board.copper

What it is ¶

board.copper(net, layer, kind) yields one row for each kind of copper a net has on a board layer. kind is track for a routed track, via for a via, and pour for filled copper such as a plane or a pour. A track or pour sits on the layer it is drawn on. A via names the two layers it joins, the outer pair for a through via, and not the inner layers it passes through. net is the net name and layer the layer word the board reader carried through (F.Cu, In1.Cu, B.Cu).

For hardware engineers ¶

This is the copper as it will be etched. A pour counts here only when the file stores the copper itself, which Allegro, Altium, IPC-2581 and ODB++ do. KiCad stores the outline a zone is filled from and computes the copper whenever it fills, so on a KiCad board a zone shows in board.zone and not here. Use it to ask which nets have a plane on an inner layer, or which nets reach a layer only through vias.

For software engineers ¶

Think of a net’s copper as three lists, tracks, vias and filled shapes, each item labelled with its layer. board.copper is the distinct (layer, kind) pairs across those lists, so a net with forty tracks on F.Cu yields one track row there. Rows are sorted by layer and then kind. An empty result means the design has no board tier, or no net has copper with a layer.

Go projector ¶

boardFacts in stdlib/relations/facts.go walks Model.BoardNets() and calls netCopper(bn), which collects each segment’s layer as track, each via’s two layers as via, and each shape’s layer as pour, deduplicated and sorted. It emits one row per pair.

The board tier is EMPTY on a netlist-only design, so the relation yields nothing there. An empty answer can mean the design carries no board at all.

Datalog ¶

Every net with a pour on the first inner layer:

board.copper(?n, "In1.Cu", "pour") => ?n

Nets that reach the back copper only through vias, with no track or pour there:

board.copper(?n, "B.Cu", "via"), not board.copper(?n, "B.Cu", "track"), not board.copper(?n, "B.Cu", "pour") => ?n