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10 The PCB Design Magazine • September 2016 Andy Shaughnessy is managing editor of The PCB Design Magazine. He has been covering PCB design for 17 years. He can be reached by clicking here. decided to get a degree in one of the STEM disci- plines after following the Mars Rover's progress on NASA's interactive website? In our own industry, one segment that's evolved in the past 50 years is flexible circuitry. Not too long ago, flex was considered too ex- pensive for most applications. When I first start- ed covering PCB design in 1999, I kept hearing, "Well, flex is cool, but it's just too expensive for us. You don't see flex in many consumer prod- ucts, except digital cameras and printers." Now, most PCB design tools include flex de- sign functionality. And flex has turned out to be the perfect circuitry for space applications. It withstands harsh environments, extreme temper- atures, and shock, and flex can last a long time. This month, our first feature is an interview with John Cardone of JMC Design Services. John spent more than 20 years designing flex, rigid- flex, and rigid boards at the Jet Propulsion Lab, and he discusses the flex circuits he designed for a variety of spacecraft, including the Mars Exploratory Rover. Along the way, John gives us a bit of a spacecraft history lesson too. For in- stance, did you know there are over 4.5 miles of flex circuitry on the rover's robotic arm alone? Next, Tom Woznicki, also known as the "Flexdude," discusses his recent foray back into the world of rigid PCB design while working on the upcoming TESS satellite. TESS (Transiting Extroplanet Survey Satellite), scheduled to be- gin its two-year mission in 2017, will monitor more than 200,000 stars, searching for drops in brightness caused by planetary transits. Tom ex- plains how the design team met the shock and temperature requirements without using any unusual materials, and why he doesn't consider rigid design work to be "slumming." Also on hand is an article by Gabriel Cio- banu of Continental Corporation and Boris Ma- rovic of Mentor Graphics that focuses on im- proving thermal design, and how proper layout and component placement can have as much effect on thermal properties as thermal vias. Rounding things out, we've got a couple of great columns by our regular contributors Bar- ry Olney and Istvan Novak, and a new Sensible Design column by Electrolube's Alistair Little, who takes the reins from our friend Phil Kinner. As you probably know, the show season is about to get underway. This month, we are at- tending PCB West and at SMTA International we will be providing Real Time with... video coverage. If you can't make it to a show, don't worry. We have the coverage you need. See you next month! PCBDESIGN SPACE: STILL THE FINAL FRONTIER Collaborative research at Notre Dame has dem- onstrated that electronic interactions play a significant role in the dimensional crossover of semiconductor nanomaterials. The laboratory of Masaru Kuno, profes- sor of chemistry and biochemistry, and the condensed matter theory group of Boldizsár Jankó, professor of physics, have now shown that a critical length scale marks the transition between a zero-dimensional, quantum dot and a one-dimensional nanowire. The findings, "Dimensional crossover in semicon- ductor nanostructures," were published in Nature Communications. Matthew P. McDonald and Rusha Chatterjee of Kuno's laboratory and Jixin Si of Jankó's group are also authors of the publication. A quantum dot structure possesses the same physical dimensions in every direction while a quan- tum wire exhibits one dimension longer than the oth- ers. Do quantum properties evolve gradually or do they suddenly transition? Kuno's laboratory discovered that a critical length exists where a quantum dot becomes nanowire-like. The researchers achieved this breakthrough by con- ducting the first direct, single particle absorption mea- surements on individual semiconductor nanorods, an intermediate species between quantum dots and nanowires. Single particle rather than ensemble mea- surements were used to avoid the effects of sample inhomogeneities. Notre Dame Researchers Find Transition Point in Semiconductor Nanomaterials

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