Electrical contact element

Abstract

The invention relates to an electrical contact element for a connector, comprising a metallic base body (111, 211) and a wear-resistant layer (113, 213) applied to the base body (111, 211). The wear-resistant layer (113, 213) is made of pure ruthenium or an alloy having the following composition: 50-100% by weight of ruthenium, 0-30% by weight of nickel, 0-20% by weight of chromium, 0-20% by weight of cobalt, 0-20% by weight of platinum and 0-1% by weight of other alloying elements. A metal intermediate layer (112, 212) is arranged between the base body (111, 211) and the wear layer (113, 213), the thickness (dm, dzn) being in the range of between 1.5 pm and 4.0 pm.

Description

[0001] This application is a divisional application of the patent application for invention with the application date of May 5, 2020, the application number of 202080008484.8, and the invention title of "Electrical Contact Element". Technical Field

[0002] The present invention relates to an electrical contact element for a plug-in connector. Background Art

[0003] Electrical plug-in connectors usually have one or more electrical contact elements and one or more insulators. The contact elements are usually designed as male or female elements here. They are made of a corrosion-sensitive base material. Usually, these base materials are copper alloys. In order to ensure the function of the contact elements during the service life of the plug-in connector, other metal thin layers are therefore applied to the base material. These metal thin layers can include an intermediate layer and a wear-resistant layer.

[0004] The intermediate layer can have various tasks. It can improve the adhesion of the wear-resistant layer to the base material, create mechanical compensation between the base material and the wear-resistant layer, and prevent a diffusion process between the wear-resistant layer and the base material. The intermediate layer usually consists of copper or nickel.

[0005] The wear-resistant layer, also called the functional layer, is located on the intermediate layer. The wear-resistant layer extends the technical service life of the contact element, can improve electrical transmission, and protects the layers located below it from corrosion. It can consist of a soft non-inert metal such as tin or silver. For example, in plug-in connectors in the automotive industry, silver is very common as the wear-resistant layer. In plug-in systems with particularly high requirements for reliability and service life, wear-resistant layers made of very expensive corrosion-resistant noble metals or their alloys are usually used. Therefore, for example, gold-cobalt alloys or palladium-nickel alloys are used.

[0006] The object of the present invention is to provide an electrical contact element that is suitable for use in a plug-in electrical connector and can be manufactured more cost-effectively compared to conventional electrical contact elements. Here, the reliability and service life of conventional contact elements will still be obtained. Summary of the Invention

[0007] This object is solved by an electrical contact element for a plug-in connector, the electrical contact element having a metallic substrate or a wear-resistant layer applied to the substrate. The wear-resistant layer can here be applied directly to the metallic substrate, or one or more additional layers can be arranged between the metallic substrate and the wear-resistant layer. The wear-resistant layer consists of the following alloying elements: 50 - 100% w / w ruthenium, 0 - 30% w / w nickel, 0 - 20% w / w chromium, 0 - 20% w / w cobalt, 0 - 20% w / w platinum, and 0 - 1% w / w of other alloying elements. Here, the sum of the alloying elements is 100% w / w. Thus, the wear-resistant layer can consist of pure ruthenium or a ruthenium alloy, which can include up to 50% of additional alloying elements. While nickel, chromium, cobalt, and platinum can be alloyed in the specified amounts, the use of amounts of additional elements is preferably avoided. However, amounts of up to 1% w / w of additional alloying elements (e.g., impurities) in the alloy are acceptable. In embodiments of the electrical contact element in which the wear-resistant layer consists essentially of pure ruthenium with 99 to 100% w / w and up to 1% w / w of additional alloying elements, the sum of the alloying elements is then 100% w / w. According to the invention, it has been found that the use of such a wear-resistant layer provides similar good electrical transmission and similar good corrosion protection as can be achieved, for example, with a wear-resistant layer made of silver. However, in contrast, the use of the pure ruthenium or ruthenium alloy enables a more cost-effective production of the electrical contact element.

