Authors: Craig Hillman, Gerd Fischer, and Robert Esser Company: DfR Solutions Date Published: 6/21/2007
Abstract: Given the use of tin-plated components throughout the history of electronics and with the movement to Pb-free components, there is a need to develop a methodical approach to qualifying and quantifying the potential risk for a tin whisker event to induce a failure. This paper uses the case study of a pure tin plated solder terminal to demonstrate how to review materials, design and environment and to correlate that data to existing tools and information to determine the need for additional mitigation or rectification. For each failure mode, existing knowledge of the behavior and physics of whiskering were used to demonstrate a maximum whisker length, the likelihood of whisker breakage, the value of a conformal coating, and a reliability prediction based upon a Monte Carlo simulation. In conclusion, it was determined that for this particular case study, the risk that whiskers emanating from the tin plated solder terminal will induce failure over a 20+ year lifetime is low.