The 10-point Gerber checklist: what to verify before you send your PCB for fabrication

By the Shara Circuits engineering team

In our experience manufacturing hundreds of boards for Indian product teams, most fabrication delays don't come from complex engineering problems. They come from small, avoidable file mistakes that surface only after your order enters the queue. Run through this checklist before sending files to any fab — ours or anyone else's — and you'll save days.

1. Export the complete layer set. Copper layers, solder mask, silkscreen (paste layers if you're getting a stencil), plus the board outline. A missing mask layer is the single most common reason we have to stop and email a customer.
2. Include the drill file — in the same units as your Gerbers. Excellon drill files exported in inches while the Gerbers are metric cause silent misalignment. Check both before zipping.
3. Put the board outline on its own layer. The outline defines what gets routed. If it lives on the silkscreen or a copper layer, expect a clarification email and a day's delay.
4. Verify annular rings and drill-to-copper clearances. Vias with hairline rings may pass your CAD's default DRC but fail the fab's capability. If you're at 0.2 mm vias or below, confirm capability first.
5. Check minimum trace width and spacing against the fab's stated capability — not your CAD defaults. For standard work, staying at or above 6 mil (0.15 mm) keeps you comfortably inside every Indian fab's process window.
6. Confirm your stackup for anything above 2 layers. Layer order, core/prepreg arrangement and copper weights should be written into your fab notes, not assumed.
7. State controlled impedance requirements explicitly. If your design has USB, RF or high-speed lines with impedance targets, the fab needs to know which traces and what tolerance — impedance is built into the stackup, not tuned afterwards.
8. Look at your silkscreen at 1:1 scale. Text under 0.8 mm height turns into smudge. Also check that reference designators aren't sitting on pads.
9. Run a final DRC after your last edit. Not after your last major edit — after the very last change, however small. "I only moved one label" is how solder bridges are born.
10. Include a readme with your order. Quantity, layer count, board thickness, copper weight, surface finish (HASL/ENIG), mask and silk colours, and any special instructions. One short text file prevents most back-and-forth.

The fastest check of all

Load your zipped Gerbers into a free viewer (not your CAD tool — a separate viewer shows what the fab actually receives) and step through every layer once. Five minutes of viewing catches what weeks of CAD familiarity hides.