Abstract
The mechanical stability of Chip Scale Packages (CSP) used in surface mount technology is primary concern. The major concern is the reliability of CSP interconnects under cyclic thermal stress and strain imposed on the system by temperature fluctuations and in-circuit power on/off. In this study, the effect of pad metallization on the life of solder crack initiation and propagation, and the Weibull cumulative failure was investigated. A viscoplastic strain ratebased finite element method, which includes the effect of pad metallization, was used to investigate the life of crack initiation and propagation. The 3P Weibull distribution was used for the cumulative failure analysis. EPMA and SEM were utilized to determine the density of gold and intermetallic compounds at the interface between solder and pad metallization. The results of the characterization and an explanation of the pad metallization factor affecting solder fatigue life are presented in this paper.
