Defining Polygons & Copper Regions for a PCB in Altium NEXUS

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A common requirement on a printed circuit board is large areas of copper. It could be a hatched region of grounding copper on an analog design, a large, solid region of copper for carrying heavy power supply currents, or a solid ground area for EMC shielding.

In Altium NEXUS, areas of copper can be defined using different design objects. In simple cases, Fills and Solid Regions can be used. These are rectangular and polygon-type objects that will not pour around other objects such as pads, vias, tracks, or text. Fill and Solid Region objects are described below on this page.

In more complex cases, Polygon Pours are used. The advantage of a Polygon Pour is that it automatically pours around copper objects that belong to another net in accordance with the applicable Electrical Clearance and Polygon Connect Style Design Rules. To learn more about Polygon Pours, see the Polygons on Signal Layers page.

To provide an electrically-stable ground or power reference throughout the PCB, power planes are used. To learn more about power planes, see the Internal Power & Split Planes page.

Fills and Solid Regions

 An example of a selected solid region
An example of a selected solid region

A fill (Place » Fill) is a rectangular-shaped design object that can be placed on any layer, including copper (signal) layers. Fills are limited to a rectangular shape and will not avoid other objects, such as pads, vias, tracks, regions, other fills or text. If a Fill is placed on a signal layer, it can be connected to a Net.

A region (Place » Solid Region) is a design object that is used for defining polygonal shapes. A Solid Region (commonly called Region) can be placed on any layer including signal (copper) layers. Like a Fill, a Region does not avoid other objects, such as pads, vias, tracks, fills, other regions or text. If a region is placed on a signal layer, it can be connected to a Net.

A region object has a number of special properties that allow it to be used for:

  • Polygon cutouts - where it is essentially a negative (empty) object that the surrounding polygon pours around.
  • Board shape cutouts - where it also acts as a negative (empty) object to define an irregular cutout or hole in the board.
  • Custom pad shapes - where it defines the copper area of an unusual pad, giving the ability to define automatically matched-shape solder and paste mask contractions/expansions.