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44 DESIGN007 MAGAZINE I MARCH 2021 electrical engineer and PCB designer to go over the details regarding the project. is is a great time, if not already provided, to docu- ment items such as from the example list above into a design specification. Once a design project begins, the PCB designer will inevitably have questions or concerns about something in the input pack- age—an obvious schematic error, mechanical conflict, etc. Although a phone call is great, we have found sometimes engineers would rather communicate via email. We find it better to keep emails short and concise. Lengthy emails with too many questions (more than three) will generally result in some questions going unanswered. On extra-large design projects that may span many months, there can be literally hundreds of emails, most with very important informa- tion from a variety of stakeholders. In these cases, it is very easy, due to a variety of rea- sons, for an instruction to be missed or forgot- ten. We find it best to organize these emails by moving them into a Word or Excel document where they can be tracked through a typical color-coding system (red, yellow, and green) to ensure nothing gets missed. Finally, as part of our ISO process, we rely on a series of checks and balances to ensure we haven't missed any critical information from getting into the design database, as well as to ensure we are not "throwing incomplete data over the fence" to one of our downstream manufacturing friends. First, we insist with our designers that all the mechanical, electri- cal, and manufacturing constraints/rules are embedded into the design database. I'm always amazed when we receive a customer's database that requires edits, or the previous designer did not enter the routing constraints into the tool. Without doing this, it is virtually impossible to say for certain that all the rules have been met. Also, as an iterative process and discipline throughout the design project, our designers have a formal checklist of 90+ items that must be reviewed and/or considered at the differ- ent phases of the project, such as the following items: • Pre-layout review with the engineer • Assembly breakaway rails • Tooling holes and global fiducials placed • ICT or flying probe test points placed • Reference designator renumbering • Fabrication drawing complete with correct dimension, notes, and stackup • Valor DFM complete • Database archived As if we haven't done enough checks to this point, once we have the final approval from the engineer to output the manufacturing files, we run a series of design for manufacturing (DFM) checks by our separate manufacturing DFM specialists. It is important to note: We believe strongly that this check is to be com- pletely unbiased (not performed by one of our PCB designers) to help ensure the integrity of the final data. With all the money and time at stake with what follows, this final check really allows our team (especially me) to sleep well at night. In conclusion, likely the most important way to help eliminate "garbage in, garbage out" is to have a detail-oriented, experienced designer at the helm that understands today's electrical and manufacturing technologies. It's not bad or missing data if the PCB designer receiving the information doesn't recognize it as such. Although, some things may be beyond PCB designers' control. But by standing in that busy information intersection, experienced designers who uti- lize documented standards, effective and pro- active communication, and a system of checks and balances can do their part to reduce or even eliminate bad or missing data. DESIGN007 Nick Barbin is the co-founder and president of Optimum Design Associates, a provider of EMS and PCB design services based in Pleasanton, California.

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