Plug connection device and method for producing a plug connector

Abstract

The invention relates to a plug connection (1), preferably a data and power plug connection, in particular preferably an SPE plug connection, comprising at least two plug connection components in the form of a mating plug connector (2) and a plug connector (3), each of which has at least one contact element (4, 5), one of the contact elements (4) is electrically contacted with the other contact element (5) in a contact region (15) by connecting the plug connector (3) into the mating plug connector (2), the metal main body (16) of the contact element (4) is provided in the contact region (15) with a coating (17) made of a single-layer or multi-layer layer in the form of a nickel-phosphorus alloy, and to a method for producing a plug connector of the plug connection (1).

Description

Technical Field

[0001] The invention relates to a plug-in connection, preferably a data and power plug-in connection, and a plug-in connection method for producing the plug-in connection. Background Art

[0002] In the field of plug-in connections, in particular data and power plug-in connections, contact elements have contact areas containing precious metals for contacting two connection elements. These contact areas are usually designed as a multilayer system with a relatively hard base coating and a gold layer arranged thereon.

[0003] The base coating provides mechanical protection against damage to the coating and substrate during multiple plugging operations, while the soft gold layer serves as a lubricant and a contact element, establishing good contact with low contact resistance between the two connection elements. Furthermore, gold, as a precious metal, is not susceptible to corrosion in industrial environments, thus maintaining a stable contact resistance.

[0004] Due to the different functionalities, multilayer systems having at least two layers have hitherto been considered absolutely necessary in the noble metal-containing contact-through region.

[0005] Especially in data plug connections, i.e. in the high-frequency range, strict threshold values ​​are imposed on the transition resistance, which must not be exceeded or fallen below. In order to ensure data transmission with standard transmission quality, especially with regard to the contact transition resistance, a gold layer is considered necessary in this case.

[0006] Documents relevant in this context to the present invention are DE 10 2012 109 057 B3, DE 10 2013 109 400 A1, DE 10 2014 105 823 A1, DE 10 2015 118 779 A1 and DE 10 2016 110 377 A1. Summary of the Invention

[0007] Based on this preliminary consideration, the object of the present invention is to achieve a good compromise between sufficient transmission of signals (data) and / or power and simple, cost-optimized production.

[0008] The invention achieves this object by a plug-in connection which can transmit data and / or power having the features of claim 1 and by a method for producing the plug-in connection having the features of claim 7 .

[0009] The plug-in connection device according to the present invention can be configured as an electrical plug-in connection device to electrically contact two plug-in connection components. Particularly preferably, the plug-in connection device can be configured as a data and / or power plug-in connection device. Thus, the plug-in connection device can be configured not only as a data plug-in connection device but also as a power plug-in connection device. The plug-in connection device includes at least two plug-in connection components in the form of a mating plug connector and a plug connector.

[0010] Each of the two plug-in connection components has a contact element, in which one of the two contact elements is electrically contacted with the other of the two contact elements in a contact region by inserting the plug-in connector into the mating plug-in connector.

[0011] According to the present invention, the metal base of one contact element is provided with a coating in the contact region. The coating comprises a single or multiple layers of a nickel-phosphorus alloy. The nickel-phosphorus layer can be applied in multiple electroplating baths in multiple processes, thereby forming a multilayer nickel-phosphorus layer system.

[0012] Single-layer means that at least one of the two contact elements has only one layer (a nickel-phosphorus alloy layer). Due to its high hardness, the alloy layer protects the base body from mechanical damage and wear. In the single-layer embodiment, no additional layers or coatings are provided.

[0013] The provision of a single layer overcomes the preconception that a contact element always requires an additional pure metal layer (primarily gold) to increase conductivity and maintain corrosion resistance. The gold layer is separated / isolated from the base material of the contact element by a nickel shielding layer. Extensive experiments have surprisingly shown that contact elements provided solely with a nickel-phosphorus alloy layer also have sufficient contact properties, in particular, sufficient contact properties for single-pair Ethernet (SPE) plug connections.

[0014] Without an additional gold layer, the production can be carried out more efficiently and with less effort, saving materials and resources, due to the omission of a coating step.

[0015] In contrast, when gold plating, a nickel content is used as a shielding layer. Without this shielding layer, the gold diffuses into the base material (e.g. brass) and is therefore less effective.

[0016] Further advantageous embodiments of the invention are described in the dependent claims.

