PHASE 05DRC / GERBER
Prove the layout obeys the fab's rules, then export the exact files that get manufactured.
Two gates stand between your layout and a box of boards: a rules check that catches what your eyes missed, and a file export that has to be exactly right — because the fab builds precisely what you send, no more and no less.
Before anyone builds your board, let the software find the mistakes.
A tests your layout against the fab's limits — minimum trace width, copper-to-copper clearance, drill sizes, and any unconnected or shorted nets. Run it until it's clean, or until every remaining flag is an intentional exception you've understood and written down. A clearance the fab can't actually make is a short waiting to happen across a whole batch of boards.
DRC flags a 5-mil clearance where the fab requires 6. Ship it anyway? No — fix it, or confirm the fab can do 5 and write down the exception. A clearance violation can short in production.
▸Deep dive· What the rules checker actually tests
A compares your layout against a list of fabrication limits and flags anything the board house can't reliably make. The usual suspects: copper-to-copper clearance (traces too close bridge together when the copper is etched), minimum trace width (too thin and it etches away or can't carry its current), annular ring (too little copper around a drilled hole and the drill can break out of the pad), drill-to-copper spacing, and silkscreen printed over a bare pad. It also re-checks the electrics — nets that should connect but don't, or nets accidentally shorted together. You load the fab's capability numbers in first, so the check is measured against the shop that will actually build the board, not a generic guess.
Gerbers are what the board house actually reads — not your design file.
A set is one file per layer — each copper layer, the solder mask, the silkscreen — plus a drill file: the precise recipe for your board. Export them, then open them in a Gerber viewer and actually look. It's your last chance to catch a mirrored layer, a missing mask opening, or a forgotten copper pour before the mistake becomes a batch of bad boards.
Why open the Gerbers in a viewer after exporting? The fab builds exactly what's in those files, not what's in your design tool — a viewer catches export mistakes while they're still free to fix.
▸Deep dive· What's inside a Gerber set
A set is a stack of flat 2D drawings, one file per physical layer: the front copper, the back copper, the for each side (the green coating, with openings where the pads are), the silkscreen (the white labels), and the paste layer (where a stencil would lay down solder). Riding alongside is a drill file — historically called Excellon — listing every hole's position and diameter, plus a board-outline file telling the fab where to cut. The format is decades old and deliberately literal: it describes shapes and nothing else, so there's no ambiguity about what gets built. That's why you open them in a viewer before ordering — the viewer shows you the actual board, not your hopeful design intent.
Quick check — DRC & Gerbers
Run DRC clean (or with documented exceptions) and attach the DRC report and the Gerber zip.