KB: Signal to plane layer conversion - Preserving polygons

Issue Overview

When converting a signal layer to a plane layer, all polygons with different net name assignments are lost. This issue arises during layer type changes in PCB design workflows, where users expect the polygons to be retained or converted into split planes.

Why polygons are lost during the conversion

Signal and plane layers are treated as different artwork types in PCB design tools. The conversion process does not support direct retention of polygons from signal layers because plane layers require split planes with net assignments, which are not automatically derived from signal layer polygons.

Available workarounds

There is no straightforward way to convert existing polygons into split planes. However, users can apply one of the following workarounds:

• Manually recreate the split planes in the plane layer.
• Export polygons as DXF and re-import them into a mechanical layer, then move outlines to the plane layer.
• Use a temporary layer to hold polygons, explode them into free primitives, and assign nets manually.

How to apply the workarounds

Option 1: Manual Recreation

1. Note the net assignments and shapes of the original polygons.
2. Recreate each split plane manually in the plane layer using the same outlines and net names.

Option 2: DXF Export/Import

1. Select all the polygons.
2. Open the Properties Panel and Change the Polygon fill mode to "None".
3. Export the polygons from the signal layer as a DXF file.
4. Import the DXF into a mechanical layer.
5. Select the outlines of each polygon.
6. Move the polygon outlines to the plane layer using the Properties Panel.
7. Assign the appropriate nets to each split plane.

Option 3: Temporary Layer and Explode

1. Create a temporary layer in the stackup.
2. Move the polygons from the signal layer to the temporary layer.
3. Change the signal layer to a plane layer.
4. Select all the polygons in the temporary layer.
5. Open the properties panel and Change the Polygon fill mode to "None"
6. Move the Polygon outlines to the plane layer.
7. Assign nets to the split planes manually.

Additional Notes

• These workarounds are manual and may require careful attention to net assignments to avoid connectivity issues.
• Always verify net connectivity after applying any workaround.

Further Reading

• Split Planes
• Polygons on Signal Layers
• Plane Layer Rules and Definitions
• Polygon pour fill mode None
• Editing Polygonal Shaped PCB Design Objects
• AutoCAD-DXF Import-Export Support