Issue link: https://iconnect007.uberflip.com/i/1327102
58 DESIGN007 MAGAZINE I JANUARY 2021 Feature Interview by the I-Connect007 Editorial Team The I-Connect007 team met with Mar- tyn Gaudion of Polar Instruments to discuss the ins and outs of stackup design, and why designers seem to be getting stackups wrong, especially if a board is going into volume pro- duction overseas. Martyn explains the many trade-offs involved in even the simplest PCB stackup, and why many OEMs are now using brokers staffed with former fabricators to help them address complex stackup challenges. Andy Shaughnessy: Martyn, why don't you start by explaining why it's so important to get stackup design right? And why do we keep seeing all these problems with stackups? Martyn Gaudion: One of the main things is really about designers and fabricators com- municating with each other. Also, what has happened in the last 10 years is a huge pro- liferation of materials. You can get materials that are great for thermal, materials that are great for high speed, and materials that are great for reliability. Suddenly, every material vendor, instead of having just FR-4, now has a whole range of specialized materials that do different things at a suite of price ranges as well. I think it's important to make the point that at Polar we don't see ourselves as stackup experts; instead, we see our customers as the experts. We always want to make sure that the fabricator, who's got the expertise on the fabri- cation side, really communicates strongly with the design authority, because that is when communication can break down. The problem starts when you don't have sufficient commu- nication between fabrication and design. Shaughnessy: There are so many tradeoffs that must be made by the designer on each stackup. Gaudion: With ultra-high-speed designs, we sometimes find that designers want to specify the design very rigorously, and they're not fully aware that the fabricators are going to plate the copper. They'll specify very smooth cop- per on the cores. But then, of course, you're going to drill and plate it. Then, actually, what you have on the core, once it's plated, or once the holes are plated up, the roughness isn't going to be the same as on the base material. Martyn Gaudion on Stackup Design Considerations