Lead-free soldering materials, reliability and process optimization

As the European and global marketplaces consider mandating lead-free electronic equipment, many questions arise about the technical feasibility of replacing lead in Printed Wiring Board (PWB) soldering applications. It is the purpose of this thesis to evaluate various emerging alternatives to lead-based solders and finishes and to recommend a viable lead-free alternative to lead based processes.; The various alternatives of lead-free materials, surface finishes and manufacturing processes were evaluated, then reduced to a more manageable set of factors and levels. These factors were combined in a set of designed experiments and analyzed, in comparison to a baseline of standard leaded processes and materials, using the quality characteristics of visual, mechanical and thermal testing criteria.; The results showed that PWB assembly with zero defects and stronger solder joints than tin-lead baseline could be achieved using lead-free alternatives. Among the lead-free alternatives selected in this research and based on their statistical analysis, Sn/Ag/Cu and Electroless Nickel Immersion Gold (ENIG) were found to be the most suitable selection for solder paste alloy and PWB surface finish. Similarly, nitrogen and linear thermal profile were recommended as significant process parameters.