Studies on Electro Mechanical Aspects in Ultrasonically Welded Al/Cu Joints

Ultrasonic welding has been widely used to bond dissimilar conductive wires, battery cell terminals in relay applications. In this paper, dissimilar metals, Al/Cu were joined using ultrasonic welding for conductive applications. Welding trials were carried out by varying three control parameters: (1) vibrational amplitude (40, 60, and 80 mu m), (2) clamping pressure (1, 1.2, and 1.4 bar), (3) weld time (0.1, 0.2, and 0.3 s). Experimental trails were designed based on L-9 Taguchi method. Interpretation of tensile strength and microhardness results revealed that the satisfactory weldments were obtained for higher welding energies when compared to low welding energies. From the microstructural analysis, the bond formation of metals and failure modes were studied. SEM and XRD images revealed the four major intermetallic compounds at the interface of joint; AlCu, Al2Cu, Al3Cu4, and Al4Cu9 with resistivity values of 11.415, 8.027, 10.612, and 14.243 Omega-cm respectively. The resistivity values of intermetallic compounds observed in the joint was almost 5-6 times higher than the Al.