GND Fill clearance from specific net


I am trying to route an antenna, and I need a specific clearance from that ONE net and the GND fill. For that one net only I want the GND plane fill to not come closer than 1/2 a mm. But for other nets, I want a much closer clearance.

Can it be done? I tried making multiple fill zones with different parameters, but KICAD merged my GND zones, so I cant have two GND zones with different parameters side by side. So that is a bust, and even if it worked, its ugly and pushes the gnd plane away from other nets when it doesn’t need to.

If i set the clearance on that net to 0.5mm I get lots of design rule check errors, because those nets are not that far from one another, and the components they connect to are not that far apart. Further, its not critical that net be 0.5mm from EVERY other Net, Just GND.

I feel like this should be achievable, but I can see how.

Any layout tips to achieve this?

I don’t know of a setting for a net to achieve this, but you can do it by hand with a footprint (may not be what you need, sounds like you need trace clearance as well).

To edit a footprint’s clearance press ‘e’ over the footprint and change the pad clearance under Local Settings to something other than zero. This will apply to all nets, not just GND.

Thanks for the tip, Unfortunately that wouldn’t work for this case. I ended up using a Keep out and manually putting it roughly around the track area i wanted the extra clearance for. Its not a great solution but its the best one I could come up with.

I think for RF applications there are two missing features of fills which would make it so much more useful.

  1. An option to set an over-ride for clearance either per Net or Per Design Rule group. (I imagine it like the Design Rule dialog where you can Add a new clearance, select the Net and then specify its clearance (either further or closer than the default).
  2. An option on the fill to add a Via/Microvia curtain. (ie, automatically punch vias around the edge of the fill at a chosen spacing, and then put them evenly spaced on the inside of the fill.)

To do the via curtain now, you have to manually route a track around the edge of a fill, punching vias as you go. It makes working in the PCB hard, because unlike the fill if you need to move a component you have to rip it up and relay it.

Anyway, they are Wishlist features. And given most people wont be doing RF layouts with Kicad, I don’t seriously expect them to arrive in Kicad anytime soon, if ever.

Be sure to add them to the launchpad bug list as a Wishlist, though. Individual input is part of the process as well and these are good ideas. Glad you found a work around for this one!