The invention relates to an electrical contact element made from an electrically conductive contact material. The invention additionally relates to a method for altering mechanical and/or electrical properties of at least one area of an electrical contact element manufactured from an electrically conductive contact material.

In the case of electrical contact elements such as contact pins, female connectors, crimp connectors or cable shoes, for example, it is frequently necessary to equip particular areas with properties which differ from those of the contact material from which a large part of the contact element is manufactured. For example, it can be necessary for a contact surface of the contact element, which can serve to make a connection to a further contact element, to be equipped with increased conductivity, improved resistance to corrosion or with a greater mechanical hardness in order to improve an electrical connection to another contact element. It is also frequently necessary to increase the durability or lifespan, for example in the case of a frequent number of connections. Expensive and complex methods are generally used in order to produce such areas. For example, at least one further material is deposited onto the contact material by means of electroplating or chemical vapour deposition. It is true that such methods can lead to desired results but they are generally costly and require several working steps, high expenditure on material and generally have a low degree of selectivity.

The problem of the invention is therefore to provide an electrical contact element and a method of the above-mentioned type, which make it possible to provide certain areas of the contact element with electrical and/or mechanical properties which differ from the contact material and which can be manufactured quickly and inexpensively with few production steps.

The problem according to the invention is solved for the abovementioned electrical contact element in that the contact element has at least one area on which particles are arranged in an adherent manner, of which at least a part has penetrated into the contact material at least in sections. For the abovementioned method, the problem according to the invention is solved in that, on the at least one area of the contact element, particles are deposited at high speed, wherein at least a part of the particles penetrates at least partially into the contact material.

The solution according to the invention offers significant advantages compared to the known contact elements and methods. At least a part of the particles has penetrated into the contact material. These particles therefore protrude into the contact material. As a result, there can be both good electrical conductivity and good adhesion between the particles and the contact material. Solid, or dry, particles can be used, as a result of which it is possible to dispense with wet-chemical methods. It is likewise possible to dispense with firstly placing materials which are intended to be deposited onto the contact material into a liquid or gaseous aggregate state. The material which is intended to form an area with improved mechanical and/or electrical properties need only be present in the form of particles and these particles must be accelerated towards the contact element. The contact element according to the invention can be formed in accordance with the requirements for the type of connection. For example, it can have at least one contact surface for connection to a mating contact element. Alternatively or in addition, it can have at least one crimp section for connection to at least one electrical conductor.

As a result of the particles hitting the contact element at high speed, at least a part of the particle penetrates at least partially into the contact material and is mechanically anchored therein as a result. In addition, it can be possible that, due to the high kinetic energy of the particles, at least one surface of the particles and/or of the contact material is surface-fused to a small extent, such that the particles firmly adhere to the contact material. However, the particles and/or the contact material are generally not heated to higher than their melting temperatures, which means that a full fusing of the materials or the formation of an alloy of these does not take place. When the particles impact on the contact material, both the contact material and the particles may be deformed. The contact material can form elevations, for example, and the particles can be pressed flat on the contact material.

The material of the particles can be selected for the desired application. In order to improve the electrical and/or mechanical properties of an area with particles, gold, silver, tin, brass, bronze, zinc or alloys of such metals, for example, can be used. However, in order to increase only the mechanical friction in an area of the contact material, for example, or in order to make the contact element more slip-proof for gripping, particles of non-conductive materials may also be used.

The solution according to the invention can be further improved by way of various respectively individually advantageous configurations which can be combined with one another as desired. These configurations and the advantages connected thereto shall be explored hereafter.

The abovementioned electrical contact element can be further improved by it being manufactured by an embodiment of the method according to the invention. Particularly preferably, the particles are deposited on the contact material by gas dynamic cold spraying. The contact element also preferably has particles which do not form an alloy with the contact material.

