The trend of lead-free soldering

Recent environmental consciousness raises a great concern on the lead in solder used in electric appliances. In this paper, we report the trend and the current status of the lead-free soldering technology used in the connections of the electrical components and devices for the substitution of the Pb-Sn solder. The lead solders used in electrical products can be classified into several groups as follows. (1)Flow soldering, (2)Re-flow soldering, (3)Bit soldering, (4) Electrode of electrical components, (5) Inner connection of the electrical components, (6)Functional materials. The lead-free solders have begun to be used for the groups denoted as (1),(2) and (3) among them. There, however, still have some challenges to be overcome to develop the lead-free technology for the groups of (4) and (5). Growing interest also demands the overall measures for total environmental protection, such as LCA (Life Cycle Assessment) and the establishment of solder recycling system.