Connecting element and assembly with a connecting element, inverter with an assembly

Abstract

Connecting element (1) for establishing an electrical and mechanical connection between a printed circuit board (20) and a busbar (10), comprising - a first contact area (2) designed for connection to the printed circuit board (20), - a second contact area (4) designed for connection to the busbar (10) and - a resilient portion (3) between the first contact region (2) and the second contact region (4), wherein the resilient portion (3) is suitable for compensating a tolerance of a distance between the first contact region (2) and the second contact region (4).

Description

The present invention relates to a connecting element for establishing an electrical and mechanical connection between a printed circuit board and a busbar ("busbar"). It further relates to an assembly comprising a printed circuit board, a busbar and a connecting element. The invention further relates to an inverter or a power inverter having at least one said assembly.In order to connect a busbar to a printed circuit board, the printed circuit boards are typically equipped with separate components in the form of metal sockets having a thread arranged therein, optionally with a plastics reinforcement. Due to the tolerances caused by the components, the tolerances can add up during the installation of the parts. These include, in particular, housing tolerances, printed circuit board tolerances, base tolerances and busbar tolerances.This can lead to the busbar deforming elastically and optionally also plastically under tensile or compressive loads during screwing onto the base. The result is voltages in the bus bar and the circuit board. The deflections resulting therefrom can reduce the service life of the components, especially of the printed circuit board and electronic components arranged thereon. Loads on the connection between the base and the printed circuit board can lead to detachment of the base and to loss of the contacting.In addition, thermal expansion of the components during operation and due to environmental influences can reinforce this effect. This is particularly critical in the case of extended components such as busbars.Flexible busbars with copper braid solve this problem, but are very cost-intensive and have a higher failure rate. Busbars with S-impact often do not reach the necessary maximum deflections in order to reliably ensure tolerance compensation over all operating points.It is therefore an object of the present invention to specify a connecting element for producing an electrical and mechanical connection between a printed circuit board and a busbar, which connecting element enables tolerance compensation in a technically simple manner and can be used with existing busbars and printed circuit boards. The connection should be durable and robust and be suitable both for stationary applications and also, for example, in the automotive sector.According to one aspect of the invention, a connecting element for producing an electrical and mechanical connection between a printed circuit board and a busbar is specified, having a first contact region designed for connection to the printed circuit board and a second contact region designed for connection to the busbar. The connecting element further comprises a resilient portion between the first contact region and the second contact region, wherein the resilient portion is suitable for compensating for a tolerance of a distance between the first contact region and the second contact region.The connecting element has the advantage that the two contact regions can be adapted to existing printed circuit boards or busbars, so that these do not have to be modified. The tolerance compensation is ensured by the resilient section therebetween. This can, for example, reliably compensate for height tolerances of up to approximately 1000 μm. Stresses in the circuit board and the busbar are reduced or avoided.The fact that the resilient section is suitable for compensating a tolerance of a distance between the first contact region and the second contact region is achieved in that the first contact region and the second contact region can spring against one another via the resilient section, that is to say their distance can be varied. The spring properties of the resilient portion are selected accordingly. In particular, the suspension must be sufficiently elastic to avoid loads on the contact regions and the connection to the printed circuit board and the busbar.In this case, the printed circuit board can be formed as a circuit carrier with fiber-reinforced plastic such as prepreg as insulating base material. Alternatively, the printed circuit board can be formed as a circuit carrier with ceramic material as the insulating base material.According to an embodiment of the invention, the first contact region comprises a number of press-fit pins. Press-fit pins of this type or press-fit pins are already used for connecting between printed circuit boards. According to one embodiment, the press-in pins are integrally formed on the resilient section.Alternatively, the first contact region can also have a number of SMD (surface mounted device), i.e. surface-mountable solder contacts, for example in the form of solder deposits.A further alternative is THT (through hole technology), i.e. through-mountable solder contacts. Alternatively, a screw connection or another type of connection can also be used.The first contact region of the connecting element can thus be embodied with a known and proven technology which is already used for contacting printed circuit boards and is compatible with existing processes.According to one embodiment, the second contact region has a thread. The thread serves to receive a screw which is inserted through a through hole in the busbar and then screwed into the thread in order to connect the busbar to the connecting element in an electrically and mechanically stable manner. This embodiment has the advantage that the connection is particularly simple to produce and at the same time is stable. However, another type of connection between the busbar and the second contact region is also conceivable, for example a welded connection.The resilient portion may comprise a helical spring, for example. Alternatively, the resilient portion may comprise at least one resilient, curved leg. The at least one resilient, bent leg can be designed in particular as a bent leaf spring, wherein the shape and number of bends are adapted to the required spring travel and the installation space present.The connecting element can be designed in particular as a stamped and bent part. In this embodiment, the connecting element is substantially stamped as a whole from a sheet metal and bent into the required shape. Stamped and bent parts of this type can be produced in the required shape in a simple and cost-effective manner.According to a further aspect of the invention, an assembly is specified having at least one printed circuit board with power semiconductor components arranged thereon and at least one busbar for electrically contacting the printed circuit board. The at least one printed circuit board is electrically and mechanically connected to the at least one busbar by means of at least one described connecting element and at least one screw.The assembly has the advantage that the busbar is connected to the printed circuit board in a stable and permanent manner. The assembly is particularly suitable for power applications where high currents flow.According to yet another aspect of the invention, an inverter, in particular a power inverter for an electric drive device of a motor vehicle, is specified, which inverter has at least one previously described assembly. In this case, the power semiconductor components of the assembly are formed as controllable power semiconductor switches each having a control terminal. The inverter further comprises a control circuit which is electrically connected via signal connections to the control terminal of the respective power semiconductor switches.Embodiments of the invention are described below by way of