Development of Lead-Free Soldering Technology and Its Application

In recent years, the solder used to mount electronic components onto printed circuit boards has become a social issue because of the lead it contains. To resolve the problem, the development of a lead-free solder and bonding technology that utilizes it are not only research themes of industry but national research programs as well.

In light of the circumstances, we developed an Sn-Ag solder with minute quantities of Bi and other additives, and applied it for the first time in the industry to a printed circuit board for portable MD player. The developed solder has proven workable under current production temperature conditions (profile that peaks at 230 degrees centigrade) and reliable for bonding electronic component leads in mass-production. Other studies are currently underway into identifying the bonding mechanism and reliability evaluation methods and standards, and to establish reflow processing technology for large boards, which are characterized by wide temperature variation, for eventual use with factory automation controllers and other products. One reflow process using a Sn-Cu solder has been brought to practical application with VCRs. Use will eventually be expanded to other products in the future.