[0017] Advantageously, the metal base body consists of copper or a copper alloy. Copper and copper alloys form a good bond compared to nickel-phosphorus alloys. The temperature changes that occur during use do not cause the coating to detach at the material transition.

[0018] In a multilayer embodiment, an intermediate layer can also be applied between the substrate and the coating. Possible intermediate layers can consist of copper, nickel and / or iron and can be configured as a binder to improve electrochemical compatibility, improve bonding energy and / or increase phase growth.

[0019] This makes it possible, for example, to improve the gas formability of a pure nickel intermediate layer. For example, when applied on copper flash plating, the adhesive is suitable for improving adhesion.

[0020] In order to achieve optimal signal transmission and sufficiently good contacting while providing mechanical protection, it is advantageous if the average layer thickness of the individual layers is advantageously between 1.5 μm and 5 μm, ideally between 2.5 μm and 4 μm.

[0021] The phosphorus content in the alloy should advantageously be greater than 9% by weight. This phosphorus content allows for the formation and adjustment of the range of amorphous content in the partially crystalline coating. This amorphous content improves corrosion resistance compared to pure nickel or nickel with a lower phosphorus content. At the same time, the phosphorus content reduces the coating's electrical conductivity and / or contributes to increased brittleness. Therefore, the phosphorus content should preferably be less than 20% by weight, particularly preferably less than 15% by weight.

[0022] Ideally, the alloy has only a few defects. The penetration of defects can be controlled, for example, via the deposition rate. Advantageously, at least 99% by weight of the coating comprises only nickel and phosphorus, and 1% by weight or less of the coating comprises the aforementioned additional inclusions, such as silicon compounds.

[0023] The plug connection device can include a plug connector having a contact element of the single-layer coating, and the second plug connector, ie the contact element of the respectively corresponding plug connector or the corresponding mating plug connector, can have a two-layer or multi-layer coating.

[0024] Here, the other of the two corresponding contact elements of the two plug-in connectors can also be designed as a two-layer structure in the contact area. A first layer made of a nickel-phosphorus alloy and a second layer made of gold with a layer thickness of less than 0.2 µm, preferably between 0.1 µm and 0.15 µm, are recommended. A typical layer thickness in the contact area is usually 0.8 µm. Since sufficiently good contact already exists, the layer thickness can be omitted in this area.

[0025] However, it is also possible for both plug-in connectors to have the described single-layer or multi-layer layers.

[0026] The present invention also relates to a method for manufacturing a plug-in connector of the plug-in connection device according to the present invention, the method comprising at least the following steps:

[0027] I. Surface cleaning of the metal base of the contact element of the plug connector and forming by stamping and / or bending;

[0028] II. Immersing the substrate in an electrolyte bath containing nickel ions and phosphorus compounds;

[0029] III. Adjusting the current density according to a predetermined target value of phosphorus content in the alloy;

[0030] This can be done, for example, by means of empirical values ​​which enable a defined phosphorus content in the alloy to be achieved at a certain current density and current-conduction time and at a known phosphorus compound concentration.

[0031] IV. drying and / or heat treatment, wherein the heat treatment is carried out at a temperature greater than 200°C;

[0032] The heat treatment significantly increases the hardness of the coating.

[0033] V. Installing the one contact element into a housing to provide the plug connector.

[0034] This type of assembly is generally known. The one contact element can be inserted into the contact carrier and / or encapsulated with a potting compound. Optionally, the contact carrier can also be provided with a shielding element, which may include outer insulation and, if necessary, locking means. The shape and design of the corresponding plug-in connector and mating connector, in particular an SPE plug-in connector, are generally known and can be implemented by this assembly.

[0035] Advantageous embodiments of the method are the subject of the dependent claims.

[0036] Advantageously, the surface cleaning can be carried out in an alkaline degreasing bath and the alkaline film can be removed subsequently by a pickling process. Thus, a plurality of method steps are effectively combined.

[0037] Advantageously, the electrolyte bath may have a pH value of less than 3.0, preferably a pH value of 2.5 + / - 0.2. In such an acidic environment, good process control for the electroplated coating can be achieved.

[0038] Advantageously, phosphonic acid and / or phosphinic acid and / or phosphates and / or hypophosphites can be used as phosphorus compounds. This reduces the need for further acids to adjust the pH value.

[0039] The preferred concentration of phosphonic acid and / or phosphate in the electrolyte may be greater than 20 g / l, preferably between 20 g / l and 35 g / l. This ensures optimal coating conditions.