The contact element can have at least one contact surface for connection to a mating contact element, wherein the at least one area can at least partially overlap the at least one contact surface. As a result, the contact surface can at least partially have particles. If the at least one area with particles has not been heated following the deposition of the particles, the contact element can in this case have a rough surface in the area of the contact surface. This can be advantageous for contact elements which are not intended to be frequently connected to a mating contact element, but for which the crucial factor is a good mechanical and electrical connection to the mating contact element. The particles on the contact surface can scratch a contact surface of a mating contact element during connection, such that any oxide layer which may be present is burst. The particles can likewise at least partially penetrate into a contact surface of the mating contact element, such that in the connected state good electrical conductivity can be formed between the two contact elements.

Alternatively or in addition to an area with particles, which overlaps a contact surface of the contact element, the contact element can have at least one crimp section which is at least partially overlapped by at least one area with particles. An area with particles in the crimp section, in particular on the surface of crimp flanks, can be advantageous in order to improve both the mechanical and the electrical connection to an electrical conductor, such as copper or aluminium wires, for example, retained in the crimp section. Particularly in the case of aluminium wires, it is advantageous if the surface of crimp flanks or of the crimp section is rough in order to burst the oxide layers which are always available in air in the case of aluminium. At the same time, particles in the crimp section can partially penetrate into an electrical conductor retained in the crimp section, such that the tensile strength of a crimped conductor can be increased.

The contact material can at least partially have a basic surface structure into which the particles have penetrated. For example, the contact material can have impressed structures. These can be formed by ribs, grooves, knobs or folding edges, for example. The contact element preferably has a crimp section which has a basic surface structure made from impressed grooves or ribs, perpendicular to a receiving direction for an electrical conductor. In addition, particles can be deposited on these grooves or ribs, so that a basic surface structure is formed which can have particularly good mechanical retaining properties. If the basic surface structure has projections and if particles are arranged on such projections, the particles are well able to penetrate into an electrical conductor in the crimp section so that, as already described, the electrical and mechanical properties of the connection between the contact element and an electrical conductor can be improved.

The at least one area on which particles are arranged can have a surface roughness which is greater than in an adjacent area which has no particles. The greater roughness can be advantageous for improving the electrical and/or mechanical properties already described.

In at least one area which has particles, the particles can be at least partially connected to one another. For example, two particles which are adjacent to one another can respectively be arranged partially penetrating into one another. As a result of this, there can be particularly good stability of the particles on the contact material.

In order to achieve a particularly uniform coating with particles and/or to further improve the adhesion of the particles to the contact material and/or to one another, the particles can be at least partially fused to one another in at least one area which has particles.

A uniform continuous coating on the contact material can be formed by means of particles which are fused to one another. If the particles are only partially fused to one another, it is also possible for a layer to be formed which still leaves open gaps or pores between several particles. Both the layer thickness and the roughness can be adjusted by means of the degree of fusing. The particles can preferably be fused to one another by being bombarded with high- energy beams such as electron beams. This has the advantage that fusing occurs so quickly that no alloy is formed between the material of the particles and the contact material.

In order to obtain a high layer thickness in at least one area which has particles, at least a part of the particles in this area can be arranged at least in multiple layers on the contact material.

The particles can be partially penetrated into one another in particular in an area in which the particles are arranged at least partially in multiple layers.

The method according to the invention can be further improved by the particles being transported using a gas flow. In this case, they are preferably deposited at supersonic speed, for example at speeds of more than 400 metres per second. The particles particularly preferably have a speed between 500 and 1000 metres per second. The speed can be relevant for how deep the particles in the area penetrate into the contact material and how well they adhere thereto. For example, at higher speed, the particles can penetrate more deeply into the contact material, but are themselves also more strongly deformed by the forces which arise when they impact on the contact element. The speed can be selected depending on the desired field of use, the selected material and the desired form of a coating formed by the particles.

The particles are particularly preferably shot onto the contact element in the form of a particle beam. The use of a beam of particles is particularly advantageous because this has a limited spatial, in particular lateral, extent such that a selective application of particles onto the contact element is made possible. The particles are particularly preferably deposited onto the contact element by gas dynamic cold spraying.

