Method and connection arrangement for connecting power electronic components and printed circuit boards

Abstract

Method for producing a mechanical and an electrical connection of a power electronic component (110, 120) with a printed circuit board (204, 404, 504, 604), wherein a first component (203, 403, 503, 603) effecting the mechanical connection and a second component (202, 302, 402, 502, 602) effecting the electrical connection are provided, wherein a bore and an electrical contact surface (513) surrounding the bore are provided in the printed circuit board (204, 404, 504, 604), wherein the first component (203, 403, 503, 603) is formed into an elongated cylinder, the cylinder having a head (215) on one side and extending lengthwise into the bore of the printed circuit board (204, 404, 504) on its other side. 604) is introduced, wherein the power electronic component (110, 120) has a mechanical fastening option (111, 121) at a point to be mechanically and electrically connected to the circuit board (204, 404, 504, 604).501) with an electrical contact surface surrounding this mounting option, wherein the second component is made of an electrically conductive material and surrounds the elongated cylinder of the first component (203, 403, 503, 603) in a sleeve-like manner, wherein the electrical contact surface of the power electronic component (110, 120) and the electrical contact surface of the printed circuit board (204, 404, 504, 604) are electrically contacted by the second component, wherein the mechanical connection is formed by a positive locking connection between the first component (203, 403, 503, 603) and the mounting option of the power electronic component (110, 120), and wherein the mechanical connection between the power electronic component (110, 120) and the printed circuit board (204, 404, 504, 604) is achieved by means of the first component (203, 403, 503, 603) also the electrical contact is effected by the second component,and in which the sleeve-like second component is formed with an L-shaped tab (311, 411) for a sensor (412).

Description

[0001] The present invention relates to a method for producing an electrical and mechanical connection between a power electronic component and a circuit board. In particular, the invention considers a connection of a battery cell to a circuit board for transmitting high currents. Furthermore, a connection arrangement is presented.

[0002] Conventional printed circuit board manufacturing technologies are designed for high structural resolution with fine track spacing, thus enabling signal transmission at low currents. In contrast, the high currents encountered in modern power electronics are not possible with the thin photostructured tracks. At the same time, a traditional manufacturing approach using discrete components and screwed busbars is not viable in modern power electronics due to the costs associated with the specialized components and their installation, or at least complicates the provision of standard interfaces to microelectronic controllers, which typically comprise surface-mounted integrated circuits and thus require printed circuit boards.

[0003] For circuit boards with at least one conductor rail, a so-called "outlay," made of copper or aluminum, for example, the conductor rail is usually mechanically and electrically connected to the circuit board via a single connection. This usually involves soldering the conductor rail to a surface metallization patterned, for example, in a lithographic etching process, but can also be connected via pins, such as press-fit.

[0004] However, for power electronic circuits, press-fit and related state-of-the-art technologies for establishing a connection are not advantageous for several reasons. Firstly, the current would first have to flow from the applied conductor rails into the circuit board and / or the press-fit element in order to be dissipated from there to the outside. However, for currents of several hundred amperes, a conventional contact barrier at a respective interface already results in high losses. Secondly, the press-fit elements used to date usually require installation space, in particular the height for threaded bolts, for example. This makes it difficult or impossible to bring the necessary cooling, e.g. using a cooling plate, directly or indirectly to the conductor rail and / or power components on the circuit board via a thin gap pad, since this requires a uniform surface without varying heights of the components.A conventional screw connection or a pressed-in, attached bolt would have to be provided at a point in a surface area of ​​the cooling plate and possibly milled out there, which would incur enormous costs in a product intended for series production. Furthermore, establishing a connection indirectly via press-fit is not ideal, since high current should be fed to or carried away from the conductor rails or a cable as directly as possible. In many automotive systems, connections are made perpendicular to the circuit board, for example. Contact between the power supply and the applied conductor rail should be as direct as possible and not be established through additional spacers, e.g., by means of a press-fit through-hole in the circuit board.

[0005] Another connection option, for example, to conductor rails running on the top side of the circuit board, is a power supply from the underside of the circuit board, with the power supply extending through the board. However, this approach has the problem of low or at least limited mechanical strength, since the power supply repeatedly pushes the conductor rail away from the circuit board over time when subjected to vibration, such as that found in a moving vehicle using such power electronics. This can cause the connection to become brittle and eventually break.