[0040] As the nickel substance, an aqueous solution composed of nickel sulfate and / or nickel sulfonate and / or nickel chloride is used in the electrolytic solution.

[0041] Preferably, the electrolyte may have a nickel concentration in the electrolyte of 80 g / l to 120 g / l.

[0042] To adjust the process conditions, in particular the pH value, the electrolyte can also contain boric acid and / or sulfuric acid.

[0043] Preferably, a nickel anode can be used as the anode in the electroplated coating.

[0044] Furthermore, the preferred target value for the preferred current density may be 5 A / dm 2 Up to 25A / dm 2 between, preferably 18A / dm 2 Up to 22A / dm 2 This forms a good compromise with respect to a low number of defect sites in the coating and at the same time good production efficiency.

[0045] Advantageously, the current density can be adjusted at a temperature greater than 50° C., preferably between 55° C. and 80° C. This increases the deposition rate and thus the production efficiency.

[0046] To further harden the coating, the heat treatment may be performed at a temperature between 200°C and 500°C.

[0047] Before or after the electroplating coating step, the metal surface of the contact element may be subjected to chemical preparation and / or chemical post-treatment, wherein each step of the chemical preparation and / or post-treatment includes rinsing the corresponding prepared or post-treated surface with deionized water to prevent impurity ions from being introduced into the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The data and power plug connection device according to the present invention will be described in detail below using a single-pair Ethernet plug connector (also called an SPE plug) with reference to the following figures. In the figures:

[0049] Figure 1 A side view showing a first plug connection according to the invention as a variant of an SPE plug;

[0050] Figure 2 Show Figure 1 A top view of the plug connection device;

[0051] Figure 3 A side view showing a metallic contact element of the two contact elements of the plug connection;

[0052] Figure 4 Show Figure 3 A top view of a metal contact element;

[0053] Figure 5 A method flow chart showing a manufacturing method according to the present invention; and

[0054] Figure 6 A sectional view shows a further variant of the plug connection according to the invention, which here is in the form of a round plug connector. DETAILED DESCRIPTION

[0055] Figures 1 to 4 A plug-in connection device 1 is shown as a data and power plug-in connection device, which has an SPE mating connector 2 and a corresponding SPE plug-in connector 3 as data and power plug-in connectors.

[0056] Both the SPE mating connector 2 and the SPE plug-in connector 3 have metallic contact elements 4 , 5 , 4 ′, 5 ′, which are each surrounded by a box-shaped shielding element 6 , 7 and at least the SPE plug-in connector 3 is additionally encapsulated.

[0057] The contact elements 4, 5, 4', 5' are each preferably constructed in one piece. Figure 3 and Figure 4 In this embodiment, the two contact elements of the mating connector 2 and / or the plug connector 3 are oriented parallel to each other. The two contact elements 4 of the SPE plug element (here, the SPE mating plug connector 3) have a contact area 8 for making contact, preferably electrical contact, with the wire end sections of the two-core cable 9. Generally speaking, this area of ​​the plug connector is also called the conductor connection area 13. The plug connector also has a transition area 14, i.e., an intermediate piece, and a contact area or contact area 15. The individual wires of the cable 9 are connected to the contact elements 4, 4' here via puncture contacts (IPC). Incision clamps (IDC) or other contacting options can also be used. Thus, the cable 9 is connected to the plug connection device.

[0058] As an alternative to the embodiment variant shown, the plug-in connector can also be designed in a different manner.

[0059] An essential element of the present invention is the contacting region 15 , at which the contacting 10 of the two plug-in connectors or the mating plug-in connector 2 and the plug-in connector 3 , ie the contact and the mating contact, takes place.

[0060] Especially in Figure 4: The mating connector 2 has a contact pin 11, which is inserted into a contact sleeve 12 of the plug-in connector 3. The contact pin 11 is clamped in two opposite spring contacts 12 by two spring arms 12a and 12b. The spring arms 12a and 12b of the spring contacts 12 are simultaneously part of the contact region 15a of the plug-in connector 3, while the region where the spring arms 12a and 12b bear on the contact pin 11 is part of the contact region 15b of the contact pin.

[0061] However, the contact areas 8a and 8b are not limited to the pin-shaped and two opposing spring contact terminal designs of the contact elements 4 and 5. Therefore, it is also possible to provide corresponding contact areas on other contact elements that do not have a pin or sleeve shape.

[0062] The contacting regions 15a and 15b of the contacting elements 4 and / or 5 have a metal base body 16. This metal base body can preferably consist of a copper alloy.

