KiCad 7 solder mask setup

What do the parameters in Board Stackup->Solder Mask/Paste mean?

For “Solder mask expansion” I would expect that a value of e.g. 0.1 mm would create NSMD pads. Ist this interpretation correct?

And what exactly does the “Solder mask to copper clearence” mean because for me this sounds to be the same?

For the constraints there are small pictograms to illustrate the exact meaning but for the solder mask these are missing.


Good question. Maybe it means the clearance between the maskless area edge and the nearest copper edge under the mask, to prevent exposing unwanted copper because of mask registration tolerance. I hope someone who really knows tells more about this because I haven’t even noticed this.


Many thanks for your guess concering the “Solder mask to copper clearance”. I was thinking about the copper of the affected pad itself. But I tried to increase the value and the reported errors are “solder mask aperture bridges items with different nets”, so your guess must be correct.

This is it. It is a constraint, not a control: Changing it changes the DRC results, but changing the expansion changes what is actually created on the mask layer.

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