SMT007 Magazine


Issue link:

Contents of this Issue


Page 17 of 110

18 SMT Magazine • February 2015 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 review- ing what is known about the mechanisms and the occurrence of both phenomena. Mitigation techniques will be discussed, and 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 fail- by dr. ronald C. Lasky inDiuM Risk and Mitigation for Tin Whiskers and Tin Pest ure risk, and over-coatings of the tin. For tin pest, the mitigation technique will be primarily adding bismuth or antimony to the tin. The article will close with a semi-quantita- tive analysis of the effect of these mitigation strategies on tin pest and tin whisker risk. Introduction Tin Whiskers The existence of tin whiskers has been known since the early days of radio. Typically, tin whiskers form in tin plating on component leads, not bulk solder. Numerous, very expen- sive failures have been caused by tin whiskers; many of these failures were in satellites. NASA has a website [1] devoted to tin whisker failures. Feature

Articles in this issue

Archives of this issue

view archives of SMT007 Magazine - SMT-Feb2015