Kinetics of Sn whisker nucleation using thermally induced stress

We have simultaneously measured the evolution of stress and formation of whiskers/hillocks in Sn layers using stress induced by thermal-expansion mismatch. The formation kinetics suggest that whisker initiation is controlled by a nucleation process. We use measurements of the nucleation rate at different stresses and temperatures to determine quantitatively how the activation barrier for nucleation is decreased by the stress in the layer.