[0008] To ensure a good degree of corrosion protection, it is preferred that the wear-resistant layer has a thickness in the range of 0.15 μm to 1.50 μm. Particularly preferably, the thickness is in the range of 0.30 μm to 1.00 μm. The wear-resistant layer used according to the invention provides such a good degree of corrosion protection and such good electrical transmission that these properties cannot be further significantly improved by further increasing the layer thickness. In contrast, for example, when using a conventional wear-resistant layer made of silver, a layer thickness of at least 3 μm is usually required so that the electrical contact element at least meets the requirements for corrosion resistance and electrical transmission. Thus, the invention not only enables the production of electrical contact elements when using more cost-effective materials, but also saves material amounts by using a particularly thin wear-resistant layer.

[0009] A metallic intermediate layer is arranged between the substrate and the wear-resistant layer. Preferably, the intermediate layer is the only layer arranged between the wear-resistant layer and the substrate, such that the substrate is directly connected to the intermediate layer and the intermediate layer is directly connected to the wear-resistant layer. As in conventional electrical contact element constructions, the intermediate layer increases the adhesion of the wear-resistant layer to the substrate, ensures mechanical compensation between the substrate and the wear-resistant layer, and prevents diffusion processes between the wear-resistant layer and the substrate.

[0010] In an embodiment of the contact element, the intermediate layer comprises 99 to 100% w / w of copper and 0 to 1% w / w of additional alloying elements. In another preferred embodiment of the contact element, the intermediate layer comprises 99 to 100% w / w of nickel and 0 to 1% w / w of additional alloying elements. The sum of the alloying elements is 100% w / w here. The amount of additional alloying elements should preferably be as low as possible, but their presence may not be completely excluded due to the presence of impurities.

[0011] The thickness of the intermediate layer is about 1.5 μm to 4.0 μm and preferably about 2.0 μm to 3.0 μm.

[0012] Furthermore, it is preferred that a metallic and / or organic sliding layer is arranged on the wear-resistant layer. On the one hand, the sliding layer can improve the sliding properties of the electrical contact elements, in particular the female and male elements. This thus helps the wear-resistant layer to remain functional under mechanical frictional stress. On the other hand, this can also optimize the electrical transmission between the electrical contact elements. When the sliding layer comprises both a metallic component and an organic component, it is preferred that the metallic partial layer is directly connected to the wear-resistant layer and the organic partial layer is attached to the metallic layer. The metallic partial layer and the organic partial layer then together form the sliding layer.

[0013] Particularly suitable metallic materials for the sliding layer are pure gold or gold alloys, which consist of the following alloying elements: 98.5 to 100.0% w / w of gold, 0 to 0.5% w / w of cobalt and 0 to 1.0% w / w of additional alloying elements. The sum of the alloying elements is 100% w / w here.

[0014] Particularly suitable organic materials for the sliding layer are at least one fluoropolymer and / or at least one fatty acid salt. The fluoropolymer can be, for example, perfluoropolyether (PFPE) or polytetrafluoroethylene (PTFE). The fatty acid salt can be, for example, lithium 12-hydroxystearate.

[0015] The thickness of the sliding layer is preferably in the range of 0.05 μm to 0.25 μm. Such thin sliding layers are already sufficient to impart good sliding properties to the electrical contact elements, such that the overall coating thickness is not significantly increased by applying the sliding layer to the wear-resistant layer.

[0016] When the substrate consists of copper, low-alloyed copper alloys or brass, the wear-resistant layer of the electrical contact element according to the invention can be used particularly advantageously. In this case, it consists of the following alloy elements: 50 to 100% w / w of copper, 0 to 45% w / w of zinc, and 0 to 5% w / w of further alloy elements. The sum of the alloy elements is 100% w / w here. Even if the sum of the further alloy elements described herein can be up to 5% w / w, it is preferred that each individual further alloy element does not constitute more than 2% w / w of the entire alloy. Furthermore, it is preferred that only the further alloy elements beryllium, chromium, iron, cobalt, magnesium, manganese, nickel, phosphorus, sulfur, silicon, tellurium, titanium, tin, and zirconium can be included in the alloy in each case in an amount of up to 2% w / w, and all further alloy elements not mentioned in this list are present in an amount of at most 1% w / w in each case.

