Electrical contact element with a finely structured contact surface

An electrical contact element is disclosed. The electrical contact element includes a contact surface of an electrically conductive contact body having a plurality of coated regions with a first coating and a plurality of uncoated regions without the first coating, the coated regions and uncoated regions arranged in an alternating manner in a variation direction along the contact surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date under 35 U.S.C. §119(a)-(d) of German Patent Application No. 102015209855.9, filed May 28, 2015.

FIELD OF THE INVENTION

The invention relates to an electrical contact element, and more particularly, to a contact surface of an electrical contact element.

BACKGROUND

Electrical contacts formed of conductive materials and used to establish a direct electrical connection to another conductive element are known in the art. Known electrical contacts, for example, are used in the contact section of a plug contact, cable shoe, ferrule, crimp section, or other known forms of electrical connectors to connect to a known conductive element such as a cable, wire, bundle of strands, plug element, or bushing.

The characteristics of the contact surface of the electrical contact are particularly important to the reliability of the electrical connection to the other conductive element. Particularly good electrical conductivity is required at the contact surface. Furthermore, since the contact surface is additionally frequently used to enter into a frictionally engaged, force-fitting, and/or materially engaged connection to the other conductive element, the mechanical characteristics of the contact surface are also important to the electrical connection.

SUMMARY

An object of the invention, among others, is to provide an electrical contact element with improved electrical conductivity and improved mechanical characteristics. The contact element of the invention is also able to be manufactured in large quantities in a cost-efficient manner. The disclosed electrical contact element includes a contact surface of an electrically conductive contact body having a plurality of coated regions with a first coating and a plurality of uncoated regions without the first coating, the coated regions and uncoated regions arranged in an alternating manner in a variation direction along the contact surface.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

The invention is explained in greater detail below with reference to embodiments of an electrical contact element. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and still fully convey the scope of the invention to those skilled in the art.

A contact element3according to the invention is shown generally inFIG. 1. In the shown exemplary embodiment, the contact element3is a stamped bending part1. One with ordinary skill in the art, however, would understand that the solution according to the invention can be employed for a wide range of contact elements3, including those forming a crimp connection, plug contact, cable shoe, ferrule, or other electrical connectors known in the art.

The contact element3includes a contact body5and a contact surface7. Contact body5is formed of an electrically conductive material, and may be a sheet metal.

Contact surface7can have any suitable form. In the shown embodiment, contact surface7forms a bending crimp section, but could also form a crimp clip, crimp wing, or other known electrical contact section. Contact surface7includes at least one recess10, at least one coated region13, and at least one uncoated region17.

The at least one recess10, as shown inFIG. 2, may be configured as an elongated furrow9. The furrow9may be impressed, stamped, chased or deep-drawn into contact body5. A longitudinal direction11of the furrow9runs perpendicular to a longitudinal direction of the contact element3. Three furrows9are shown in the embodiment ofFIGS. 1-7, but one with ordinary skill in the art would understand that the number of furrows9could vary. As shown inFIG. 3A, furrows9form surface offsets25between, in each case, a base surface21of the furrow9and a top surface23of the contact surface7. Surface offsets25represent flanks or shoulders of the furrows9in cross-section.

In other embodiments, contact surface7can have recesses10formed differently than the shown furrows9. Instead of a furrow9, the recess10can also have the form of a groove or a corrugation. Alternatively, the recess10can also have a large-area rectangular form. Furthermore, the furrows9may not be continuous. Likewise, alternatively or additionally, contact surface7can have elevations instead of recesses.

The at least one coated region13, shown inFIGS. 2 and 3A, has a first coating15. The first coating15can be selected, for example, such that it has increased electrical conductivity compared to the contact body5. The first coating15may also be harder than the contact body5. The first coating15may be formed from tin, zinc, silver, bismuth, or other materials known to those with ordinary skill in the art.

