抄録
In recent years there have been serious debates about the environmental problem where Pb should be removed from the solder joints. And the debates are now developing to a remarkable movement to establish regulations for theremoval of Pb, especially in European countries and Japan. Although the amount of Pb used in the electric and electronic devices small, it still have a possibility to resolve in the under-ground water and have a bad influence to human body if the printed circuit boards, abandoned as parts of the wasted electric and electronic components, are exposed to the rain. Therefore, many studies are aggressively promoted to develop technologies for replacing Sn-Pb solder by lead-free ones.
