Development of electroplated Ni-xZn films for under bump metallization application

The feasibility of using electroplated Ni-xZn films was evaluated for a new application as the under bump metallization. Considering the alloy films in electroplating process, determining the deposition potential (affecting nucleation) and current density (affecting growth) is crucial. A suitable Ni-5Zn film exhibiting smooth and dense surface was derived at a low current density of 0.067 ASD. After a 30 s liquid reaction, intermetallic phase formation and Cu6Sn5 growth at the interface were visualized and analyzed using a field-emission electron probe microanalyzer. This study demonstrated that binary Ni-Zn films fabricated by electroplating might be a potential candidate for under bump metallization application.