Comparisons of the electrical and mechanical reliabilities between Sn-3.5Ag and Sn-0.7Cu Pb-free solder bumps

The effects of surface finishes on the in situ interfacial reaction characteristics on both ball grid array (BGA) typed Sn-3.5Ag and Sn-0.7Cu lead-free solder bumps were investigated under annealing and electromigration (EM) test conditions of 135 °C to 170°C with 5.0 × 10
³
A/cm
²
. The failure mechanisms were explored in detail via in-situ EM tests. For the shear test, the shear force of both Sn-3.5Ag and Sn-0.7Cu solder joints increased and the shear energy decreased with increasing shear speed for the high speed of 1000 mm/s.