Tolerance compensation for current contact with a circuit board
Patent Information
- Application Number
- EP2024707702
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-28
- Filing Date
- 2024-02-16
- Publication Date
- 2025-11-12
AI Technical Summary
Existing circuit board structures face challenges in transmitting large currents while maintaining precise orientation and distance alignment, leading to potential damage and overheating due to inadequate tolerance compensation and small contact areas.
A circuit board structure with a passage opening having a clear width larger than the sleeve neck, allowing lateral play, and a holding structure that fixes the sleeve head to prevent rotation, enabling both lateral and vertical tolerance compensation and distributing tensile loads effectively.
This configuration allows for efficient current transmission with reduced risk of damage, improved contact area, and enhanced current carrying capacity, while preventing overheating and mechanical stress on the circuit board.
Smart Images
Figure EP2024053949_03102024_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Tolerance compensation for power contact to circuit board
[0003] The present invention is based on a printed circuit board structure,
[0004] - wherein the printed circuit board structure comprises a printed circuit board,
[0005] - wherein the circuit board has a through-opening,
[0006] - wherein the circuit board has a contact surface on its upper side in an area surrounding the passage opening,
[0007] - wherein the printed circuit board structure comprises a fastening sleeve with a sleeve head and a sleeve neck,
[0008] - wherein the fastening sleeve is guided from below through the through-opening of the printed circuit board, so that the sleeve head is arranged on the underside of the printed circuit board and the sleeve neck passes through the through-opening,
[0009] - wherein the printed circuit board structure has a holding structure which is fixed below the printed circuit board in a rotationally secure manner relative to the printed circuit board,
[0010] - the sleeve head is fixed in the holding structure in a rotationally secure manner,
[0011] - wherein the sleeve neck has an internal thread for receiving the screw neck of a fastening screw.
[0012] Printed circuit board structures are well known. They are used, for example, in power supply systems for electric drives.
[0013] With such a circuit board structure, high currents often have to be supplied to or discharged from the circuit board. For this, appropriate contact options must be available.
[0014] In the prior art, such currents are often supplied or discharged via intermediate elements which are geometrically designed similarly to a dual-in-line chip. Such intermediate elements have a rectangular central region which, on two opposite edges, has a row of solid pins which are soldered into the circuit board. In their central region, the intermediate elements have threads into which fastening screws can be screwed. When soldering such intermediate elements, great care must be taken to ensure that the central region of the respective intermediate element is oriented exactly parallel to the circuit board and has the "correct" distance from the surface of the circuit board.Otherwise, this can lead to considerable distortion of the printed circuit board, to high contact resistances from the respective intermediate element to a conductor structure connected to the intermediate element, with associated local overheating and possibly even to squeezing or other damage to the printed circuit board.
[0015] Alternatively, it is known to use fastening sleeves with a sleeve head and a sleeve neck - so-called solder nuts - which are soldered with their sleeve head onto the top side of the circuit board. The sleeve neck protrudes from the top side of the circuit board. The sleeve head is therefore arranged between the top side of the circuit board and the sleeve neck. Even with this procedure, great care must be taken when soldering to ensure that the sleeve head is oriented exactly parallel to the circuit board. Furthermore, care must be taken to ensure that the soldering point is not subjected to tensile stress. This is all the more critical because the sleeve heads usually only have a very small contact surface and the force of the screws is therefore transmitted to a correspondingly small area of the circuit board.When larger mounting sleeves are used, the mounting sleeves are correspondingly larger and heavier, which can cause problems on the underside of the circuit board. This is especially true if a press-fit module or other mechanical structure is to be arranged in the corresponding area on the underside. The company brochure "Z-Ray Press-Fit Alignment Hardware" from Samtec, retrieved from the Internet on March 3, 2023 at https: / / does.rs-onl ine.com / 7262 / A700000007153398.pdf, describes various elements that can be press-fitted into a circuit board. When using these elements, the circuit board must be able to absorb considerable mechanical forces, which is not always desired and often not possible. The circuit board must also be manufactured with high geometric accuracy.Furthermore, the elements are rigidly fixed to the circuit board, so that no compensation for tolerances on the top surface of the circuit board is possible. Similar press-fit elements are also offered and distributed by Würth Elektronik ICS GmbH & Co. KG, Niedernhall, Germany.
[0016] A printed circuit board structure of the type mentioned above is known, for example, from US 2014 / 0 211 432 Al.
