I have this small single layer LED PCB I created in Altium, with a Polygon poured on the top layer defining the board limits.


When I try to create the board shape by using the polygon as reference, Altium says it can't find the complete polygon, and doesn't define the board shape based on it.

If I try to copy the polygon and convert it to its original primitives, all the primitives disappear.

I created the polygon by using arcs and tracks on the top layer.

Is there another way for me to define it as the shape for the PCB?

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    – Andy aka
    Mar 18, 2022 at 17:11
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    \$\begingroup\$ @Andyaka I've been searching on and on the whole morning. The only answer I came close is from Altium user manual here: altium.com/documentation/knowledge-base/altium-designer/… but It didn't work out for me so far... And I'm still trying... \$\endgroup\$
    – Rodrigo
    Mar 18, 2022 at 17:15
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    \$\begingroup\$ @Andyaka If these tool-specific questions are not wanted, the EE-SE rules should be changed, but downvoting each individual question is not a good way. \$\endgroup\$
    – asdfex
    Mar 18, 2022 at 18:17

2 Answers 2


Took me a while as well:

  • Duplicate the polygon, e.g. on a mechanical layer
  • Select the polygon, set fill style to 'none'.
  • Tools -> Convert -> Explode Polygon to Free Primitives (now you have a set of tracks)
  • Select all tracks
  • Design -> Board Shape -> Define Board Shape from Selected Primitives

If you can't find a way to define the board shape directly from a polygon pour, you can easily reproduce your outline on a mechanical layer since it consist only of two different types of arcs. With this outline selected you can use "Design » Board Shape » Define from selected objects" to use it as PCB outline. For more details refer to the altium documentation.


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