Electrical connector contact and connection element with electrical connector contact

Abstract

An electrical connector contact (101, 201) has a connection section (102, 202) for contacting a complementary, further electrical connector contact (201, 101). A first electroplated nickel layer (107, 207) is arranged on the connection section (102, 202). A second electroplated nickel layer (108, 208) is arranged on the first electroplated nickel layer (107, 207).

Description

[0001] The present invention relates to an electrical connector contact and a connecting element with an electrical connector contact.

[0002] Electrical connector contacts are known from the prior art.

[0003] One object of the present invention is to provide an improved electrical connector contact and a connection element with an electrical connector contact. This object is achieved by an electrical connector contact and a connection element having the features of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0004] An electrical connector contact has a terminal section for contacting a complementary, further electrical connector contact. A first electroplated nickel layer is applied to the terminal section. A second electroplated nickel layer is applied to the first electroplated nickel layer.

[0005] In one embodiment, the electrical connector contact has a soldered section permanently bonded to the terminal section. The terminal section and the soldered section are arranged opposite each other with respect to the mounting direction of the electrical connector contact. A solder joint can be arranged on the soldered section. The first electroplated nickel layer is applied to both the terminal section and the soldered section. The second electroplated nickel layer is applied only in the area of ​​the terminal section, on top of the first electroplated nickel layer. The soldered section, however, remains uncovered and uncoated by the second electroplated nickel layer. For tribological reasons, the second nickel layer is electrolyzed only in the area of ​​the terminal section to optimize its hardness.

[0006] The electrical connector contact can be designed as a plug or a socket. It can be intended for installation in, or as part of, a panel-mount plug or socket. For example, the electrical connector contact can be part of, or intended for, a backplane bus. This allows the electrical connector contact to be used, for instance, in control cabinets.

[0007] The connection section is designed to connect the electrical connector contact to a complementary, additional electrical connector contact. Thus, electrical contact with the additional electrical connector takes place within the connection section.

[0008] The solder section is designed to connect the electrical connector contact to a printed circuit board (PCB). The solder section has a soldering area opposite the connection section in terms of the mounting direction. The solder section can also be referred to as a soldering boss. Thus, the solder section is located in the soldering area opposite the connection section for connecting the electrical connector contact to the PCB. The solder joint between the solder section and the PCB can be created, for example, using surface mount technology (SMT) or through-hole reflow technology (THR). The PCB can also be referred to as a connector-assembled PCB.

[0009] The electrical connector contact has a base material, for example, a copper alloy. However, the base material can alternatively be a zinc, tin, silicon, nickel, iron, and / or steel alloy. A first electroplated nickel layer is applied to the base material. Preferably, the first electroplated nickel layer completely covers the connection section. The second electroplated nickel layer is applied to the first electroplated nickel layer and preferably completely covers the first electroplated nickel layer, i.e., for example, that the second electroplated nickel layer completely covers the first electroplated nickel layer in the connection section, including its electroplated layer run-off areas.

[0010] In one embodiment, a third electroplated nickel layer is arranged on top of the second electroplated nickel layer. The third electroplated nickel layer is designed as an adhesion promoter layer. In one embodiment, the third electroplated nickel layer is arranged on top of the first electroplated nickel layer in the area of ​​the soldering section.

[0011] The third electroplated nickel layer can be described as a so-called electroplated nickel strike layer. This third electroplated nickel layer is designed to remove oxidized nickel species from the solder area in the first electroplated nickel layer and from the connection area in the second electroplated nickel layer. This third nickel layer thus advantageously enables a further layer build-up with improved adhesion.

[0012] In one embodiment, a fourth electroplated nickel layer is arranged above the second electroplated nickel layer. The fourth electroplated nickel layer contains phosphorus. In one embodiment, the fourth electroplated nickel layer has a phosphorus content of 11–16% wt. If a third electroplated nickel layer is provided, the fourth electroplated nickel layer is arranged on top of the third electroplated nickel layer. If a third electroplated nickel layer is not provided, the fourth electroplated nickel layer is arranged on top of the second electroplated nickel layer.

[0013] In one embodiment, the first electroplated nickel layer is designed as a matte nickel layer. The second electroplated nickel layer is designed as a semi-gloss or a full-gloss nickel layer.

[0014] In one embodiment, the second electroplated nickel layer contains a fine-grain additive. In another embodiment, the first electroplated nickel layer does not contain a fine-grain additive. The fine-grain additive, in one embodiment, comprises, for example, an ionic and / or anionic and / or non-ionic surfactant and / or a derivative of the ionic and / or anionic and / or non-ionic surfactant and / or a mixture of the aforementioned surfactants. A surfactant can also be referred to as a wetting agent component. The surfactants can be cationic or anionic. Non-ionic surfactants are electrically neutral. In another embodiment, the first electroplated nickel layer does not contain a fine-grain additive.

[0015] For simplicity, the electroplated nickel layers are referred to as nickel layers in the following text. These nickel layers can be electroplated onto the electrical connector contact. The nickel layers can be deposited either electrolytically or chemically reductively without external current. For example, the nickel layers can be electroplated using a nickel sulfamate bath. A nickel layer produced in this way is highly pure (e.g., with at least 99% wt), exhibits high hardness, and provides corrosion protection for the electrical connector contact. The electroplated nickel layers, which are available as matte nickel, semi-gloss nickel, or bright nickel layers, can each be deposited using a nickel sulfamate bath. The nickel sulfamate can also be referred to as nickel(II) amidosulfate.Instead of a nickel sulfamate bath, an electroplating Watts nickel bath or an electroplating nickel strike bath can alternatively be used for electroplating the respective nickel layers. Alternatively, the nickel layers can also be electroplated with the addition of a fine-grained aggregate.

[0016] These nickel layers each serve both as a barrier layer to the base material and as a leveling and stress-relieving layer. On the base material of the electrical connector contact, the first electroplated nickel layer is preferably applied as a ductile, matte nickel layer free of fine grain additives. The second electroplated nickel layer preferably contains the fine grain additive and is therefore formed as a semi-gloss to glossy nickel layer, and is electrolytically deposited onto the first matte nickel layer.

[0017] The third electroplated nickel layer is the nickel strike layer for adhesion promotion, which is preferably electroplated over the entire connection area as well as the solder connection area. The subsequent fourth electroplated nickel layer is the nickel-phosphorus layer, which is also preferably metallized over the entire connection and solder connection area.

