Investigations on Resistance Behavior at the Interface of Ultrasonically Welded Dissimilar Al/Cu Joints

The key focus of this research study is to analyze the weld joint resistance with microstructural evaluation of ultrasonically welded Al and Cu dissimilar wires. The typical applications of dissimilar wire bonding include automobile parts, electrical safety, and battery terminals. The weldments are further subjected to metallurgical characterization to understand the extent of molecular movements at the interface, uniformity in material diffusibility and the corresponding changes in weld joint resistance due to various ultrasonic welding energies. Ultrasonic welding trials were performed with different levels of process parameters (pressure, weld time, and amplitude) based on design of experiments. Subsequently, the welded specimens were examined through optical microscopy and the corresponding images are captured using image analyzers. Further, SEM images were investigated for understanding the surface morphology and the extent of intermetallic compounds formation and performance. The experimental results show that the increase in welding energy is inversely proportional to the degree of formation of intermetallic compounds/weld joint resistance. Besides, the surface morphology unwinds a uniform weld pattern in most of the samples while there are few voids and non-uniformity for low heat input samples.