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70 PCB007 MAGAZINE I JULY 2019 and with a good yield given the technological hurdles involved. Until one day, several months ago, when the company doing the PCB assembly noticed a slight color and texture difference between some of the pieces. Significant time and effort were put into review and analysis of those parts from both a PCB fabrication perspective and from an end-use perspective. The final analysis showed this to be measling acceptable per IPC standards. Good, right? The product should be usable. Unfortunately, while the parts meet the IPC specification they were built to, it was de- termined that this condition was not going to be acceptable for end use. Once again, we all had to sit down together to figure out a solution to this latest hurdle. Product that was built is now being sorted at the contract manufacturer, further testing on the final product is being done, and there are discussions about a potential field recall. The engineering groups throughout all segments of the full build cycle are meeting to find the best path forward. In one recent meeting, we talked about how to have a specification written to quantify the texture issue in a way that can be inspected, and parts will now be screened be- fore shipping to assembly. I imagine there will be additional discussions as we move toward the long-term solution. In these situations, I think there is a natural tendency to want to place blame on something that is frustratingly causing a considerable de- lay in product launch and comes with consid- erable cost to all involved. But this example really shows that even when everyone is doing everything right, something unexpected can still go wrong. It would be satisfying to be able to finish this with a list of lessons learned from this example, but from a technical perspective, I don't think we will be able to do that. I believe the lesson learned in this case study is that strong com- munication and a timely response have been critical from the beginning of this project and are key ingredients to working through com- plex design requirements. Frank discussions during the process development phase were critical to developing a reliable and repeatable fabrication process. And when this latest issue was identified, a swift response, testing, and reporting were crucial as we worked to under- stand this texture anomaly that was ultimately determined to have a significant impact on the end use. As far as a final resolution, this is still to be determined. Watch for a future column to help bring an ending to this PCB tale—one that will be used as an example for years to come. PCB007 Tara Dunn is the president of Omni PCB, a manufacturer's rep firm specializing in the PCB industry. To read past columns or contact Dunn, click here. Scientists at Oak Ridge National Laboratory (ORNL) studying quantum communications have discovered a more practical way to share secret messages among three parties, which could ultimately lead to better cybersecurity for the electric grid and other energy assets. Current protocols, such as quantum key distribution— a prevailing approach in cybersecurity research—are de- signed for only two parties, and in one instance, uses a pair of light particles called entangled photons. Securely extending quantum cryptography to three parties usually requires the difficult step of creating a three-photon en- tangled state. "In our experiment, we were able to add the laser source as a third active participant while only needing to produce one pair of photons," said ORNL's Brian Williams, lead author of the study published in Physical Review A. "Our method removes the need for producing a third pho- ton, which dramatically improves operation efficiency." This finding could inspire improved security for existing and future computer networks. (Source: Oak Ridge National Laboratory) Widening the Net

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