By Ning-Cheng Lee Ph.D.
This course covers the detailed material considerations required for achieving high reliability for lead-free solder joints. The reliability discussed includes joint mechanical properties, development of type and extent of intermetallic compounds (IMC) under a variety of material combinations and aging conditions and how those IMCs affect the reliability. The failure modes, thermal cycling reliability, and fragility of solder joints as a function of material combination, thermal history, and stress history will be addressed in details, and novel alloys with high reliability and reduced fragility will be presented. Electromigration and tin whisker will also be discussed. The emphasis of this course is placed on the understanding of how the various factors contributing to the failure modes, and how to select proper solder alloys and surface finishes for achieving high reliability.