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AUGUST 2022 I DESIGN007 MAGAZINE 67 Feng Shui in PCB Design? e traditional practice of feng shui claims to use energy forces to harmonize individuals with their surrounding environment. I recall hearing a production floor manager once com- plain about a dangerously unorganized area of a stockroom, facetiously pointing out that the room was not feng shui. Was he serious? Regardless, I've always wondered if there was a place for feng shui in PCB layout. Looking at a printed board assembly from a distance, one can imagine it looks much like a city with components appearing as neatly placed build- ings and traces as pristine roads. A well laid out PCBA should provide a feeling of positive energy from the product. I've experienced this feeling many times while visiting PCB fabrica- tion or assembly suppliers. e front lobby fea- tures an impressive glass cabinet display housing various bare printed boards or full assemblies— examples of their work—and I feel the energy of project stakeholder success. e high-tech examples in these cases radiate the case that the PCB engineering and manufacturing teams in this company have worked together to achieve the satisfaction of their customer and are proud of what they have produced. But what happens to these designs if a part or material becomes unavailable? e design will no longer be feng shui because it has become "out of balance" and must change. Now what? Practical Packaging Density, Plus We see how using an abundance of mate- rial to solve a single problem can create other problems. On the other hand, we see efforts to shrink and shave every last scrap of real estate or material can cause adverse effects regard- ing producibility. We now consider the con- cept of feng shui in establishing just the right balance of PCB yin and yang to come up with an ideally balanced PCB assembly. Consider the words of Greek philosopher Heraclitus, who is credited with exclaiming: "Change is the only constant." design features to intelligently set design rule constraints. But when it comes to compromis- ing on well-established manufacturing prox- imity constraints, I become anxious. ese days, it makes my skin crawl to have to tighten up a tolerance or nudge a trace or component knowing that I'm pushing a systemic problem downstream which may cause a logjam of chal- lenges for my fellow stakeholders. Over the years there have been many log- jams and I have developed special empathy for all the valuable stakeholders in our elec- tronics industry struggling to play a part in a PCB assembly project's success when DFM considerations are ignored. Dense packaging solutions are not easy. I seriously consider any decision moving a layout from the IPC general design producibility level A to a reduced pro- ducibility level C without substantial justifica- tion and buy-in from all project stakeholders. Sometimes though, any of us can get caught up in the shimmer of new technology with- out counting the project costs from a holistic viewpoint. Figure 3: Extremely-dense PCB means minimal material usage, micro-scale packaging density; 0.24 mm pitch BGA shown presumed to exceed IPC producibility class C.