Aging of Solder Connections to Ti-Pd-Au Films

Soldered connections to TiPdAu film composites show enhanced resistance changes (up to 0.02 ohms) during elevated temperature aging. This is attributed to solid-state dissolution by solder of Au from under the fillet edge, forming a AuSn intermetallic phase. The pull strength of soldered external leads decreases by as much as 40 percent during aging, probably by solid-state dissolution of Pd, forming PdSn4. Neither of these effects is expected to be troublesome at normal operating temperatures.