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32 The PCB Design Magazine • August 2017 The engineering community is an interest- ing breed. Sometimes we experience the diva complex when things are going well in the design cockpit. We send our designs off to our manufacturing counterparts with high expecta- tions. But why is it that when problems arise, we are so quick to switch suppliers or to issue that corrective action report? "Wham! Take that! And tell me how you're going to keep it from happening again!" We in the engineering and design commu- nity must realize that we are at the hub of the PCB information wheel. We need to understand that all of our data must be interpreted, and if it is not clear, it is prone to error. It's an interesting point to ponder. What happens when the source of the problem is determined to be PEBCAK (Problem Exists Between Chair and Keyboard)? Why don't we hear about it in the form of a CAR from our customer or boss or the supplier? Yes, it's hard to admit it, but there are times when designers make mistakes too. What should happen at that rare time when a de- signer points the manufacturing finger at a PCB problem and sees there are three design fingers pointing back? Rather than playing Led Zeppe- lin's "Nobody's Fault but Mine" over and over for everyone to hear, it is time to think about the root cause of your design failure. "Sheesh! How'd that happen?" No, that's never an acceptable response. An experienced PCB designer will know the importance of quickly getting to the root cause of a problem by examining the design process—yes, a docu- mented, formal process. Does your design pro- cess include design rule checking? Of course. But automatic design rule checking doesn't check for everything. It won't check your sol- der mask color. It won't check your legend color either. Do you always check your dimensions, tolerances and next assembly fit? Probably not. There are many other examples. A wise de- signer will solicit a design review from associat- ed PCB project stakeholders and formulate a dy- namic design checklist, adding to it each time a design problem is found. PCB stakeholder rela- tionships are only torn down by assigning fault and blame. Industry relationships grow, how- ever, when stakeholders work together to find the cause of a problem and correctly address the process it relates to, in order to prevent it from happening again. Let's stop pointing the fickle finger of fault when there's a misstep or miscue. We'll all be better off if we concentrate on ensuring that it never happens again. PCBDESIGN References 1. Root Cause Analysis: A Tool for Total Qual- ity Management, by Paul F. Wilson, Larry D. Dell, and Gaylord F. Anderson, 1993. Kelly Dack, CID+, is a PCB designer for a contract manufacturer in the Pacific Northwest. Addition- ally, Kelly serves on the executive staff of the IPC Designer Council and is employed by EPTAC Corporation as a CID instructor teaching classes nationwide. FAULT-FINDING: IT'S ALL ABOUT PREVENTION, NOT BLAME In a paper published in Physical Review Applied in July 2017, researchers at the London Centre for Nanotechnology, led by Dr Jon Fenton, have demonstrated the incorporation of supercon- ducting nanowires within high-quality niobium nitride resonators. These nanowires were fabrica- ted by neon focussed-ion-beam milling. Using an inert-gas ion-beam allows fabrication of constric- tions as small as 20nm while introducing minimal levels of the two-level systems which contribute to loss. Careful studies of the losses from these resonators have allowed the team to conclude that these reso- nators have quality factors better than 200000 in the low-temperature, single-photon limit relevant for quantum circuits. This is approximately 100× larger than equivalent resonators with embedded nanow- ires and compares favourably with the mature tech- nology of AlOx-based Josephson junctions. These results suggest that there are excellent pros- pects for superconducting-nanowire-based quantum circuits. Neon FIB Solves Loss Issue in Superconducting Nanowire Devices

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