Effect of Bonding Time on Microstructure and Shear Property of Cu/In-50Ag/Cu TLP Solder Joints

Here, we study the effect of bonding time on the intermetallic compound (IMC) formation and shear property of Cu/In-50Ag/Cu TLP solder joints based on low-temperature transition liquid phase (TLP) bonding of In-Ag composite powder. The bonding process was carried out at a temperature of 260°C using a wafer bonding machine. The results show that the solder joints are composed of an (Ag,Cu)2In phase and a Cu2In phase in the interfacial diffusion reaction zone and an Ag2In phase and In rich phase in the in␣situ reaction zone. It was observed that the (Ag,Cu)2In phase is formed firstly in the diffusion reaction zone when the bonding time is 0.5 min, then transforms completely into the Cu2In phase when the bonding time reaches 30 min. The shear strength increased and then decreased with increasing bonding time. The observed shear fracture mode of solder joints is brittle.