SOLDER FREE FROM LEAD FOR ADDITIONAL SUPPLY AND METHOD OF REGULATING Cu CONCENTRATION AND Ni CONCENTRATION IN SOLDER BATH

摘要

A solder free from lead for additional supply to control the Cu concentration and Ni concentration in solder bath which sharply vary depending upon the particularity of post-process; and a method of regulating the Cu concentration and Ni concentration in solder bath under such particular conditions. A lead-free solder composed mainly of Sn wherein at least Ni is contained in an amount of 0.01 to 0.5 mass% is supplied to a solder bath employed for a work of printed board, copper lead wire or copper tape furnished with a copper foil to be processed by an air knife or a die after soldering. By charging of the lead-free solder of this composition, the solder concentration in solder bath having been sharply changed by post-process HASL unit or die is rapidly returned into an appropriate concentration range.