Influence of the Bead Geometry and the Tin Layer on the Contact Resistance of Copper Conductors

For electrical wire connectors, a low contact resistance between the busbar and the conductor is essential for a low power loss. Results of a parameter study with a novel test device are presented. The impact of different contact radii (0.2 and 1.0 mm), coating systems (15-μm Sn and 4-μm Sn/2-μm Ni), and contact forces (1-10 N) is investigated. It has been found that a low contact radius in combination with a thick tin layer leads to the lowest contact resistances for the considered force range. Preliminary investigations have also shown a strong influence of the wire batch because of organic contaminations on the conductor surface.