[0017] The electrical contact element according to the invention can be manufactured with good technical properties without having to use large amounts of expensive noble metals in the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Exemplary embodiments of the invention are depicted in the drawings and explained in more detail in the following description.

[0019] Figure 1 A schematic longitudinal sectional view showing an arrangement made up of two electrical plug connectors is shown.

[0020] Figure 2 A sectional view showing the contact area between two electrical contact elements in a comparative example is shown.

[0021] Figure 3 A sectional view showing the contact area between two electrical contact elements according to an exemplary embodiment of the invention is shown. DETAILED DESCRIPTION

[0022] Figure 1 A schematic construction of a plug connector pair is shown. The first plug connector 10 has an electrical contact element 11 in the form of a male element. The electrical contact element 11 is surrounded by a first insulator 12 made of plastic. The second plug connector 20 has a second electrical contact element 21 in the form of a female element. The second electrical contact element 21 is surrounded by a second insulator 22 made of plastic. When the two plug connectors 10, 20 are inserted into each other in the depicted manner, the second insulator 22 is pushed into the first insulator 12, and the first electrical contact element 11 is introduced into the second electrical contact element 21. In doing so, the first electrical contact element 11 causes the tongues of the second contact element 21 to bend apart, and then the tongues are fixedly pressed onto the first contact element 11 by their elastic force. In the contact area 30 where the two contact elements 11, 21 are in contact, electrical transmission becomes possible.

[0023] In electrical plug connectors 10, 20 having contact elements 11, 21 according to the prior art, Figure 2 the depicted configuration of the contact elements 11, 21 exists in the contact area 30. The first contact element 11 has a base body 111, an intermediate layer 112 arranged on the base body, and a wear-resistant layer 113 arranged on the intermediate layer. The second contact element 21 has a base body 211, an intermediate layer 212 arranged on the base body 211, and a wear-resistant layer 213 arranged on the intermediate layer 212. The base bodies 111, 211, the intermediate layers 112, 212, and the wear-resistant layers 113, 213 each have a composition with the weight percentages specified in Table 1:

[0024] Table 1

[0025]

[0026]

[0027] In this example, the intermediate layers 112, 212 each have a thickness d of 3 μm 112 , d 212 , and the wear-resistant layers 113, 213 each have a thickness d of 4 μm 113 , d 213 . The wear layers 113, 213 contact in the contact area 30, which can lead to wear of silver. The large amount of silver required for producing the wear-resistant layers makes the production of the electrical contact elements 11, 21 expensive.

[0028] Figure 3 shows the configuration of electrical contact elements 11, 21 according to several exemplary embodiments of the present invention, which can be used in plug connector pairs 10, 20 according to Figure 1 . In addition to the configuration of the electrical contact elements 11, 21 made of the base bodies 111, 211, the intermediate layers 112, 212, and the wear-resistant layers 113, 213 already depicted in Figure 2 , the contact elements 11, 21 each have additional sliding layers 114, 214 according to these exemplary embodiments of the present invention on their wear-resistant layers 113, 213. This results in the wear-resistant layers 113, 213 in the contact area 30 not contacting, but rather the sliding layers 114, 214 contacting. Although the thicknesses of the intermediate layers 112, 212 in the exemplary embodiments of the present invention are consistent with the thicknesses of the intermediate layers 112, 212 in the comparative example, significantly thinner wear-resistant layers 113, 213 with thicknesses d 113 , d 213 of only 0.65 μm each are used according to the exemplary embodiments of the present invention. This results in a considerable material saving compared to the comparative example. In the exemplary embodiments of the present invention, the sliding layers 114, 214 each have a thickness d of 0.10 μm114 and d 214 Therefore, each wear-resistant layer 113, 213 itself, together with the corresponding sliding layer 114, 214, is also thinner than the wear-resistant layers 113, 213 in the comparative example.

[0029] In the first exemplary embodiment of the present invention, the components of the contact elements 11, 21 have the composition with the weight percentages described in Table 2.

