Issue link: https://iconnect007.uberflip.com/i/1276973
66 DESIGN007 MAGAZINE I AUGUST 2020 Interview by Nolan Johnson I-CONNECT007 I spoke with Kelly Dack about certain things you can't unsee from a designer's perspec- tive. We cover myths on topics ranging from SMT assembly to the "perfect" 0201 footprint. We delve into design issues relating to board outlines, panelization for production, and the need for enough copper pullback from board edges. We end by discussing the myth that a PCB designer is in the best position to specify material temperature grades and how elec- tronic manufacturing services (EMS) com- panies must work together with designers to reduce costs. Myth #1: There Is One Perfect 0201 Chip Component Nolan Johnson: Kelly, we've been talking about some myths which exist between some design and manufacturing stakeholders that still live on. One myth has to do with the design of some small component footprints, and another affects PCB panelization of the board outlines for assembly. The last affects our perception regarding which PCB process stakeholder is responsible for determining material temperature grade and processing requirements. And before we started this interview, you said that the idea of a perfect 0201 PCB design library footprint is a myth due to physical part geometry and solder deposition variables and that there is no single geometric answer. Yet, some PCB designers perceive that their job is to come up with a single, "perfect" PCB layout footprint for an 0201. Is this where the myth begins? How do you talk to your design cus- tomer about these concerns? Kelly Dack: This is a very timely topic because designs continue to scale down. We've been talking about reducing fab and assembly sizes for decades, and they continue to shrink. I work for a manufacturing company in a PCB assembly context, and in a design context; we are constantly trying to stay ahead of customer designs utilizing some really challenging foot- print strategies for smaller and smaller com- ponents. 0201 tolerance range. Things Designers Can't Unsee