Electromigration in Solder Joints Using Sn-3.0Cu Solder in Power Modules

Abstract

Solder electromigration (EM) is recognized as a potential reliability problem in power modules. This study investigates the fundamental EM phenomena of a Cu/Ni-P/Sn-3.0Cu/Ni-P/Cu joint at 175°C and 50 A/mm² using a Sn-3.0Cu solder known as one of candidates for high-temperature solders. After reflow, a thicker Cu-rich (Cu,Ni)₆Sn₅ layer and a thinner P-rich layer formed at the solder-electrode interfaces. This structural feature suppresses both the disappearance of the (Cu,Ni)₆Sn₅ layer and increase of the P-rich layer caused by EM which results in an open failure at the cathode.