Ni-Sn solid liquid interdiffusion (SLID) bonding — Process, bond characteristics and strength

Ni-Sn joints created by solid liquid interdiffusion (SLID) bonding were investigated. Process parameters were varied between 300 °C and 360 °C with annealing times up to 20 min to study the joint development. Symmetric Ni / Ni-Sn intermetallic compound / Ni joints were fabricated. It was found that a bond profile of 5 min at 300 °C was insufficient to completely solidify the joint. 5 min at 360 °C or 20 min at 300 °C solidified the joint and initiated the homogenization stage to form a stable high temperature compatible Ni / Ni3Sn / Ni joint structure. Early development of scallop shaped structures of Ni3Sn4 between the Ni and Sn layers was observed. Coalescent scallops form solid pillars between die and substrate, which results in large irregular voids in the center of the bond line. Initial shear strength results indicate extremely strong bonds, with a joint strength of more than 200 MPa.