Microstructure and mechanical properties of transient liquid phase bonded joints with lotus-type porous Cu interlayer

This study investigates the use of lotus-type porous copper (Lotus Cu) as an interlayer for transient liquid phase (TLP) bonding, assessing its potential for industrial applications. The bonding process was performed at 300 °C under a pressure of 0.1 MPa. The evolution of microstructure and mechanical properties was examined as a function of bonding time. In both Lotus Cu TLP joints and the conventional TLP joints, the thickness of the Cu 3 Sn layer increased with bonding time. Fractographic analysis showed an increased Cu 3 Sn fraction at longer bonding times. Lotus Cu TLP joints showed higher shear strength than the conventional TLP joints up to 120 min because the porous structure impeded crack propagation and enhanced fracture resistance. After 180 min, the excessive formation of intermetallic compounds led to volume shrinkage in Lotus Cu pores, which generated tensile stress and caused void formation. This work highlights the promising potential of Lotus Cu, laying a crucial foundation for future research into high-reliability applications.