10 Rules for better 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. We derived these 10 rules from the most common issues we encounter in our daily frontend engineering process.
Rule number 1
- Do not scale your data - All data provided must be scale 1/1 (100 %).
Rule number 2
- Make sure that your Gerber files 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).
Rule number 3
- Use the same offset for all your Gerber layers and the Excellon drill data. Preferably use no offset at all.
Rule number 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.
Rule number 5
- Use the same resolution (grid) for your Gerber & Excellon data to allow a perfect match.
Also make sure that the resolution (grid) used for your output (Gerber & Excellon) is at least a
factor 10 better than the resolution (grid) used in your CAD PCB design software.
- Example: If you use a 10 mil resolution to draw your board in your CAD PCB design software,
then use a 1mil output resolution for your Gerber & Excellon output.
Rule number 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).
Rule number 7
- Put some small text (board identification, company name, 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.
Rule number 8
- RECOMMENDATION. In your Gerber files use flashed pads as often as possible.
Rule number 9
- RECOMMENDATION. In your CAD PCB design software try to create an aperture list for Gerber output
which only shows the apertures used in the design.
Rule number 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.
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