Risk and Mitigation for Tin Whiskers and Tin Pest

ABSTRACT There is considerable and justifiable concern over the risks of tin whiskers. However, the same concern is not apparent regarding the dangers of tin pest. This paper will present an overview of both of these reliability concerns by reviewing what is known about the mechanisms and the occurrence of both phenomena. Mitigation techniques will then be discussed. For tin whiskers, the discussion will focus on barriers between the tin and copper base metal, additions of bismuth to the tin, annealing of the tin, designs that minimize tin whisker failure risk, and over-coatings of the tin. For tin pest, the mitigation technique will be primarily adding bismuth or antimony to the tin. The paper will close with a semi-quantitative analysis of the effect of these mitigation strategies on tin pest and tin whisker risk.