The diameter and form of the particles can be selected for the desired application. It is particularly advantageous if the particles have diameters between 1 and 50 μηη. Particles of this size can, on the one hand, accelerate well, for example through a jet of gas, and can be used to form thin layers on the contact material. The particles may be spherical. However, they may also have other forms such as, for example, the form of fragments or of crystal shapes such as cubes.

Particles deposited onto the contact material can form a rough surface on the contact material. This is particularly the case if the particles or conglomerates of particles are spaced apart from one another. A rough surface can be particularly advantageous in order to burst oxide layers on the mating contact element or on the conductor, for example when the contact element is connected to a mating contact element or to an electrical conductor, in order to improve the electrical connection. Likewise, the particles which are firmly arranged on the contact material can penetrate at least partially into another contact element or into an electrical conductor, which can also improve the electrical conductivity.

If, on the other hand, it is desired that the particles on the contact material form a uniform surface or a smooth surface, the contact element can be heated at least in sections after the particles are deposited. If it is desired that at least the area with the particles is heated so that the individual particles can fuse with one another and/or with the contact material, then at least one section of the contact element, which has at least one area with particles, can be heated. If, when manufacturing a contact element, it is necessary to heat an area of the contact element which has no particles, for example in order to solder or weld a part on, this can also take place following the depositing of particles because these are not damaged by partial heating as long as the temperature in the area of the particles does not exceed their melting point.

For heating the at least one area having particles, it is particularly advantageous if this area is selectively heated. The at least one area having particles is preferably heated at least in sections by high-energy beams, particularly preferably with electron beams, after the particles have been deposited. Alternatively, other energy-rich types of radiation such as, for example, lasers, X-rays or matter jets made from parts other than electrons, can also be used.

In order to achieve a high spatial resolution when depositing particles onto the contact material, a mask can be used which allows a particle beam to only reach sections which are not covered by the mask. The mask is then located between a particle source, for example a nozzle of a gas dynamic cold spraying device and the contact element.

The production of the electrical contact element or at least of the area with improved mechanical and/or electrical properties rules out further coating methods prior to or subsequent to the application of the particles. If required for certain properties, the contact element can also be additionally coated, for example galvanically, through printing techniques or through chemical vapour deposition.

Hereinafter, the invention will be explained in greater detail by way of example using advantageous embodiments with reference to the drawings. The combinations of features depicted by way of example in the embodiments can be supplemented accordingly by additional features for a particular application in accordance with the comments above. It is also possible, also in accordance with the comments above, for individual features to be omitted in the described embodiments, if the effect of this feature is not important in a specific application.

In the drawings, the same reference signs are always used for elements with the same function and/or the same design.

The drawings show:

Fig. 1 a schematic depiction of an exemplary embodiment of a contact element according to the invention in a top view with opened crimp flanks;

Fig. 2 a cross-section through a contact element according to the invention in the area of a contact surface having a single-layer particle coating;

Fig. 3 a sectional depiction as in Fig. 2 but with a partial multilayer particle coating;

Fig. 4 a coating made from a single-layer particle layer following a heating process;

Fig. 5 a coating made from a multi-layer particle layer following a heating process; Fig. 6 a sectional depiction through an advantageous crimp section of a contact element having deposited particles;

Fig. 7 the crimp section from Fig. 6 after the particles have fused.

Fig. 1 shows, merely by way of example and schematically, an electrical contact element 1 according to the invention made from an electrically conductive contact material 3. The contact element 1 has at least one contact surface 5 for connection to another contact element. The electrical contact element 1 is preferably formed as a stamped bending part from the contact material 3. Alternatively it can, however, also be formed as a solid part.

The contact element 1 has at least one contact surface 5 for connection to another electrically conductive element. Merely by way of example, the contact element 1 is depicted with a crimp section 7 which has two crimp flanks 9. Fig. 1 shows the contact element with folded back crimp flanks 9 without an electrical conductor being retained in the crimp section 7.

