Observed Whisker Growth Statistics 28 Days of Incubation Observations: Large whisker densities are observed for both compressive and tensile net stress states. This is in agreement with earlier work in our laboratory with “imposed” stress states formed by deliberate coupon curvature. There are whiskers observed for the “zero” stress state, but the density is relatively lower. As incubation time increases, the largest whisker density is observed for the compressive stress state. Whisker observations here agree with the very early experiments in our laboratory which established the validity of the Hoffman approach to the whisker growth issue. Sn Film State Whisker Density (cm-2) Average Whisker Length (µm) Comp 4,585 4.3 None 786 2.3 Tensile 7,991 16.5 96 Days of Incubation Longest whisker from tensile stressed film: 338 µm. Sn Film State Whisker Density (cm-2) Average Whisker Length (µm) Comp 15,850 5.3 None 4,061 3.4 Tensile 12,051 26.8 Large average whisker length

Whisker Micrographs Compressive None Tensile 9380x 16900x 3260x 5910x