W. E. Eslinger, Boston Scientific, St. Paul, MN

Summary: This case study details a latent IC (integrated circuit) failure mechanism caused by migration of silver (Ag) inside the encapsulated package of a CMOS (complementary metal-oxide-silicon) device. The source of the migrated silver was the plating of the lead frame and metallic ‘stringers’ were deposited at the material interface between the die attach epoxy and the plastic encapsulate. The migrated metal created fragile electrical connections between adjacent lead frame legs, over distances greater than 150 µm.