Electrical contact and method of manufacturing an electrical contact

Abstract

The invention relates to an electrical contact comprising a carrier substrate made of a metallic material, a metallic coating applied on the carrier substrate, and a coating barrier material applied on the carrier substrate in a sub-area of the carrier substrate, wherein the coating barrier material substantially prevents a coating of the carrier substrate in the sub-area.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrical contact and to a method for manufacturing an electrical contact. BACKGROUND

[0002] Bimetallic electrical contacts are long known. In particular in the connection of mutually different noble metals, bimetallic contacts are in demand. The contact can be composed of a first metal material and a second component to be connected with the contact can be composed of a second metal material which is different from the first metal material. In particular in automotive applications, combinations of aluminum materials and copper materials often occur. The contact and the further component are formed from these two mutually different materials. In order to prevent contact corrosion at the transition between the components, a certain region on the contact is usually metal-coated in order to achieve as pure a transition as possible at the material-fit connection between the two components.

[0003] It is known to connect two elongate plates to one another along their longitudinal edges, wherein the plates are formed from different materials. At the transition between the two plates a metal coating can be provided in order to protect the transition from the environment. On one end of the contact a first conductor can be connected and on a second end of the contact a second conductor can be connected, wherein the connected conductors can then be identical to the metal material of the two ends.

[0004] It is also known to apply a plate or film to a flat part, subsequently mask a central region of the applied plate or film, coat the contact and finally remove the mask. In the region of the removed mask a first conductor can be connected and in the coated region a second conductor can be connected. However, the masking and the final removal of the mask are expensive and prone to error. The application of the mask serves only to prevent coating in the region of the mask. The mask is usually pasted to the contact in the form of a tape and is removed again after the coating.

[0005] However, the application and removal of the mask is disadvantageous in terms of manufacturing technology, since in particular the removal of the mask cannot always be carried out fully automatically. SUMMARY

[0006] It is therefore an object of the present invention to provide an electrical contact having coated and uncoated regions, wherein the manufacture of the electrical contact can be carried out fully automatically.

[0007] This object is achieved by the contact according to claim 1 and the method according to claim 13.

[0008] The contact element is initially composed of a carrier substrate. The carrier substrate is formed from a metallic material. The carrier substrate is in particular a flat element and can in particular be provided as a plate or strip in an almost continuous process. The carrier substrate is in particular made of an aluminum material or a copper material. The metallic material is a pure metal or a metal alloy.

[0009] The carrier substrate can be provided as an elongate flat element. The carrier substrate preferably has a material thickness of between 0.5 mm and 50 mm and a width of between 1 cm and 10 cm here. The carrier substrate can be provided as a flat conductor. In particular, the carrier substrate can be formed from an aluminum material which is not fully annealed.

[0010] For the contact, a metallic coating is applied to the carrier substrate. The coating can be made of a metallic material. This can be, for example, tin plating and / or nickel plating.

[0011] In order now to achieve that not the entire surface of the carrier substrate is coated with the metallic coating, the application proposes that the carrier substrate is coated in sub-areas with a coating barrier material and that this coating barrier material substantially prevents the coating of the carrier substrate in the sub-areas.

[0012] The coating barrier material is composed here of a material which results in that the material of the coating cannot be applied to the material of the carrier substrate during the coating, or that the material of the coating cannot accumulate on the material of the carrier substrate, or that the surface of the carrier substrate cannot be wetted or enriched by the material of the coating.

[0013] During the coating, an intermetallic bonding zone between the material of the carrier substrate and the material of the coating is produced. The coating barrier material prevents the formation of such an intermetallic bonding zone between the material of the carrier substrate and the material of the metallic coating in the sub-areas. By using the coating barrier material, the sticking of a masking and the subsequent removal of the masking can be dispensed with.

