wire for conducting electric current

Abstract

Wire (1) for conducting electric current, consisting of a radially oriented first inner material (2) and a radially oriented second outer material (3) with which the first inner material (2) is sheathed, wherein the second outer material (3) has a higher electrical conductivity than the first inner material (2), wherein at least the second outer material (3) has a polygonal cross-section.

Description

[0001] The invention relates to a wire for conducting electric current, consisting of a radially oriented first inner material and a radially oriented second outer material with which the first inner material is sheathed, wherein the second outer material has a higher electrical conductivity than the first inner material.

[0002] Wires of this type are known from the prior art and are used particularly in electrical installations where good conductivity and good mechanical strength are required. An inner wire made of a first material provides the necessary strength, while an outer sheath made of a second material provides the necessary conductivity.

[0003] Due to manufacturing difficulties, these wires can currently only be produced with a round cross-section and relatively large dimensions. Therefore, they are unsuitable for microelectronics, particularly in the field of integrated circuits.

[0004] On the other hand, wires with a rectangular cross-section are known in principle and can also be used in microelectronics. The use of wires with a round cross-section in microelectronics has the disadvantage that the contact area between the wire and the wire holder, for example on a printed circuit board, is comparatively small. Furthermore, gaps between the wire holders must be taken into account, resulting from the close packing of the wires. To overcome these disadvantages, wires with a square or profiled cross-section and precisely defined edge radii are used. However, these can currently only be manufactured as solid wires from a single material, which necessarily must have good electrical conductivity. Therefore, a compromise between the mechanical strength and the conductivity of the chosen material is always required.

[0005] Based on this state of the art, the invention aims to create a generic wire with improved mechanical strength and simultaneously higher electrical conductivity.

[0006] The invention provides a solution to this problem by means of a wire for conducting electric current, consisting of a radially oriented first inner material and a radially oriented second outer material with which the first inner material is sheathed, wherein the second outer material has a higher electrical conductivity than the first inner material, wherein at least the second outer material is formed with a polygonal cross-section.

[0007] The polygonal cross-section of the second outer material according to the invention now makes it possible, for the first time in the field of microelectronics, to provide an electrically conductive wire with a comparatively high electrical conductivity, namely through the outer second material. According to the invention, the two materials form a "hybrid material" with different electrical conductivities and a polygonal cross-section. The wire according to the invention is a "hybrid conductor" if it is intended for and / or used to conduct electric current. The outer second material has a higher electrical conductivity compared to the first inner material. It forms the outer sheath of the inner first material and thus simultaneously the outer surface that defines the radial boundary of the wire according to the invention.The mechanical stability and strength of the wire, in particular its tensile strength, flexural strength, and bending strength, are provided partly by the combination of both materials, but predominantly by the first inner material. Advantageously, conductivity and mechanical strength are thus largely decoupled from a material perspective. Compared to wires made of a single material, which must provide both electrical conductivity and mechanical strength for the respective application profile, the wire according to the invention achieves higher conductivities with simultaneously higher mechanical stability.Compared to other known wires made of two materials with a round cross-section, the wires according to the invention with a polygonal cross-section are particularly suitable for use in microelectronics due to their section modulus and the associated bending stiffness, which differs from that of wires with a round cross-section. Their use as electrical connectors or in press-fit technology as press-fit pins for the electrical connection of electronic components and / or electronic assemblies to printed circuit boards and the like is especially envisioned. Due to the polygonal, and in particular rectangular, cross-section of the second outer material, the contact area is advantageously larger in these applications compared to a circular cross-section, thanks to the planar contact of the outer material.

