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28 The PCB Design Magazine • September 2016 Shaughnessy: What sort of technologies and materials did you deal with, if you can talk about that? Woznicki: Fortunately, we were able to meet the system requirements without any unusual materials or technologies. We did need blind and buried vias, but not stacked vias. Shaughnessy: In one survey, our military and aerospace designers said they have trouble with data and specs—inaccurate data, not enough data, confusing specs, and unclear requirements. Did you encounter any of these issues? Woznicki: Yes, I did. Flight components sometimes have oddball sizes and packages: 0505 resistors, transistors in UB packages, etc. Spec sheets don't have recommended footprints and the tech support from vendors was slow or non-responsive. Shaughnessy: So are you back designing flex now? Woznicki: Yes, I'm back to designing flex cir- cuits. Shaughnessy: Is there anything else you'd like to add? Woznicki: There were many times I'd think, "Can I really do this? I'm not a rigid board de- signer." But good design techniques work! To build on the experience I got my CID certifica- tion last year, and I'll be taking the CID+ test later this month. Shaughnessy: Great. I appreciate your time, Tom. Woznicki: Thank you, Andy. PCBDESIGN FLEXDUDE ABIDES: PCB DESIGN FOR SATELLITES "Promising" and "remarkable" are two words U.S. Department of Energy's Ames Laboratory scientist Javier Vela uses to de- scribe recent research results on organ- olead mixed-halide perovskites. Perovskites are optically active, semi- conducting compounds that are known to display intriguing electronic, light- emitting and chemical properties. Scientists found that depending on how the material is made there can be significant nonstoichiometric impurities or "dop- ants" permeating the material, which could signifi- cantly affect the material's chemistry, moisture sta- bility and transport properties. The answers came via the combination of the use of optical absorption spectroscopy, powder X-ray diffraction and for the first time, the advanced prob- ing capabilities of lead solid-state NMR. "We were only able to see these dop- ants, along with other semicrystalline impurities, through the use of lead solid- state NMR," said Vela. Another major discovery scientists made was that solid state synthesis is far superior to solution-phase synthesis in making mixed-halide perovskites. Ac - cording to Vela, the advanced spectros- copy and materials capabilities of Ames Laboratory and ISU were critical in understanding how various synthetic procedures affect the true composition, speciation, stability and optoelectron- ic properties of these materials. "We found you can make clean mixed halide perovskites without semi-crystalline impurities if you make them in the absence of a solvent," Vela said. New Perovskite Research Discoveries May Lead to Solar Cell, LED Advances