Unused Pad Shape Removal

Pas and vias are an essential ingredient of a modern PCB design, as well as providing mounting points for components, pads, along with vias, allow a net to traverse the different layers of a PCB as it travels from one component pin to another. Pads and vias come at a cost though; they consume valuable board space, they create impedance mismatches for high-speed signals, and they create holes in large copper areas defined by polygon pours.

To help reduce their impact on copper areas, Altium Designer includes an Unused Pad Shapes removal tool. The tool scans all pads or vias in the design, and removes the pad shape from each layer that the pad or via is not used on (meaning it has no other objects touching it on that layer). Polygons that surround that pad or via then only need to create the specified clearance to the pad or via hole, instead of to the edge of the unused pad shape. In some situations, such as under a BGA, this can recover a substantial amount of copper lost in polygons.

In the image on the left unused pad shapes are present, in the image on the right they have been removed and the polygons repoured.

Removing Unused Pad Shapes

This tool is intended to be used once the routing is complete, before the fabrication files are generated. To remove unused pad shapes, select Tools » Remove Unused Pad Shapes from the menus, the Unused Pad Shapes dialog will open, as shown below.

Configure the unused pad shape removal tool as required.

Configure the dialog options as follows:

• Scope
  • Vias - examine all vias in the design, and remove unused pad shapes.
  • Pads - examine all pads in the design, and remove unused pad shapes.
• Operation
  • Remove unused - use the tool to remove unused pad shapes.
  • Restore unused - use the tool to restore removed pad shapes to all vias.
• Selected only - examine only selected vias or pads, and remove unused pad shapes.
• Preserve pads on start and end layers - a pad or via might not use the pad shape on the outer most layers that its structure exists on, these outer-layer pad shapes can be retained if required. Confirm that pad-less-outer-layer pads or vias are supported by your fabricator before disabling this option.

Repour Polygons

To ensure that existing polygons recover all available copper area that was lost to unused pad shapes in pads and vias, run the Tools » Polygon Pours » Repour All Polygons command after removing unused pad shapes.