[0017] From JP 2013 077 687 A a structure is known in which a semiconductor chip is cast in a molded body. The molded body has a heat sink which is arranged on one side of the semiconductor chip. On the opposite side, 2x2 connections protrude from the molded body and are bent towards one another at a certain distance from the molded body so that they form a connection level arranged above the molded body. The bent areas each have a recess for a fastening screw. A holding body made of plastic can be pushed laterally into the area between the molded body and the connection level. The holding body has 2x2 hexagonal receptacles for fastening nuts. Fastening screws can be inserted into the recesses from above and can then be screwed into the fastening nuts. In this way, conductors can be connected to the semiconductor chip.The fastening nuts are held in the hexagonal receptacles in a twist-proof manner, but are not fixed. DE 10 2018 105 784 A1 discloses a printed circuit board structure which has two printed circuit boards arranged one above the other. The lower printed circuit board has through-openings into which contact pins are inserted from above. The contact pins rest with a collar on the upper side of the lower printed circuit board. The respective collar and also the respective area beyond the respective collar are electrically contacted with the lower printed circuit board. The lower printed circuit board has contact areas in the areas where the collars rest on the upper side of the lower printed circuit board. The upper printed circuit board is placed on the ends of the contact pins which are spaced apart from the lower printed circuit board. The contact pins have slots in these areas so that they can give way radially.As a result, the arms of the contact pins formed by the slots rest under spring force on the openings of the upper circuit board.
[0018] From GB 2 202 993 A an arrangement is known which has a semiconductor chip, a printed circuit board, an intermediate structure arranged between the semiconductor chip and the printed circuit board and a fastening screw. The semiconductor chip carries a fastening element which on the one hand has an annular, circumferential step and on the other hand a sleeve with an internal thread protruding from the step. The circular shape of the step is interrupted at one point. There is a straight section instead. The chip is inserted into the intermediate structure which has a recess corresponding to the step. This fixes the chip in the intermediate structure so that it cannot twist. The intermediate structure is inserted into the printed circuit board via two pins and is therefore fixed so that it cannot twist relative to the printed circuit board. The sleeve protruding from the step passes through a recess in the printed circuit board. The fastening screw is screwed into the sleeve.This means that the semiconductor chip is firmly connected to the circuit board.
[0019] The object of the present invention is to create possibilities by means of which electrical contacting of a printed circuit board is possible, via which large currents can be transmitted. At the same time, tolerance compensation relative to the circuit board plane should be possible, both with regard to the distance from the top of the circuit board and with regard to the orientation relative to the top of the circuit board.
[0020] The object is achieved by a printed circuit board structure having the features of claim 1. Advantageous embodiments of the printed circuit board structure are the subject of dependent claims 2 to 8.
[0021] According to the invention, a printed circuit board structure of the type mentioned at the outset is designed in that the through-opening is designed as a closed opening which has a clear width, and that the clear width is greater than an associated dimension of the sleeve neck, so that the sleeve neck is arranged in the through-opening with a lateral play.
[0022] A large-area contact with a connecting element can be made at the contact surface. The connecting element can, for example, be designed as a contact sleeve that is slipped over the sleeve neck and pressed against the contact surface. The contact sleeve is usually made of copper or brass.
[0023] Because the mounting sleeve is positioned so that the sleeve head is on the underside of the circuit board, tensile loads can be easily absorbed. Furthermore, the resulting height by which the mounting sleeve projects above the top side of the circuit board is reduced. At the same time, the extent to which the mounting sleeve projects beyond the underside of the circuit board can also be kept to a minimum.
[0024] Due to the holding structure, the torque that occurs when the fastening screw is screwed into the internal thread can be absorbed by the holding structure and then introduced into the circuit board, so that the fastening sleeve does not rotate when the fastening screw is screwed in.
[0025] The matching of the clear width of the through-hole and the corresponding dimensions of the sleeve neck enables simple lateral tolerance compensation. Furthermore, vertical tolerance compensation is also facilitated because there is no clamping between the circuit board and the sleeve neck, which could hinder such vertical tolerance compensation.
[0026] Preferably, the sleeve head is held in the support structure in a form-fitting manner. This configuration is particularly simple and reliable to implement. For example, the sleeve head can have a polygonal shape, in particular be square or hexagonal.
[0027] In a particularly preferred embodiment, the sleeve neck has an enlarged diameter at its end facing away from the sleeve head compared to its region facing the sleeve head, and the sleeve neck further has slots at its end facing away from the sleeve head, so that the regions of the sleeve neck can spring in between the slots.
