Reduction of copper content from dip-type lead-free soldering bath

The high dissolution rate of lead-free solders was confirmed by the dissolution test of copper conductor on printed circuit. This brings the faster contamination and frequent replacement of lead-free solder bath used for dip-type soldering. If there is a simple reduction method of copper content from contaminated solder, it contributes the reduction of solder waste. The work developed the filtering method, which effectively removes the copper rich intermetallic phase by holding the solder with hypereutectic copper content just above the eutectic temperature of Sn-Cu. The filtering method developed by this study reduced copper content of Sn-1.5Cu to about 1%Cu after filtration.