Mechanical response of indium micro-joints to low temperature cycling

In this study, mechanical properties of indium micro-joints exposed to low temperature cycling were investigated. The metallization structure of Ni/Cu was specially used as a substrate to form indium joints for mechanical tests. This paper focuses mainly on the tensile test of indium joints at thermal cycling from 300 K to 77 K. The Young's modulus, the ultimate strength and yield strength of the material were obtained. The failure mode after different loading histories was analyzed. The results indicate the decline of the Young's modulus with the increase in the number of thermal cycles; however, the ultimate/yield strength of indium joints did not show an obvious trend with the number of thermal cycling. It was confirmed that indium joints still maintain a high ductility even after 20 thermal cycles. Finally, the associated modeling provides an insight predicting that an interface between indium and copper could be the potential site for failure in thermal cycling.