In response to the current trend of multi-functional electronic products, integrated circuits become smaller with higher I/O counts. Thermosonic bonding is a potential microelectronic stacking technology for three-dimensional (3D) integration and advanced packaging. Therefore, it is important to comprehend the relation between strength and bonding condition. In this paper, parameters of ultrasonic vibration for low temperature Cu pillar to Cu/In bonding are investigated through shear test. Moreover, electrical performance is evaluated by Kelvin structure and Daisy chain. Experiment results show that heating temperature and bonding force possess a positive correlation with shear strength, which can be up to 39 MPa. In addition, it exhibits good electrical performance in the range of 10−8 Ω-cm2 as well as high resistance to environmental degradation. This work provides guidelines of Cu/In thermosonic bonding for future fine pitch applications.