In-situ observation of whisker nucleation in air with AFM

This study proposed in-situ observation of whisker initiation in an air. Since most in-situ observations were performed in a vacuum, a novel continuous observation method in the air using atomic force microscopy and spring-back effect was developed. Whiskers induced by spring-back effect on Sn-Cu finish were observed by using the proposed method. The observation indicates that a surface grain grows to be a whisker. The surface profiles of the top of whisker and the adjacent grain reveal that deformation on surfaces of grain takes place during whisker initiation.