Tin whiskers are individual crystals of tin that grow spontaneously from a tinned surface, usually as a result of stress of some sort. The phenomenon poses problems for manufacturers who would prefer using tin rather than lead for interconnections. As electronics manufacturers seek to make electronic interconnections lead-free, many are looking at pure tin soldering and coating as an economical alternative to traditional tin-lead alloys. However, pure tin is much more prone to creating whiskers than alloys.
Tin whiskers are typically only a few millimeters (mm) long, but some grow to lengths of more than 10 mm. Tin whiskers can cause two serious problems in electronic assemblies: they can cause electrical shorts and they can break loose from their substrate and cause mechanical damage. A lack of industry understanding about tin whisker growth factors and a lack of testing methodology to identify whisker-prone products has made pure tin interconnections and plating risky for high reliability systems, such as satellites. However, it is generally thought that the market demand for environmentally friendly components will eventually outweigh the potential for tin whisker component failure. Other metals that may grow whiskers include zinc, cadmium, indium, and antimony.
First reported in the 1940s, tin whiskers have caused problems with pacemakers, electronic devices, missiles, satellites, nuclear power plants and space shuttles. According to some estimates, tin whiskers have been responsible for $10 billion in damages since their discovery.