[0014] In order to apply the coating barrier material particularly simply, it is proposed that the coating barrier material is a fluid. This fluid can be a liquid or a paste-like medium and preferably has a viscosity of between 0.1 mPas and 1000 mPas. Thereby, the coating material can be applied almost liquid to the sub-areas of the carrier substrate.

[0015] The carrier substrate can in particular be guided in a continuous motion under an application device for the coating barrier material and the coating barrier material is applied continuously to the sub-areas of the carrier substrate. If the carrier substrate is subsequently coated with a metal, the coating barrier material prevents the coating of the carrier substrate in the areas in which it is applied to the carrier substrate.

[0016] According to one embodiment it is proposed that the coating barrier material is liquid or pasty. In this regard it is noted that the coating barrier material is preferably formed from a single material, rather than from a combination of materials, for example from an adhesive strip formed from a carrier and an adhesive coating.

[0017] According to one embodiment it is proposed that the coating barrier material is hydrophobic. By hydrophobic it is prevented that the metal coating reaches the carrier substrate in the subregion and is deposited there in a wet-chemical coating process. Thereby the metal coating in the subregion is prevented by the coating barrier material.

[0018] The coating barrier material is connected to the carrier substrate by adhesion or cohesion. In particular a material-fit connection can be formed between the coating barrier material and the carrier substrate. However, in this regard the coating barrier material does not involve a material-to-material intermetallic connection with the carrier substrate. The coating barrier material is in particular not a metallic material, but a non-metallic material. In particular, the coating barrier material is only located on the surface of the carrier substrate and does not penetrate into the surface of the carrier substrate. The coating barrier material is in particular electrically non-conductive.

[0019] According to one embodiment the coating barrier material is an organic material, in particular a lipid. As such it can in particular be an oil, a wax or a resin.

[0020] According to one embodiment the coating barrier material is a silicone material or an inorganic material, in particular a lacquer. The coating barrier material, whether organic, inorganic or silicone, can be applied to the carrier substrate in liquid or pasty form.

[0021] In order to prevent the galvanic coating in the region of the coating barrier material it is proposed that the coating barrier material is electrically non-conductive. Thus, when galvanizing, no coating material is deposited on the carrier substrate in the region of the coating barrier material.

[0022] As already mentioned, after the application of the coating barrier material the carrier substrate is metal-coated. This is carried out according to one embodiment wet-chemically, in particular galvanically. The coating barrier material prevents the deposition of the metal coating material in the wet-chemical coating.

[0023] Generally, the contact pieces to be coated are fed to the soldering tool and the contact pieces are soldered to the conductors. At this point, one side of the contact pieces is in contact with the soldering tool and the other side of the contact pieces serves as a connection area. It is preferred that the subregion in which the coating barrier material is applied forms the connection area of the contact pieces, in which the contact pieces are connected to the electrical conductors. However, it is also proposed that the subregion in which the coating barrier material is applied faces away from the connection area.

[0024] If the contact is a flat piece, it has two wide, flat surfaces facing each other. A connection area is arranged on one of these surfaces, in which an electrical conductor is fixed to the contact, particularly by welding. A sub-region is provided on the opposite side, in which a barrier coating is applied. Due to the barrier coating, the uncoated sub-region thus comes into contact with the welding tool. This can be, for example, an anvil, especially in ultrasonic welding.

[0025] Because there is no metal coating on the contact element in the sub-region, the anvil is not contaminated by the metal coating of the contact element. In conventional welding of coated contact elements, the anvil is in direct contact with the coating material. Under the mechanical loads and numerous welding processes of ultrasonic welding, the anvil becomes contaminated / wears down with the coating material and must be replaced. This does not occur if the uncoated sub-region contacts the anvil, thus extending the service life of the welding tool.

