10 Rules for Better PCB Gerber Data

Keeping some simple rules in mind can avoid that we have to contact you after you place an order to resolve pcb design issues. There are 10 rules from the most common issues we encounter in our daily frontend engineering process.

1. Do not scale your data – All data provided must be scale 1/1 (100 %).

2. Make sure that your DO NOT contain apertures with a zero-size (size =0.00 mm or inches) and that your Excellon data DOES NOT have zero sized tools (size=0.00mm or inches).

3. Use the same offset for all your Gerber layers and the Excellon drill data. Preferably use no offset at all.

4. Use the same units (mm or inch) in your Gerber & Excellon output files as in your CAD PCB design software. This will eliminate conversion or rounding errors.

5. Use the same resolution (grid) for your Gerber & Excellon data to allow a perfect match. Set the resolution (grid) for output (Gerber & Excellon) to 6 decimals using the imperial system and 5 to decimals using the metric system as recommended in the Gerber specification. If your CAD system supports only lower resolutions than what is recommended then use the highest available number of decimals.

6. Make sure that your data is supplied as seen from top to bottom through the PCB. DO NOT mirror (or reflect) any data layer – image or drill.

Viewing a PCB from top to bottom through the board is the universal practice in the PCB industry. We view and handle your data in that way, as does your CAD PCB design software.

This means that when viewing your Gerber data, text on the top side of your board (copper, soldermask, legend) should be readable and text on the bottom side (copper, soldermask, legend) should be non-readable (= mirrored).

7. Put some small text (board identification, layer number, etc…) in the copper layers. Make sure the text complies with the readability rules. (Rule number 6). This will help us to avoid mirroring errors.

8. It is recommended to use flashed pads as often as possible in your gerber files.

9. It is recommended that in your CAD PCB design software try to create an aperture list for Gerber output which only shows the apertures used in the design.

10. Make sure that you include the board outline on all layers. This will enable us to properly align all layers in case of an offset problem. Also include the board outline in a separate Gerber mechanical plan.

Please feel free to contact Alex@sdy-pcb.com or engineer for any questions. SDY engineers will check your gerber data provided before production in details and will send engineering question notes to you for any issues of gerber data.