[0006] For circuit boards with outlay busbars or embedded, so-called inlay busbars, a screw connection to the respective busbars is generally possible starting at a thickness of approximately 1 mm. Since insulating circuit board material, which can be made, for example, from glass fiber reinforced epoxy resin, so-called prepreg, would begin to flow in the areas exposed to pressure from the screw connection, it is removed from these areas, particularly in the case of inlays, and the screw connection is driven directly into the inlay. If there is no reinforcement by a busbar in or on the circuit board, the pressure can be redirected from the prepreg to dimensionally stable metal using a metal sleeve. This is shown, for example, in the document US 2005 / 0134254 A1, in which the screw is guided through a type of sleeve.

[0007] In the US publication US 2018 / 0235071 A1, conductive layers are also connected to one another using a conductive sleeve and a screw. The overall assembly represents a power electronic control system for an electric motor. The screw is guided through the sleeve and driven into a bottom layer made of a composite material.

[0008] Battery cells, in particular, often have threaded bolts or blind holes with internal threads, with a contact surface surrounding the bolt or hole. In the document US 2010 / 0062329 A1, for example, a screw is screwed into such a blind hole of a respective terminal of several battery cells to connect the battery cells in series via a connecting frame. A battery current is then transferred through the respective screw to the connecting rails of the connecting frame.

[0009] The publication DE 10 2016 213 225 A1 discusses electrical contacting with mechanical fastening means, disclosing a circuit arrangement comprising a first circuit component, a second circuit component, an electrically conductive contact sleeve for establishing electrical and mechanical connections between the first circuit component and the second circuit component, and an electrically conductive contact socket, which is in planar and electrically conductive contact with the second circuit component. The contact sleeve surrounds the contact socket and is in planar and electrically conductive contact with it.

[0010] US Patent No. 4,863,389 describes a terminal block for connecting an electronic component to a printed circuit board. A screw hole in the terminal block and the printed circuit board allows a threaded screw to be inserted into the electronic component, firmly connecting it to the circuit board.

[0011] The document US 2018 / 0027692A1 discloses an electrical assembly comprising: a conductor surrounded by an insulator element; a core surrounding the insulator element and the conductor such that a current flowing through the conductor induces a magnetic field in the core; a transducer connected to the core for generating a signal representative of the current in the conductor; a thermal interface element engaging the core; and a housing supporting the insulator element, the housing engaging the thermal interface element such that the interface element conducts heat to the housing.

[0012] Against this background, it is an object of the present invention to provide a method for connecting power electronic components and printed circuit boards that establishes both a mechanical and an electrical connection, ensuring the transmission of high currents and preventing the associated thermal expansion of the materials used from affecting the strength of the mechanical connection and, in turn, impairing the electrical connection. Furthermore, a system is to be disclosed that includes a connection effected or established according to the presented method.

[0013] To achieve the above-mentioned object, a method for producing a mechanical and an electrical connection between a power electronic component and a printed circuit board is proposed, wherein a first component which effects the mechanical connection and a second sleeve-like component which effects the electrical connection are provided. A bore and an electrical contact surface surrounding the bore are introduced into the printed circuit board. The first component is shaped into an elongated cylinder, wherein the cylinder has a head on one side and is inserted lengthwise into the bore of the printed circuit board towards its other side. The power electronic component has, at a point to be mechanically and electrically connected to the printed circuit board, a mechanical fastening option with an electrical contact surface surrounding this fastening option.The second component is made of an electrically conductive material and surrounds the elongated cylinder of the first component in a sleeve-like manner. This second component electrically connects the electrical contact surface of the power electronic component and the electrical contact surface of the circuit board. The mechanical connection is formed by a positive connection between the first component and the fastening means of the power electronic component. The mechanical connection between the power electronic component and the circuit board by means of the first component also creates electrical contact through the second component.

[0014] The circuit board advantageously has a metallic inlay at the location of the hole, through which the hole and the first component are guided. However, the electrical contact surface surrounding the hole can also be a metallized layer on the underside of the circuit board if the first component with a head is guided through the hole from above.

[0015] Furthermore, the method according to the invention advantageously achieves a low overall height on one side of the printed circuit board on which the head of the first component rests.

[0016] Alternatively, a material is selected for the first component without taking electrical conductivity into account. The first component, together with the fastening option for the power electronic component, carries out contact pressing of the power electronic component to the circuit board. Since this first component does not need to have any electrical properties, it can be selected regardless of electrical conductivity. For example, copper has a high electrical conductivity among metals, but its use as a fastening element is limited due to its ease of deformability compared to steel. With material properties reduced by the electrical conductivity, comparatively poorly conductive steels can also be considered as a material choice for the first component. Therefore, in one embodiment of the method according to the invention, steel is selected as the material for the first component.