[0026] Bimetallic contacts are manufactured, in particular, by providing a thin material in the connection area on a carrier substrate, for example by friction welding, roll cladding, or similar methods. This material in the connection area is bonded to the carrier substrate material. At the transition between the material and the carrier substrate, ambient moisture can penetrate into the connection. To prevent this, a coating is recommended in such bimetallic contacts. Unlike conventional contacts where the connection area is partially masked with tape, according to the invention, a sub-region with a coating barrier material is arranged inside the connection area. Here, the sub-region is spaced apart from the transition between the material of the connection area and the material of the carrier substrate. This transition is coated with a metallic coating. The sub-region is located in the central region of the connection area, and this sub-region is shielded from the metallic coating by the coating barrier material.

[0027] According to one embodiment, it is proposed that in the connection area, the contact element is connected to a metallic conductor material in a mating manner. After a metallic coating is applied, the material of the carrier substrate in this sub-region is coated with a coating barrier material. The coating barrier material can be evaporated by thermal action or mechanically removed, and then the metallic conductor can be applied, particularly welded, to the exposed material of the carrier substrate. Evaporation of the coating barrier material can also occur during the welding process itself, particularly during ultrasonic welding.

[0028] According to one embodiment, a pretreatment is proposed for the sub-regions to which the coating barrier material is to be applied. This can, in particular, reduce surface quality, especially surface roughness. It can also remove residues such as unwanted grease, burrs, and the like. This can be achieved, for example, by radiation treatment, especially by laser. Thus, the surface of the contact in the sub-region where the coating barrier material is to be applied is prepared to be suitable for the coating barrier material, allowing it to adhere particularly well to the carrier substrate.

[0029] A further aspect is a method according to claim 13.

[0030] As already set out, in order to prolong the life of the joining tool, in particular of an ultrasonic welding tool, in particular of an anvil, it is proposed to place the contact piece onto the joining tool with a coating barrier material. Here, the joining tool can in particular be an anvil of an ultrasonic welding tool or an ultrasonic welding electrode. The surface of the joining tool can be roughened and thus directly abut against the material of the carrier substrate through the coating material. The side of the carrier substrate opposite the coating barrier material is joined, in particular welded, in particular ultrasonic welded, to the component, for example a conductor material.

[0031] According to one embodiment it is proposed that the carrier substrate is coated in the joining region with a material which is thinner relative to the carrier substrate. The coating is in particular made of a metal material which is different from the material of the carrier substrate. If the carrier substrate is an aluminum material, the material can be a copper material. If the carrier substrate is a copper material, the material can be an aluminum material.

[0032] On the transition between the material of the joining region and the carrier substrate, the contact piece can be metallized with a coating material, in particular nickel-plated or tin-plated. The subregion provided with the coating barrier material is located inside the applied thin material which forms the joining region. The joining region is not completely coated, in particular the metal coating is cancelled in the region in which the coating barrier material is applied. After the metal coating, there is a joining region which is free of the metal coating, so that a component can be directly contacted thereon.

[0033] After the metal coating, the coating barrier material can be removed, in particular evaporated.

[0034] In order to form the contact piece, the contact piece can be deformed non-cuttingly or cuttingly after the metal coating. In particular, the contact piece can be separated from the solid material of the carrier substrate, in particular by means of cutting, for example laser cutting, or by means of punching. It is also possible that the carrier substrate is non-cuttingly or cuttingly shaped, in particular separated, in particular cut or punched, before the metal coating. Then the metal coating is carried out, wherein the subregion remains free of the metal coating, since the coating barrier material is applied there.

[0035] The carrier substrate can be continuously guided under a nozzle through which the coating barrier material is applied.

[0036] Here, the coating barrier material can be applied in the coating process in liquid or paste form. After the application, the carrier substrate can be metallized, in particular electroplated, with a wet-chemical coating method. BRIEF DESCRIPTION OF DRAWINGS

[0037] The application is explained further below with the aid of the drawings which show embodiments. The drawings show:

[0038] Figures la-d The coating of the contact element according to an embodiment is shown;

[0039] Figures 2a-c The coating of the contact element according to an embodiment is shown;

[0040] Figures 3a-e This illustrates establishing a connection between a contact and a conductor according to an embodiment;

[0041] Figure 4 A schematic diagram of an apparatus for coating contacts is shown.

