Reliability Evaluation of Hermetic Integrated Circuit Chips in Plastic Packages

Previous studies of the basic failure mechanisms of conventional plastic-encapsulated integrated circuits have led to improvements in materials and processes which have yielded two orders of magnitude improvement in reliability. Additionally, it has been demonstrated that, where severe environmental conditions are encountered, enhanced reliability is provided by device surfaces passivated with a silicon nitride dielectric and metallized with a titanium, platinum, gold interconnecting system. Failures associated witlh gold electro-plating under severe humidity-bias conditions are avoided by the deposition of a dielectric layer over tlle metallizationi pattern. Subsequent thermal, electrical, and moisture stress testinig his confirmed earlier indications that predicted lifetimes greater than 107 hours can be anticipated for these types of initegrated circuits when they are operated at a maximuim rated temperature of 125°C. An automated duial-in-linle-package assembly system has been evaluated that provides plastic packages in which the convenitional wire bonds have been eliminated and replaced with thermocom-pression bonds of metal beams to both the device and the lead-frame bond sites. The advantages gained from this type of assembly system are discussed.