[0018] In this preferred embodiment, the first nickel layer is formed as a matte nickel layer, while the second nickel layer is formed as a semi-bright or bright nickel layer. However, it is also possible for the first nickel layer to be formed as a semi-bright or bright nickel layer and the second nickel layer to be formed as a matte nickel layer. The first and second nickel layers can also both be formed as matte nickel layers, or both as semi-bright or bright nickel layers. If a nickel layer is formed as a semi-bright or bright nickel layer, it can contain a fine-grain additive. The third and fourth nickel layers can also each contain a fine-grain additive or be deposited using a fine-grain additive, although this is not necessary.

[0019] The first and second nickel layers can be deposited, for example, on raw stamping strips or sections thereof, or on individual bulk stamped contacts. These electroplated contacts or strips are then assembled into electrical connectors. Suitable substrates for electroplating include raw stamping strips, sections thereof, or individual bulk stamped contacts. In a subsequent manufacturing step, the electroplated contacts or strips are assembled into electrical connectors.

[0020] The first and second nickel layers are polycrystalline and exhibit crystallites or grains separated by grain boundaries. In the preferred embodiment, the first and second nickel layers have different microstructures because the second nickel layer contains the fine-grained aggregate. Compared to the first nickel layer, which has a coarse-grained structure, the second nickel layer has a fine-grained structure. Therefore, the only important factor is that the second nickel layer has a fine-grained structure relative to the first nickel layer, and vice versa. Absolute grain sizes, for example, are not essential and are not explicitly considered.

[0021] In one embodiment, the grain size of crystallites in the second electroplated nickel layer is smaller than the grain size of crystallites in the first electroplated nickel layer. The fact that the grain size of the crystallites in the second electroplated nickel layer is smaller than that of the first electroplated nickel layer means that at least some of the crystallites in the second electroplated nickel layer have, on average, smaller grain sizes than the crystallites in the first electroplated nickel layer, at least along one direction of extension. The grain sizes of the first and second nickel layers may be similar or identical. The grain sizes of the first and second nickel layers can be determined, for example, according to the standards ASTM E112 and DIN EN ISO 643.

[0022] In addition to grain size, grain boundary densities of the nickel layers can also be considered to differentiate their microstructures. In one embodiment, the grain boundary density of the second nickel layer is greater than that of the first nickel layer. Compared to the second nickel layer, the first nickel layer exhibits isotropic layer growth with few grain boundaries. The second nickel layer has a higher number of grain boundaries and a finer-grained microstructure.

[0023] The second nickel layer is less ductile compared to the first nickel layer, but exhibits higher hardness. This higher hardness can be attributed, for example, to a higher grain boundary density, since cracks typically propagate along grain boundaries, and a higher density of grain boundaries reduces the likelihood of crack propagation.

[0024] The fine grain additive acts as an inhibitor of anisotropic layer growth and is incorporated into the microstructure during electroplating. In this way, it influences the growth and growth rate along specific crystallographic orientations of the crystallites and grain boundaries. Fine grain additives can reduce the crystallite size and / or cause the formation of rounded crystallites. Electroplated nickel layers containing fine grain additives are, according to the electrochemical series, less noble, ranging from semi-bright to bright, compared to more noble matte nickel layers without fine grain additives.

[0025] Visually, the first nickel layer is characterized by its matte surface appearance when uncovered, compared to the second nickel layer. As a result of this multi-layer nickel plating, the electroplated contacts assembled into connectors exhibit optimized friction and wear behavior, as well as an extended service life. Therefore, due to the optimized hardness of the second nickel layer, the electrical connector contact can be used in applications where it is subjected to higher mechanical stresses, such as vibrations, in the connection area.Advantageously, the fourth nickel layer, particularly due to its high phosphorus concentration of 11-16% wt, further improves the wear properties in the connecting section, as the fourth nickel layer has a particularly high hardness.

[0026] The fact that the second nickel layer contains a fine grain additive means that the deposited second nickel layer contains components of the fine grain additive which are incorporated into the second nickel layer during electroplating and thus influence the growth of the crystallites and grain boundaries.

[0027] In one embodiment, the fine grain additive comprises primary and / or secondary brighteners and / or derivatives of the primary and / or secondary brighteners, which also achieve a leveling effect for subsequent electrogalvanic nickel metallization, resulting in an electrogalvanically anisotropic and homogeneous layer structure.

[0028] The gloss-forming agent contains a gloss carrier and / or at least one gloss additive. Gloss carriers are also referred to as primary gloss agents and significantly reduce the size of the deposited crystallites. Gloss additives are also referred to as secondary gloss agents and, on their own, produce highly glossy, but usually brittle, layers. In combination with gloss carriers, a solid high gloss can be achieved.

[0029] In one embodiment, the gloss former comprises one of the following materials: a sulfoximide, a sulfonamide, a benzenesulfonic acid, a naphthalenesulfonic acid, an alkanesulfonic acid, a sulfinic acid and an arylsulfonesulfonate and / or an aldehyde, a thiocyanate, thiourea, acylthiourea, a sulfanylalkylsulfonic acid, a disulfide, a thiocarboxylic acid amide, a thiocarbamate, a thiosemicarbazone and / or thiohydantoins.

[0030] An additional heat treatment of the fourth nickel layer, within a temperature range of, for example, T = 300°C to a maximum of T = 400°C, can induce a crystalline microstructure transformation. This heat treatment can convert the microstructure into a crystalline, semi-crystalline, and / or nanocrystalline structure. This results in layer hardening through the precipitation of nickel phosphide, such as trinickel phosphide (Ni3P). Consequently, a maximum microhardness of approximately 1500 HV can be achieved for the fourth nickel layer.

[0031] The fourth nickel layer can also be produced by adding a layer-hardening dispersion additive to the electroplating nickel-phosphorus bath during the electroplating process. For example, silicon carbides, silicon oxides, boron nitrides, and / or aluminum ceramics can be used as dispersion additives.

[0032] This results in the fourth nickel layer containing the dispersion additive, which is incorporated into the fourth nickel layer during deposition. A fourth nickel layer produced in this way exhibits higher microhardness and improved friction and wear resistance compared to a dispersion-additive-free, pure electroplated nickel (phosphorus) coating.