[0030] Table 2

[0031] substrate intermediate layer wear-resistant layer sliding layer 111、211 112、212 113、213 114、214 Ag Au 99.8 Co 0.2 Cu 100 Ni 100 Ru 100 PTFE

[0032] Therefore, the intermediate layer composed of pure silver in the comparative example is composed of pure ruthenium in the first exemplary embodiment. This results in cost savings, not only because less metal is used for the wear-resistant layer, but also because a more cost-effective metal is used. The sliding layer is composed of an alloy of gold and cobalt, which enables excellent electrical transmission, and furthermore, has better sliding characteristics compared to silver used in the comparative example due to the softness of this alloy. However, the sliding layer is so thin that despite the use of precious metals, it does not cause any notable cost increase for the contact elements 11, 21.

[0033] In the second exemplary embodiment of the electrical contact elements 11, 21 according to the present invention, their components have the composition stated in weight percentages in Table 3:

[0034] Table 3

[0035]

[0036] The pure ruthenium of the wear-resistant layers 113, 213 according to the first exemplary embodiment has here been replaced by a ruthenium-nickel alloy. It has been determined that when using this alloy, the characteristics of the electrical contact elements according to the comparative example in terms of corrosion resistance and electrical transmission can still be achieved or even exceeded.

[0037] In the third exemplary embodiment of the electrical contact elements 11, 21, their components have the composition stated in weight percentages in Table 4:

[0038] Table 4

[0039]

[0040]

[0041] Compared with the first exemplary embodiment, the metallic sliding layers 114, 214 have been replaced by organic sliding layers, each consisting of PTFE. It has been determined that by dispensing with expensive noble metals, excellent sliding characteristics of the contact elements 11, 21 can still be achieved in the third exemplary embodiment, where the electrical transmission is still not inferior to that of the electrical contact elements 11, 21 in the comparative example.

[0042] All three of the exemplary embodiments of the electrical contact elements 11, 21 according to the invention enable a cost-effective replacement of the electrical contact elements 11, 21 according to the comparative example, without this resulting in a deterioration of the properties associated with the electrical contact elements 11, 21.

Claims

1. An electrical contact element (11, 21) for a plug-in connector (10, 20), comprising a metal base body (111, 211), a metal intermediate layer (112, 212) applied to the base body (111, 211), and a wear-resistant layer (113, 213) applied to the intermediate layer (112, 212), wherein the metal intermediate layer (112, 212) has a thickness (d 100, 100) in the range of 1.5 μm to 4.0 μm. 112 d 212 ), wherein the wear-resistant layer (113, 213) is composed of the following alloy elements composition: 50-100% w / w ruthenium 0-30% w / w Nickel 0-20% w / w chromium 0-20% w / w Cobalt 0-20% w / w platinum 0-1% w / w of additional alloying elements, The total amount of the alloying elements is 100% w / w, characterized in that the wear-resistant layer (113, 213) is composed of a ruthenium alloy and has a thickness (d ) in the range of 0.65 μm to 1.00 μm. 113 d 213 ), a sliding layer (114, 214) comprising an organic partial layer is arranged on the wear-resistant layer (113, 213), and the sliding layer (114, 214) has a thickness (d ) in the range of 0.05 μm to 0.25 μm 114 d 214 ).

2. The electrical contact element (11, 21) according to claim 1, It is characterized in that The intermediate layer (112, 212) is composed of the following alloy elements: 99-100% w / w copper or nickel 0-1% w / w of additional alloying elements, The sum of the alloying elements is 100% w / w.

3. The electrical contact element (11, 21) according to claim 1, It is characterized in that The sliding layer (114, 214) contains an alloy consisting of the following alloying elements: 98.5-100.0% w / w gold 0-0.5% w / w Cobalt 0-1.0% w / w of additional alloying elements, The sum of the alloying elements is 100% w / w.

4. The electrical contact element (11, 21) according to claim 1, It is characterized in that The sliding layer (114, 214) contains at least one fluorine-containing polymer and / or at least one fatty acid salt.

5. The electrical contact element (11, 21) according to claim 1, It is characterized in that The sliding layer (114, 214) further comprises a metal partial layer.

6. The electrical contact element (11, 21) according to claim 1, It is characterized in that The matrix (111, 211) is composed of the following alloy elements: 50-100% w / w copper 0-45% w / w zinc 0-5% w / w of additional alloying elements, The sum of the alloying elements is 100% w / w.

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