Comparative Study of Metal Films and Their Affinity for Metal Whisker Growth

The problem of tin (Sn) whiskers has been a significant reliability issue in electronics for the past several decades. Despite the large amount of research conducted on this issue, the growth of whiskers remains a challenge for the research community. A comparative study of different metal whiskers could provide a deeper insight toward the development of more permanent mitigation strategies for Sn whisker growth. In this paper, the surface and microstructural evolution of various film/substrate combinations of 10-μm thick zinc (Zn) and Sn metal films and their affinity for whisker growth were observed under two environmental conditions-ambient temperature and elevated temperature of 55^°C and 85% humidity. The films were analyzed using a scanning electron microscope, focused ion beam, and electron dispersive spectroscope. In addition, several decades-aged samples with Zn, Sn, and cadmium films with a high density population of whiskers were observed for comparison.