Issue link: https://iconnect007.uberflip.com/i/1361971
10 PCB007 MAGAZINE I APRIL 2021 Feature Interview by the I-Connect007 Editorial Team Mark ompson has been in bare board fab- rication for over 30 years. He is now laying out printed circuit boards at Monsoon Solu- tions, a high-tech design bureau near Seattle, Washington. With Mark's extensive hands-on knowledge of PCB manufacturing, he brings a unique perspective to PCB design. In this discussion with the I-Connect007 edi- torial team, Mark shares what's important from a process engineer's point of view, and how to stay on top of evaluating and benchmarking your manufacturing process, along with in- sights from his new role as a designer. Barry Matties: Mark, now that you're a PCB de- signer, aer decades in fabrication, what is the most surprising thing you've learned? Mark Thompson: Oh, gosh, there are a number of them. For years I preached things like, "Don't design at minimums due to etch com- pensations based on copper weights." But now I find myself living that because I'm running out of space. I'm designing it 4/4 and then thinking, "Well, gosh, if I do that, now I'm going to have to etch compensate it on 1/2 oz copper, and it's going to be 4.5 and 3.5 oz, which means they're going to be relegated to 3/8 oz copper foils." And that might be a problem for power functions. It might be a problem for the part itself, and it may not live with that. So that's one of the things I've learned. I've also learned a lot about component placement and footprint design. We've talk- ed about footprints before and how critical it is to get your footprints right. And truthful- ly, the footprints themselves are pretty much the same. What changes is the courtyard, the distance around the component that you're actually putting on the board, and that dis- tance is dictating how much space you have. ere could be a tall part, and you might need to actually reach in and hand solder something in on a very tall part. So that be- comes an issue, and that's one of the other things that I've learned. Benchmarking Your Process Engineering