[0008] The wire according to the invention, which itself has a polygonal cross-section due to the polygonal cross-sectional shape of the outer material, is preferably produced by forming previously manufactured wires with a circular cross-section. The preferred forming method is cold forming by means of rolling, in particular by means of precision rolling. An additional process step can be provided to specifically shape the corner regions of the polygonal cross-section of the second material. Rectangular, and in particular square, cross-sectional shapes of the second outer material with rounded and / or truncated corner regions are particularly preferred. With regard to its three-dimensional appearance, the wire thus has rounded and / or truncated longitudinal edges.For this purpose, the wire, which has already been formed into a polygonal, in particular rectangular, wire, is either drawn through a correspondingly shaped die or pressed through a correspondingly shaped nozzle in the manner of an extrusion.

[0009] To adjust the strength of the wire according to the invention, it is preferred that the first inner material has a higher mechanical strength, in particular tensile strength and / or flexural strength, than the second outer material. It is particularly preferred if the first inner material is made of aluminum, in particular an aluminum alloy, or steel, in particular stainless steel. For reasons of lightweight construction, aluminum can preferably be used as the first inner material. If particularly high strength is required, stainless steel is particularly suitable as the first inner material.

[0010] To adjust the conductivity of the wire according to the invention, the second outer material is provided to have a higher electrical conductivity than the first inner material. It is particularly preferred if the second outer material is made of a precious metal, especially gold, silver, or copper. The use of copper is particularly preferred.

[0011] In accordance with the invention, the first inner material forms a carrier wire. This carrier wire is completely encased by the second outer material. The second outer material forms an outer sheath that defines the outer boundary of the wire in the radial direction. The outer sheath surfaces provided by the sheath form the outer boundary between the environment and the wire.

[0012] Various geometries are preferred with respect to the cross-sectional shape of the first inner and the outer second material. The first inner material can preferably have a polygonal cross-section or a round, particularly circular, cross-section. In combination with the polygonal cross-sectional shape of the outer second material, this results in either a homogeneous or a heterogeneous layer thickness of the outer second material in cross-section.

[0013] Particularly preferred is that the outer second material has a rectangular, especially square, cross-section with rounded and / or truncated corner areas. This allows the wire's cross-section to be adapted to specific corresponding geometries of electrical connections, thereby increasing the packing density of a multitude of adjacent wires and / or maximizing the contact area for the electrical connection.

[0014] In a particularly preferred embodiment of the invention, the first inner material and the second outer material are formed with a rectangular, and in particular square, cross-section, each with rounded corner regions. This results in a homogeneous layer thickness of the outer material in the circumferential direction. This is especially advantageous when, as provided, the inner and outer materials are arranged coaxially with respect to the longitudinal axis of the wire according to the invention. This embodiment is particularly suitable for the lightweight construction mentioned above, in which the first inner material is made of aluminum and the second outer material is made of copper.

[0015] According to an alternative preferred embodiment, the first inner material has a round, particularly circular, cross-section, and the second outer material has a rectangular, particularly square, cross-section with truncated corner areas. In this embodiment, the combination of round and rectangular cross-sections results in a heterogeneous layer thickness of the second outer material. Overall, the layer thickness of the second outer material is increased compared to the previous alternative embodiment, thus advantageously increasing the contact area between the electrically conductive material and the respective terminal. The resulting reduction in mechanical strength can be compensated for by a suitable material selection for the first inner material.It is therefore particularly preferred if, in this embodiment, the outer second material is formed by copper, while the first inner material is formed by stainless steel.

[0016] For the use of the wire according to the invention in microelectronic applications, it is preferred that the second outer material has edge lengths between 0.10 mm and 7.0 mm with a very low tolerance. At these edge lengths, sufficient conductivity of the wire is achieved while simultaneously maintaining mechanical strength.

[0017] Another embodiment provides that the rounded corner areas are formed with an edge radius of 0.02 to 0.3 mm. These edge radii ensure a sufficiently large contact surface between adjacent surfaces to be coated, and that the coating adheres to these contact surfaces without reducing the layer thickness.

