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September 2016 • The PCB Magazine 33 The evolution of small unmanned air systems (sUAS) technologies is fueling the exponential growth of the commercial drone sector, creat- ing new asymmetric threats for warfighters. sUASs' size and low cost enable novel concepts of employment that present challenges to cur- rent defense systems. These emerging irregular systems in diverse environments require tech- nology advancements to quickly detect, iden- tify, track, and neutralize sUASs while mitigating collateral damage and providing flexibility to operations. Wanted: Ideas for Protecting Against Small Unmanned Air Systems in the array as possible to add stability. The flex can be pre-routed with tabs left to hold this into the array during assembly. Once parts have been assembled, simply cut the tabs to release the flex from the array. Caution: stencil tolerance over this long length is an issue to be aware of. 3. A custom pallet is another common choice for assembly, especially when you are running more than a few panels. Most often this is designed with FR-4 material. The ben- efit to this is stability and flatness during as- sembly and also the ability to nest the flexible circuits in the tightest configuration possible to reduce the cost of the fabrication. There is no need to add in extra copper area in the ar- ray for stability. These are just a few of the lessons learned that we have accumulated over time. I hope that they provide insight and information that will help with your future flex designs, or at the very least, let you commiserate and know that you are not the only one challenged with these types of issues. Feel free to get in touch and share your stories with us! PCB Tara Dunn is president of Omni PCB. To contact Dunn, or read past columns, click here. TROUBLESHOOTING FLEX CIRCUIT APPLICATIONS FOR MIL/AERO PROJECTS Figure 2: Full panel array with cross-hatched copper and stiffeners.