Morphology and chemical composition of Ag/Sn/Ag interconnections

The main goal of the present contribution was to describe morphology and chemical composition of the intermetallic phases, which were formed during diffusion soldering process of the silver using tin. The Ag₃Sn intermetallics is the main constituent of the joint after diffusion soldering at 235°C and 265°C. A closer inspection of the Ag/Ag₃Sn interface revealed also the small crystallites of the second intermetallic phase, Ag₅Sn, which was not previously observed using scanning electron microscope. Both phases are characterized by high melting temperatures: 480°C and 724°C, respectively. Therefore, their presence guarantees high thermal stability of the interconnection, which can be even three times higher than the temperature used for soldering.