Investigation of Cu particles size and bonding time on the microstructure and shear property of Cu/In-45Cu/Cu solder joints

The effect of Cu particles size and bonding time on the microstructure and shear property of Cu/In-45Cu/Cu solder joint was studied, and the shedding mechanism of intermetallic compounds (IMCs) in the solder joint during transient liquid phase (TLP) bonding process was investigated. The results showed that the microstructure of Cu/In-45Cu/Cu solder joint was composed of Cu11In9 phase, residual In phase and Cu particles, and the microstructure of solder joints prepared by small Cu particles was dense. The content of IMCs was increased with increasing bonding time, and the Cu/In-45Cu/Cu solder joint was composed of Cu11In9 phase and Cu particles under bonding time 30 min. The Cu2In phase was formed in the solder joint at 60 min, and many cracks appeared at the interface of Cu11In9 and Cu2In phases. The shear strength of Cu/In-45/Cu solder joints with brittle fracture was increased firstly and then decreased with increasing bonding time, and the maximum shear strength of the solder joint was 16.35 MPa at 30 min.