Drill Specs, Settings and File Format

The hole diameter after plating will be within +/-2.5 mil of the drill size specified on the drill file, although it’s typically within 1.5 mil of the size specified. For tight-fitting components, it’s important to note this spec, and make sure that the component will still fit if the hole size shrinks. If the hole grows, it typically does not present a problem since it simply reduces the annular ring slightly.

The positional alignment for drill hits is 2.5 mil, with an average alignment error of about 1 mil.

Fabrication Specs

For 2 layer boards, the smallest drill size is 10 mil, with a 5 mil annular ring.

For 4 layer boards, the smallest drill size is 10 mil, with a 4 mil annular ring.

The largest plated hole size is 265 mils. Unplated holes do not have a maximum size.

The hole diameter after plating will be within +/-2.5 mil of the drill size specified on the drill file, although it’s typically within 1.5 mil of the size specified. For tight-fitting components, it’s important to note this spec, and make sure that the component will still fit if the hole size shrinks. If the hole grows, it typically does not present a problem since it simply reduces the annular ring slightly.

The positional alignment for drill hits is 2.5 mil, with an average alignment error of about 1 mil.

File Format Requirements

Your drill file should be in “Excellon” or “NC Drills” format. Make sure it’s in 2:4 precision if using imperial units, or 3:3 precision if using metric. No Zero Suppression or Leading Zero Suppression are acceptable. Do not enable trailing zero suppression, as that will likely cause manufacturing issues.

We cannot accept “drill drawing” files, often labelled as “Drill Ident” or “Drill Symbol”, or “Fab Drawing”. We also cannot process Altium’s binary drill format.

We support both vias (plated holes) and unplated holes. The fab uses the presence of copper underneath the drill hit to determine plating. Copper underneath the drill indicates a via/plated hole, no copper indicates an unplated hole.

Due to the detection method, “Pilot holes” or “Starter holes” will often result in unusable boards by removing copper under plated drill hits. This option is typically not present (such as eagle and kicad) or disabled by default (notably Altium, Diptrace, and Designspark), so it’s rarely a problem. However, if you’ve previously enabled it, ensure that it’s turned off when producing drill files.

We currently require all drill hits to be in a single file that contains both unplated and plated drill hits. Submitting a board with multiple drill files is likely to cause issues during fabrication. Typically the CAM settings can be adjusted to produce a single drill file, but sometimes they must be merged using additional tools such as GerbV.

Issues when submitting drill files are one of the more common issues we see, but they are typically easy to identify on the previews before you place your order. When you upload your design, the preview should look like the picture below, with all drill hits in the center of the pad like you’d expect on your final product. If your board shows any issues (board is zoomed out, pushed to the side, or shows missing drill hits), please see our Drill Troubleshooting FAQ

Drill holes should appear black on a good board preview.