[0018] Further features and advantages of the invention will become apparent from the following description of the accompanying drawing. The drawing shows: Fig. 1 a wire according to the invention in perspective view; Fig. 2 a first embodiment of the wire according to the invention with a square cross-section; Fig. 3 a second embodiment of the wire according to the invention with a square cross-section;

[0019] Fig. Figure 1 shows a wire 1 according to the invention. A first inner material 2 and a second outer material 3, also radially oriented, are visible. In the illustration, the second outer material 3 has been partially removed to expose the first inner material. However, as intended, the first inner material 2 is completely encased by the second outer material in both the circumferential and longitudinal directions.

[0020] The first inner material 2 is made of a material with comparatively high mechanical strength and comparatively low electrical conductivity. The second outer material 3, in contrast, is a material with comparatively high electrical conductivity and comparatively low mechanical strength. The combination according to the invention provides a wire 1 that, overall, possesses both high electrical conductivity and high mechanical strength.

[0021] Fig. Figure 2 shows a first cross-sectional geometry of the wire 1 according to the invention. Accordingly, both the first inner material 2 and the second outer material 3 have a rectangular, in particular square, cross-section. Both also have rounded corner regions 4, 6. The layer thickness of the second outer material 3 is uniform throughout, and thus homogeneous.

[0022] The first inner material 2 is made of aluminum. The second outer material 3 is made of copper.

[0023] The rounded corner areas 4, 6 have an edge radius of 0.02 to 0.3 mm. Between the corner areas 4, the second outer material has 3 surfaces 7 with edge lengths between 0.10 mm and 7.0 mm with a tolerance of ± 0.005 mm.

[0024] Fig. Figure 3 shows a second cross-sectional geometry of the wire 1 according to the invention. Accordingly, the first inner material 2 has a round, in particular circular, cross-section. The second outer material 3, on the other hand, has a rectangular, in particular square, cross-section. The second outer material 3 also has truncated corner areas 5.

[0025] The first inner material 2 is made of stainless steel. The second outer material 3 is made of copper.

[0026] Between the corner areas 5, the second outer material has 3 surfaces 7 with edge lengths between 0.10 mm and 7.0 mm with a tolerance of ± 0.005 mm. Reference sign 1 wire 2 first inner material 3 second outer material 4 rounded corner area 5. Cut-off corner area 6 rounded corner area 7 Area

Claims

[1] Wire (1) for conducting electric current, consisting of a radially first inner material (2) and a radially second outer material (3) with which the first inner material (2) is sheathed, wherein the second outer material (3) has a higher electrical conductivity than the first inner material (2), wherein at least the second outer material (3) has a polygonal cross-section. [2] Wire according to claim 1, characterized by , that the first inner material (2) has a higher mechanical strength, in particular tensile strength and / or flexural strength, than the second outer material (3). [3] Wire according to one of claims 1 or 2, characterized by , that the first internal material (2) is made of aluminium, in particular an aluminium alloy, or steel, in particular stainless steel. [4] Wire according to any one of claims 1 to 3, characterized by, that the second outer material (3) is made of a precious metal, in particular copper. [5] Wire according to any one of claims 1 to 4, characterized by , that the first inner material (2) is formed with a polygonal cross-section or a round, in particular circular, cross-section. [6] Wire according to any one of claims 1 to 5, characterized by , that the outer second material (3) is formed with a rectangular, in particular square, cross-section with rounded and / or truncated corner areas (4, 5). [7] Wire according to any one of claims 1 to 6, characterized by , that the first inner material (2) and the second outer material (3) are formed with a rectangular, in particular square, cross-section with rounded corner areas (4, 6) each. [8] Wire according to any one of claims 1 to 6, characterized by, that the first inner material (2) is formed with a round, in particular circular, cross-section and that the second outer material (3) is formed with a rectangular, in particular square, cross-section with truncated corner areas (5). [9] Wire according to any one of claims 6 to 8, characterized by , that the outer second material (3) has edge lengths between 0.10 mm and 7.0 mm with a tolerance. [10] Wire according to any one of claims 6 to 9, characterized by , that the rounded corner areas (4, 6) are formed with an edge radius of 0.02 mm to 0.3 mm.

Images