Current Induced Interfacial Microstructure and Strength Weakening of SAC/FeNi-Cu Connection

Abstract

The interface microstructure and shear strength weakening of eutectic SnAgCu (SAC)/FeNi-Cu connection after current stressing for 0~12 h were investigated to discuss the stability of the FeNi layer as UBM film layer for Sn base solder. The experiments showed that the FeNi layer separated to two layers with different Fe/Ni ratio rather than intermetallic compound (IMC) thickness variation between the cathode and anode. The IMCs became rougher with a bulk amount of (Cu,Ni)6Sn5 emerging in the regains near to interfaces. The shear failure mode exhibited a ductile manner companied by a fracture surface rougher and even grain boundary weakening with the current exposure time increasing.