[0033] In one embodiment, as an alternative to the fourth electroplated nickel layer, a fourth electroplated layer is arranged above the second electroplated nickel layer. The fourth electroplated layer comprises a palladium-nickel alloy, in particular a palladium-nickel alloy with 80% wt palladium and 20% wt nickel. The fourth electroplated layer can therefore be used as an alternative to the fourth electroplated nickel layer in the layer structure. If the third electroplated nickel layer is provided, the fourth electroplated layer is arranged on top of the third electroplated nickel layer. If the third electroplated nickel layer is not provided, the fourth electroplated layer is arranged on top of the second electroplated nickel layer.

[0034] In one embodiment, the fourth electroplated nickel layer, or the fourth electroplated layer in the area of ​​the connection section, is arranged on the third electroplated nickel layer, or on the second electroplated nickel layer. In another embodiment, the fourth electroplated nickel layer, or the fourth electroplated layer, is arranged on the third electroplated nickel layer, or on the first electroplated nickel layer, in the area of ​​the soldering section.

[0035] The second electroplated nickel layer is not located in the soldered area, as this could cause delamination of the fourth electroplated nickel layer. To prevent this, the fourth electroplated nickel layer is positioned above the first electroplated nickel layer in the soldered area, resulting in improved adhesion compared to its position above the second electroplated nickel layer. This advantageously prevents delamination of the fourth electroplated nickel layer in the soldered area. Furthermore, the fourth electroplated layer can exhibit improved adhesion to the first, second, or third nickel layer compared to its position above the second electroplated nickel layer.

[0036] In one embodiment, the first electroplated nickel layer completely covers the connection section and the solder section, and the second electroplated nickel layer completely covers the first electroplated nickel layer in the area of ​​the connection section, and / or the third electroplated nickel layer completely covers the first electroplated nickel layer in the area of ​​the solder section and the second electroplated nickel layer in the area of ​​the connection section, and / or the fourth electroplated nickel layer completely covers the third electroplated nickel layer in the connection section and the solder section. Alternatively, selective or partial coverage of the aforementioned layers is possible.

[0037] In one embodiment, the first electroplated nickel layer has a thickness of 0.5 µm to 3 µm, and / or the second electroplated nickel layer has a thickness of 0.5 µm to 3 µm, and / or the third electroplated nickel layer has a thickness of 100 nm to 1000 nm, and / or the fourth electroplated nickel layer has a thickness of 0.2 µm to 2 µm. The fourth electroplated nickel layer may, for example, have a nominal thickness of 1 µm. The respective thickness ranges of the first, second, third, and fourth electroplated nickel layers are merely exemplary and are not intended to be restrictive. Rather, deviations from these specific values ​​are permissible without altering the underlying concept of the electrical connector contact.

[0038] In one embodiment, a gold layer is arranged on the fourth electroplated nickel layer. Advantageously, the fourth electroplated nickel layer is positioned between more noble layers, since the first electroplated nickel layer, the second electroplated nickel layer, and the gold layer are each more noble than the third nickel layer. The gold layer can, for example, be electroplated. The gold layer can also be referred to as a so-called gold flash.

[0039] The gold layer can completely cover the fourth electroplated nickel layer in the connection section, but this is not mandatory. The gold layer can, for example, have a thickness of 0.05 µm to 0.1 µm, but this is not limited to the specified range. Since the fourth electroplated nickel layer, or the fourth and third electroplated nickel layers, are merely optional, the gold layer can alternatively be applied to the second electroplated nickel layer and, for example, completely cover it.

[0040] In one embodiment, the connection section of the electrical connector contact is designed as a plug, and the gold layer is located entirely within the area of ​​the second electroplated nickel layer. In another embodiment, the connection section of the electrical connector contact is designed as a plug coupling, and the gold layer is located entirely within the area of ​​the second electroplated nickel layer. However, it is not essential that the gold layer be located entirely within the area of ​​the second nickel layer, i.e., entirely within the connection section. For example, the connection section of the electrical connector contact can be designed as a spring coupling, and the gold layer can be located only within the area of ​​one of the spring coupling's tips.

[0041] Advantageously, the electrical connector contact is designed to be particularly corrosion-resistant. The first and second electroplated nickel layers can each be of a higher noble metal than the base material of the electrical connector contact, from which the terminal section and the soldered section are formed. This alone can protect the base material against corrosion. Additionally, the first electroplated nickel layer is protected by the second electroplated nickel layer.

[0042] In the preferred embodiment, the second electroplated nickel layer is formed as a semi-bright or bright nickel layer and is therefore less noble than the first electroplated nickel layer, which is formed as a matte nickel layer. However, the second electroplated nickel layer is more noble than the fourth electroplated nickel layer, which is advantageous for the corrosion resistance of the first and second electroplated nickel layers, particularly when the fourth electroplated nickel layer is located in the connection section between the second electroplated nickel layer and the gold layer, and in the soldered section between the first electroplated nickel layer and the gold layer, which is the most noble of all the aforementioned layers. The third electroplated nickel layer (nickel strike layer) is provided solely as an adhesion promoter layer for the fourth electroplated nickel layer.The third electroplated nickel layer and the fourth electroplated nickel layer or the fourth electroplated layer are merely optional and can also be omitted.

[0043] In the layered structure of the preferred embodiment, the second electroplated nickel layer provides cathodic corrosion protection. If the second electroplated nickel layer were not present at the electrical connector contact, the first electroplated nickel layer would act as a sacrificial anode, particularly in the presence of the fourth electroplated nickel layer or the fourth electroplated layer and the gold layer. Corrosion of the first electroplated nickel layer can occur, for example, if the fourth electroplated nickel layer or the fourth electroplated layer exhibits cracks and fractures. Overall, the probability of corrosion of the first electroplated nickel layer would be increased, which could consequently lead to its detachment from the electrical connector contact.

[0044] The presence of the second electroplated nickel layer, which in the preferred embodiment is less noble than the first electroplated nickel layer, and the fourth electroplated nickel layer, which is less noble than both the first and second electroplated nickel layers, protects the first electroplated nickel layer. Even if the fourth electroplated nickel layer should develop cracks, the first electroplated nickel layer is protected against corrosion in the presence of the second nickel layer.

[0045] In one embodiment, a sealing layer is arranged on the gold layer. The sealing layer comprises an inorganic or organic material. For example, the sealing layer can contain a thiol. The sealing layer is designed to fill cracks in the gold plating and advantageously provides additional protection to the electrical connector contact in the connection section. Preferably, the sealing layer completely covers the gold layer.

