The movement to eliminate lead (Pb), especially active in Japan and the European Union, has resulted in an increasing use of pure tin (Sn) coatings on leads and other external and internal surfaces of capacitors, resistors, and other passive components. This paper discusses the issues of tin whisker growth with respect to passive components. It also presents both a critical analysis of existing published documents on tin whisker nucleation and growth and a summary of very recent experiments that provide further understanding of the potential means of whisker formation mitigation. Many of the proposed mechanisms for mitigation, including control of the immediate underplating material, use of conformal coating, regulating the thickness of the tin coating, use of matte tin electroplating, and annealing or fusing of the tin layer, are inadequate. They likely reduce the incidence of nucleation or growth but do not provide an absolute guarantee of lack of whisker formation.
展开▼
