Issue link: https://iconnect007.uberflip.com/i/1449048
38 DESIGN007 MAGAZINE I FEBRUARY 2022 a process, and you're all going to help us come to consensus in what that process is." One of the key elements that came up was that during the design of a printed circuit board, the designer always had questions that another designer couldn't answer. ey had to be answered by somebody in fabrication, manufacturing, or test. Because of schedules, a lot of times you couldn't find the right per- son to answer your question. You just did it the way you did it the last time or turned to some- body close to you and asked them and stayed on schedule. e one thing that we endeavored to do was identify these key milestones that fundamen- tally define the printed circuit layout process, costs, and everything else, while also devel- oping alternatives, including the cost of each alternative. To get past the cost, we invented a fake currency called the relative cost index, RCI, that was not dollars and had no units, but it allowed you then to compare one alterna- tive to another, by which one had the lower percent cost and/or the higher reliability, and then move on. I'm using the concept of milestones in that I've never seen any flow chart of the design process that recognizes that a lot of decisions must be made. e answers come from some- body else, not from the design engineer, but from the fabricator and the assembler. How do they want to do inspection and test? Fabricators and assemblers need to collect information to help answer the questions at these milestones that make it easier for design- ers to find a path to complete a board, because there's an almost infinite number of ways you could design a printed circuit board. Matties: Kelly, what are your thoughts about what Happy just described? Kelly Dack: I appreciate Happy's experience with regard to design over the years, especially as he has worked for a large company with its own captive fabrication capabilities. When a captive designer is in touch in this way with the capabilities of a manufacturer which sits directly on the same project table, design can easily be—and must be standardized to match the documented in-house, or corporate manu- facturing capabilities. Pushing designs into new technology only comes by a corporate deci- sion to invest in new tooling and machinery to match the proposed design concept which can exist within or without common, commercially available manufacturing capabilities. Having worked my entire career only for companies which must purchase their PCBs from third-party sources, however, gives me a bit of a different perspective. At the start of every PCB design project, I myself and many other designers are systematically put in the position of not knowing where the boards we design will end up being fabricated. Even when we rely on commercially available design stan- dards, like the IPC 222X family, we've come to always expect requests from a new supplier to allow manufacturing discrepancies or modifi- cations which were not considered a problem for a previous supplier. Without establishing the milestone of selecting a dedicated supplier with known Happy Holden