[0046] In one embodiment, a tin layer is arranged on the fourth electroplated nickel layer in an area opposite the connection section in the mounting direction. The tin layer is therefore not located entirely within the soldering area, but only in an area opposite the connection section. The tin layer defines the soldering area of ​​the soldering section for connection to a printed circuit board. The fourth electroplated nickel layer, or the fourth electroplated layer, advantageously forms a diffusion barrier against the tin layer. The tin layer can, for example, have a thickness of 2 µm to 6 µm, but it is not limited to the specified range. The tin layer can also be referred to as a solder metal.

[0047] In one embodiment, a lubricant layer is arranged on the gold layer or on the sealing layer. Preferably, the lubricant layer completely covers the gold layer or the sealing layer. The lubricant layer comprises, for example, perfluoropolyether (PFPE). However, the lubricant layer can also comprise another material. The lubricant layer can also be referred to as electroplating contact lubrication. The lubricant layer can be applied particularly homogeneously to the gold layer or the sealing layer. Advantageously, the lubricant layer also reduces the wear of the electrical connector contact when connecting the electrical connector contact to the complementary, further electrical connector contact.If no gold layer is provided, the lubricant layer is arranged on the fourth electroplated nickel layer or the fourth electroplated layer and preferably covers it completely. If, in addition, no fourth electroplated nickel layer or no fourth electroplated layer is provided, the lubricant layer is arranged on the second electroplated nickel layer and preferably covers it completely.

[0048] The lubricant layer can also be applied, preferably entirely, to the electrical connector contact within the soldered section. In this case, the lubricant layer optionally covers the tin layer, the fourth electroplated nickel layer, the fourth electroplated layer, or the first electroplated layer. The lubricant layer covers the first electroplated layer if the fourth electroplated nickel layer or the fourth electroplated nickel layer, which are optional, are not present. Similarly, the tin layer can be applied to the first electroplated nickel layer if the fourth electroplated nickel layer or the fourth electroplated layer is not present.

[0049] A connection element comprises a housing, a printed circuit board arranged on the housing, and at least one electrical connector contact arranged in the housing and connected to the printed circuit board, according to one of the embodiments. The connection element is designed for connection with a complementary, further connection element having at least one further connector contact complementary to the electrical connector contact.

[0050] The electrical connector contact is explained in detail below with reference to schematic drawings. These show: Fig. 1a: an electrical connector contact according to a first embodiment with a layer sequence; Fig. 1b: a sectional view along a Fig. Section AA shown in 1a through the layer sequence; Fig. 1c: a sectional view along a Fig. 1a section plane BB shown through the layer sequence; Fig. 2a: an electrical connector contact according to a second embodiment with a layer sequence; Fig. 2b: a sectional view along a Fig. 2a section plane AA shown through the layer sequence; Fig. 2c: a sectional view along a Fig. 2a section plane BB through the layer sequence shown; Fig. 3: A connecting element with electrical connector contacts in a perspective view; Fig. 4: Results of a load test of an electrical connector contact; Fig. 5a: Results of further load tests of an electrical connector contact in accordance with the state of the art; Fig. 5b: Results of further load tests of the electrical connector contact according to Fig. 1a to 1c or 2a to 2c with the layer sequence according to Fig. 1a to 1c or 2a to 2c and Fig. 5b; Fig. 6a: a scanning electron microscope image of a layer sequence of an electrical connector contact without fine grain addition in a cross-sectional view; Fig. 6b: a scanning electron microscope image of a layer sequence of an electrical connector contact with a fine grain additive in a cross-sectional view; Fig. 6c: an enlargement of a layer of the layer sequence of Fig. 6a without fine grain addition and an enlargement of one layer of the stratigraphic sequence of Fig. 6b with fine grain addition, each in a cross-sectional view; Fig. 7a: a current density diagram of a unipolar electroplating process of a phosphorus-containing nickel layer; and Fig. 7b: a current density diagram of a bipolar electroplating process of a phosphorus-containing nickel layer.

[0051] Fig. Figure 1a schematically shows three electrical connector contacts 101 according to a first embodiment. The electrical connector contacts 101 are shown in a state in which they are, by way of example, part of a raw stamping strip section.

[0052] The electrical connector contact 101 has a terminal section 102 and a solder section 103, which can also be referred to as a soldering boss 103. The terminal section 102 and the solder section 103 are rigidly connected to each other. In other words, the electrical connector contact 101 is monolithic, i.e., the terminal section 102 and the solder section 103 are formed by different sections of a single body. The terminal section 102 and the solder section 103 are arranged such that they face each other along a principal extension direction 104 of the electrical connector contact 101, which can also be referred to as the mounting direction 104.

[0053] The electrical connector contact 101 according to Fig. Figure 1 is designed as an example of a plug. In this case, the connection section 102 is configured as a contact pin and is designed to engage with a complementary coupling or a socket contact. Of course, the connection section 102 can also be configured as a socket and designed to receive a complementary or corresponding plug contact.

[0054] The electrical connector contact 101 has a base material 106 and a layer sequence 105 arranged on the base material 106, which is located on a surface of the base material 106. The arrangement of the layer sequence 105 and the extent of individual layers of the layer sequence 105 along the main extent direction 104 is for one of the electrical connector contacts 101 in Fig. 1a schematically indicated.

[0055] Fig. 1b shows a sectional view along a Fig. Section 1a shown section plane AA through the layer sequence 105. Fig. 1c shows a sectional view along a Fig. 1a shows the section plane BB through the layer sequence 105. The first cross-section AA runs in the area of ​​the connection section 102, while the second cross-section BB runs in the area of ​​the soldering section 103 on a side opposite the connection section 102.

[0056] The individual layers of the layer sequence 105 preferably completely or at least partially enclose the electrical connector contact 101 azimuthally around the main extension direction 104.

[0057] The layer sequence 105 comprises, in the connecting section 102, a first electroplated nickel layer 107, a second electroplated nickel layer 108, a third electroplated nickel layer 109, a fourth electroplated nickel layer 110, a gold layer 111, a sealing layer 112, and a lubricant layer 113. The electroplated nickel layers 7, 8, 9, 10 are also referred to as nickel layers 7, 8, 9, 10 in the following description. The third nickel layer 109, the sealing layer 112, and the lubricant layer 113 are in Fig. 1a is not shown for the sake of simplicity. The third nickel layer 109, the fourth nickel layer 110 and / or the gold layer 111 and / or the sealing layer 112 and / or the lubricant layer 113 can also be omitted.

