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Design Rule Checks - For Your Protection

I have designed multitudes of PCBs over the years, but I have a confession to make: It can be hard for me to run that final design rule check.

I know that it is important, but at the end of a long design cycle, I just want to be done. I don’t want to redo anything, and I sure don’t want to look at my own errors. Do any of you feel that way? As the manager of customer support for my company, I have helped users who have run into problems because they didn’t run their DRCs. So I’m guessing that I’m not the only one who has contemplated skipping this particular step.

DRCs exist as a barrier of protection for designers, and whenever I contemplate skipping some of those protections, I think back to the story of one of my heroes. I have a great love of aviation, and through the years I have studied its different aspects from aircraft specifications to the exploits of courageous pilots. My heroes have included pilots like Eddie Rickenbacker, Wiley Post, Amelia Earhart and Chuck Yeager, just to name just a few. One of the pilots who most intrigued me was America’s No. 2 air ace of WWII, Major Thomas B. McGuire.

Tommy McGuire amassed 38 confirmed victories while flying the P-38 Lightning, the big twin-tail, twin-engine fighter built by Lockheed. McGuire was said to have “the pilot’s touch” and those who flew with him claimed that he could do things with the P-38 that were impossible for ordinary pilots. He was known as “the best of the best,” and in addition to being a phenomenal pilot, he was also a great teacher. He taught other pilots from his own experiences, not only in the skills of aerial attack, but how to be prepared for the unexpected.

Above all else, Tommy McGuire had three cardinal rules for P-38 pilots:

1. Never attempt combat at low altitude.
2. Never let your airspeed fall below 300 miles per hour.
3. Never keep your wing drop-tanks in a fight.

The P-38 was a big, heavy airplane that performed poorly when going low and slow. Therefore, these three rules were designed to protect pilots from getting into a situation that would limit their productivity, or in a worst-case scenario, cost them their lives.

So why would McGuire’s story come to mind when I would consider skipping a DRC?


Read the full column here.


Editor's Note: This column originally appeared in the June 2014 issue of The PCB Design Magazine.