Tin Whiskers Remain A Concern

The elimination of lead in electronic equipment due to governmental regulations (European Union End of Life Vehicle Directive and European Union Restriction of Hazardous Substances Directive) has increased the risk of electrical shorting due to the formation of tin whiskers in electronic products. Tin whiskers are hair-like tin structures that grow sporadically on surfaces coated with tin. Whiskers are often difficult to detect due to their small cross-sectional dimensions, typically ranging between 1 and 5 micrometers, which may be 10 to 50 times finer than a human hair. While their cross-sectional dimensions are small, whiskers can grow to lengths greater than a millimeter. Such lengths are sufficient to bridge the distance between tightly spaced electronic parts. Despite the difficulty of detecting them, tin whiskers have been identified as a cause of failure in medical, aerospace, power, and automotive equipment. In particular, control systems, such those found in automotive applications, have been found to have significant tin whisker failure risks [1]. Further, coupled with the increased use of tin as a surface finish in electronics, the continued trend towards higher interconnect densities and compact electronics is expected to increase the failure risk presented by the formation of tin whiskers.