Lead Contamination of a Transient Liquid-Phase-Processed Sn-Bi Lead-Free Solder Paste

摘要

The influence of Pb contamination on the solidification behavior of a transient liquid-phase powder-processed Sn-Bi solder paste has been studied using differential scanning calorimetry.The development of low-temperature ternary reactions was found to be very sensitive to both the Pb and Bi content of the solder.Solders with high Bi content favored the formation of the ternary eu-tectic reaction.Solders with high Pb contents favored the formation of a ternary peritectic reaction.These results agree very well with solidification predictions present in the literature for ternary Sn-Bi-Pb alloys.In particular,the dependence of ternary reactions on composition is due to a change in solidification path.Alloy compositions which mark the transition from one path to the next were identified.