[0042] Figure 5a The arrangement of the contacts on the anvil according to an embodiment is shown;

[0043] Figure 5b An ultrasonic welding of a contact to a conductor according to an embodiment is shown. Detailed Implementation

[0044] Figure 1 shows a carrier base 2, which is provided as a flat member. The carrier base 2 extends along the longitudinal axis X. The carrier base 2 has two wide surfaces 2a opposite each other and two narrow surfaces 2b opposite each other, and is thus formed into a square shape. The length of the carrier base 2 extending in the longitudinal direction X is preferably greater than the length of any axis extending transversely to the longitudinal extension X. The carrier base 2 is formed of copper or aluminum. Preferably, the carrier base 2 is provided in a nearly continuous process, and preferably in the direction of the longitudinal extension X. It is also possible that the carrier base 2 is provided separately as rod-shaped members.

[0045] In subsequent steps, such as Figure 1b As shown, a coating barrier material 4 is applied to at least one wide surface 2a of the carrier substrate 2. The sub-regions on which the coating barrier material 4 is applied preferably also extend along the longitudinal extension X of the carrier substrate 2. The coating barrier material 4 extends on the wide surface 2a within a width extension ranging from 10% to 70% of the width extension of the wide surface 2a.

[0046] Preferably, the coating barrier material 4 is applied to the wide surface 2a in a liquid or paste form in a preferably almost continuous process. After coating the carrier substrate 2 with the coating barrier material 4, a metal coating is applied to the carrier substrate. The result of the metal coating can be seen in Figure 1c. The metal coating 6 is applied around the carrier substrate 2. Here, a wet chemical coating process, such as electroplating, can be particularly implemented. During this coating process, the metal material 6 is deposited on the surface of the carrier substrate 2. This can be, for example, tin, zinc, nickel, etc.

[0047] Deposition of the metal coating 6 is prevented in the sub-areas in which the coating barrier material 4 is applied on the carrier substrate 2 by the coating barrier material 4. This can be achieved, for example, by the coating barrier material 4 being formed from a hydrophobic material. Thus, in a wet-chemical process, no coating material 6 is deposited on the surface of the carrier substrate 2 on which the coating barrier material 4 is applied.

[0048] After the coating, the carrier substrate 2 coated with the coating material 6 is obtained, wherein in the region of the coating barrier material 4, this coating material 6 is not present. After the coating with the coating material 6, the carrier substrate 2 is divided, so that individual contact pieces 8 are formed, as Figure 1d is shown. Here, the contact pieces 8 can be produced from the carrier substrate 2 by means of cutting or stamping. Here, in addition to the separation of the contact pieces 8 from the carrier substrate 2, a shaping can also be carried out, so that the contact pieces 8 are configured as cable sleeves, connection plates, connection tabs, crimp cable sleeves or the like.

[0049] A further possibility of producing the contact pieces 8 is shown in Figures 2a-c . A carrier substrate 2 after the coating with the coating barrier material 4 corresponding to Figure lb is shown in Figure 2a .

[0050] Before the coating with the coating material 6, the carrier substrate 2 is divided and the semi-finished products 8' of the contact pieces 8 are produced. Here, the division can be carried out according to the design of Figure lc. The semi-finished products 8' are present, for example, as loose parts as shown in Figure 2b . On each semi-finished product 8', the carrier substrate 2 is coated with the coating barrier material 4.

[0051] The semi-finished products 8' are fed to the coating process, which can be carried out according to the coating of Figure lc. By the fact that the semi-finished products 8' have already been divided, a complete circumferential coating with the coating material 6 is achieved, wherein the cut edges which arise when the carrier substrate 2 is divided into the semi-finished products 8' are also coated with the coating material 6. Here, the carrier substrate 2 also remains free of the coating material 6 in the region of the coating barrier material 4.

