Mitigating Tin Whisker Risks

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.

Takahiko Kato, PhD, is a chief researcher in the Center for Technology Innovation – Materials, Research & Development Group at Hitachi Ltd, Tokyo, Japan. He is also a Guest Professor in the Center for Advanced Research of Energy and Materials at Hokkaido University in Japan. Dr. Kato has over thirty years’ research experience in the areas of practical materials technology and materials science related to boiling water reactors, fusion reactors, superconductors, electrical devices, and sustainable energy devices.

Carol Handwerker is the Reinhardt Schuhmann Jr. Professor of Materials Engineering at Purdue University, Indiana, US. Previously, she was chief of the Metallurgy Division at the National Institute of Standards and Technology (NIST), where she participated in the NCMS (National Center for Manufacturing Sciences) Lead-Free Solder Project, co-chaired the iNEMI Lead-Free Alloy Selection Team, and participated in the iNEMI Tin Whisker Fundamentals Project.

Jasbir Bath is the owner of Bath and Associates Consultancy LLC, California, US. He has more than twenty years' experience in research, design, development, and implementation in the areas of soldering, surface mount, and packaging technologies. Bath has been chair of various iNEMI lead-free consortia involving OEMs, EMS, and component and material supplier companies on alloy selection, assembly, and rework.