Abstract
The influence of indium (0 - 29.5 wt.%) and copper (0; 0.4 wt.%) in the lead-free Sn3.5Ag solder was studied on both the temperature of transition from the solid to liquid state and vice-versa and the wetting of copper substrate. The influence of indium and copper on the strength of Cu-solder-Cu joints and on the microstructure of the Cu substrate/solder interface is also presented. The results are compared with those for the copper-free Sn3.5Ag solder. Indium and copper were found to decrease the transition temperature from solid to liquid state and vice-versa, to decrease the wetting angle of copper substrates and mildly to decrease the strength of copper-solder-copper joints. Influence of copper is stronger compared with indium.

Key words
lead-free solder, wetting, indium, Cu-solder joint, interface

Full text (442 KB)