[0052] Figures 3a-e A cross section perpendicular to the longitudinal axis X of the carrier substrate 2 is shown. It can be seen in Figure 3a that the carrier substrate 2 has a rectangular cross-sectional profile. It is to be noted that any cross-sectional profile of the carrier material 2 is meaningful and conceivable. In particular, cross-sectional profiles having at least one straight running edge are meaningful.

[0053] As in Figure 3bAs is shown in Fig. 1, the metal inlay 10 is preferably applied on the surface of the carrier substrate 2 which is formed by the straight edges and the longitudinal axis. The inlay 10 can be provided as a sheet or strip, in particular in the form of a foil. The inlay 10 can also be applied to the carrier substrate 2 by means of friction welding. The inlay 10 is made of a metal material which is in particular different from the metal material of the carrier substrate 2. Preference is given here to a material combination consisting of aluminum and copper, wherein alloys of these metals can be referred to in each case.

[0054] It can be feared that the contact corrosion is increased at the transition between the inlay 10 and the carrier substrate 2, so that this transition must be protected. On the other hand, the inlay 10 is intended to be used for contacting the contact piece 8 to the component, so that bare metal of the inlay 10 should be able to be provided on the inlay 10.

[0055] In order to achieve this, it is proposed to apply a coating barrier material 4 along the longitudinal extension of the inlay 10 to extend less than the width of the inlay 10 and to be spaced from the transition between the inlay 10 and the carrier substrate 2, as is shown in Figure 3c The coating barrier material 4 can be applied in correspondence with the above-described embodiments and in particular by means of a nozzle.

[0056] After the application of the coating barrier material 4, a metal coating 6 is applied on the carrier substrate 2, as is shown in Figure 1c or Figure 2c As is shown in Figure 3d , the intermediate region of the inlay 10 remains free of the coating material 6, in which intermediate region the coating barrier material 4 is applied.

[0057] The coating barrier material 4 can then be removed by suitable methods, for example by laser cleaning. The coating barrier material 4 can also be washed off, for example in an alcohol solution.

[0058] After the coating barrier material 4 has been removed or through the coating barrier material 4, the electrical conductor 12 can be fixed on the inlay 10 in a material-fit manner. This can be achieved, for example, by friction welding, ultrasonic welding, resistance welding or the like.

[0059] The fixing of the conductor 12 on the bare metal of the inlay 10 is shown in Figure 3e . If the conductor 12 is composed of an aluminum material, for example, the inlay 10 can be composed of an aluminum material. If the conductor 12 is composed of a copper material, the inlay 10 can be composed of a copper material. Here, the carrier substrate 2 differs from the material of the inlay 10, for example in the first case is composed of a copper material and in the second case is composed of an aluminum material.

[0060] Figure 4 It is shown how the carrier substrate 2 is unwound from a web 14 and is continuously fed to a coating device 16. The carrier substrate 2 is moved along its longitudinal axis X past the coating device 16. Here, as isFigure 1b and Figure 2a The coating barrier material 4 is applied, for example sprayed, on the broad surface 2a of the carrier substrate 2 as shown in

[0061] Subsequently, the carrier substrate 2 is fed to a punching machine 18. From the carrier substrate 2, a semi-finished product 8' is punched out by the punching machine 18. The punched semi-finished product 8' is fed to a wet-chemical coating process 20 and coated there with a metal coating 6, so that a contact piece 8 according to Figure 2c is formed.

[0062] By means of the coating barrier material 4, the carrier substrate 2 is free of coating material 6 in certain regions of its broad surface 2a. This can not only be used to establish a kind of pure connection between the electrical conductor 12 and the carrier substrate 2 by means of the inlay 10 as shown in Figure 3e , but also to increase the service life of anvil of a soldering tool, for example an ultrasonic soldering tool.

