Tin whisker growth on bulk Sn-Pb eutectic doping with Nd

Tin whisker growth is a serious reliability concern for electronics using high-density packaging. Whisker growth behavior of tin lead eutectic solders doped with different neodymium concentration (5-0.1wt.%) was studied in present work. Results indicate that the Nd in the all of the Sn-Pb-Nd alloys mainly exists in NdSn3 intermetallic compound, and that the distribution of the NdSn3 phase is very non-uniform in the alloy with low Nd concentration. Tin whiskers growth was observed on all samples doped with Nd. All of these whiskers were seen to originate from the NdSn3 phase, it appears that the Pb does not suppress whisker growth in these alloy because it does not influence the formation of the tin-rare earth intermetallic compound. These results suggest that the addition of rare earth elements into tin alloy systems renders whisker formation nearly inevitable. Therefore, any suggestion to dope tin-based solders with rare earth elements for application in high-density electronic packaging should be carefully reconsidered.