Abstract
Sn-Ag alloys are important solders, and Co and Co alloys are investigated as barrier layers. Interfacial reactions in Sn-Ag/Co couples were examined in this study for Ag contents of 1.0 wt.%, 2.0 wt.%, and 3.5 wt.% and reaction temperatures of 250 C, 200 C, and 150 C. Only CoSn 3 formed in Sn-Ag/Co couples reacted at 250 C, but both CoSn 3 and Ag 3 Sn formed in couples reacted at 200 C and 150 C. The reaction layer was 100 μm thick in Sn-3.5 wt.%Ag/Co couples reacted at 200 C for 110 h. The reaction rates were lower if Ag was added, but remained very fast compared with those for Ni and Ni-based substrates. © 2013 TMS.