[0063] A conductive, wear-resistant layer is applied to the metal substrate as coating 17. This coating is a nickel-phosphorus alloy layer, preferably containing at least 9% phosphorus by weight. It is particularly preferred that the only two alloy components are phosphorus and nickel, with the nickel content being higher than the phosphorus content. It is particularly preferred that the phosphorus content in the alloy is less than 20% by weight, preferably less than 15% by weight.

[0064] The average layer thickness of the nickel-phosphorus layer is between 1.5 µm and 5 µm, ideally between 2.5 µm and 4 µm. The latter ideal range of 2.5 µm to 4 µm represents a particularly good compromise between reliable wear protection and the quality of the signal transmission with respect to the transition resistance between the involved contact elements.

[0065] The nickel-phosphorus layer has a completely amorphous structure or an at least partially amorphous structure having a predominantly amorphous volume fraction in the structure.

[0066] Unlike pure nickel, the nickel-phosphorus layer is not formed as ceramic nickel oxide. As a result, the attenuation of signals passing through the layer is relatively low when transmitting in the high-frequency range, in particular in the range of 600 MHz to 1 GHz.

[0067] It has surprisingly been found that a gold layer for improving the signal transmission in the contact region 15a or 15b of the contact element in the plug-in connection is not necessary, since the signal transmission is already sufficient. Rather, a single layer of the above-mentioned nickel-phosphorus alloy on the metal base of the contact element is sufficient for sufficiently good signal transmission.

[0068] Testing, evaluation, and classification of plug-in connectors using measuring equipment can be performed using test adapters and are described, for example, in standard IEC 63171, which also specifies plug-in connectors for transmitting the Ethernet protocol via two conductors. In addition to the mechanical dimensions of the connector's plug, this standard also includes specifications regarding transmission quality. These specifications, for example, cover values ​​for insertion and return attenuation, transmission impedance, coupling attenuation, and other characteristic variables. Therefore, the transmission quality of SPE plug-in connectors can be determined based on this standard and compared with other plug-in connectors.

[0069] However, it is possible that the contact element of one of the plug-in connectors has such a gold layer on a nickel shielding layer as a covering layer, while the contact element of the other plug-in connector has the above-mentioned single-layer layer. If the contact element of one of the plug-in connectors has a gold layer, its average layer thickness is preferably between 0.1 μm and 0.15 μm.

[0070] As in Figure 3 and Figure 4 As shown in FIG, the single-layer coating 17 is provided only in the contact region 15, which is defined not only by the region actually in contact with the contact region of the complementary contact element, but also by a small region extending beyond the contact element 10. Outside this contact region 15, the base body 16 is preferably free of coating in the transition region 14, i.e., between the contact region 15 and the conductor connection region 13.

[0071] The layer thickness of the above-mentioned single-layer or multi-layer metal coating can be determined using conventional eddy current thickness measuring equipment. In this case, commercial measuring equipment measures in the range of a few nanometers to the millimeter range.

[0072] The nickel phosphorus alloy layer can be applied to the metal substrate by an electroplating coating process. Figure 5 explain.

[0073] This involves, in a first step 101, surface cleaning and forming the workpiece into the shape of the contact element by stamping and / or bending the workpiece. The order of surface cleaning and forming is arbitrary. Before forming the substrate, the surface of the substrate or sheet metal can be cleaned in an alkaline cleaning bath containing a surfactant. For this purpose, the cleaning bath can preferably be configured as a pickling bath, which simultaneously removes oxidation stains and surface oxides. Alternatively, degreasing and pickling to remove oxidation stains or oxide layers can be performed separately.

[0074] In a second step 102 , the substrate is immersed in a bath of electrolyte.

[0075] The electrolyte bath has a pH value preferably less than 2.0, preferably a pH value of 1.0 + / - 0.2.

[0076] Phosphonic acid or phosphinate or phosphonate or phosphinate is suitable as the phosphorus compound for depositing the phosphorus-containing alloy. Phosphonic acid is preferred, since it has been shown that phosphates produce lower layer weights.

[0077] The preferred concentration of phosphonic acid or phosphonate in the electrolyte may be greater than 5 g / l, preferably between 15 g / l and 25 g / l.

[0078] Nickel sulfate or nickel chloride dissolved in water can be used as the electrolyte salt. The weight may fluctuate depending on the proportion of water of crystallization in the electrolyte salt. The preferred nickel concentration in the electrolyte can be between 45 g / l and 65 g / l.

