Issue link: https://iconnect007.uberflip.com/i/723195
30 The PCB Magazine • September 2016 I imagine that everyone has been in this position at one time or another: Despite every- one's best attempt at creating the perfect design, PCB fabrication and assembly, something goes wrong and the troubleshooting begins. I had the opportunity to sit down with Ed Knutson, the president and founder of Dima- tion, to swap some of our best war stories. Ed specializes in quick-turn assembly and design. Our banter, to which I brought the fabrication piece of the puzzle, was primarily focused on flexible circuit applications for mil/aero proj- ects. I am not sure if that is because of the more stringent requirements for those applications or because we both work regularly in that indus- try segment. At the end of our discussion, we concluded that most of our war stories could be traced back to a breakdown in communication and often simply not fully understanding how each piece of the design-fabrication-assembly puzzle fits together. Here are a few of our stories and lessons learned. UL Materials Aircraft applications typically require ma- terials rated to UL94V-0. The assembly is com- plete and the burn test fails. What happened? The perfect storm. When the design files were created for fabrication and assembly, the UL requirements were noted in the assembly files only and called out by test requirements, not UL 94V-0. This was an ITAR application, so the PCB fab files were separated from the assembly files and forwarded to the flex manufacturer. Because there were no UL requirements listed on the fabrication notes, the supplier defaulted to their standard materials and the flex was not built with flame-retardant materials. That ex- by Tara Dunn 0MNI PCB Troubleshooting Flex Circuit Applications for Mil/Aero Projects FEATURE COLUMN: FLEX TALK