Abstract
Recently, the problem of electromigration failure in flip-chip solder joints has become a critical issue because of miniaturization of the solder joint structure. In this paper, we report on a newly developed method of predicting the electromigration failure of a solder joint. This method was based on the atomic flux divergence (AFD) method and could predict the behaviors of voids and hillock growth in a micro solder joint. We compared the electromigration failure lives of two solder joint structures using our method. One structure was a conventional solder ball joint and another was a Cu-cored solder ball joint. We found that the Cu-cored solder ball joint had a longer life because crack growth near the center of the Cu-cored joint was prevented because of its geometric feature. Moreover, we measured the failure lives and observed void shapes using synchrotron radiation X-ray microtomography. Accordingly, we could find that the results predicted by our method corresponded to actual results.