[0079] Furthermore, to optimize the process, boric acid can be used, for example in amounts between 20 g / l and 40 g / l.

[0080] Nickel anodes can be used as anodes in electroplated coatings.

[0081] In the third step 103, the current density is preferably adjusted according to the concentration of the dissolved nickel sulfate and / or dissolved phosphorus compound in the electrolyte. The preferred current density for the above application is 0.7 A / dm 2 Up to 5.0A / dm 2 between, preferably between 0.8 A / dm 2 Up to 4.0A / dm 2 between.

[0082] In the third step, the electroplating coating is preferably carried out at a temperature greater than 50°C, preferably between 55°C and 8°C.

[0083] In this case, the pH value may vary due to the incorporation of phosphorus into the alloy and the associated consumption of phosphonic acid. The pH value may be adjusted during the third step 103 by adding sulfuric acid.

[0084] Finally, in the fourth step 104 , drying and / or heat treatment may be performed at a temperature greater than 200° C., preferably between 300° C. and 500° C. The hardness characteristics of the nickel-phosphorus alloy layer may be significantly improved by heat treatment.

[0085] In summary, steps 102 and 103 are combined into two sub-steps of electroplating deposition.

[0086] Preferably, after each step of preparation and / or before each step of post-treatment of the electroplated deposition, the metal surface is rinsed 120 , preferably with deionized water, both the substrate to be coated and the layer applied electroplatically.

[0087] Finally, the contact element is mounted in a known manner by positioning it in the shielding element 6 or 7 and providing a plug connector. The contact element can be arranged, for example, in a contact carrier which is in turn surrounded by the shielding element 6 or 7.

[0088] The above-mentioned variants of the plug connection device and the electroplating application method are only part of an embodiment. Those skilled in the art can make many other changes based on the shown examples, and these changes also belong to the technical solutions of the present invention.

[0089] Figure 6 A further embodiment variant of a plug-in connection 101 is shown, which has a plug-in connector 103 and a mating plug-in connector 102 , which here is in the form of a round plug-in connector.

[0090] Correspondingly, contact elements 104 and 104 ′ as well as 105 and 105 ′ are provided in the two plug-type connection components.

[0091] With Figures 1 to 4 In the variant of , contact areas 108, 108a and 108b are also provided. Each plug-in connection component has a cable 109 at the end. In the plugged-in state, contact 110 is made by means of a contact pin 111 and a spring contact 112 comprising two spring arms 112a and 112b. In addition, a conductor connection area is provided. The plug-in connector 103 has a transition area 114, i.e. an intermediate piece, and a contact area or contact area 115. The contact area 115b of the contact element 105 is similar to Figures 1 to 4 There is a metal base body 116. This metal base body preferably consists of a copper alloy and has a coating 117 as wear protection.

[0092] Specifically, in Figure 6 In this case, an unshielded four-pole M8 circular plug-in connector is shown, with only two corresponding poles (contacts) visible in the cross-sectional view. Plug-in connector 103 is equipped with a union nut that screws into the mating thread of mating connector 102. The contacts are located in a contact carrier (not referenced), the area between the end of the contact carrier and the cable end being encapsulated in plastic and forming a housing. Mating connector 102 is shown in an angled embodiment. In this example, coating 117 is located on mating connector 102.

[0093] Reference Signs List

[0094] 1. 101 plug connection device

[0095] 2. 102 mating plug connector

[0096] 3. 103 plug connector

[0097] 4, 4', 104, 104' contact element

[0098] 5, 5', 105, 105' contact element

[0099] 6 Shielding elements

[0100] 7 Shielding elements

[0101] 8.108 contact area

[0102] 8a, 108a contact area (contact element 4)

[0103] 8b, 108b contact area (contact element 4')

[0104] 9. 109 cable

[0105] 10. Contact 110

[0106] 11, 111 contact pin

[0107] 12, 112 spring contacts

[0108] 12a, 112a spring arms

[0109] 12b, 112b spring arms

[0110] 13, 113 conductor connection area

[0111] 14, 114 transition area

[0112] 15, 115 touch area

[0113] 15a, 115a contact area (socket)

[0114] 15b, 115b contact area (contact pin)

[0115] 16, 116 matrix

[0116] 17, 117 coating

[0117] 101 Surface Cleaning and Forming

[0118] 102 is immersed in the electrolyte tank

[0119] 103 Adjusting current density

[0120] 104 Drying and / or heat treatment

[0121] 105 Installation

[0122] 120 flushes.

