2015 Volume 33 Issue 2 Pages 171-179
Al-rich Zn/Al/Zn clad solder were developed as Pb-free solder for a die-attachment. The Zn/Al/Zn clad solder was produced by clad rolling of Zn and Al strips in order to prevent Al from oxidation and improve wettability. The Zn/Al/Zn clad solder melted at 382°C after solid-state interdiffusion of the Zn and Al layers. Bonding was successfully achieved with bonding pressure of a few kPa. Thermal cycle life of Invar-to-Cu substrate joint using the Zn/Al/Zn clad solder was longer than that of Pb-Sn-Ag solder. No kirken-dall voids were observed in the vicinity of the bonded interface after aging at 250°C for 1000 h.