Growth Kinetics and Growth Suppression of Au-containing Ternary Intermetallic at Solder/UBM Interface during Solid Aging

摘要

In this study, effects of under bump metallurgy (UBM) structure and Cu content in solders on redeposition rate of Au-containing ternary intermetallics at solder/UBM interface were investigated. A UBM structure with Ni diffusion barrier, Au/Ni/Cu, appeared to promote the redeposition during solid state aging treatment, leading to an Au-embrittlement of solder interconnections. Addition of Cu into eutectic Sn-Pb and Sn-Ag solders, however, were observed to be very effective in retarding the redeposition and preventing the Au-embrittlement. These effects were discussed with the microstructures observed.