example with reference to schematic drawings. FIG. 1 shows a first view of a connecting element according to a first embodiment of the invention, FIG. 2 shows a second view of the connecting element according to FIG. 1, FIG. 3 shows a third view of the connecting element according to FIGS. 2 and 3, FIG. 4 shows a first view of a connecting element according to a second embodiment of the invention, FIG. 5 shows a second view of the connecting element according to FIG. 4, FIG. 6 shows a third view of the connecting element according to FIGS. 4 and 5, FIG. 7 shows a first view of a connecting element according to a third embodiment of the invention, FIG. 8 shows a second view of the connecting element according to FIG. 7, FIG. 9 shows a third view of the connecting element according to FIGS. 7 and 8, FIG. 10 shows a connecting element connected to a busbar according to a further embodiment of the invention, FIG. 11 shows a connecting element connected to a busbar and to a printed circuit board according to one embodiment of the invention, and FIG. 12 shows the connection of two printed circuit boards to one another by means of a busbar and a plurality of connecting elements.FIG. 1 shows a side view of a connecting element 1 for connecting a busbar to a printed circuit board according to a first embodiment of the invention, in particular for power applications. In the embodiment shown, the connecting element 1 is formed as a stamped bent part from a metal sheet and serves for the electrically conductive and mechanical connection between a busbar and a printed circuit board, which are not shown in the figure.The connecting element 1 has a first contact region 2 for connection to a printed circuit board and a second contact region 4 for connection to a busbar. Between the first contact region 2 and the second contact region 4 a resilient section 3 is arranged for compensating position tolerances or height tolerances.The first contact region 1 is formed by a plurality of press-fit pins 5, which can be press-fit into through holes provided for this purpose in the printed circuit board in order simultaneously to produce an electrical and mechanical connection to the printed circuit board.The second contact region 4 has a plate 6 with a through hole 7 which is formed for receiving a screw and has an internal thread which is not shown in the figures. Alternatively, the through hole 7 can also be formed as a blind hole. The second contact region 4 is designed to receive a busbar which is placed on the plate 6. A screw can then be passed through a through hole in the busbar into the through hole 7 in order to connect the busbar to the connecting element 1.In the embodiment shown, the resilient portion 3 arranged between the contact areas 2, 4 consists of a portion of the metal sheet which has different cut-outs 8 in order to form a plurality of limbs 9, which can be compressed in the vertical direction, i.e. Z-direction, in order to compensate height tolerances between the printed circuit board and the busbar and thus between the first contact area 2 and the second contact area 4.FIG. 2 shows the connecting element 1 in a side view rotated through 90° with respect to the view shown in FIG. 1. In this view, it can be seen that the connecting element 1 is of U-shaped cross section and the first contact region has two mutually opposite rows of press-fit pins 5. As a result, the connecting element 1 has particularly good stability.FIG. 3 shows a perspective view of the connecting element 1 according to FIGS. 1 and 2.FIG. 4 shows a side view of a connecting element 1 according to a second embodiment. This is likewise designed as a stamped bent part and differs from that shown in FIGS. 1 to 3 in the design of the resilient section 3.According to the second embodiment, this has on each side two bent legs 9 comprising a substantially horizontally running upper section 13, a likewise substantially horizontally running lower section 14 and a bend 15 connecting the sections 13, 14. The lower portion 14 is connected to the first contact region 2, while the upper portion 13 is connected to the second contact region 4. The lower section 14 and the upper section 13 are designed to be resilient with respect to one another, so that the distance between the contact regions 2, 4 is variable within the limits of the spring travel.In this embodiment, the legs 9 protrude significantly laterally beyond the first contact region 2 and the second contact region 4 and provide a spring path in the Z direction in the manner of a leaf spring.In this embodiment too, the connecting element has a U-shaped cross section with two rows of press-fit pins 5 which are opposite one another and between which the second contact region 4 is arranged, as can be seen in particular in FIGS. 5 and 6.Figures 7 to 9 show a third embodiment of the connecting element 1, which differs from those shown in Figures 1 to 6 in the configuration of the resilient portion 3. According to the third embodiment, the resilient portion has two limbs 9, which are separated from one another by a cutout 8 and provide a spring path similar to the second embodiment shown in Figures 4 to 6, but asymmetrically only on one side.In this embodiment too, the lower section 14 is connected to the first contact region 2, while the upper section 13 is connected to the second contact region 4.FIG. 10 shows an assembly 30 with a busbar 10 which is connected to a connecting element 1 according to a further embodiment of the invention. According to this embodiment, the connecting region 3 of the connecting element 1 is formed as a helical spring 11 which is compressible in the Z direction and which is arranged between the first contact region 2 and the second contact region 4. The second contact region 2 is merely indicated in this embodiment and could likewise have press-fit pins or else surface-mountable contacts or THT contacts.For connecting the busbar 10 to the connecting element 1, a screw 12 is passed through the through hole 7 of the connecting element 1 and through a through hole in the busbar 10 and screwed into the through hole 7.FIG. 11 shows an assembly 30 with a printed circuit board 20 and a busbar 10, which are electrically and mechanically connected to one another via a connecting element 1. The connecting element 1 is designed as shown in FIGS. 7 to 9. It is guided with its press-in pins 5 into correspondingly formed through-holes of the printed circuit board 20.A bolt 12 is passed through a through hole 16 in the bus bar 10 and through the threaded through hole 7 of the connector 1, and is screwed in the through hole 7. The distance in the Z direction between the printed circuit board 20 and the busbar 10 can be compensated by the spring travel of the resilient section 3.FIG. 12 shows an assembly 30 comprising two printed circuit boards 20 which are connected to one another via a busbar 10, wherein the busbar 10 is connected to each of the printed circuit boards 20 via the connecting element 1 shown in FIG. 11. As can be seen in FIG. 12, the connecting elements 1 can also serve to connect printed circuit boards 20 at different levels, which are connected to one another via bent busbars 10, in a tolerance-compensating manner. In such arrangements, the height and position tolerances that add up can become considerable, so that the use of the connecting element 1 is particularly advantageous.The assembly (30) is, for example. Part of a power inverter of an electric drive device of a motor vehicle, which, in addition to the assembly (30), also has, inter alia, a control circuit. In this case, the power semiconductor components are formed as controllable power semiconductor switches each having a control terminal. The control circuit is electrically connected to the control terminal of the respective power semiconductor switches via signal connections.List of reference characters1 Connecting element 2 First contact region 3 Resilient portion 4 Second contact region 5 Press-fit pin 6 Plate 7 Through hole 8 Cutout 9 Leg 10 Busbar 11 Coil spring 12 Screw 13 Upper portion 14 Lower portion 15 Sheet 16 Through hole 20 Printed circuit board 30 Assembly

