Most designers know to watch their annular rings. Fewer pay attention to drill-to-copper clearance - and that gap (pun intended) shows up as shorts, delamination, and fab rejections.

Drill-to-copper clearance is the distance between the edge of your drilled hole and the nearest copper feature that isn't supposed to be connected to it. Push that too close and you're one registration shift away from a short. Your fab knows this. They'll flag it, surcharge it, or reject it.

The fix: Maintain at least 8mil drill-to-copper clearance on standard designs. Set it in your DRC rules so violations get caught before the files leave your desk - not after your fab comes back with a question.

This is a two-minute DRC rule change. It will save you re-spins, rejections, and the kind of back-and-forth with your fab that burns a week of schedule.

Catch it in design. Don't let your fab find it for you.