Tin Whiskers in Electronic Circuits

Fibrous, conducting whiskers often grow on pure tin plating. These tin whiskers have, for many years, been known to pose a reliability problem in electronic circuitry. The use of pure tin coatings in any critical electronic application is therefore not recommended. Despite the warnings of the experts, tin plating is still found on electronic and mechanical components and problems with whiskers still arise. This document summarizes what is known about the growth of tin whiskers. A number of factors e.g., coating thickness, plating conditions are thought to be important in determining whether whiskers will grow. Although tin whiskers have been investigated from some decades, there is still disagreement on the effects of virtually every coating parameter. There is no disagreement, however, on the essential fact that it is very difficult to predict with certainty whether whiskers will grow on any specific tin-plated component, which of course is the basis of the experts advice not to use pure tin plating. If tin-plated components are found in an electronic system, replacement is the safest policy. Some additional recommendations to minimize risk are presented here that may be of use in situations in which replacement of all suspect components is not the option of choice because of cost or schedule constraints.