IN-PLACE TRACKING FOR TIN WHISKERS AND TIN DEPLETED AREAS AT DIFFERENT STRESS STATUS
Authors: Jing Cheng, Ph.D. and Paul T. Vianco, Ph.D. Company: University of Rochester and Sandia National Laboratories Date Published: 10/4/2009
Abstract: Pure tin film was mechanically stressed to form compressive stress or tensile stress over the whole coating. Tin film was setup at four kinds of stress status: stress-free to compression, stress-free to tension, compression to tension, tension to compression, then were annealed in vacuum at 180? individually. For each setup, the first stress status was kept for one week then changed to the second stress status for another week. Tin whiskers were found growing inside depleted areas. At various stress status as well as different locations on the tin film, the whiskers and the depleted areas exhibited multiple characteristics. By analyzing the phenomena, a new mechanism—interface fluid flow was proposed to explain tin whisker growth.
Key words: Tin whiskers, depleted areas, stress, mechanism