Minimum clearance setting explanation

[poco]

Regarding this (link to issue tracker)

There is a setting under File -> Board setup -> Design Rules -> Constrains in PCB Editor, called Minimum Clearance.

Citation from issue tracker:

This is by design. 0 is special-cased to mean “don’t set a board-wide minimum clearance”.

What does this mean?

I have used to to set this to 0.2 mm (because of fab house specs) to make sure there will be no less copper to copper gaps between different nets in my boards, and DRC enfine takes this number for board check.

What is the purpose of this setting then, where should I use it? Where from does the DRC engine take clearances to check for?

[eelik]

@poco

Where from does the DRC engine take clearances to check for?

In case of tracks, from net classes. Zones and footprints/pads can have their own values. The effective value is the largest of the values when deciding the clearance between two items.

[JeffYoung]

Or from custom rules if you have any of them defined.

If you do define a board minimum, then it sets the absolute minimum.

Next are any local overrides (again, if not set to 0).

Next are any rules that match, with the last match winning.

Next are the netclasses.

To see what’s happening, select two items and do a Inspect > Clearance Resolution…