The current status of lead-free solder alloys

The issue of lead-free soldering has gripped the electronics assembly industry as of late. What was once something that appeared to be too far away to worry about now has become a pressing reality. In order to avoid confusion, panic, and a misunderstanding of how the issue of lead-free soldering will affect the industry and individuals, it is necessary for all suppliers and assemblers to become educated in this matter. There currently exist several lead-free alloys deemed "acceptable" for various applications. However, it is important to note that many differences occur from alloy to alloy, and much research and background information is required before the successful implementation of a lead-free solder. This paper shall provide a comparison of the tin-silver, tin-copper, and tin-silver-copper alloys with each other and the tin-lead alloy, and well as process advice for the implementation of these solders and an overview of where the industry stands on the issue today. Highlighted in this is comparative test data of the aforementioned alloys, along with a discussion of other "alternative" alloys.