Claims

1. A plug-in connection device (1), preferably a data and power plug-in connection device, particularly preferably an SPE plug-in connection device, comprising at least two plug-in connection components in the form of a mating plug-in connector (2) and a plug-in connector (3), each of the two plug-in connection components having at least one contact element (4, 5), one of the contact elements (4) being electrically contacted with the other contact element (5) in a contact region (15) by connecting the plug-in connector (3) to the mating plug-in connector (2), characterized in that The metal base body (16) of the contacting element (4) is provided with a coating (17) in the contacting region (15), which coating consists of a single or multi-layer layer in the form of a nickel-phosphorus alloy, the metal base body (16) consisting of copper or a copper alloy.

2. The plug connection device according to claim 1 or 2, characterized in that An intermediate layer is applied between the metal base body (16) and the coating (17).

3. The plug connection device according to claim 1 or 2, characterized in that The average layer thickness of the single-layer or multi-layer coating ( 17 ) is between 1.5 μm and 5 μm, ideally between 2.5 μm and 4 μm.

4. The plug connection according to any one of the preceding claims, characterized in that The phosphorus content in the nickel-phosphorus alloy of the coating (17) is greater than 9% by weight and preferably less than 20% by weight, particularly preferably less than 15% by weight.

5. The plug connection according to any one of the preceding claims, characterized in that The nickel-phosphorus alloy comprises at least 99% by weight only nickel and phosphorus.

6. The plug connection according to any one of the preceding claims, characterized in that Another of the contact elements (5) is formed with a double-layer coating in the contact region (15), the double-layer coating comprising a first layer of a nickel-phosphorus alloy and a second layer of gold, the thickness of the second layer being less than 0.2 μm, preferably between 0.1 μm and 0.15 μm.

7. A method for producing a plug-in connector of a plug-in connection device (1) according to any one of the preceding claims, the method comprising at least the following steps: I. Cleaning the surface of the metal base body (16) of the contact element (4) of the plug connector and forming it by stamping and / or bending (101); II. immersing the metal substrate (16) (102) into an electrolyte bath containing nickel ions and a phosphorus compound; III. adjusting (103) the current density according to a predetermined target value for the phosphorus content in the alloy in order to form the coating (17); IV. drying and / or heat treatment (104), wherein the heat treatment is performed at a temperature greater than 200°C; and V. Installing (105) the one contact element (4) into the housing (6) to provide the plug connector.

8. The method according to claim 8, characterized in that The surface cleaning is carried out in an alkaline degreasing bath and the alkaline film is subsequently removed by a pickling process.

9. The method according to claim 8 or 9, characterized in that The electrolyte bath has a pH value of less than 3.0, preferably a pH value of 2.5+ / -0.

2.

10. The method according to any one of the preceding claims, characterized in that Phosphoric acid and / or hypophosphorous acid and / or phosphates and / or hypophosphites are used as phosphorus compounds.

11. The method according to any one of the preceding claims, characterized in that The preferred concentration of phosphoric acid and / or phosphate in the electrolyte is greater than 20 g / l, preferably between 20 g / l and 35 g / l.

12. The method according to any one of the preceding claims, characterized in that The electrolyte includes an aqueous solution composed of nickel sulfate and / or nickel sulfonate and / or nickel chloride.

13. The method according to any one of the preceding claims, characterized in that The electrolyte has a preferred concentration of nickel in the electrolyte of 80 g / l to 120 g / l.

14. The method according to any one of the preceding claims, characterized in that The electrolyte contains boric acid and / or sulfuric acid for setting the process conditions, in particular the pH value.

15. The method according to any one of the preceding claims, characterized in that Nickel anodes are used as anodes in electroplated coatings.

16. The method according to any one of the preceding claims, characterized in that The preferred target value for the optimal current density is 5 A / dm 2 Up to 25A / dm 2 between, preferably 18 A / dm 2 Up to 22A / dm 2 between.

17. The method according to any one of the preceding claims, characterized in that The current density is adjusted at a temperature greater than 50°C, preferably between 55°C and 80°C.

18. The method according to any one of the preceding claims, characterized in that The heat treatment is performed at a temperature between 200°C and 500°C.

19. The method according to any one of the preceding claims, characterized in that Before or after steps II and III, the metal surface of the one contact element (4) is subjected to chemical preparation and / or chemical post-treatment, each step of the chemical preparation and / or the post-treatment comprising rinsing with deionized water.

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