Copper pours

Copper pours in Fusion create electrical copper areas on circuit board routing layers. They connect to specific signals, such as ground or power nets, while maintaining clearances from unrelated signals and parts based on your Design Rule Check (DRC) rules.

Fusion distinguishes electrical copper planes from graphic shapes and void cutouts:

• Copper Pour: An electrical copper region assigned to a signal on a routing layer. It fills with solid copper or hatch patterns, creates thermal reliefs for pads, and isolates from non-matching signals.
• Copper Pour Cutout: A void area drawn on a routing layer that prevents copper pours from filling inside that region.
• Polygon Shape: A non-electrical graphic polygon on any layer. It carries no signal name and does not calculate clearances or thermal reliefs.

Key properties

• Fill style: Solid fill is standard for power planes and ground planes. The Hatched style provides a mesh pattern for lower-capacitance fill.
• Thermals: Enabled by default to provide electrical connectivity between pads and copper pours while reducing thermal conductivity during soldering.
• Orphans: Small isolated areas of copper created when clearances disconnect copper islands from the primary signal net. These are dropped by default, but you can choose to keep them.
• Isolate: The minimum clearance distance maintained between the copper pour and other signals or objects. The default value of 0 uses clearance values from the DRC rules.

Limitations

• Routing layers only: Copper pours must reside on copper routing layers and require a valid signal name to connect to a net.
• Manual refill when auto-pour is off: When you turn off Auto-pour all Copper Pours, the canvas will not recalculate pour shapes automatically when you move parts. You must run Re-fill Copper Pours to update fills manually.
• Cutouts apply to copper pours only: A copper pour cutout creates voids in copper pours on the same routing layer, but does not affect non-copper shapes or mechanical drawings.
• Signal loss during shape conversion: Converting an existing copper pour to a polygon shape removes its signal name and electrical connectivity.

Best practices and considerations

• Define board boundaries first: Create your board outline and specify your layer stackup before pouring broad ground and power planes.
• Use auto-pour strategically: Keep auto-pour active on small to medium boards for immediate feedback. Turn auto-pour off on dense boards during active routing to maintain high canvas speed.
• Verify fills before manufacturing: Turn on copper pour fill visibility and run Re-fill Copper Pours before you run DRC checks or export CAM manufacturing files.
• Use cutouts for keepout zones: Draw copper pour cutouts under sensitive analog circuitry, high-voltage zones, or antenna areas to keep them free of copper fill.
• Check thermal reliefs and isolate values: Inspect solder pad connections to ensure thermal relief spokes provide good soldering heat isolation without limiting current flow.