SMT Magazine

SMT-Dec2017

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December 2017 • SMT Magazine 15 THE ROLE OF BISMUTH (BI) IN ELECTRONICS, PART 2 to the amplitude of fatigue strain range used (De = 0.2%), which is well below the plastic strain at fracture (e p = ~12%). Under the relatively low fa- tigue strain range, the high strength is a leading factor contributing to the high fatigue resistance. In a Bi-Pb system, a solid solubility of Bi in Pb is 23.5 wt.%, and a Sn-Bi system indicates a solid solubility of Bi in Sn is 21 wt.%. When Sn- Pb-Bi constructs a ternary system, the underly- ing basic physical interactions are not expected to be grossly changed. Overall, the Sn-Pb-Bi ter- nary solder alloys containing 2 wt.% Bi demon- strated a much higher strength, a higher fatigue life, as well as a higher plasticity than 63Sn37Pb eutectic solder. The alloy melting temperatures slightly decreased. When Bi increased to 5 wt.%, the strength and fatigue life of the Sn-Pb-Bi still remained higher than 63Sn37Pb, but their plas- ticity decreased significantly. SMT Dr. Hwang, an international busi- nesswoman, international speak- er, and business and technology ad- visor, is a pioneer and long-stand- ing contributor to SMT manufactur- ing since its inception as well as to the lead-free electronics implementation. Among her many awards and honors are induction into the International Hall of Fame-Women in Tech- nology and the National Academy of Engineer- ing, named R&D-Stars-to-Watch, and a recipient of YWCA Achievement Award and Distinguished Alumni Awards. Having held senior executive po- sitions with Lockheed Martin Corp., Sherwin Wil- liams Co., SCM Corp, IEM Corp., she is current- ly CEO of H-Technologies Group providing busi- ness, technology and manufacturing solutions. She serves as Chairman of Assessment Board of DoD Army Research Laboratory, Commerce De- partment's Export Council, National Materials and Manufacturing Board, various national pan- els/committees, international leadership posi- tions, and the board of Fortune-500 NYSE com- panies and civic and university boards. She is the author of 500+ publications and several books, and a speaker and author on trade, business, ed- ucation, and social issues. Her formal education includes four academic degrees, Harvard Business School Executive Program and Columbia Univer- sity Corporate Governance Program. Further info: www.JennieHwang.com. Researchers from the University of Cambridge, working with colleagues in Italy and China, have successfully incorporated washable, stretchable and breathable electronic circuits into fabric, opening up new possibilities for smart textiles and wearable electronics. The circuits were made with cheap, safe and environmentally friendly inks, and printed us- ing conventional inkjet printing techniques. The researchers have demonstrated how gra- phene can be directly printed onto fabric to pro- duce integrated electronic circuits which are com- fortable to wear and can survive up to 20 cycles in a typical washing machine. The new textile elec- tronic devices are based on low-cost, sustainable and scalable inkjet printing of inks based on gra- phene and other two-dimensional materials, and Researchers Develop Fully Integrated Circuits Printed Directly onto Fabric are produced by standard processing techniques. The work opens up a number of commercial oppor- tunities for two-dimensional material inks, ranging from personal health and well-being technology, to wearable energy harvesting and storage, mili- tary garments, wearable computing, and fashion.

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