Characteristics of the PbO-Bi₂O₃-B₂O ₃-ZnO-SiO₂ glass system doped with Pb metal filler

We investigated the effect of Pb-metal filler added to a hybrid paste(PbO-Bi₂O₃-B₂O₃-ZnO glass frit and Pb-powder), for joining flip-chip sat lower temperatures than normal. The glass transition temperature was detected at 250°C and the softening point occurred at 330°C. As the temperature increased, the specific density decreased due to the volatility of the Pb-metal and boron component in the glass. When the glass was heat-treated at 350°C for 5 min, XRD results revealed a crystalline Pb₄Bi₃B₇O₁₉ phase that had been initiated by the addition of Pb-filler in the hybrid paste. The addition of the Pb-metal filler caused are action between the Pb-metal and glass that accelerated the formation of the liquid phase. The liquid phase that formed, promoted bonding between the flip-chip substrate sat lower temperature.