Mitigation strategies of tin whisker growth

Electronics is one of the most important engineering disciplines in today's world. The rapid advancement of electronic systems has excelled the performance of products and services available to us on a daily basis.;Electronic systems consist of many electronic components that undergo common electroplating processes. The components are metal or alloy coated for corrosion resistance, better outside appearance, solderability, and increased electrical conductivity. For years, the alloy of choice for electroplating electronic components has been tin-lead (Sn-Pb) alloy. However, the recent legislation established in Europe on July 1, 2006, required significant lead (Pb) content reductions from electronic hardware due to its toxic nature. A popular alternative for coating electronic components is pure tin (Sn). However, pure tin has the tendency to spontaneously grow electrically conductive Sn whisker during storage. Sn whisker is usually a pure single crystal tin with filament or hair-like structures grown directly from the electroplated surfaces. Sn whisker is highly conductive, and can cause short circuits in electronic components, which is a very significant reliability problem. The damages caused by Sn whisker growth are reported in very critical applications such as aircraft, spacecraft, satellites, and military weapons systems. It is very hard to predict the period for the growth of Sn whiskers, which can vary from hours to years. They are also naturally very strong and are believed to grow from compressive stresses developed in the Sn coating during deposition or over time. The new directive, even though environmentally friendly, has placed all lead-free electronic devices at risk because of whisker growth in pure tin. Over the past several decades, a tremendous number of studies have been performed by industry and academia to better understand the fundamental properties of Sn whisker growth and at the same time develop effective mitigation practices for whisker-free components. To date, there is no successful method that can eliminate the growth of Sn whisker. This dissertation gives a detailed overview of some fundamental issues related to the growth of Sn whisker; in addition, a proposal of new potential techniques for the mitigation of Sn whisker is analyzed and discussed.