Electrical contact elements

Abstract

The invention relates to a one-piece stamped and rolled electrical contact element (3) for electrically contacting a contact surface by means of a soldered connection, comprising a connecting section (4) and a soldering section (5) connecting the connecting section, wherein the soldering section (5) has the shape of a sleeve slit in the longitudinal direction, wherein the sleeve edge (10) formed along the slit (6) is bent inwards and extends into the inner cavity (11) of the sleeve-shaped soldering section (5). With the electrical contact element, an inexpensive contact can be realized which requires little space on a printed circuit board and at the same time achieves good mounting stability. The solder can be raised to a desired height inside as required, thereby further increasing the strength of the soldered connection.

Description

Technical Field

[0001] The invention relates to a one-piece stamped and rolled electrical contact element for electrically contacting a contact surface, comprising a connecting section and a welding section connecting the connecting section. Background Art

[0002] Such contact elements are used to make electrical contact with contact surfaces on a printed circuit board, preferably by means of a soldered connection, and are usually inserted longitudinally into a contact carrier. The rear connection section is used to connect the electrical line either directly to the contact element, depending on the specific technical solution, or to establish contact by means of a contact pin that can be inserted longitudinally into the contact element and is connected to the electrical conductor.

[0003] In principle, products for SMD assembly for surface mounting on printed circuit boards are preferably manufactured as turned parts or stamped and rolled parts. Due to space considerations in the contact pattern in the plug-in area, only a wall thickness or plate thickness of 0.2 to 0.25 mm is allowed, so the fixation is usually implemented by an interference fit between the contact and the contact holder / insulator. The necessary accuracy is thus achieved for all surfaces to be soldered, especially for SMD products. In addition to the positional accuracy of the surface to be soldered, there are also regulations regarding the geometry of the surface to be soldered. In particular, due to the geometric boundary conditions for multi-pole and cylindrically arranged contact systems, sufficient mechanical strength must be ensured in the case of small space requirements, so that known joints are not very suitable.

[0004] For example, L-shaped wall connectors can only be used to a limited extent, since the space required from the contact to the printed circuit board is relatively large. In addition, such connectors are usually prone to elasticity due to the use of thinner metal sheets in the soldering area (generally the area where soldering is performed), so that this surface cannot be used at the same time for mounting the contact in the contact body. For this purpose, an additional flat surface must be provided on the contact for applying the mounting force. This results in inaccuracies in the manufacturing process, since the tolerances of the press-fit surface and the soldering surface must also be taken into account.

[0005] Also known are so-called J-joints, in which the metal sheet is bent in the welding area, so that more welding surface is achieved with a thinner sheet thickness. Compared to the aforementioned L-joints, these joints require less space and have a higher rigidity due to the double wall thickness to reinforce the welding area. However, such joints are more expensive to produce, since the sheet metal strips used to produce the contacts must have larger dimensions due to the material bent through 180°.

[0006] Another type of joint with a soldering point is equivalent to a rotating contact. A solid rear area is provided for soldering, which provides a sufficient soldering surface and enhances the stability of the installation process. The front area is sleeve-shaped to enable the insertion of the contact pin. This joint has a minimum space requirement due to this coaxial structure. The implementation of the stamped and rolled contacts must be placed on a stepped metal plate based on the necessary thinner strips in a contact diagram of 0.2 to 0.25 mm. In order to provide sufficient stability during the installation process and to provide sufficient surface for soldering, a thicker metal plate is used in the basic state, which must then be laboriously reduced to the necessary thinner plate thickness for the front area. This increases the manufacturing costs and the weight of the contacts. Summary of the invention

[0007] In view of the above, the object of the present invention is to provide a one-piece stamped and rolled contact which requires little space on the printed circuit board and at the same time achieves good mounting stability, optimized solderability and low costs.

[0008] The solution of the present invention to achieve the above-mentioned purpose is an electrical contact element. More advantageous technical solutions are described below.

[0009] According to the present invention, the contact element has a welding section, which has the shape of a slotted sleeve and is constructed as a slotted sleeve. This rolled sleeve has a slot, which is produced by manufacturing and is as narrow as possible for stability considerations, close to zero in extreme cases because the sleeve edges abut each other. Depending on the specific technical solution, this inner cavity of the welding section is hollow, interrupted or at least partially filled along the longitudinal direction. This technical solution is aimed at the required stability of the welding section and the amount of available solder used to weld the welding section on the pad of the printed circuit board. The solder rises in the inner cavity by capillary force, thereby helping to enhance stability in addition to forming solder grooves on the periphery of the welding section on the printed circuit board. When there is not enough solder on the pad or when this additional stability is not needed, soldering resistance is required. The welding section can have an inner cavity filled with solder continuously over the entire length, only at a certain specific distance, or does not have an inner cavity at all. Compared to rotating contact elements, contact elements with this design thus have a much lower weight, wherein the stability is increased by further measures or inflowing solder in the soldering area. The invention is applicable both to SMD and to THR / THT. In SMD, the contacts terminate above the printed circuit board, whereas in THR / THT they do not terminate above the printed circuit board, but are immersed in the printed circuit board by drilling or penetrate the printed circuit board.

