing enclosure; wherein the support plate includes a connector pin that is over-molded in the support plate and extends the through the support plate, wherein the connector pin project in opposite directions outwardly from the first side and the second side of the support plate; wherein the connector pin is electrically connected to both the first and second printed circuit boards; wherein the connector pin electrically connects at least one first electronic component attached to the first circuit board to at least one second electronic component attached to the second circuit board.

2. The assembly of claim 1, wherein the first mounting feature is a first mounting boss and includes a threaded portion, wherein a first fastener extends through the first printed circuit board and is threaded into the threaded portion and secures the first printed circuit board to the support plate.Attorney Docket No. 25065-2241 (713643PCT)3. The assembly of claim 1 , wherein the threaded portion is an insert received in the first mounting boss.

4. The assembly of claim 2, wherein the second mounting feature is a second mounting boss have a non-threaded through-portion, wherein a second fastener extends through the first printed circuit board, through the non-threaded through portion, through the second printed circuit board, and into a threaded member, wherein the second fastener secures the first printed circuit board, the support plate, and the second circuit board together.

5. The assembly of claim 2, wherein the non-threaded through-portion is an insert received in the second mounting boss.

6. The assembly of claim 5, wherein the threaded member includes a threaded insert received in an outer sleeve.

7. The assembly of claim 6, wherein the outer sleeve includes heat sink features.

8. The assembly of claim 4, wherein the third mounting feature is a third mounting boss having a non-threaded through-hole, wherein a third fastener extends through the third mounting boss and into a threaded portion of an inverter enclosure.

9. The assembly of claim 8, wherein the threaded portion is a threaded bore defined in an enclosure mounting feature of the inverter enclosure.Attorney Docket No. 25065-2241 (713643PCT)10. The assembly of claim 1, wherein the first printed circuit board is secured to the support plate via a first fastener extending therethrough, the second printed circuit board is secured to the first printed circuit board and the support plate via a second fastener extended therethrough, and the support plate includes the third mounting features that receives a third fastener configured for attachment to an inverter enclosure, wherein the third fastener does not extend through the first circuit board and does not extend through the second circuit board.

11. The assembly of claim 1, wherein the connector pin includes compressible engagement portions projecting from the first side and the second side of the support plate.

12. The assembly of claim 11, wherein the engagement portions project at a height that is greater than the first and second printed circuit boards attached to the support plate.

13. The assembly of claim 12, wherein the first and second printed circuit boards are pressed onto the engagement portions, wherein conductive traces in each of the first and second circuit boards electrically connect the first and second electrical components to the engagement portions, wherein the first and second electrical components are electrically connected to each other via the connector pin.

14. The assembly of claim 1, wherein the connector pin is over-molded in a non-conductive portion of the support plate.Attorney Docket No. 25065-2241 (713643PCT)15. The assembly of claim 14, wherein the support plate is a multi-material unit, wherein the non-conductive portion defines an electrical isolation zone.

16. The assembly of claim 1, wherein the first electrical component is a low voltage electrical component and the second electrical component is a high voltage electrical component.

17. The assembly of claim 16, wherein the first electrical component is a gate driver and the second electrical component is a half bridge circuit configuration for a pair of semiconductors.

18. The assembly of claim 1, wherein the support plate includes multiple first mounting features, multiple second mounting features, and multiple third mounting features.

19. The assembly of claim 18, wherein the first mounting features are closed on the second side and open on the first side, wherein the second and third mounting features are open on both sides.

20. The assembly of claim 19, wherein the second and third mounting features each include a through-bore defined by an insert.

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