Conductive sidewall for microbumps

Electromigration in microbump connections causes voids in the microbumps, which reduces the lifetime of an integrated circuit containing the microbump. Electromigration lifetime may be increased in microbumps by forming a copper shell around the solder. The copper shell of one microbump contacts the copper shell of a second microbump to enclose the solder of the microbump connection. The copper shell allows higher current densities through the microbump. Thus, smaller microbumps may be manufactured on a smaller pitch without suffering failure from electromigration. Additionally, the copper shell reduces shorting or bridging between microbump connections on a substrate.