[0010] Advantageously, the soldering section has a solder receiving surface at least partially in the inner cavity on the inner surface starting from the free end. This surface is produced by electroplating and ensures good wettability of the inner surface by the flowing solder. Depending on the specific application, electroplating can also be carried out after rolling.

[0011] According to one embodiment of the invention, a solder barrier is arranged in the inner cavity to prevent the solder from rising from the free end in the inner cavity. The solder barrier can have different structures depending on the specific technical solution of the welding section. In one embodiment of the invention, the welding section is continuously tubular in principle, that is, the edges of the sleeve are completely or slightly spaced apart, but still produce a tubular impression. In this embodiment, the solder barrier is a cover plate punched and bent from the circumference of the contact area, which is located in the inner cavity and closes the inner cavity to prevent the solder from rising further. The solder barrier is preferably similar to an omega, so that the round diameter of the inner cavity is closed as tightly as possible and the rising solder cannot pass through the solder barrier. This solder barrier is punched from a blank and bent after rolling. It can be arranged at any position in the length of the welding section.

[0012] According to another preferred embodiment of the invention, the sleeve edge formed along the slit is bent inwards and extends into the inner cavity of the sleeve or the sleeve-shaped welding section. As a result, the contact element has a profile in cross section that is known when crimping contacts with wires. The cross-sectional profile can be constructed in such a way that the slit is completely closed in the longitudinal direction, so that there is no distance between the bent sleeve edges or there is a distance sufficient to ensure stability, so that it is only slightly open. In addition, the cross-sectional profile can be completely or only partially closed, so that either there is no cavity or there is an inner cavity extending in the longitudinal direction of the welding section. By completely closing, a certain cross-sectional profile is achieved, which is equivalent to a rotating contact and thus has the advantages of higher stability and lower space requirements, without having to pay the price of the stepped contacts of the strips on the known welding joints mentioned above, the greater weight or the higher material requirements.

[0013] The completely closed cross-sectional contour prevents solder from penetrating into the free ends placed on the soldering surface from top to bottom during SMD implementation, or into the soldering section when passing through the soldering section (THR / THT) of the printed circuit board, so that soldering can only be performed outside the soldering section.

[0014] In the case of a cross-sectional profile that is only partially closed (hereinafter referred to as an open cross-sectional profile), the solder rises not only in the outer region of the soldering section, where the solder groove is formed, but also partially inside the soldering section. The solder wetted surface thus increased can increase the strength of the soldering area between the contact element or the soldering section and the soldering pad. Depending on the specific properties of the printed circuit board, this increased specific stability in the soldering area allows a connection strength between the contact element and the printed circuit board that is similar to that of the prior art to be achieved by providing only a smaller surface for the soldering pad. This allows a simpler and more compact printed circuit board design and a smaller template opening, or, in the case of a larger template opening, an increased force transmission and the robustness of the soldered connection.

[0015] Such a contact element is preferably produced in such a way that the sleeve edge is bent into the interior after the electroplating of the contact element.

[0016] According to another embodiment of the contact element, in the case of an open cross-sectional profile, the length of the sleeve edge that is bent into the interior is 70 to 90% of the inner diameter of the sleeve-shaped soldering section. The substantially parallel sleeve edges extend more deeply into the interior of the sleeve-shaped soldering section, thereby increasing the strength. Depending on the extent of the extension, the cross section of the increased solder volume is affected.

[0017] According to another construction scheme, the cross-sectional profile is completely closed. As mentioned above, this prevents any solder from rising inside the welding section.

[0018] According to another particularly preferred embodiment, the cross-sectional profile of the sleeve-shaped welding section is not completely closed in the front region at the free end of the welding section, and is completely closed in the rear region adjoining the front region. Thus, in this technical solution, a solder barrier whose height can be adjusted as desired is provided. The advantage of this technical solution is that a solder groove is formed externally in the front region of the welding section, and the solder is pulled upwards internally along the sleeve edge of the front region, thereby contributing to the stability in addition to the welding connection established inside the welding section. This can be set depending on the specific application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features and feature combinations previously listed in the specification and the features and feature combinations mentioned below in the description of the drawings and / or shown separately in the drawings can be combined in the manner given in this application, or can be applied in combination or separately in other ways. All features and / or advantages in the claims, description or drawings, whether alone or in various combinations, are the essence of the present invention. The same or similar components in the drawings are represented by the same or similar figure numbers. The present invention is described below in conjunction with an embodiment. Among them:

[0020] Figure 1is a contact having a stamped and rolled contact on a lath;

[0021] Figure 2 is an enlarged view of a sleeve-shaped contact element having a welding section with a sleeve edge bent in an inner cavity;

[0022] Figure 3 for Figure 2 A perspective view of the different soldering sections of the contact element and a SMD cross-sectional view are shown, including a contact element that is completely closed in the cross-sectional profile ( Figure 3 A) Contact elements that are closed in the cross-sectional profile from a certain height ( Figure 3 B), and the contact element fully opened in the cross-sectional profile ( Figure 3 C); and

