Addressing opportunities and risks of pb-free solder alloy alternatives

Significant innovations in Pb-free solder alloy compositions are being driven by volume manufacturing and field experiences. As a result, the industry has seen an increase in the number of Pb-free solder alloy choices beyond the common near-eutectic Sn-Ag-Cu (SAC) alloys. The increasing number of Pb-free alloys provides opportunities to address shortcomings of near-eutectic SAC, such as the poor mechanical shock performance, alloy cost, copper dissolution, and poor mechanical behavior of joints in bending. At the same time, the increase in alloy choice presents challenges in managing the supply chain and introduces a variety of technical and logistical risks, such as a potential decrease in thermal fatigue resistance and the complexity of managing process parameters given the variability of alloy compositions. This paper summarizes the results of an iNEMI project to address the opportunities and risks of new Pb-free alloy alternatives. The results of our analysis of the state of industry knowledge on Sn-Ag-Cu alloy alternatives are provided, and focus areas for closing key gaps are identified. Progress in updating or creating industry standards to manage the introduction and use of new alloys is also presented. Finally, our plans to investigate thermal fatigue reliability of new alloys are described.