First coating15is directly deposited on contact body5without any intervening layers. The coated regions13may be formed by methods in which the first coating15is selectively directly deposited on the contact surface7and then hardened, surface-fused and/or sintered using energy-rich radiation. The first coating15can alternatively be deposited in the desired form and dimensions onto the contact surface7, for example, by printing methods. The first coating15can be fixed and connected to the contact surface7by the energy-rich radiation which may be electron radiation, ion radiation or laser radiation.

Each coated region13has a surface16. As shown inFIG. 2, each coated region13may be formed as a stripe27, with a longitudinal direction of the stripe27running parallel to the longitudinal direction11of the furrows9. Each stripe27has edge regions31and a width33. In the shown embodiment, the stripe width33measured perpendicular to the longitudinal direction of the stripe is less than 500 μm, and is another embodiment, is less than 300 μm.

The at least one uncoated region17is located between coated regions13with first coating15. The uncoated regions17have no coating. The coated regions13with first coating15and the uncoated regions17without first coating15, as shown in the embodiment ofFIG. 2, alternate along the first direction of variation19. First direction of variation19may run perpendicular to longitudinal direction11of furrows9. The uncoated regions17without first coating15can be situated inside furrows9.

As shown inFIG. 3A, the stripes27are arranged on the top surface23of contact surface7between uncoated regions17, and extend toward base surface21of furrows9; as a result, surface offsets25of furrows9are covered with first coating15. Edge regions31of each stripe27extend in two adjacent furrows9.

The contact element3is used to form an electrical connection with a conductive element (not shown). The contact surface7contacts the conductive element to form the electrical connection. If the contact surface7according to the invention is pressed against the conductive element, for example by contact surface7being arranged in a crimp region which is squeezed onto the conductive element, surface offsets25exert a particularly large force onto the conductive element and partially penetrate into the conductive element. Particularly good electrical conductivity and mechanical hardness in the region of surface offsets25is of great significance for a good connection between contact surface7and the conductive element. Since the surface offsets25are covered by coated regions13with first coating15, a reliable connection between the contact surface7and the conductive element is formed.

FIG. 3Bshows two additional embodiments of the coated region13configuration. The configurations shown are merely exemplary, and the two configurations do not necessarily have to be arranged on the same contact element3.

The left side ofFIG. 3Bshows a coated region13with a smooth surface16. In this embodiment, first coating15is divided into two different phases18aand18b. In the different phases, the material of first coating15can have different characteristics. For example, the composition of the material can be different in the two phases, even if they have been generated from the same starting material of first coating15. The phases18aand18bcan be generated through the selection of a suitable material for first coating15and/or a suitable after-treatment, for example, via the energy-rich radiation. Alternatively or in addition, two different materials, for example first coating15and a second coating41, can be used instead of two different phases18aand18b.

The right side ofFIG. 3Bshows a coated region13with first coating15, wherein the surface16of the first coating15is structured. Surface16is structured such that a thickness20of first coating15varies in cross-section. Surface16can have burls, ribs or teeth, for example, such that a structure is formed with varying thickness20.

FIG. 4shows a second embodiment of a contact surface7according to the invention. For the sake of brevity, only the differences from the contact surface7described with reference toFIGS. 2 and 3are explored hereafter.

The second embodiment of contact surface7according to the invention has a second direction of variation35which runs parallel to longitudinal direction11of furrows9. The coated regions13therefore also alternate with uncoated regions17in the direction of variation35. Through the alternating arrangement of coated regions13and uncoated regions17along two directions of variation19and35which are perpendicular to one another, an at least partial coating can be achieved with a very low amount of coating material15. In order to obtain as uniform a distribution of regions13and17over contact surface7as possible, coated regions13have, at least in direction of variation35, a length37, which substantially corresponds to the length39of a uncoated region17in direction of variation35. Length39of uncoated region17is the distance between two adjacent regions13in direction of variation35.

