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18 The PCB Design Magazine • March 2017 Tools Should be Enablers As mentioned throughout this article, de- sign of a rigid-flex product is significantly differ- ent from the design of a rigid-only product. The ECAD design realm has seen huge advances in the last decade. As the more traditional "design- separately-then-assemble" approach moves to current-generation rigid-flex design, product development teams need to leverage and take advantage of these advances in order to im- prove productivity and reduce development costs. Proper education on rigid-flex terminol- ogy, requirements, processes, and best practices, combined access and proper utilization of tools that facilitate rather than hinder both process compliance and correct-by-construction design are equally important. Education combined with tool enablement will ease the develop- ment process and ensure a high probability for first-pass success. PCBDESIGN Craig Armenti is a PCB market- ing engineer for the Board Systems Division of Mentor Graphics. Ar- menti has more than 25 years of experience in the EDA industry. He has held Marketing and Applica- tion Engineering positions with several major telecommunication and software companies. RIGID-FLEX DESIGN TIPS AND BEST PRACTICES Researchers at the Technical University of Mu- nich (TUM) have, for the first time ever, produced a composite material com- bining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applica- tions like flexible displays and photosensors. Similar to carbon, silicon forms two dimensional networks that are only one atomic layer thick. Like graphene, these layers possess extraordinary op- toelectrical properties. Silicon nanosheets might thus find application in nanoelectronics, for exam- ple in flexible displays, field-effect transistors and photodetectors. "Silicon nanosheets are particularly interesting because today's information technology builds on silicon and, unlike with graphene, the basic materi- al does not need to be exchanged," explains Tobias Helbich from the WACKER Chair for Macromolec- ular Chemistry at TUM. "However, the nanosheets themselves are very delicate and quickly disinte- grate when exposed to UV light, which has signifi- cantly limited their application thus far." Now Helbich, in collabo- ration with Professor Bern- hard Rieger, Chair of Mac- romolecular Chemistry, has for the first time success- fully embedded the silicon nanosheets into a polymer, protecting them from decay. Its flexibility and dura- bility against external in- fluences also makes the newly developed material amenable to standard poly- mer technology for industrial processing. This puts actual applications within an arm's reach. The first successful application of the nanocom- posite constructed by Helbich was only recently presented in the context of the ATUMS Gradu- ate Program (Alberta / TUM International Gradu- ate School for Functional Hybrid Materials): Alina Lyuleeva and Prof. Paolo Lugli from the Institute of Nanoelectronics at TU Munich, in collaboration with Helbich and Rieger, succeeded in building a photodetector based on these silicon nanosheets. To this end, they mounted the polymer em- bedded silicon nanosheets onto a silicon dioxide surface coated with gold contacts. Because of its Lilliputian dimensions, this kind of nanoelectronic detector saves a lot of both space and energy. A Perfect Team for Nanoelectronics