[0063] In the known method, the soldered coated component, the coating material 6 directly lies against the anvil and causes increased wear on the anvil. According to the application, the contact piece 8 can be placed onto the anvil 22 with the coating barrier material 4, in particular the surface of the carrier substrate 2 which is free of coating material 6, as shown in Figure 5a . The anvil 22 can have a relief-like surface in order to achieve an enhanced adhesion of the contact piece 8 to the anvil 22. By means of the relief-like surface, the coating barrier material 4 can be pierced, so that the anvil 22 comes into direct contact with the carrier substrate 2, although the coating barrier material 4 is still present. This is shown in Figure 5a , in which the contact piece 8 is placed against the surface of the anvil 22.

[0064] As shown in Figure 5b , the anvil 22 penetrates the coating barrier material 4 with its relief-like surface and lies against the pure material of the carrier substrate 2. The electrical conductor 12 can be placed on the coating material 6 on the opposite side and the conductor 12 can be soldered to the contact piece 8 in the region of the metal coating 6 by means of the ultrasonic soldering electrode 24. The introduced vibrations cause the soldering of the conductor 12 to the coating material 6. Since the anvil 22 is not in contact with the coating material 6, its service life can be extended.

[0065] Legend of the Figures

[0066] 2 carrier substrate

[0067] 4 coating barrier material

[0068] 6 coating material

[0069] X longitudinal axis

[0070] 8 contact piece

[0071] 8' semi-finished product

[0072] 10 insert

[0073] 12 electrical conductor

[0074] 14 roll material

[0075] 16 coating apparatus

[0076] 18 punch

[0077] 20 coating apparatus

[0078] 22 anvil

[0079] 24 ultrasonic welding electrode

Claims

1. A method for connecting an electrical contact to a metallic conductor, wherein... Manufacturing the contact element, wherein Provide a carrier substrate made of metallic material, A barrier coating is applied to a sub-region of the carrier substrate. A metal coating is applied to the carrier substrate, wherein The coating barrier material substantially prevents the carrier substrate from forming a metallic coating in the sub-region. Its features are, The contact element is placed onto a bonding tool with a coating barrier material. The bonding tool is an anvil or ultrasonic welding electrode of an ultrasonic welding tool, and the surface of the bonding tool is roughened. The contact is welded to the metal conductor within the connection area using the ultrasonic welding tool. The sub-region is located on the side of the contact away from the connection area, and the connection area has the metal coating.

2. The method according to claim 1, Its features are, After the metal coating is applied, the contacts are separated from the carrier substrate.

3. The method according to claim 2, Its features are, The separation is achieved by cutting or stamping.

4. The method according to claim 1, Its features are, The coating barrier material is continuously applied to the carrier material through a nozzle.

5. The method according to claim 1, Its features are, The coating barrier material is applied to the carrier material in liquid or paste form.

6. The method according to claim 1, Its features are, After applying the barrier coating material, a wet chemical metal coating is applied to the carrier substrate.

7. The method according to claim 6, Its features are, The wet chemical metal coating is achieved by electroplating.

8. The method according to claim 1, Its features are, The coating barrier material is a fluid.

9. The method according to claim 8, Its features are, The fluid has a dynamic viscosity between 0.1 mPas and 1000 mPas.

10. The method according to claim 1, Its features are, The coating barrier material is hydrophobic.

11. The method according to claim 1, Its features are, The coating barrier material is connected to the carrier substrate by means of adhesion or cohesion.

12. The method according to claim 1, Its features are, The coating barrier material is an organic material, or the coating barrier material is a silicone material or an inorganic material.

13. The method according to claim 12, Its features are, The organic material is a lipid.

14. The method according to claim 12, Its features are, The inorganic material is paint.

15. The method according to claim 1, Its features are, The coating barrier material is non-conductive.

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