MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF PB-FREE SOLDER ALLOYS FORLOW-COST ELECTRONIC ASSEMBLY - A REVIEW

Lead-free solders, including Sn-58Bi, Sn-52In, and Sn-3.5Ag, are poten tial replacements for Sn-37Pb solder in low-cost electronic assembly. This paper reviews the literature on the microstructure and mechanical properties of these alloys. Because of the processing and testing con ditions, many of the data are not predictive for electronic assembly a pplications. However, eutectic Sn-Bi seems to have properties approach ing those of eutectic Sn-Pb under most conditions, while eutectic Sn-I n seems far inferior in most respects. Eutectic Sn-Ag has many promisi ng characteristics, but its relatively high melting temperature may pr eclude its use for this type of application.