I have Blind Vias (LAYERS 1-8) and (LAYERS 13-20) stacked on top of
I also have mask to mask clearance in constraints set to 4 mil.
Problem is that I get Mask to Mask DRC for overlapped top and bottom
Mask for top via defined on top.
Mask for bottom via defined on bottom.
In Padstack definition Xsection not showing all layers.
Mark,This was an issue in releases prior to 15.5. It was fixed in PCR 763298. 15-5.1 does not exhibit this behaviour. You'll need to upgrade to resolve those DRCs.