Overall Technological Results of IMS-EFSOT Japanese Project --- Environmental Impact of Lead-Free Soldering ---

As for lead-free solder, we evaluated not only jointability (workability and joint reliability) but also energy consumption i.e. CO2emission, toxicity, resource depletion, recyclability and reusability of various types of solder. Next we attempted to integrate the environmental impacts of these factors of each solder and compare them among these solders. We finally recommended some types of solder whose integrated environmental impact was assumed to be relatively low. We recommended Sn-Ag-Cu and Sn-Cu types of solder as the best solutions in the present state. That is, total environmental impact of these solders is minimum, although they have a problem of Ag and Sn scarce. Then, we suggested it was necessary to construct recycling system of Ag and Sn in the long term. 2^ndSelection was Sn-Zn(-Bi) type solder. This solder has only problem about jointability. If this problem should be solved by improvement, this solder would be one of the best selections of lead-free solder. Furthermore we proposed refraining from use of Sb containing solder and In containing solder because of their toxicity and scarce respectively.