Mitigating Tin Whisker Risks

This practical guide provides a fully up-to-date, practical approach to implementing lead-free soldering, presented by leading industry experts. It addresses a list of key topics not covered sufficiently in other texts, such as soldering fluxes, SMT, wave, rework, alloys, component finishes, EDXRF, and certain areas on reliability. A fully up-to-date approach to implementing lead-free soldering Environmental and health concerns have led to a growing movement to eliminate lead from electronics, specifically from electronics soldering. Lead-based solder has been used for many years with a good history of use, so the change to lead-free solder alternatives requires companies to re-examine, develop, and re-test manufacturing processes as they make the transition. Lead-Free Solder Process Development covers general lead-free soldering topics written by those specializing in these areas. Timely and up to date, this reference covers key topics including legislation, SMT, wave, rework, alloys, test, and reliability. It provides updates in areas where research is ongoing and addresses various topics that are relevant to lead-free soldering, including: Government and legislative activities Lead-free SMT assembly Lead-free wave soldering Lead-free rework Lead-free alloys for BGA/CSP components Lead-free mechanical reliability Tin whiskers Lead-free reliability in aerospace and military environments Lead-free reliability in automotive environments Testability of lead-free printed circuit assemblies Emphasizing practical knowledge of lead-free soldering rather than theory, Lead-Free Solder Process Development is written by experts who are or who have been heavily involved in lead-free implementation at the product level. Being an up-to-date book on this changing field, it is an essential read for engineers in the industry who are or will be migrating to lead-free soldering. Discusses the growth mechanisms of tin whiskers and the effective mitigation strategies necessary to reduce whisker growth risks This book covers key tin whisker topics, ranging from fundamental science to practical mitigation strategies. The text begins with a review of the characteristic properties of local microstructures around whisker and hillock grains to identify why these particular grains and locations become predisposed to forming whiskers and hillocks. The book discusses the basic properties of tin-based alloy finishes and the effects of various alloying elements on whisker formation, with a focus on potential mechanisms for whisker suppression or enhancement for each element. Tin whisker risk mitigation strategies for each tier of the supply chain for high reliability electronic systems are also described. Discusses whisker formation factors including surface grain geometry, crystallographic orientation-dependent surface grain boundary structure, and the localization of elastic strain/strain energy density distribution Examines how whiskers and hillocks evolve in time through real-time studies of whisker growth with the scanning electron microscope/focused ion beaming milling (SEM/FIB) Covers characterization methods of tin and tin-based alloy finishes such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) Reviews theories of mechanically-induced tin whiskers with case studies using pure tin and other lead-free finishes shown to evaluate the pressure-induced tin whiskers Mitigating Tin Whisker Risks: Theory and Practice is intended for the broader electronic packaging and manufacturing community including: manufacturing engineers, packaging development engineers, as well as engineers and researchers in high reliability industries.