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The Shaughnessy Report: Simply Speaking

During a recent trade show, a group of us were wondering how much money and labor is wasted annually because of PCB designs that are over-constrained or otherwise needlessly complex. It had to be millions of dollars, or maybe even tens of millions.

Like a lot of long-running challenges in PCB design, this issue didn’t pop up overnight. It’s not like anyone wants to make their designs more complicated than is necessary. As we’ll see in this month’s issue of Design007 Magazine, this happens for a variety of reasons, such as increasing signal speeds, faster rise and fall times, and shrinking silicon technologies.

If your documentation template is too constrained, but the system has been in place for years, you may have already spent hundreds of thousands of dollars in extra fab costs and wasted labor resources, along with jobs put on hold unnecessarily. Some designers over-constrain their entire boards when only a handful of features actually require tight tolerances. Every dimension specifically called out is bought and paid for, because it has to be inspected, and that can be an expensive habit.

So, in this issue, our expert contributors explain how to design PCBs without making them complex and over-constrained—whatever the level of technology. We also discuss the effect your decisions and tradeoffs have on design complexity, as well as the need to thoroughly understand how electrical and manufacturing limitations can lead to over-constraining your board.

We start off with a conversation with Kris Moyer, who explains why “one size fits all” is not a great plan for setting board constraints. Next, Martyn Gaudion discusses various ways to design the simplest—and best—stackup possible. Doug Brooks and Johannes Adam tell us why thermal vias are usually ineffective at dissipating heat, but do a great job of blocking potential routing channels. Chris Young has a great set of guidelines called “8 Simple Rules for Streamlining Your Design.”

Zach Peterson explains why designers should stop designing PCBs like Ferraris, the famously complex Italian supercars. Tim Haag describes why designers should follow the lead of “Star Trek’s” Montgomery “Scotty” Scott and keep their designs simple, and Joe Fjelstad points out why the simplest design is usually the best. We also have columns by Matt Stevenson and Barry Olney, and Steve Williams has a conversation with American Standard Circuit’s John Johnson on UHDI.

This column originally appears in the November 2023 issue of Design007 Magazine.