[0058] The base material 106 is, by way of example, a copper alloy. However, the base material 106 can also be a zinc, tin, silicon, nickel, iron, and / or steel alloy. The first nickel layer 107 is arranged on the base material 106. The first nickel layer 107 is arranged on the base material 106 in both the connection section 102 and the soldering section 103. The first nickel layer 107 preferably covers the entire base material 106.

[0059] A second nickel layer 108 is arranged on the first nickel layer 107 in the connecting section 102. The second nickel layer 108 preferably completely covers the first nickel layer 107 in the connecting section 102. The second nickel layer 108 can also be deposited, for example, by electroplating. The second nickel layer 108 is omitted in the soldering section 103.

[0060] The first and second nickel layers 107, 108 are each polycrystalline, i.e., they exhibit a multitude of crystallites separated from one another by grain boundaries. In the preferred embodiment according to Fig. In Figure 1, the first nickel layer 107 is designed as a matte nickel layer. The second nickel layer 108 is designed as a semi-bright or bright nickel layer. The second nickel layer 108 can have a fine-grained microstructure compared to the first nickel layer 107. Conversely, the first nickel layer 107 can have a coarse-grained microstructure compared to the second nickel layer 8.

[0061] This results in the second nickel layer 108 being harder than the first nickel layer 107. For this reason, the electrical connector contact 101 exhibits improved wear properties in the area of ​​the connection section 102. This ensures that the corrosion-resistant properties of the nickel and the layer sequence 105 are maintained in the long term. Furthermore, the corrosion-resistant properties are retained even under high loads acting on the electrical connector contact 101.

[0062] For example, it is possible that the second nickel layer 108 has crystallites with an average grain size that is smaller than the average grain size of the crystallites of the first nickel layer 107.

[0063] The fact that the grain size of the crystallites in the second nickel layer 108 is smaller than the grain size of the crystallites in the first nickel layer 107 can be achieved, for example, by using a fine-grain additive during the deposition of the second nickel layer 108. In this case, the second nickel layer 108 contains the fine-grain additive because the additive is incorporated into the second nickel layer 108 during its deposition. These residues of the fine-grain additive modify the crystal growth within the second nickel layer 108 in such a way that it can exhibit a fine-grained microstructure compared to the first nickel layer 107.

[0064] The third nickel layer 109 is arranged on the second nickel layer 108 in the area of ​​the connection section 102 and on the first nickel layer 107 in the area of ​​the soldering section 3.

[0065] The third nickel layer 109 preferably completely covers the second nickel layer 108 in the area of ​​the connection section 102. Furthermore, the third nickel layer 109 preferably completely covers the first nickel layer 107 in the area of ​​the soldering section 103. The third nickel layer 109 can also be referred to as a nickel strike layer. The third nickel layer 109 is intended to provide improved adhesion for a fourth nickel layer 110. The third nickel layer 109 can also be omitted.

[0066] The fourth nickel layer 110 is arranged in the area of ​​the connection section 102 above the second nickel layer 108 and on the third nickel layer 109, and in the area of ​​the soldering section 103 above the first nickel layer 107 and on the third nickel layer 109. If no third nickel layer 109 is provided for adhesion, the fourth nickel layer 110 is arranged directly on the second nickel layer 108 in the area of ​​the connection section 102 and directly on the first nickel layer 107 in the area of ​​the soldering section 103. The fourth nickel layer 110 preferably completely covers the second nickel layer 108 or the optional third nickel layer 109 in the area of ​​the connection section 102. Furthermore, the fourth nickel layer 109 preferably completely covers the first nickel layer 107 or the optional third nickel layer 109 in the area of ​​the soldering section 3.

[0067] The fourth nickel layer 110 contains phosphorus in addition to nickel. The phosphorus content of the fourth nickel layer 110 can be, for example, eleven to sixteen percent by weight. Alternatively, instead of the phosphorus-containing fourth nickel layer 110, the layer sequence can include a fourth layer 110 which also contains nickel, but should not be referred to as a nickel layer, since it is a PdNi alloy with a mass fraction of, for example, 80% wt Pd and 20% wt Ni.

[0068] The fourth nickel layer 110 is more brittle and less noble than the second nickel layer 108. The fact that the second nickel layer 108 is only located in the connection section 102 and not also in the soldering section 103 has the advantage of preventing delamination of the fourth nickel layer 110 in the soldering section 103 under high temperatures and stresses. Compared to the phosphorus-containing fourth nickel layer 110, the fourth layer 110, which contains the PdNi alloy, exhibits improved adhesion to the first nickel layer 107 and to the optional third nickel layer 910 in the area of ​​the soldering section 103.

[0069] In the area of ​​the connection section 102, the gold layer 111 is arranged on the fourth nickel layer 110 or the fourth layer 110. The connection section 102 of the electrical connector contact 101 is in the embodiment of the Fig. 1 is designed as a connector. The gold layer 111 is preferably arranged entirely within the area of ​​the second nickel layer 109 or entirely within the area of ​​the connection section 102 and covers it radially on the outside with respect to the main direction of extension 104. The gold layer 111 additionally protects the electrical connector contact 101 and the nickel layers 107, 108, 109, 1010 from environmental influences. Furthermore, the third nickel layer 109 in the connection section 102 is arranged between two less noble layers, namely the second nickel layer 108 and the gold layer 111, which has a positive effect on the corrosion resistance of the electrical connector contact 101.

[0070] A lubricant layer 113, which may, for example, consist of PFPE, is arranged on the gold layer 111. A sealing layer 112 may be arranged between the gold layer 111 and the lubricant layer 113. Although the gold layer 111, the sealing layer 112, and the lubricant layer 113 are optional, they further improve corrosion protection and reduce abrasion during use of the electrical connector contact 1.

[0071] To connect the electrical connector contact 101 to a circuit board or printed circuit board, a tin layer 114 is arranged opposite the soldering section 103 and the connection section 102. However, the tin layer 114 can also be omitted.

[0072] Fig. Figure 2a schematically shows four electrical connector contacts 201 according to a second embodiment. Fig. 2b shows a sectional view along a Fig. 2a section plane AA shown through the layer sequence 5. Fig. 2c shows a sectional view along a Fig. 2a shows the section plane BB through the layer sequence 5. The first cross-section AA runs in the area of ​​the connection section 202, while the second cross-section BB runs in the area of ​​the soldering section 203 on a side opposite the connection section 202.

