De-mystifying materials selection for lead-free soldering

Purpose The lead-free soldering process has been confounding the PWB fabricators when they set out to select the right materials for lead-free soldering. This paper discusses the compatibility of currently available laminate materials for lead-free assembly. Design/methodology/approach This paper has been written to provide a review of material characteristics. Problem areas are highlighted and methods for choosing each type of material for compatibility with lead-free soldering process are described. Findings When lead is banned and taken out of the traditional tin-lead solder, there are other metal alternatives to alloy with tin such as silver, bismuth, copper, and zinc, etc. The melting point of these lead-free alloys is higher than the conventional tin-lead solder. Consequently, the reflow temperature of the lead-free solder can now reach 240-250°C. As the reflow temperature is elevated, it will pose a severe reliability challenge to the laminate materials. The compatibility of currently available commercial laminate materials for lead-free assembly are discussed in this paper. Originality/value The value of this paper is that it provides information and solutions relating to the selection of the most appropriate materials for use in lead-free soldering and assembly.