Temperature-dependent failure mechanism of SnAg solder joints with Cu metallization after current stressing: Experimentation and analysis

Abstract

Temperature-dependent electromigration failure was investigated in solder joints with Cu metallization at 126 degrees C, 136 degrees C, 158 degrees C, 172 degrees C, and 185 degrees C. At 126 degrees C and 136 degrees C, voids formed at the interface of Cu6Sn5 intermetallic compounds and the solder layer. However, at temperature 158 degrees C and above, extensive Cu dissolution and thickening of Cu6Sn5 occurred, and few voids were observed. We proposed a model considering the flux divergency at the interface. At temperatures below 131 degrees C, the electromigration flux leaving the interface is larger than the in-coming flux. Yet, the in-coming Cu electromigration flux surpasses the out-going flux at temperatures above 131 degrees C. This model successfully explains the experimental results. (C) 2013 AIP Publishing LLC.