Ag sinter die-attach is utilized for bonding SiC Schottky-barrier diode (SBD) dies on Cu lead frames metalized by Ni/Pd/Pt/Ag electroless plating. After Al wiring, the assembled structure was mold-packaged by imide-based high temperature thermosetting resin. The produced devices are then subjected to environmental tests of high temperature storage at 250 degrees C, and of thermal cycling between -50 degrees C and 250 degrees C. The metallization layers at the bond interface remain unchanged after the harsh reliability tests because of the underlying Pt diffusion barrier layer, proving thermal stability of the bond structure up to 250 degrees C.