Nitrogen in Reflow Soldering of Lead-Free Solders

Due to environmental and health demands for lead contamination, there is increasing pressure in legislation and a growing market demand to eliminate toxic materials. Lead-free soldering for the electronic industry is becoming a global trend, and several alloy systems alternatives have been recommended. The present article investigates the effect of changing soldering atmosphere from air to nitrogen, time above solder liquidus temperature and peak soldering temperature on solder wetting. It has been shown that spreading is better in nitrogen: the time above liquidus temperature can be reduced by about 18% or the peak temperatures can be reduced by about 6-8 degC, resulting in the same solder-spread for the nitrogen process, as when soldering is performed in the air atmosphere.