The crimp section 7 can have a basic surface structure 11 which can improve the electrical and mechanical connection to an electrical conductor which is to be retained in the crimp section 7. A basic surface structure 11 is depicted merely by way of example as grooves 13 impressed in the contact material 3. The basic surface structure 11 can also be formed by other suitable forms. Likewise, other areas of the contact element 1 can also have basic surface structures 11. However, for the sake of clarity, these are not depicted.

Merely by way of example, the electrical contact element 1 is depicted with two areas 15 which have particles (not shown in Fig. 1 ). In this case, an area 15 overlaps the contact surface 5 and a further area 15 overlaps the crimp section 7. Exemplary configurations of the area 15 which overlaps the contact surface 5 are described in greater detail with reference to Figures 2 to 5. Configurations of the area 15 which overlaps the crimp section 7 are described in greater detail with reference to Figures 6 and 7.

Hereafter, a first advantageous configuration of an area 15 with particles 17 is described. Fig. 2 schematically shows a cross-section along the sectional line marked as A-A in Fig. 1 through the contact element 1 in the area of the contact surface 5. On the contact material 3 there are deposited particles 17 which are arranged in an adherent manner on the surface 19 of the contact element 1. The particles 17 have preferably been deposited onto the contact material 3 using the method according to the invention. The depicted form of the particles 17 is only intended for viewing purposes. In principle, any form which allows the particles 17 to be deposited sufficiently quickly onto the contact material 3 is possible. For example, the particles 17 can be spherical, drop-shaped, or can take the form of non-uniform fragments. If it is crystal-forming material, a particle 17 can also have a cubic or other angularly shaped form.

At least some of the particles 17 penetrate into the contact material 3 in sections. At these locations, the contact material 3 can be displaced at least partially by the particles 17. It can likewise be possible that undulations or elevations in the surface 19 are formed by particles 17 bouncing off of the contact material 3. For example, crater-like structures can be formed in the surface 19. The partial deformation of the contact material 3 can serve to improve the adhesion of the particles 17 to the surface 19. In addition, a reshaping of the surface 19 can also be advantageous in order to increase a surface roughness.

Some of the particles 17 form particle conglomerates 21 , at which several particles 17 adhere to one another. The particles 17 of the conglomerates 21 can partially penetrate into one another. Particles 17 can also form a network-like structure (not shown) on the surface 19 in the area 15. Between some of the individual particles 17 and particle conglomerates 21 , there can also be free locations 23 through which the contact material 3 is accessible from the outside. As a result of this structure, the contact element 1 can have a high degree of roughness in the area 15. Such a structure can arise, for example, if only a thin or simple layer of particles 17 is intended to be formed. In this case, particles are deposited onto the contact material 3 either at lower speed or with a smaller particle density, which means that the contact material 3 is not entirely coated.

Fig. 3 shows a further example of a coated area which, merely by way of example, shows a section through the electrical contact element 1 in the area of the contact surface 5 (depicted by the section line A-A in Fig. 1 ).

The particles 17 in the area 15 are arranged at least partially in multilayers on the contact material 3. In this case, adjacent particles 17 preferably penetrate at least partially into one another. As a result, not only is the layer of particles 17 which are directly connected to the contact material 3 securely retained, but so too are successive layers of particles 17.

Fig. 4 schematically shows an area 15 as was depicted in Fig. 2, but following heating of the area 15, for example selectively by electron beams. The particles 17 are fused into one layer 25 by heating. The layer 25 can be continuous and uniformly cover the surface 19 in the area 15. However, if sufficient particles 17 were not available to fully cover the surface 19 or if a layer of particles 17 had many free locations 23, the layer 25 can also be formed such that it is not uniform.

The layer 25 preferably substantially consists of the material of the particles 17. In other words, no formation of an alloy made up of the material of the particles 17 and the contact material 3 takes place. This can, for example, be achieved through rapid heating by electron beams. Alternatively, the contact element 1 is heated at least in sections such that the material of the particles 17 is mixed with the contact material 3 and alloys form. This can be made to depend on the planned application. As a result of a melting of the particles 17, the thickness 27 of the layer 25 is generally smaller than a particle diameter 29 (depicted in Fig. 2).

