Mechanical and Microstructural Characterization of Ultrasonic Metal Welded Large Cross Section Aluminum Wire/Copper Terminal Joints

In automotive cable harness production the substitution of copper by aluminum wires is pursued more and more as the weight of aluminum is 50% lower than that of copper considering to reach the same conductivity and an additional cost decrease of 2.5 times. Moreover joining aluminum wires to copper terminals is often realized via crimping, which shows several disadvantages especially for cross sections of more than 10 mm2, e.g. reduced conductivity due to the oxide layers on aluminum or electrochemical corrosion of the contact points. Ultrasonic metal welding is a promising technology, which can avoid these problems. With the availability of torsional ultrasonic welding machines, joining of aluminum wires with cross sections of up to 200 mm2 is possible. Recent investigations focus on the microstructural and mechanical properties of large cross section aluminum wire to copper terminal joints whereas current joint strengths reach values of 31% of the weaker base material.