Tin plating may be used on circuit boards as a lead free solderable surface. It is subject to 3 problems: tin whiskers, tin pest and slivers. Tin whiskers appear after plating in several hour to several years and are caused by compressive stressed plating or external compressively conductors. Some plating baths are grow whiskers while others do not. The worst subtrate for whisker growth is brass with a possibility when on copper and nil when on nickel. See S.C. Britton, Tin Research Institute 1974. Later research in Japan, mainly by T. Sonada in Plating and Surface Finishing in J Sur. Fin Japan and J. Metal Fin. Japan 1990-1995 provide much of the information on plating and tin whiskers. Tin pest or alpha-tin forms at low temperatures(0 to -50 deg.C) only if the surface is seeded with alpha tin. See R. M. MacIntosh, Journal of Tin Research, No 72 (1966). Decreased by codeposit of antimony or bismuth. Breakaway tin slivers can be reduced by using a more ductile tin plate or by reflowing, MP 232 deg C. or plating over nickel. All problems are decreased by applying a solder mask that prevent tin whihiser from growing through, prevent accidental seeding surface with alphas tin, and capture slivers. Some fabricators strip tin from all but the lands and others plate a nickel underplate and using the Santa Clara process plate only the lands that are to be soldered with tin. Phil Hinton Hinton PWB Engineering [log in to unmask]