Prediction model of lifetime for copper pillar bumps under coupling effects of current and thermal cycling

Considering the current induced voids flow will accelerate the creep strain rate and lower the strength of the solder, a current induced activation energy change, ΔQ e is added in the Anand model. A lifetime prediction model was constructed based on linear damage rule for the current-thermal cycling coupling test. To verify the accuracy of the model, mean-time-to-failure (MTTF) of copper pillar has been experimentally and analytically investigated under the combination of thermal cycling with temperature range of −40 to 125 °C and a superimposed electric current with current densities of 17.4–22.4 × 10 4 A/cm 2 . The experimental results reveal that the MTTF sharply decreases with the increasing current density. The acceleration factors are calculated, which is consistent well with the prediction model.