How to not apply global soldermask expansion to vias

Layout
1

Hi,

How do I configure the soldermask expansion for untented vias?

If I set the ‘global’ soldermask expansion under Board Stackup → Soldermask/Paste->Solder Mask Settings, then this expansion is applies to all untented vias too. I want 0 (or even some negative) expansion on my untented vias, how do I do this?

Thanks

2

Soldermask is not made with absolute accuracy but can be little shifted (technology has some tolerances). This is addressed by ‘global’ soldermask expansion. So even it is little shifted it still don’t get on pads edge.
I don’t think anyone considered soldermask having different accuracy near pads than near vias.

I don’t know if you can set different soldermask expansion for vias, but you can set it for pads. So the solution could be to set global to zero and then overwrite it for all pads.