[0028] This design makes it possible to additionally press an annular contact sleeve, which is pressed onto the contact surface of the circuit board by means of the fastening screw, onto the areas between the slots on its inside as well, so that the annular contact sleeve is firstly fixed in place before the fastening screw is screwed into the internal thread of the sleeve neck and secondly to allow part of the current to flow via the contact areas where the annular contact element is pressed onto the areas between the slots. As a result, the current-carrying capacity of the contact sleeve is increased. Preferably, the passage opening is circular and the sleeve neck has a circular cross-section, so that the clear width and the associated dimension of the sleeve neck are the diameter. This design is particularly simple.
[0029] Depending on the specific situation, the support structure can be made of an electrically insulating material or an electrically conductive material, as required. In the case of an electrically insulating material, the support structure can be made of a plastic, and in the case of an electrically conductive material, it can be made of steel. Materials based on metals and metal alloys, in particular, often exhibit considerably greater structural strength than can be achieved with plastics.
[0030] The fastening sleeve preferably has a trench-like undercut in a transition area from the sleeve head to the sleeve neck. In this case, the area in which the sleeve head can be pressed against the underside of the circuit board by the fastening screw can be precisely adjusted. Furthermore, it is possible to solder the sleeve head to the underside of the circuit board while still ensuring that solder does not penetrate through the through-hole in the circuit board to the top side of the circuit board.
[0031] Typically, the printed circuit board structure has a power module arranged beneath the printed circuit board. Such a power module is generally connected to the printed circuit board in connection areas. The connection can be a plug-in connection. In many cases, the power module is pressed onto the printed circuit board. Preferably, the sleeve head and the holding structure are arranged within a volume delimited by the printed circuit board, the power module, and the connection areas. The present invention demonstrates its full advantages particularly in this embodiment.
[0032] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Herein, in schematic representation:
[0033] FIG 1 shows a section through a printed circuit board structure,
[0034] FIG 2 is a plan view of a printed circuit board,
[0035] FIG 3 a perspective view of a fastening sleeve,
[0036] FIG 4 a possible contour of a sleeve head,
[0037] FIG 5 is a perspective sectional view of a printed circuit board structure,
[0038] FIG 6 a perspective view of a holding structure with several fastening sleeves,
[0039] FIG 7 a fastening sleeve in longitudinal section,
[0040] FIG 8 another fastening sleeve in longitudinal section,
[0041] FIG 9 is a perspective view of the fastening sleeve of FIG 8 and
[0042] FIG 10 a perspective view of a printed circuit board structure.
[0043] 1, a printed circuit board structure has a printed circuit board 1. Conductor tracks are arranged on the top side 2 and / or the bottom side 3 of the printed circuit board 1 - sometimes also in intermediate layers between the top side 2 and the bottom side 3. The conductor tracks are not shown because they are of secondary importance within the scope of the present invention. What is important, however, is that the printed circuit board 1 has a through-opening 4. The through-opening 4 is a closed opening and has a clear width d4 as seen in the plane of the printed circuit board 1. In the simplest case, the through-opening 4 is circular and therefore has a diameter d4 as a clear width d4 (see also FIG. 2). It is also important that the printed circuit board 1 has a contact surface 5 on its top side 2 in an area surrounding the through-opening 4.
[0044] The printed circuit board structure further comprises a fastening sleeve 6 with a sleeve head 7 and a sleeve neck 8. The fastening sleeve 6 is guided from below through the through-opening 4. As a result, the sleeve head 7 is arranged on the underside 3, and the sleeve neck 8 also passes through the through-opening 4.
[0045] The printed circuit board structure further comprises a holding structure 9. The holding structure 9 is often made of an electrically insulating material, in particular a plastic. In some cases, however, it can also be made of an electrically conductive material, in particular steel. The holding structure 9 is arranged beneath the printed circuit board 1. The holding structure 9 is fixed in a rotationally secure manner relative to the printed circuit board 1. For example, the holding structure 9 can be connected to the printed circuit board 1 by screw connections, as indicated in FIG. 1 by dashed lines 10. However, the precise manner of the rotationally secure fixing of the holding structure 9 relative to the printed circuit board 1 is of secondary importance.
