The delamination of solder ball involving moisture and thermal effect in IC package

The difference of CTE leads to stress concentration at the interface in the package. The underfill material is wildly used for reducing the mismatch of CTE in the flip chip package. Moreover, the ingress of moisture in underfill material will affect the failure behaviour of solder ball. In this paper, the analysis of solder ball delamination involving thermal and moisture concentration is performed. The results demonstrate that the moisture concentration can not be ignored in reflow, especially in lower temperature range. The swelling coefficient of moisture is additional factor assist delamination except mismatch of CTE during solder reflow.