Recent Tin Whisker Research At Sandia

Tin (Sn) whiskers are conductive Sn filaments that grow from Sn-plated surfaces, such as surface finishes on electronic packages. The phenomenon of Sn whiskering has become a major concern in recent years due to requirements for lead (Pb)-free soldering and surface finishes in commercial electronics. In general, pure Sn finishes are more prone to whisker growth than their Sn-Pb counterparts and high profile failures due to whisker formation (causing short circuits) in space applications have been documented. Despite the long history of Sn whisker research and the recently renewed interest in this topic, a comprehensive understanding of whisker growth remains elusive. This overview will describe recent research at Sandia National Laboratories to characterize Sn whisker growth with the aim of understanding the underlying whisker growth mechanism(s). Topics to be covered include Sn plating of samples for whisker growth studies, characterization by electron microscopy and other techniques, experiments to study whisker growth, and conformal coating techniques for mitigating whiskers. The overview is intended for those in the structural brazing and soldering community, who may not be familiar with tin whiskers encountered in microelectronics.