Recesses or undulations in the surface 19 which possibly arise due to the impact of particles 17 can remain in existence so that the material of the fused particles 17 fills them (not depicted). If, as a result, the layer 25 penetrates partially into recesses in the surface 19, this is particularly advantageous for the adhesion of the layer 25 on the contact material 3.

As an alternative to the depicted layer formation, particles 17 can also be only partially surface- fused by heating, so that these connect to one another more strongly, or the surface of the particles and/or of particle conglomerates 21 is smoothed.

Fig. 5 shows the example from Fig. 3 with several tiers of particles 17 following heat treatment. As in the embodiment example described with reference to Fig. 4, a layer 25 consisting of the material of the particles is also formed here. Since an at least partially multilayer arrangement of particles was previously present, the layer thickness 27 is larger than in the example described with reference to Fig. 4. The layer thickness 27 can therefore be adjusted following heating by the number of particles 17.

It is also possible here that the material of the particles 17 or layer 25 fills recesses or undulations generated previously by the impact of particles 17, such that the material of the layer 25 penetrates at least partially into the contact material 3 and is anchored in the contact material 3 as a result.

Likewise, here too only a partial fusing of some particles 17 can be generated instead of a continuous layer 25. This can be achieved, for example, in that the particles 17 are heated at a lower intensity or for a shorter irradiation period. Fig. 6 schematically shows a sectional depiction through a basic surface structure 11 in the crimp section 7 of the contact element 1. An area 15 of the contact element 1 preferably overlaps the crimp section 7. Fig. 6 shows a depiction along section line B-B from Fig. 1.

The basic surface structure 11 in the contact material 3 is formed by grooves 13. These represent longitudinal recesses in the contact material 3. However, the contact material 3 can also have any other suitable basic surface structures 11 desired for the respective requirements. The area 15 with the particles 17 can be formed analogously to the embodiment described with reference to Figs. 2 and 3. The only difference is in the basic surface structure 11. The particles 17 are deposited on the surface 19 and some of the particles 17 penetrate at least partially into the contact material 3. Merely by way of example, Fig. 6 shows a non- continuous coating with particles 17.

Basic surface structures 11 , as formed by the grooves 13, have several advantages. In particular in crimp sections 7, they can be of great benefit because both the stability and the conductivity of a connection with an electrical conductor can be improved. In the case of the depicted longitudinal grooves 13, an electrical conductor such as a wire, for example, can be arranged perpendicular to a longitudinal direction of the grooves 13. When the crimp flanks are closed, the electrical conductor is pressed at least partially into the grooves 13 and the areas 31 protruding from the surface 19 are pressed into the material of the conductor. As a result, an electrical conductor is retained securely in the crimp section 7. At the same time, the protruding areas 31 , which can in particular have the form of edges, can burst any oxide layers which may be present on the conductor and, by penetrating into the latter, can improve the electrical connection to the conductor.

If, as depicted in Fig. 6, particles 17 are now present on the surface 19, these too can also penetrate into an inlaid or pressed-in conductor and improve both the mechanical adhesion and the electrical conductivity from the contact material 3 to the electrical conductor.

Fig. 7 shows the example from Fig. 6 after the particles 17 have been heated. As already described with reference to Figures 4 and 5, heating by irradiation with electron beams, for example, can fuse the particles 17 so that a layer 25 is formed. The layer 25 can be arranged on the basic surface structure 11 and in that case can cover the whole surface 19 including the grooves 13. As in the previously described examples, here too it can be possible to only heat the particles 17 to the extent that these are fused with one another or surface-fused and substantially retain their particle shape. Reference Signs electrical contact element

contact material

contact surface

crimp section

crimp flanks

basic surface structure

groove

area with particles

particles

surface

conglomerate

free locations

layer

layer thickness

particle diameter

protruding areas