[0073] The electrical connector contact 201 according to the second embodiment is essentially identical to that in the Fig. The electrical connector contact 101 described in sections 1a to 1c is formed. The following description explains only the differences between the electrical connector contact 201 according to the second embodiment and the electrical connector contact 101 according to the first embodiment. Similar reference numerals are used for similar or identical elements.

[0074] The electrical connector contact 201 according to Fig. In addition to the connection section 202 and the soldering section 203, the component 2 also has a connecting section 215. The connecting section 215 is arranged between the connection section 202 and the soldering section 203 with respect to the mounting direction 205 and connects the connection section 202 and the soldering section 203 to each other.

[0075] In contrast to the connection section 102 of the electrical connector contact 1 according to Fig. 1 The connection section 202 of the electrical connector contact 201 is designed as a spring coupling 216, i.e. the electrical connector contact 201 according to Fig. 2 is for receiving the electrical connector contact 101 according to Fig. 1. The spring coupling 216 has a tulip-shaped element 217. For this reason, the gold layer 211 in the embodiment according to Fig. 2 is arranged only in the area of ​​the tulip 215. However, it is not necessary for the gold layer 211 to be arranged only in the area of ​​the tulip 217. For example, the gold layer 211 can be arranged in the entire connection section 202, i.e., in the exemplary embodiment of the Fig. 2a on the entire spring coupling 216. The reception of the electrical connector contact 101 according to Fig. 1 in the spring coupling 216 is in Fig. 3 illustrated.

[0076] Fig. Figure 3 schematically shows a first connection element 301 in a perspective view. The first connection element 301 can also be referred to as a knife-side connection element 301. The first connection element 301 has a first housing 303, which can also be referred to as a knife housing 303. By way of example, the first connection element 301 has a plurality of electrical connector contacts 101 according to Fig. 1a to 1c, which are arranged in the first housing 303. It may also suffice if the first connecting element 301 merely has an electrical connector contact 101 according to Fig. 1. The first connection element 301 can, for example, be part of a backplane bus and thus be used, for example, in a control cabinet.

[0077] Fig. Figure 3 also shows a complementary, second connection element 302 with a plurality of electrical connector contacts 201 according to Fig. 2a to 2c, which are arranged in a second housing 304, which can also be referred to as a spring housing 304, of the second terminal element 302. It may also suffice if the second terminal element 302 merely has an electrical connector contact 202 according to Fig. 2.

[0078] Fig. Figure 3 illustrates the engagement of the second terminal element 302 with the first terminal element 301, wherein the electrical connector contacts 101 are connected according to Fig. 1a to 1c of the first connecting element 301 into the electrical connector contacts 201 according to Fig. 2a to 2c of the second connection element 302 engage. It is also possible, in principle, for the first connection element 301 to engage with the second connection element 302, with the electrical connector contacts 101 according to Fig. 1a to 1c of the first connecting element 301 into the electrical connector contacts 201 according to Fig. 2a to 2c of the second connection element 302 engage.

[0079] The electrical connector contacts 101 of the first connecting element 301 can each be connected to a Fig. 3. The first circuit board (not shown), which is located on the first housing, may be connected. Alternatively or additionally, the electrical connector contacts 201 of the second connection element 302 may each be connected to a Fig. The circuit boards are connected to the second circuit board (not shown), which is located on the second housing. With respect to the mounting direction 104, 204, the circuit boards can, for example, be arranged on opposite housing walls of the first and second housings 303, 304, although this is not mandatory, as the circuit boards can be arranged arbitrarily on the respective housings 303, 304. Alternatively, at least one or both circuit boards can be omitted. In this case, the electrical connector contacts 101, 201 are each configured for connection to a circuit board.

[0080] Fig. Figure 4 schematically shows the results of a load test of an electrical connector contact 101, 201 according to Fig. 1 or Fig. 2. The abscissa shows the test duration in hours. The ordinate shows the ohmic resistance of the electrical connector contact 101, 201 in mΩ. The electrical connector contact 101, 201 was exposed to a temperature of 125°C (dry-heat test). Fig. Figure 4 shows that the resistance change after 1000 hours increased by less than 5 mΩ. This demonstrates the improved wear characteristics of the electrical connector contact 101, 201. Furthermore, no corrosion occurs despite the load.

[0081] Fig. 5a and Fig. Section 5b shows further stress tests. Fig. Figure 5a shows a load test of an electrical connector contact according to the state of the art, while in Fig. 5b a load test of the electrical connector 101, 201 of the Fig. 1 or Fig. Figure 2 shows an ohmic resistance in mΩ as a function of a number of insertion cycles N.

[0082] A mating cycle is defined by connecting the electrical connector contact 101, 201 to the complementary connector contact 201, 101 and moving it along the assembly direction 104, 204 by a definable distance within a definable time period. For example, the electrical connector contact 101, 201 can be moved by ±25 µm within one second along the assembly direction 104, 204 in one cycle. Fig. 5a and Fig. Figure 5b shows exemplary results after a total of 100,000 cycles. Enlargements of the relevant parts of the diagrams are also shown to better illustrate changes in resistance.

[0083] While a significant change in resistance can be observed in the case of electrical connector contacts according to the prior art with an increasing number of cycles, the resistance of electrical connector contact 101, 202 does not increase significantly with the number of mating cycles. This indicates that, due to the improved wear properties, little or no diffusion occurs into the base material 106, 206 of the electrical connector contact 101, 201, and that no intermetallic phases are formed that could negatively affect the quality of the electrical connector contact 101, 201. As a result, the electrical connector contact 101, 201 has a longer service life.

[0084] Fig. Figure 6a schematically shows a scanning electron microscope image in cross-section of a layer sequence 105, 205, the second electroplated nickel layer 108, 208 of which has no fine grain additive. Likewise, the layers in Fig. Figure 6a shows the first electroplated nickel layer 107, 207 and the fourth layer 110, 210 as examples without any fine grain additive. Instead of the fourth layer 110, 210, the fourth electroplated nickel layer 110, 210 can also be provided. The third electroplated nickel layer 109, 209 is shown in Fig. 6a is not recognizable because it is too thin. The third electroplated nickel layer 109, 209 also shows no fine grain additive, for example.

