ABSTRACT
The move to lead-free technology is ironically juxtaposed against the unparalleled virtues of lead (Pb)-based solders. Tin-lead solder is virtually an ideal material in nearly every regard. As will be discussed in this chapter, the features of that binary phase diagram, the mechanical properties of that alloy, and its thermomechanical fatigue behavior in service are extremely well suited to its utilization in microelectronic packages, providing a family of solders with a range of melting temperatures for a variety of applications. Lead-free systems, on the other hand, offer fewer options.