Claims

Connecting element (1) for producing an electrical and mechanical connection between a printed circuit board (20) and a busbar (10), having - a first contact region (2) designed for connection to the printed circuit board (20), - a second contact region (4) designed for connection to the busbar (10), and - a resilient section (3) between the first contact region (2) and the second contact region (4), wherein the resilient section (3) is suitable for compensating for a tolerance of a distance between the first contact region (2) and the second contact region (4).The connector (1) according to claim 1, wherein the first contact area (2) comprises a number of press-fit pins (5).The connector (1) according to claim 1, wherein the first contact area (2) comprises a number of SMD solder contacts.The connector (1) according to claim 1, wherein the first contact area (2) comprises a number of THT solder contacts.Connecting element (1) according to one of claims 1 to 4, wherein the second contact region (4) has a thread.Connecting element (1) according to one of claims 1 to 5, wherein the resilient portion (3) has a helical spring (11).Connecting element (1) according to one of claims 1 to 6, wherein the resilient section (3) has at least one resilient, curved leg (9).Connecting element (1) according to Claim 7, wherein the connecting element (1) is designed as a stamped bent part.Assembly (30), comprising - at least one printed circuit board (20) having power semiconductor components arranged thereon; - at least one busbar (10) for electrically contacting the printed circuit board (20), wherein the at least one printed circuit board (20) is electrically and mechanically connected to the at least one busbar (10) by means of at least one connecting element (1) according to one of Claims 1 to 8 and at least one screw (12).Inverter, comprising - an assembly (30) according to claim 9, wherein the power semiconductor components are formed as controllable power semiconductor switches each having a control terminal, - a control circuit, wherein the control circuit is electrically connected to the control terminal of the respective power semiconductor switches via signal connections.

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