[0023] Figure 4 A perspective view of several soldering sections of a contact element, wherein the cross-sectional profile of one soldering section is circular; and a SMD cross-sectional view, including a solder barrier ( Figure 4 A) and a solder barrier arranged away from the free end ( Figure 4 B). DETAILED DESCRIPTION

[0024] Figure 1 The contact 1 in the embodiment has a strip 2 on which a stamped and rolled contact element 3 is fixed. Figure 2 As shown, the contact element 3 has a connection area 4 and a soldering section 5. In this case, the connection area 4 is used to insert a contact pin (not shown). The soldering section 5 is sleeve-shaped and has a longitudinally extending slit 6 that connects the connection area 4 to the free end, that is, in the case of SMD, to the contact area 7 of the printed circuit board (not shown), at which the bent edges 10 of the sleeve-shaped soldering section 5 abut against each other. The edges 10 of the sleeve-shaped soldering section 5 are bent inwards and are more or less pressed together. In this figure, the edges 10 of the sleeve-shaped soldering section 5 are only pressed together to a certain extent, so that the solder 12' can rise from the free end 7 into the entire soldering section 5, see Figure 3 C.

[0025] Figure 3A shows a welding section 5, in which the edge 10 is completely compressed so that, as shown in the cross-sectional view, the unillustrated pad located on the printed circuit board can only form a solder groove with solder 12. In this embodiment, the welding section 5 has a closed cross-sectional profile. In Figure B, the welding section 5 is divided into a front area 8 and a rear area 9. In the front area 8, the curved sleeve edge 10 is not completely closed (open cross-sectional profile), that is, an inner cavity 11 is provided, in which the solder 12' can rise in the welding section 5 until the rear area 9 with a closed cross-sectional profile. In this technical solution, in addition to the solder groove with solder 12, the stability of the entire joint is enhanced by the solder 12' rising in the inner cavity 11. The lengths of the front area 8 and the rear area 9 can be variable. Finally, in Figure 3 In the variant shown in c, the entire soldering section 5 is not closed (open cross-sectional profile), so that the solder 12 can rise in the inner cavity 11 until no more solder 12' is available. In this technical solution, the stability is improved by the solder 12' in addition to the solder groove with solder 12. Figure 3 The technical solution in B is further enhanced.

[0026] Figure 4 An embodiment with a perfectly round tubular welding section 5 is shown, wherein the same reference numerals denote the same components disclosed in the previous figures. Figure 4 In FIG. 1A , a solder barrier 13 is formed on the free end 7 , which is folded over the end of the soldering section 5 and closes the inner cavity 11 (not shown in this figure) and prevents the penetration of solder which is only located as a solder groove on the periphery of the soldering section 5 . Figure 4 B shows the solder barrier 13 far away from the free end 7, wherein the distance from the free end 7 can be adjusted arbitrarily.

[0027] Description of Reference Numerals

[0028] 1 Contact

[0029] 2 Slats

[0030] 3 Contact elements

[0031] 4 Connecting sections

[0032] 5 Welding section

[0033] 6. Opening

[0034] 7 Free end / contact area on printed circuit board

[0035] 8 Front area

[0036] 9 Post Area

[0037] 10 Casing edge

[0038] 11 Inner cavity

[0039] 12, 12' Solder

[0040] 13 solder barrier

Claims

1. A one-piece stamped and rolled electrical contact element (3) for electrically contacting a contact surface by means of a welded connection, comprising a connecting section (4) and a welding section (5) connecting the connecting section, characterized in that: The welding section (5) has the shape of a sleeve with a slit in the longitudinal direction, wherein the inner cavity (11) of the welding section (5) is hollow, interrupted or at least partially filled in the longitudinal direction, wherein the sleeve edge (10) formed along the slit (6) is bent inwardly and extends into the inner cavity (11) of the sleeve-shaped welding section (5).

2. The contact element (3) according to claim 1, characterized in that The soldering section (5) has, at least partially in the inner cavity (11), a surface for receiving solder starting from the contact area (7).

3. The contact element (3) according to claim 1 or 2, characterized in that A solder barrier (13) is arranged in the inner cavity (11) to prevent solder from rising from the contact area (7) in the inner cavity (11).

4. The contact element (3) according to claim 3, characterized in that The solder barrier (13) is an Omega-shaped cover plate formed by stamping and bending the circumference of the contact area (7). The cover plate is located in the inner cavity (11) and closes the inner cavity to prevent the solder from further rising.

5. The contact element according to claim 1, characterized in that The length of the sleeve edge (10) bent and extending into the inner cavity (11) is 70% to 90% of the inner diameter of the sleeve-shaped welding section (5).

6. The contact element according to claim 1, characterized in that The sleeve-shaped welding section (5) has a completely closed cross-sectional profile.

7. The contact element according to claim 1, characterized in that At the free end of the welding section (5), the sleeve-shaped welding section (5) has an incompletely closed cross-sectional profile in a front region (8) and a completely closed cross-sectional profile in a rear region (9) connecting the front region.

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