Low Cost Lead Free Solution Evaluation for Electronic Consumer Applications

摘要

Lead products are no longer an option if you want to export to the EU market. RoHS regulations requiring the manufacture of lead-free electronic products by July 2006 are pushing the industry to evaluate and find lead free solutions soon. There are several important issues in undertaking a transition to lead free, including: 1) finding PCB materials and plating finishes that can withstand the high reflow and wave temperatures of lead free alloys, 2) selecting lead free alloys that have similar or better quality and reliability characteristics than SnPb, 3) assessing whether the lead-free components can withstand high reflow temperatures, 4) finding a cost effective solution, and 5) understanding and solving the challenges of the lead-free process on PCBs, components and solder joint quality. In this paper we address these issues by evaluating a) two PCB materials -FR1 and FR4, b) PCB plating finish -OSP and Ni/Au, c) lead-free alloy Sn 3.5Ag0.5Cu (SAC) and 58Bi42Sn, and d) the number of reflows (single -sided vs. double-sided). We evaluated 58Bi42Sn eutectic alloy as a solution for those components that cannot withstand the high temperature process of SAC alloy. Our goal is to determine a cost effective solution for a low temperature application. Different reliability tests, warpage measurements, and cross sections were used to evaluate each configuration.