Suppressing effect of 1 wt.% nano-TiO2 addition into low Ag content Sn-Ag-Cu solder alloy on the intermetallic growth with Cu substrate during isothermal aging

This study investigated the effects of adding 1 wt.% nano-TiO₂ particles into low-Ag content Sn0.35Ag0.7Cu (SAC) lead-free solder alloys on the growth of intermetallic compounds (IMC) with Cu substrates during solid-state isothermal aging at temperatures of 125, 150, and 175°C for up to 7 days. The results indicate that the morphology of the Cu₆Sn₅ phase transformed from scallop-type to layer-type in low-Ag SAC composite solder/Cu joints. The growth rate of these IMCs increased with the aging temperature and time. Kinetics analyses showed that growth of the overall IMC layers was diffusion controlled. The apparent activation energies for the growth of overall IMC layers are calculated to be 50.62 kJ/mol.