Characterization of lead-free solder by reliability testing

Green materials have become a hot topic recently due to environmental issues. Lead contamination problems from end products in landfills have gathered industrial attention over the past decade. Several research programs on lead free solder have been performed, but no drop-in alternative was found to replace traditional tin-lead solder alloy. Tin-silver base solder alloys, such as Sn-Ag and Sn-Ag-Cu, are some of the more promising materials for tin-lead solder alloy replacement. However, most of the alternatives lack long-term data for reliability and/or mechanical testing results. In this paper, a chip scale package (CSP) is used to investigate the characteristics of the tin-silver solder alloy. Two surface finishes are implemented on the printed circuit boards (PCBs) to compare the solderability of the alternative materials. Several testing methods are performed to examine the properties and failure modes of tin-silver solder and tin-lead solder alloys.