Control of compound forming reaction at the interface between SnZn solder and Cu substrate

Effects of additives, Cu and Ni, on intermetallic compound formation at the interface between Sn-Zn-based solder and Cu substrate have been studied. (Sn(91)Zng)(99.98-x)MxAl0.02, (wt.%) solder (M=Cu or Ni) alloys were prepared. The microstructures of the samples after annealing at 120 degrees C for 100 h were investigated using a scanning electron microscope, and the melting temperatures of the alloys were measured with a differential scanning calorimeter for different Cu or Ni contents. Although the melting (liquidus) temperature increases up to about 210-220 degrees C by alloying Cu or Ni of 2.6--2.7 wt.% to the solder, the well-known formation of intermetallic compounds, Cu(5)Zns and Sn6Cu5, are found to be significantly restrained. (c) 2004 Elsevier B.V. All rights reserved.