HOW-TO: Eagle Keepout and Restrict layers

in Eagle, tutorials by DP | 3 comments

Keepout, and restrict polygons are powerful tools at your disposal as a PCB designer. Keepout is used when you don’t want components placed within an area, like edges of a board, or where your heatsink will be placed.

Restrict polygons make sure the specific copper layer cant be placed within the polygon. We use them to keep other traces away from noise sensitive traces and parts. Both keepout, and restrict together are used to keep part, and copper away from metal standoffs on our Sick of Beige cases.

How to use

Create a polygon with one of the layers described below, covering an area for which you need keepout, or restrict. For more information on polygons in general check out our polygons guide.

Special Layers you could use

tKeepout / bKeepout

When a component contains a keepout layer on its perimeter, the DRC checks if there are overlaps with your keepout polygon. If there are overlaps, you will be informed about it through the DRC error report.

‘Keepout errors’

‘Keepout clearance for components overlaps’

tRestrict/bRestrict/vRestrict

These layers check for overlap of top copper, bottom copper, and vias when running a DRC with “Check Restrict” toggled under Misc. Tab in DRC. Also informing you about overlaps in the DRC error report.

‘Restrict errors’

‘DRC window, Miscellaneous Tab’

This will also cut through, or prevent power planes. Great for protecting noise prone areas.

Conclusion
You can turn-off tKeepout/bKeepout layers under ‘View>Display/Hide Layers’ to bypass the check.

Restrict will still be checked even it’s layer is off, you should un-check it in the DRC menu if bypassing is required.

Here’s an interesting use of Restrict layer. You could etch away your logo or text using restrict.

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Comments

  1. Don says:

    That is all well and good but how do you keep AutoRouter from putting traces and vias in the Keepout areas?

    • You don’t :-) The autorouter doesn’t care about the Keepout-layers. You need to add Restrict-layers to those areas to avoid having the autorouter putting stuff there.

      39 tKeepout No-go areas for components, top side
      40 bKeepout No-go areas for components, bottom side
      41 tRestrict No-go areas for tracks, top side
      42 bRestrict No-go areas for tracks, bottom side
      43 vRestrict No-go areas for via-holes

  2. Don says:

    Yeah, I first tried Keepout and it had no effect on the autorouter. So then I read what this article had to say about Restrict and the only thing it said was that DRC would tell you if Restrict area was violated but said nothing about the autorouter so I assumed that it was like Keepout in that respect. But then I decided to try it just to see and, sure enough, it *did* affect the autorouter in the way that I assumed Keepout would. Thanks for replying!

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