Optimized Brazing Performance of Amorphized Cu-P-Sn-Ni Fillers for Copper Joining

In this study, amorphous Cu86P7.5Sn4.5Ni2(wt.%) fillers were prepared using the melt spinning method with different rolling speeds. The wetting performance of these fillers on copper was assessed under different temperatures and holding times. The results indicated that the fillers obtained through the melt spinning technique exhibited lower melting temperatures than the as-cast filler. When processed at a rolling speed of 20 m/s, the amorphization of the filler was not sufficient. The higher rolling speed promoted the formation of the amorphous structure. The amorphous filler produced at 30 m/s exhibited the narrowest melting range and the lowest liquidus temperature (622 °C), which is approximately 100 °C lower than that of the as-cast filler (725 °C). Furthermore, the amorphous fillers also exhibited better wettability toward copper under the same conditions. Notably, the amorphous filler fabricated at 30 m/s demonstrated superior wettability at 750 °C for 90 s. Owing to the optimal wettability of the amorphized filler toward copper and the lower liquid temperature, the brazed copper joint achieved a shear strength of 223.2 MPa. The fracture of the four joints occurred in the base metal. In this study, we explored the brazing performance of amorphized Cu-based fillers, facilitating the solid bonding of copper at lower brazing temperatures.