Lead free electronics soldering is driven by a combination of health and environmental concerns, international legislation and marketing pressure by lead free electronics manufacturing competitors. Since July 1, 2006 companies that do not comply with the European Union legislation are not able to sell circuit assemblies with lead solder in the European Union. China has developed its own regulations, based on the European Union documents with a compliance date of March 1, 2007. Lead free soldering requires an increase in reflow peak temperatures which will further aggravate component moisture sensitivity risks and thereby decrease assembly yield. Prior research has revealed a counterintuitive enhanced solder spreading phenomena at lower peak temperature and shorter time above liquidus with 63Sn/37Pb solder. This present study investigated solder wetting reactions in 96.5Sn/3.0Ag/.5Cu (WT%) (SAC305) using materials and manufacturing systems that are relevant to the electronics manufacturing industry. The objective was to advance the knowledge base of metal wetting such that solder joints can be effectively produced while avoiding heating the assembly any hotter then necessary for effective soldering, which would increase the risk of component damage due to rapid moisture outgassing and associated popcorn delamination. A classical design of experiments (DOE) approach was used with wetted area as the response variable. Additional sample characterization will be conducted outside of the DOE. The samples will be analyzed for correlation of reflow peak temperature, reflow time above liquidus, and wetted area. The expected results are 1) improved understanding of SAC lead free solder wetting reactions, 2) reduced SAC reflow peak temperatures, and thereby reduced risk of moisture sensitivity damage to components.

Volume Subject Area:
Electronic and Photonic Packaging
Topics:
Alloys, Solders, Tin, Wetting, Temperature, Electronics, Manufacturing, Soldering, Damage, Risk, China, Circuits, Delamination, Experimental design, Heating, Lead-free solders, Manufacturing industry, Manufacturing systems, Metals, Pressure, Regulations, Solder joints
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