[0046] The sleeve head 7 is fixed in the holding structure 9 in a rotation-proof manner. It is possible that this rotation-proof fixing is achieved by a force fit. Preferably, however, the sleeve head 7 is held in the holding structure 9 in a form-fitting manner. For example, the sleeve head 7 can have a polygonal shape, in particular be hexagonal, as shown in FIG 2 and also in FIG 3. However, other polygonal shapes are also possible, for example a square or octagonal shape. The decisive factor for a form-fitting fixing is that the contour of the sleeve head 7 is different from a circular shape. For example, the sleeve head 7 can even have a contour that runs in a wave-like manner around a central axis, as shown in FIG 4.
[0047] The sleeve neck 8 has an internal thread 11. A fastening screw 12 (see FIG. 5 purely as an example) can be received by the internal thread 11, i.e., can be screwed in.
[0048] FIG 5 further shows a number of facts which are generally implemented and can also be implemented in further embodiments explained in more detail below, but which are not absolutely necessary. For example, in the embodiment of FIG 5, a number of fastening sleeves 6 are present. Furthermore, the fastening sleeves 6 are fixed in the same holding structure 9 in a rotationally secure manner. Contact sleeves 13 are also placed on the sleeve necks 8, the contact sleeves 13 being connected on the one hand to the associated contact surfaces 5 and on the other hand to busbars 14. Not all of the contact sleeves 13 and the busbars 14 are provided with their reference symbols in FIG 5.
[0049] FIG. 6 shows, in isolation, the holding structure 9 as used in the embodiment according to FIG. 5. FIG. 6 clearly shows the polygonal shape of the sleeve heads 7 and also the positive fixation of the fastening sleeves 6 in the holding structure 9.
[0050] FIG 7 shows a section through a typical fastening sleeve 6. According to FIG 7 (see additionally FIG 1 and also other FIGS), the sleeve neck 8 has a corresponding dimension d8 in relation to the clear width d4. The dimension d8 is also related to the plane of the printed circuit board 1. The dimension d8 of the sleeve neck 8 is smaller than the clear width d4 of the through opening 4. This ensures that the sleeve neck 8 is arranged in the through opening 4 - in both transverse directions - with lateral play. The play - i.e. the difference between the clear width d4 and the corresponding dimension d8 - is preferably in the range between 1 mm and 3 mm. If the clear width d4 is a diameter, i.e., the passage opening 4 is circular, the corresponding dimension d8 is preferably also a diameter. In this case, the sleeve neck 8 has a circular cross-section.
[0051] 8 and 9 show a further, particularly preferred embodiment of the fastening sleeve 6. According to FIGS. 8 and 9, the sleeve neck 8 has a region 15 facing the sleeve head 7, an end 16 facing away from the sleeve head 7 and a transition region 17 in between. At its end 16 facing away from the sleeve head 7, the sleeve neck 8 has an enlarged diameter dl 6 compared to its region 15 facing the sleeve head 7. The diameter dl 6 may also be a maximum of as large as the diameter d4 of the through-opening 4. Furthermore, the sleeve neck 8 has slots 18 at its end 16 facing away from the sleeve head 7. The slots 18 extend at least substantially in the longitudinal direction of the sleeve neck 8. Due to this configuration, the areas of the sleeve neck 8 located between the slots 18 can deflect. This is indicated in FIG. 8 by corresponding arrows 19.
[0052] In many cases, the printed circuit board structure has a power module 20 as shown in FIG. 1 (also indicated by dashed lines in FIG. 2 and also shown in FIG. 10). The power module 20, if present, carries semiconductor switching elements. For example, it can implement a single bridge arm or several bridge arms of a converter circuit. The power module 20, if present, is generally arranged below the printed circuit board 1. A heat sink is generally arranged below the power module 20 (indicated in FIG. 1, but not provided with a reference symbol).
[0053] The power module 20 is connected to the printed circuit board 1 in connection areas 21. FIG. 10 shows the corresponding pins extending from the power module 20, which are inserted into the printed circuit board 1. The connection of the power module 20 to the printed circuit board 1 can in particular be designed as a press fit. Regardless of the specific type of connection, however, the printed circuit board 1, the power module 20 and the connection areas 21 delimit a volume. As can be seen from the illustrations in FIGS. 1 and 10, the sleeve head 7 and the holding structure 9 are arranged within this volume.
[0054] A further preferred embodiment of the fastening sleeve 6 can be seen in particular in FIG. 3. Specifically, the fastening sleeve 6 according to FIG. 3 has a trench-like undercut 22 in a transition region from the sleeve head 7 to the sleeve neck 8. The undercut 22 can be used to determine the areas in which the sleeve head 7 may rest against the underside 3 of the printed circuit board 1.