[0017] In a further embodiment of the method according to the invention, the power electronic component has a bolt as a fastening option, whereupon the elongated cylinder of the first component is formed into a hollow cylinder.

[0018] In another embodiment of the method according to the invention, the power electronic component has a blind hole as a fastening option, whereupon the elongated cylinder of the first component is formed into a bolt.

[0019] In a further embodiment of the method according to the invention, the positive connection is selected from the following list: screwing, riveting. It is conceivable that the positive connection is implemented by soldering or gluing.

[0020] If a positive-locking connection is selected as a screw connection, a thread is arranged on the fastening option of the power electronic component. If this is a bolt, an external thread is cut on the bolt. Accordingly, an internal thread is cut into the elongated cylinder of the first component, which is shaped like a hollow cylinder. If it is a blind hole, an internal thread is cut into the blind hole. Accordingly, an external thread is cut into the elongated cylinder of the first component, which is shaped like a bolt. Furthermore, the head of the first component is provided with a connection to a turning tool. This can be, for example, a slot, a Phillips recess, an Allen key, a Torx key, or similar.

[0021] In yet another embodiment of the method according to the invention, a further component, which can be a washer and distributes a contact force, is arranged between the electrical contact surface of the circuit board surrounding the bore and the head of the first component. The contact force exerted directly on the circuit board by a chin of the head can, under vibration loading, reach such an extent that the strength of the circuit board at the location of the bore and of the electrical contact surface surrounding the bore is stressed beyond a load limit, for example with regard to plastic deformability or a yield point. In such a case, the contact force can be distributed by enlarging the area stressed by the chin by means of a washer.

[0022] The vibration load mentioned above can occur, for example, during operation of a motor vehicle, which can be an electric car, in which the connection produced according to the invention is arranged between a battery cell as part of a traction battery and a power electronic circuit used for engine control.

[0023] In a further embodiment of the method according to the invention, the power electronic component is selected as a battery cell or as a contactor or as another power electronic component designed for high current transfer.

[0024] According to the invention, the sleeve-like second component is formed with an L-shaped tab for a sensor.

[0025] Furthermore, a connection arrangement comprising a first component, a sleeve, a power electronic component and a printed circuit board is claimed, wherein the sleeve is configured to be provided as a second component bringing about the electrical connection in addition to a first component bringing about a mechanical connection. A bore and an electrical contact surface surrounding the bore are introduced into the printed circuit board. The first component is shaped into an elongated cylinder, wherein the cylinder has a head on one side and is inserted lengthwise into the bore of the printed circuit board towards its other side. The power electronic component has, at a point to be mechanically and electrically connected to the printed circuit board, a mechanical fastening option with an electrical contact surface surrounding this fastening option.The sleeve is formed from an electrically conductive material and is configured to enclose the elongated cylinder of the first component in a sleeve-like manner and to electrically contact the electrical contact surface of the power electronic component and the electrical contact surface of the circuit board. The mechanical connection is formed by a positive connection between the first component and the fastening option of the power electronic component. Finally, the sleeve is configured to effect electrical contact through the mechanical connection of the power electronic component and the circuit board by means of the first component.

[0026] An electrical line is conducted within the sleeve according to the invention. This is formed, for example, from brass or preferably from copper or plated copper, e.g., with nickel or tin. To provide an enlarged contact surface, the sleeve according to the invention can have a radially inwardly or outwardly extending L-shaped cross-section or L-shaped rotational body. Regardless of the selected form of the positive connection between the first component and the power electronic device, such as a screw connection via respectively arranged screw threads, the sleeve according to the invention does not need to have a thread. A minimum requirement is merely a not excessively high plastic deformability within an estimated pressure range. Furthermore, depending on the requirements, the sleeve according to the invention can additionally have further connections or, for example, a welded-on metal rail portion.

[0027] According to the invention, the sleeve has an L-shaped tab for a sensor. This can be used, for example, to measure the voltage of a battery cell, since the sleeve with the tab enables a type of Kelvin connection, i.e., a four-wire measurement, since a load current from the battery cell flows through a main body of the sleeve, which generates ohmic and inductive voltage drops, to the circuit board, but not through the L-shaped extension of the sleeve.

