Lead-Free Soldering Progress and Technical Five Issues; Whiskers, Bath Erosion, Pb Contamination and Low/High Temperature Solders

摘要

Lead-free soldering has been emerged as one of the key technologies in electronics of the new century. Much effort has been poured into the establishment of the lead-free mass-production world-widely before the ban of the use of leaded solders in July 2006. After the tremendous effort of the companies, the academies and the related consortiums, the piles of process know-how and material information have been accumulated for developers and technicians, which can provide great help for the promotion of lead-free conversion. In Japan in the middle of 2005, 80 % - 90 % of new electronic products become lead-free. There are many products that still remain as quite difficult objects to be established. One of the problems is tin whisker, especially for lead-frames of semiconductors and fine-pitch flexible cable/connectors. Elimination of lead from terminal finishes easily causes growth of tin whiskers. Lead contamination, lowering soldering temperature, erosion of solder bath and lead-free high temperature solders are also the other crucial issues.