Effect of Crystal Orientation on Mechanically Induced Sn Whiskers on Sn-Cu Plating

Effect of Crystal Orientation on Sn Whisker-Free Sn–Ag–Cu Plating

“…Typical Sn whiskers are formed on columnar grains. 3,6) In contrast, the analysis reveals that nodules did not form on columnar grains; rather, they are in direct contact with the Ni layer. The size of nodule was larger than that of the columnar grains in its vicinity.…”

“…In the previous study, the authors found that the mechanical stress dramatically altered the microstructure of whisker-prone SnCu plating. 3) In contrast, the results in Fig. 8 suggest that it is difficult to induce microstructural changes (including twin formation) in plating with non-columnar large Sn grains by applying mechanical stress.…”

“…Excess strain around these newly formed twinned grains appears to cause whisker nucleation from these grains to relax the strain induced by the application of mechanical stress. 3) In contrast, whisker-free plating has fewer grain orientations than columnar grains (Figs. 4 and 8).…”

“…3,6,7) Another important feature of it is the whisker roots need to be stable so that they do not undergo grain boundary migration. 7) The authors found that twins form on columnar grains and that newly formed twin grains are likely to act as stable whisker roots during growth of mechanically induced whiskers, even though large microstructural changes occur concurrently due to recrystallization and/or grain growth.…”

“…3,6,7) In the previous study, the authors reported effect of crystal orientation on mechanically induced Sn whiskers on SnCu plating. The analysis revealed that many Sn whiskers nucleated from twinned grains, which were formed on columnar Sn grains.…”