[0028] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0029] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention. Fig. Figure 1 schematically shows two battery cells from the prior art, each with a connection of the poles through a bolt or through a blind hole. Fig. 2 shows a schematic sectional view through components arranged according to the invention according to an embodiment of the method according to the invention. Fig. 3 shows schematically a sleeve with an L-shaped tab for a sensor in an embodiment of the sleeve according to the invention. Fig. 4 shows schematically a sectional view through a connection produced according to the invention according to an embodiment of the method according to the invention. Fig. 5 shows exploded views of the connection process according to the invention in one embodiment of the method according to the invention. Fig. 6 shows a schematic sectional view through a connection produced according to the invention with a bolt-like first component in an embodiment of the method according to the invention.

[0030] In Fig. 1 schematically shows two battery cells 110, 120 from the prior art, each with a terminal connection via a bolt 111 or a blind hole 121. The respective bolt 111 or the respective blind hole 121 forms a respective fastening element, which, when an embodiment of the method according to the invention is carried out, forms a positive connection with the first component provided according to the invention.

[0031] In Fig. 2 schematically shows a sectional view 200 through components 202, 203, 204 arranged according to the invention according to one embodiment of the method according to the invention. The first component 203 provided according to the invention is guided through a bore in a circuit board 204, wherein a head 215 has a connection for a turning tool and presses onto a washer 209, whereby a force is transmitted to an upper side of the circuit board 204. The first component 203 is preferably made of a mechanically stable material that does not need to be electrically conductive. An elongated shape of the first component 203 is designed here as a hollow cylinder with an internal thread 207, wherein the hollow cylinder is provided, for example, for receiving 201 for fastening to a power electronic component, which can be a battery cell.The printed circuit board 204 has a metal layer 213 on its underside, against which a sleeve 202 according to the invention with an upper contact surface 214 is pressed from below. The sleeve 202 is advantageously designed in an inwardly L-shaped manner, whereby a lower contact surface 208 is enlarged to form a power electronic component. It is further advantageously formed from a highly electrically conductive material, e.g., copper. Since the sleeve does not serve to provide mechanical connection strength, a material that is more easily deformable than, for example, steel can also be selected as the highly electrically conductive material. The sleeve 202 is pressed against the printed circuit board 204 by a positive connection between the first component 203 and the fastening option of the power electronic component, wherein this fastening option is a bolt in this case.Due to the positive connection, the power electronic component presses against the lower contact surface 208 of the sleeve 202, whereby the sleeve 202 is pressed against the printed circuit board 204.

[0032] In Fig. Figure 3 schematically shows a sleeve 300 with an L-shaped tab 311 for a sensor receptacle 312 in one embodiment of the sleeve 302 according to the invention. According to the invention, the first component is guided into the cavity 301 of the sleeve 302 from above. Through a positive connection with a power electronic component pressing against the sleeve from below, the first component presses the sleeve with its contact surface 314 upwards onto the circuit board.

[0033] In Fig. 4 schematically shows a sectional view 400 through a connection produced according to the invention according to one embodiment of the method according to the invention. The first component 403 presses from above with the chin of its head directly onto an inlay 413 of a printed circuit board 404 and, designed as a hollow cylinder with an internal thread 407, has a receptacle 401 for a bolt-like pole connection with an external thread. From below, a sleeve 402, which has a contact surface 408 to a pole cap of a battery cell, is pressed against the inlay 413 and thus establishes electrical contact between the battery cell and the inlay 413. Furthermore, the sleeve sits on a battery cell frame 406, which is designed as a receptacle 405 for the pole cap. Finally, the sleeve 402 has an L-shaped tab 411 with a connection for a sensor 412. The sensor 412 can, for example,be formed by a cell measuring contact for a battery management and arranged by riveting in the L-shaped tab 411.

[0034] In Fig. 5 shows the connection process according to the invention in an exploded view 510 from below and in an exploded view 520 from above in one embodiment of the method according to the invention. The sleeve 502 according to the invention, the printed circuit board 504 with a stripped contact surface 513 running around a bore, and the first component 503 are placed or screwed onto the terminal connection 501 of a battery cell 505 with the attached battery cell frame 506.

[0035] In Fig.6 schematically shows a sectional view 600 through a connection produced according to the invention with a bolt-like first component 603 according to one embodiment of the method according to the invention. The first component 603 presses from above with its head onto a washer 609 on a printed circuit board 604 and, designed as a bolt with an external thread 607, is screwed directly into a blind hole of a pole cap 605. As a result, a sleeve 602 according to the invention, located between the pole cap 605, the battery cell frame 606, and the inlay 613 in the printed circuit board, establishes the electrical contact between the pole cap 605 and the inlay 613.