[0055] In summary, the present invention relates to the following:
[0056] A printed circuit board 1 has a through-opening 4 and, on its upper side 2 in an area surrounding the through-opening 4, a contact surface 5. A fastening sleeve 6 has a sleeve head 7 and a sleeve neck 8. The fastening sleeve 6 is guided from below through the through-opening 4 of the printed circuit board 1, so that the sleeve head 7 is arranged on the underside 3 of the printed circuit board 1 and the sleeve neck 8 passes through the through-opening 4. A holding structure 9 is fixed beneath the printed circuit board 1 in a rotationally secure manner relative to the printed circuit board 1, the sleeve head 7 in the holding structure 9. The sleeve neck 8 has an internal thread 11 for receiving the screw neck of a fastening screw 12. The passage opening 4 is designed as a closed opening having a clear width d4.The clear width d4 is greater than an associated dimension d8 of the sleeve neck 8, so that the sleeve neck 8 is arranged in the passage opening 4 with lateral play. The present invention has many advantages. In particular, when connecting a contact sleeve 13 (or another contact element), both lateral and vertical tolerance compensation can be implemented in a simple manner, while nevertheless a rotation-proof fixation of the fastening sleeve 6 relative to the printed circuit board 1 can be achieved in an equally simple manner. This makes it possible to avoid distortions and other damage to the printed circuit board 1. Furthermore, the electrical contact of the contact sleeve 13 (or the other contact element) can be optimized, so that in particular local overheating can be reliably avoided.
[0057] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.
Claims
Patent claims 1. PCB structure, - wherein the printed circuit board structure comprises a printed circuit board (1), - wherein the circuit board (1) has a through-opening (4), - wherein the printed circuit board (1) has a contact surface (5) on its upper side (2) in an area surrounding the passage opening (4), - wherein the printed circuit board structure comprises a fastening sleeve (6) with a sleeve head (7) and a sleeve neck (8), - wherein the fastening sleeve (6) is guided from below through the through-opening (4) of the printed circuit board (1), so that the sleeve head (7) is arranged on the underside (3) of the printed circuit board (1) and the sleeve neck (8) passes through the through-opening (4), - wherein the printed circuit board structure has a holding structure (9) which is fixed below the printed circuit board (1) in a rotationally secure manner relative to the printed circuit board (1), - wherein the sleeve head (7) is fixed in the holding structure (9) in a rotationally secure manner, - wherein the sleeve neck (8) has an internal thread (11) for receiving the screw neck of a fastening screw (12), characterized in that the passage opening (4) is designed as a closed opening which has a clear width (d4), and that the clear width (d4) is greater than an associated dimension (d8) of the sleeve neck (8), so that the sleeve neck (8) is arranged in the passage opening (4) with a lateral play.
2. Printed circuit board structure according to claim 1, characterized in that the sleeve head (7) is held in a form-fitting manner in the holding structure (9).
3. Printed circuit board structure according to claim 2, characterized in that the sleeve head (7) has a polygonal shape, in particular is square or hexagonal.
4. Printed circuit board structure according to claim 1, 2 or 3, characterized in that the sleeve neck (8) has an enlarged diameter (dl6) at its end (16) facing away from the sleeve head (7) compared to its region (15) facing the sleeve head (7) and that the sleeve neck (8) has slots (18) at its end (16) facing away from the sleeve head (7) so that the regions of the sleeve neck (8) can spring in between the slots (18).
5. Printed circuit board structure according to one of the above claims, characterized in that the passage opening (4) is circular and the sleeve neck (8) has a circular cross-section, so that the clear width (4) and the associated dimension (d8) of the sleeve neck (8) are diameters (d4, d8).
6. Printed circuit board structure according to one of the above claims, characterized in that the holding structure (9) consists of an electrically insulating material, in particular a plastic, or of an electrically conductive material, in particular steel.
7. Printed circuit board structure according to one of the above claims, characterized in that the fastening sleeve (6) has a trench-like undercut (22) in a transition region from the sleeve head (7) to the sleeve neck (8).
8. Printed circuit board structure according to one of the above claims, characterized in that - that the printed circuit board structure has a power module (20), - that the power module (20) is arranged below the printed circuit board (1) and is connected to the printed circuit board (1) in connecting regions (21), in particular is pressed onto the printed circuit board (1), and - that the sleeve head (7) and the holding structure (9) are arranged within a volume delimited by the printed circuit board (1), the power module (20) and the connecting regions (21).