Through the described arrangement of coated regions13of the second embodiment, direction of variation39follows the course of surface offsets25, which run parallel to longitudinal direction11of furrows9. Two coated regions13respectively are situated opposite one another over a furrow9. Therefore, coated regions13are each situated at the same height along longitudinal direction11of furrows9.

FIG. 5shows a third embodiment of a contact surface7according to the invention. Here too, for the sake of brevity, only the differences from the preceding embodiments are described. Coated regions13alternate with uncoated regions17in two directions of variation19and35, which are perpendicular to one another. In contrast to the second embodiment, coated regions13are, however, staggered relative to one another in longitudinal direction11of furrows9. As a result, in longitudinal direction11of furrows9, a coated region13is arranged in each case at a surface offset25of a furrow9between two opposing coated regions13. The coated regions13can extend into a middle of base surface21of furrows9. Through the arrangement of regions13and17of the third embodiment, a substantial covering of contact surface7with coated regions13can be achieved with a low quantity of coating material.

FIG. 6shows a fourth embodiment of a contact surface7according to the invention. Contact surface7has coated regions13which correspond to those of the embodiment described with reference toFIG. 5. Uncoated regions17, at least those which are located between coated regions13in direction of variation35, can have a second coating41. Second coating41can consist of a material other than first coating15. Alternatively or in addition, second coating41can also consist of the same material as coating15, but, through a suitable treatment, can have a structure which is different from first coating15. For example, at least one of coatings15or41can have a surface16or42which is structured such that two different surface structures are formed.

FIG. 7shows a fifth embodiment of a contact surface7according to the invention. In this embodiment, purely by way of example, coated regions13and uncoated regions17in inner region43are depicted identically to those of the third embodiment described with reference toFIG. 5. Inner region43, however, can be formed in accordance with each of the embodiments described previously. Inner region43can also be formed in accordance with all other contact surfaces7according to the invention.

In contrast to the embodiments described above, the fifth embodiment of contact surface7according to the invention has boundary regions47with a third coating45. In this case, boundary regions47are arranged in an edge region49of contact surface7. The boundary regions47are formed in the form of stripes and follow edge region49of contact surface7. Individual boundary regions47touch or cover one another, such that a continuous boundary region47is formed which fully surrounds inner region43of contact surface7.

Third coating45is softer than first coating15and, if it is present, second coating41. Third coating45can serve to seal contact surface7, in particular if contact surface7is part of a crimp section which is pressed together or against another element. Third coating45is formed by a metal which is more base than the material of first coating15, second coating41and contact body5. As a result, third coating45can serve as a sacrificial anode51for contact element3. A surface53of third coating45can be structured similarly to surface16of the first coating and surface42of the second coating.

According to a further advantageous configuration of the invention, at least one coated region13or a combination of coated regions13can be formed at least in sections as a data-carrying structure. The data-carrying structure can, for example, have data regarding the type or the characteristics of the contact element13. Data such as the name or contact information regarding the manufacturer or its logo can be formed in the at least one coated region13. The data-carrying structure may be formed as a two-dimensional code, for example as a barcode. A two-dimensional code can vary greatly over a large surface, permitting the first coating15to still cover a substantial area. It is likewise possible that the data-carrying structure is formed as a one-dimensional bar code, for example as digits or as letters.

Advantageously, according to the invention, the first coating15disposed over the surface offsets25provides a more reliable electrical connection to another conductive element. Furthermore, by having uncoated regions17located between coated regions15, coating material and corresponding manufacturing cost can be saved in comparison to a complete coating of the contact surface while maintaining uniform coverage of the contact surface. The alternating arrangement of coated regions13and uncoated regions17also improves the mechanical stability of the contact element3in the region of the contact surface7, because twisting, as can arise in the case of large area coating, can be avoided. Furthermore, since one stripe27can cover two adjacent surface offsets25of two adjacent furrows9, manufacturing is easier.