[0085] In contrast to the first electroplated nickel layer 107, 207, the second electroplated nickel layer 108, 208 exhibits, by way of example, smaller crystallites or grains. The first electroplated nickel layer 107, 207, which does not contain any fine grain additives, exhibits, by way of example, primarily crystallites that are larger than 1 µm along at least one direction, while the crystallites of the second electroplated nickel layer 108, 208 predominantly have grain sizes in the submicrometer range. However, the grain sizes shown and specified are not to be understood as limiting, but are merely examples.

[0086] Fig. Figure 6b schematically shows a scanning electron microscope image in cross-section of a layer sequence 105, 205, the second electroplated nickel layer 108, 208 of which has a fine grain additive. The in Fig. The first electroplated nickel layer 107, 207 and the fourth layer 110, 210 shown in Figure 6a do not contain any fine grain additive. Instead of the fourth layer 110, 210, the fourth electroplated nickel layer 110, 210 can also be provided. The third electroplated nickel layer 109, 209 is shown in Fig. 6b is likewise not discernible, as it is too thin. The third electroplated nickel layer 109, 209 also shows no fine grain addition, for example. The fine grain addition of the second electroplated nickel layer 108, 208 is likewise not discernible, as it is located predominantly in the grain boundary region of the second electroplated nickel layer 108, 208.

[0087] In principle, the first electroplated nickel layer 107, 207, the second electroplated nickel layer 108, 208, the optional third electroplated nickel layer 109, 209, and the optional fourth layer 110, 210 or the fourth electroplated nickel layer 110, 210 may each, individually, contain a fine grain additive or not. Preferably, however, at least the second electroplated nickel layer 108, 208 contains the fine grain additive.

[0088] As in Fig. 6a shows that the second electroplated nickel layer 108, 208 has smaller crystallites than the first electroplated nickel layer 107, 207. However, in Fig. 6b to recognize that the microstructure of the second electroplated nickel layers 108, 208 of the Fig. 6a and Fig. 6b differ, since the second electroplated nickel layer 108, 208 of the Fig. 6a in contrast to the second electroplated nickel layer 108, 208 of the Fig. 6a contains a fine grain additive.

[0089] Fig. Figure 6c schematically shows magnifications of the second electroplated nickel layers 108, 208 of the Fig. 6a and Fig. 6b. The second electroplated nickel layer 108, 208 with fine grain addition according to Fig. 6b exhibits smaller crystallites than the second electroplated nickel layer 108, 208 without fine grain addition according to Fig. 6a. The fact that the grain size of the crystallites of the second electroplated nickel layer 108, 208 with fine grain addition is smaller than the crystallites of the second electroplated nickel layer 108, 208 without fine grain addition means that at least some of the crystallites of the second electroplated nickel layer 108, 208 with fine grain addition have, on average, smaller grain sizes along at least one direction of extension than the crystallites of the second electroplated nickel layer 108, 208 without fine grain addition.

[0090] In the exemplary embodiment of the Fig. 6c can, for example, contain 25% to 75% of the crystallites of the second electroplated nickel layer 108, 208 with fine grain addition according to Fig. 6b, for example, exhibit average grain sizes exceeding 500 nm along at least one direction of extension. Similarly, for example, 25% to 75% of the crystallites of the second electroplated nickel layer 108, 208 without the addition of fine grains according to Fig. 6a, for example, exhibit average grain sizes along at least one direction of extension below 500 nm. These grain sizes are merely exemplary and are not intended to limit the electrical connectors 101, 201. Rather, they illustrate a possible embodiment that exhibits the explained advantages of the improved wear properties of the electrical connectors 101, 202.

[0091] Furthermore, the grain boundary density of the second electroplated nickel layer is 108, 208 with fine grain addition according to Fig. 6b higher than the grain boundary density of the second electroplated nickel layer 108, 208 without fine grain addition according to Fig. 6a. In other words, the microstructure with added fine grains is finer. Furthermore, the crystallites of the second electroplated nickel layer 108, 208 with added fine grains are more rounded than the crystallites of the second electroplated nickel layer 108, 208 without added fine grains.

[0092] In Fig. 6a and Fig. Figure 6b shows the fourth electroplated nickel layer 110, 210 next to the first and second electroplated nickel layers 107, 207, 108, 208. Alternatively, the fourth layer 110, 210 can be provided instead of the fourth electroplated nickel layer 110, 210. The fourth electroplated nickel layer 110, 210 can be electroplated, for example, by direct current deposition, like the first electroplated nickel layer 107, 207, the second electroplated nickel layer 108, 208, the third electroplated nickel layer 109, 209, and the fourth layer 110, 210. However, the fourth electroplated nickel layer 110, 210 can also be deposited on the second or third electroplated nickel layer 108, 208, 109, 209 by pulsed current deposition.

[0093] Fig. Figure 7a schematically shows an exemplary current density diagram for the electroplating pulsed current deposition of the fourth electroplating nickel layer 110, 210. A current density is plotted against a coating duration. Fig. Figure 7a shows a unipolar electroplating of the fourth electroplated nickel layer 110, 210.

[0094] The current density j exhibits a rectangular profile with a period T and maxima j P The current density only assumes values ​​greater than or equal to zero, since unipolar deposition occurs. Within one period T, the maximum current density j is reached. P maintained for a time period T1, while the current density assumes zero for a time period T0, so that T = T1 + T0. Fig. Figure 7a also shows a median value j M the current density.

[0095] Fig. Figure 7b schematically shows another exemplary current density diagram for the electroplating pulsed current deposition of the fourth electroplating nickel layer 110, 210. Here, a current density is again plotted against a coating duration. Fig. Figure 7b shows a bipolar electroplating of the fourth electroplated nickel layer 110, 210.

[0096] In contrast to unipolar deposition, the current density also assumes negative values ​​within a period T; that is, it is not direct current deposition but alternating current deposition. The current density profile of the Fig. 7b also exhibits a rectangular profile. Within one period T, a maximum current density j is observed. P1 The current density is maintained for a time period T1. Subsequently, the current density reaches a minimum for a time period T2. P2 and assigns the value zero for a time period T0, such that T = T1 + T2 + T0.

[0097] In comparison to direct current deposition, a fourth electroplated nickel layer 110, 210 deposited with pulsed current parameters exhibits a more uniform and finer-grained layer structure. Pulsed current deposition results in a reduction of the grain size and an increase in the gloss level of this layer, as well as a higher layer hardness.