Claims

[1] Method for producing a mechanical and an electrical connection of a power electronic component (110, 120) to a printed circuit board (204, 404, 504, 604), wherein a first component (203, 403, 503, 603) effecting the mechanical connection and a second component (202, 302, 402, 502, 602) effecting the electrical connection are provided, wherein a bore and an electrical contact surface (513) surrounding the bore are introduced into the printed circuit board (204, 404, 504, 604), wherein the first component (203, 403, 503, 603) is formed into an elongated cylinder, wherein the cylinder has a head (215) on one side and is inserted lengthwise towards its other side into the bore of the printed circuit board (204, 404, 504, 604), wherein the power electronic component (110, 120) has a mechanical fastening possibility (111, 121,501) with an electrical contact surface surrounding this fastening possibility, wherein the second component is formed from an electrically conductive material and surrounds the elongated cylinder of the first component (203, 403, 503, 603) in a sleeve-like manner, wherein the electrical contact surface of the power electronic component (110, 120) and the electrical contact surface of the printed circuit board (204, 404, 504, 604) are electrically contacted by the second component, wherein the mechanical connection is formed by a positive connection of the first component (203, 403, 503, 603) and the fastening possibility of the power electronic component (110, 120), and wherein the mechanical connection of the power electronic component (110, 120) and the printed circuit board (204, 404, 504, 604) by means of the first component (203, 403, 503, 603) the electrical contact is also effected by the second component,and in which the sleeve-like second component is formed with an L-shaped tab (311, 411) for a sensor (412). [2] Method according to claim 1, wherein a steel is selected as the material for the first component (203, 403, 503, 603). [3] Method according to one of the preceding claims, in which the power electronic component (110, 120) has a bolt as a fastening option, and accordingly the elongated cylinder of the first component (203, 403, 503, 603) is formed into a hollow cylinder. [4] Method according to one of claims 1 or 2, in which the power electronic component (110, 120) has a blind hole as a fastening option, and accordingly the elongated cylinder of the first component (203, 403, 503, 603) is formed into a bolt. [5] Method according to one of the preceding claims, in which the positive connection is selected from the following list: screwing, riveting. [6] Method according to one of the preceding claims, in which a further component which distributes a contact force and which can be a washer (209, 609) is arranged between the electrical contact surface of the printed circuit board (204, 404, 504, 604) surrounding the bore and the head of the first component (203, 403, 503, 603). [7] Method according to one of the preceding claims, in which the power electronic component (110, 120) is selected as a battery cell or as a contactor or as another power electronic component (110, 120) designed for high current transfer. [8] A connection arrangement comprising a first component (203, 403, 503, 603), a sleeve (202, 302, 402, 502, 602), a power electronic component (110, 120) and a printed circuit board (204, 404, 504, 604), wherein the sleeve (202, 302, 402, 502, 602) is configured to be provided as a second component that effects the electrical connection in addition to the first component (203, 403, 503, 603) that effects a mechanical connection, wherein a bore and an electrical contact surface (513) surrounding the bore are introduced into the printed circuit board (204, 404, 504, 604), wherein the first component (203, 403, 503, 603) is formed into an elongated cylinder, the cylinder having a head (215) on one side and being inserted lengthwise into the bore of the printed circuit board (204, 404, 504, 604) towards its other side, the power electronic component (110, 120) being fixed to the printed circuit board (204, 404, 504,604) has a mechanical fastening possibility (111, 121, 501) with an electrical contact surface running around this fastening possibility, wherein the sleeve (202, 302, 402, 502, 602) is formed from an electrically conductive material, has an L-shaped tab (311, 411) for a sensor (412), and is configured to enclose the elongated cylinder of the first component (203, 403, 503, 603) in a sleeve-like manner and to electrically contact the electrical contact surface of the power electronic component (110, 120) and the electrical contact surface of the printed circuit board (204, 404, 504, 604), wherein the mechanical connection is achieved by a positive connection of the first component (203, 403, 503, 603) and the Fastening possibility of the power electronic component (110, 120) is formed and wherein the sleeve (202, 302, 402, 502, 602) is configured toto effect electrical contact by mechanically connecting the power electronic component (110, 120) and the printed circuit board (204, 404, 504, 604) by means of the first component (203, 403, 503, 603).

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