COMPOUND GROWTH AND FRACTURE AT COPPER/TIN-SILVER SOLDER INTERFACES.

The rates of compound growth at a solid copper/molten eutectic tin-silver alloy interface have been determined in the temperature range 240-360 degree C. The rate of total compound growth (Cu//3Sn plus Cu//6Sn//5) increased with increase in temperature, showing a (time) **1**/**3 dependence. The growth of the Cu//3Sn layer alone showed a (time)** one-half dependence. The effects of intermetallic compounds at the solder/substrate interface on the fracture path in soldered joints have also been examined in both tension and shear. In the as-soldered condition, the fracture path runs along the compound/solder interface, whereas in aged joints with thicker compound layers, the fracture path lies within the compound itself.