[0098] The fourth electroplated nickel layer 110, 210 deposited using pulsed current parameters also exhibits a higher phosphorus content compared to a fourth electroplated nickel layer 110, 210 deposited using direct current deposition. The local phosphorus distribution of the fourth electroplated nickel layer 110, 210 deposited using pulsed current is comparable to the phosphorus distribution of nickel layers deposited without electrolysis. Reference symbol list 101 electrical connector according to the first embodiment 102 Connection section 103 Soldering section 104 Mounting direction / Main extension direction 105 layer sequence 106 Basic material 107 first electroplated nickel layer 108 second electroplated nickel layer 109 third electroplated nickel layer 110 fourth electroplated nickel layer / fourth electroplated layer 111 Gold layer 112 Sealing layer 113 Lubricant layer 114 Tin layer / Solder metal 201 electrical connector according to the second embodiment 202 Connection section 203 Soldering section 204 Mounting direction / Main extension direction 205 layer sequence 206 Basic material 207 first electroplated nickel layer 208 second electroplated nickel layer 209 third electroplated nickel layer 210 fourth electroplated nickel layer / fourth electroplated layer 211 gold layer 212 Sealing layer 213 Lubricant layer 214 Tin layer / Solder metal 215 Connecting section 216 Spring coupling 217 Tulip of the spring coupling 301 knife-side, first connection element 302 spring-side, second connecting element 303 first housing / knife housing 304 second housing / spring housing

Claims

[1] Electrical connector contact (101, 201) having a connection section (102, 202) for contacting a complementary, further electrical connector contact (201, 101), wherein a first electroplated nickel layer (107, 207) is arranged on the connection section (102, 202), wherein a second electroplated nickel layer (108, 208) is arranged on the first electroplated nickel layer (107, 207). [2] Electrical connector contact (101, 201) according to claim 1, wherein the first electroplated nickel layer (107, 207) is formed as a matte nickel layer, wherein the second electroplated nickel layer (108, 208) is formed as a semi-gloss or as a full-gloss nickel layer. [3] Electrical connector contact (101, 201) according to one of the preceding claims, having a soldered section (103, 203) permanently connected to the connecting section (102, 202), wherein the connection section (102, 202) and the soldering section (103, 203) are arranged opposite each other with respect to a mounting direction (104, 204) of the electrical connector contact (101, 201), wherein a solder joint can be arranged on the soldering section (103, 203), wherein the first electroplated nickel layer (107, 207) is arranged on the connection section (102, 202) and on the soldering section (103, 203), wherein the second electroplated nickel layer (108, 208) is arranged only in the area of ​​the connection section (102, 202) on the first electroplated nickel layer (107, 207). [4] Electrical connector contact (101, 201) according to one of the preceding claims, wherein a third electroplated nickel layer (109, 209) is arranged on the second electroplated nickel layer (108, 208), wherein the third electroplated nickel layer (9) is designed as an adhesion promoter layer. [5] Electrical connector contact (101, 201) according to one of the preceding claims, wherein a fourth electroplated nickel layer (110, 210) is arranged over the second electroplated nickel layer (108, 208), wherein the fourth electroplated nickel layer (110, 210) contains phosphorus, in particular 11-16% wt phosphorus. [6] Electrical connector contact (101, 201) according to claim 5, wherein the fourth electroplated nickel layer (110, 210) has a dispersion additive, wherein the dispersion additive comprises one of the following materials or a combination of materials: Silicon carbide, silicon dioxide, boron nitride, an aluminum ceramic. [7] Electrical connector contact (101, 201) according to any one of the preceding claims 1 to 4, wherein a fourth electroplated layer (110, 210) is arranged over the second electroplated nickel layer (108, 208), wherein the fourth electroplated layer (110, 210) comprises a palladium-nickel alloy, in particular a palladium-nickel alloy with a mass fraction of 80% wt palladium and 20% wt nickel. [8] Electrical connector contact (101, 201) according to claim 3 or 4 and one of claims 5 to 7, wherein the fourth electroplated nickel layer (110, 210) or the fourth electroplated layer (110, 210) in the area of ​​the connection section (102, 202) is arranged on the third electroplated nickel layer (9) or on the second electroplated nickel layer (8) and / or, wherein the fourth electroplated nickel layer (10) or the fourth electroplated layer (10) in the area of ​​the solder section (103 ,203) is arranged on the third electroplated nickel layer (109 ,209) or on the first electroplated nickel layer (107, 207). [9] Electrical connector contact (101, 201) according to any one of the preceding claims 4 to 8, wherein the first electroplated nickel layer (107, 207) completely covers the connection section (102, 202) and the solder section (103, 203) and the second electroplated nickel layer (108, 208) completely covers the first electroplated nickel layer (107, 207) in the area of ​​the connection section (102, 202) and / or, wherein the third electroplated nickel layer (109, 209) completely covers the first electroplated nickel layer (107, 207) in the area of ​​the soldering section (103, 203) and the second electroplated nickel layer (8) in the area of ​​the connection section (102, 202) and / or, wherein the fourth electroplated nickel layer (110, 210) completely covers the third electroplated nickel layer (109, 209) in the connection section (102, 202) and in the soldering section (103, 203). [10] Electrical connector contact (101, 201) according to one of claims 5 to 9, wherein a gold layer (11) is arranged on the fourth electroplated nickel layer (10) or on the fourth electroplated layer (10). [11] Electrical connector contact (101, 201) according to claim 10, wherein a sealing layer (12) is arranged on the gold layer (11). [12] Electrical connector contact (101, 201) according to one of claims 10 and 11, wherein a lubricant layer (15) is arranged on the gold layer (11) or on the sealing layer (12). [13] Electrical connector contact (101, 201) according to one of the preceding claims 4 to 12, wherein in the area of ​​the soldering section (103, 203) in an area opposite the connection section (2) with respect to the mounting direction (104, 204) a tin layer (114, 214) is arranged on the fourth electroplated nickel layer (110, 210) or the fourth electroplated layer (110, 210). [14] Electrical connector contact (101, 201) according to one of the preceding claims, wherein the second electroplated nickel layer (108, 208) has a fine grain addition. [15] Connection element (301, 302) comprising a housing (303, 304), a printed circuit board arranged on the housing (303, 304) and at least one electrical connector contact (101, 201) arranged in the housing (303, 304) and connected to the printed circuit board according to one of the preceding claims, wherein the connecting element (301, 302) is provided for connection with a complementary, further connecting element (302, 301) with at least one further connector contact (201, 101) complementary to the electrical connector contact (101, 201).

Images