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16 SMT Magazine • March 2014 simplistic. Yet, some results do support that a too-thick coating can bury whiskering tenden- cy and a too-thin coating can shortchange the materials needed to grow whiskers. The proper thickness also is related to stress distribution ability. Temperature Effect Temperature drives the kinetics of defect dy- namics in the tin layer by affecting stress relax- ation and atomic mobility-related phenomena. A high temperature relative to tin's recrystaliza- tion temperature is expected to impede the con- tinued growth along the protruding direction, resulting short whiskers. conclusion Overall, from the atomic lattice structure standpoint, most of the above sources do not play out by themselves in the tin coating layer, rather they are intricately interplayed. This is the very challenge imposed to the evaluation of tin whisker propensity based on a set of testing conditions. SmT references 1. (ISBN: 9780901150400) "Environment- Friendly Electronics—Lead Free Technology," Elec- trochemical Publications, LTD, Great Britain, 2001, Chapter 26. 2. BAE Systems/Celestica study. 3. George Milad, Uyemura International. 4. (ISBN: 9780901150400) "Environment- Friendly Electronics—Lead Free Technology," Elec- trochemical Publications, LTD, Great Britain, 2001, Page 697. Dr. hwang will present an SMTa webtorial, Tin Whisker—All You Should Know on March 11 and 13, and deliver a lecture, "Preventing Manufacturing De- fects and Product failures" at IPc aPeX eXPo in las vegas, nevada, on March 24. Dr. hwang, a pioneer and long-standing contributor to SMT manufacturing since its inception, as well as to the lead-free develop- ment and implementation, has helped im- prove production yield and solved challenging reliability issues. among her many awards and honors, she is inducted to the WIT Interna- tional hall of fame, elected to the national academy of engineering, and named an r&D- Stars-to-watch. having held senior executive positions with lockheed Martin Corp., Sher- win williams Co., SCM Corp, and ieM Corp., she is currently ceo of h-Technologies group, providing business, technology and manufac- turing solutions. She has served on the u.S. Commerce Department's export Council, various national panels/committees, and the board of Fortune 500 nySe companies and civic and university boards. She is the author of 400+ publications and several textbooks, and an international speaker and author on trade, business, education, and social issues. her formal education includes four academic degrees (ph.D., M.S., M.a., b.S.) as well as harvard business School executive program and columbia university corporate gover- nance Program. To contact the author, or to read past columns, click here. SMT proSpeCTS & perSpeCTiveS TIN WhISkErS, ParT 4: caUSES aND cONTrIBUTING FacTOrS continues researchers at the Materials and Surface Science institute (MSSi), university of limerick, Ireland, have made a significant breakthrough in rechargeable battery technology. an ever-in- creasing demand for portable electronic devices and improved technology for battery life and stability is a vital factor in device performance. The combined value of the rechargeable battery technology market is set to grow from $11.8 billion in 2010 to $53.7 billion in 2020. a re- search team at ul has developed a technology that more than doubles and retains the capacity of lithium-ion battery anodes even after being charged and discharged over 1,000 times. Breakthrough in Rechargeable Battery technology

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