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54 PCB007 MAGAZINE I MAY 2022 the national security space see the trends, and they are justifiably concerned. In fact, micro- electronics are one of six "technology pillars" designated by DoD to invest in. Over the past two decades, domestic pro- duction of printed circuit boards has decreased from 26% to 4%. In that same period, the indus- try has shrunk from nearly 2,500 U.S.-based companies to only 145. is invites unaccept- able supply chain and national security risks. As we modernize our military and address global threats, policymakers should consider the following: • A modern military must be a high-tech military. From electronics that our men and women in uniform wear into battle, to the precision weapons and systems in every military service, printed circuit boards make it all possible. • Supply chain security is national security. To trust that military systems are secure and reliable, we need to trust where every component originates. From rare earth raw materials to the most complex platforms, we can't afford to wonder who made it, where it came from or even if it will arrive on time. e ubiquitous nature of printed circuit boards demands a secure and reliable domes- tic supply chain. e Printed Circuit Board Association of America was formed to edu- cate, advocate, and legislate with this outcome in mind. e members of the PCBAA are proud to provide technologies that contribute to our nations' defense. If you're interested in joining our effort, please visit us online or contact me directly. PCB007 Travis Kelly is CEO is Isola-Group and current chairman of the Printed Circuit Board Association of America. To read past columns or contact Kelly, click here. Rice University researcher Ming Tang worked with the U.S. Department of Energy to analyze nano- and micro-scale interactions within lithium iron phosphate cathodes through modeling and imaging offered by the transmission X-ray micros- copy capabilities at Brookhaven National Labora- tory and Argonne National Laboratory. Their paper in the American Chemical Soci- ety journal ACS Energy Letters supports theories Tang and his colleagues formed several years ago that foresaw how lithium travels in the dynamic envi- ronment inside a typical commercial cathode. Being able to watch sealed cathodes charge and discharge at Brookhaven offered absolute proof. "Batteries have a lot of particle aggregates that soak up and give up lithium, and we wanted to know what happens on their surfaces, how uniform the reaction is," said Tang, an associate professor of materials science and nanoengineering. "In gen- eral, we always want a more uniform reaction so we can charge the battery faster." In images taken at Brookhaven's powerful X-ray synchrotron, the researchers saw some regions inside the cathode were better at absorp- tion than others. The ability to look at single or aggregated particles in 3D showed that rather than reacting over their entire surfaces, lithium favored particular regions over others. "This is very different from conventional wisdom," Tang said. "The most interesting observation is that these reaction regions are shaped like one-dimen- sional filaments lying across the surface of these aggregated particles. It was kind of weird, but it matched what we saw in our models." Tang said the lithium filaments looked something like thick nanotubes and were several hundred nanometers wide and several microns long. (Source: Rice University) Lithium's Narrow Paths Limit Batteries

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