KiCadRoutingTools: Skill for Claude Code

Recommend Plane Mappings

When this skill is invoked with a KiCad PCB file, recommend which nets should get copper planes and on which layers, with the reasoning a layout engineer would apply.

Step 1: Read the Board

import sys
sys.path.insert(0, "py_router")
from kicad_parser import parse_kicad_pcb
pcb = parse_kicad_pcb('path/to/file.kicad_pcb')

print(pcb.board_info.copper_layers)                # e.g. ['F.Cu', 'In1.Cu', 'In2.Cu', 'B.Cu']
for layer in pcb.board_info.stackup:               # List[StackupLayer], ordered top to bottom
    print(layer.name, layer.layer_type, layer.thickness, layer.epsilon_r)

# Existing zones - don't silently duplicate them
for zone in pcb.zones:
    print(zone.net_name, zone.layer, 'priority', zone.priority)

Report the layer count up front. On a 2-layer board there are no inner layers to give away: recommend a pour on B.Cu (and/or F.Cu) for GND, note the compromise, and suggest /recommend-stackup if the board's signal content justifies 4 layers.

Step 2: Identify Plane-Worthy Nets

Use pad counts plus the /analyze-power-nets approach (datasheet lookup for supply pins and current estimates) rather than name matching alone:

python3 -X utf8 py_router/list_nets.py path/to/file.kicad_pcb --power

• GND (or the dominant ground net): always plane-worthy.
• Power rails: plane-worthy when pad count is high or estimated current is large; a rail feeding a handful of pins is better served by wide traces (--power-nets / --power-nets-widths) - say so instead of forcing a plane.
• Multiple low-current rails can share one split layer when their regions don't interleave; flag the split seams as return-path hazards for any signals that cross them.

Step 3: Assign Layers with SI Rationale

• Put GND adjacent to the primary signal layers (return paths for outer-layer routing; on 4-layer boards: signals on F.Cu -> GND on In1.Cu).
• Pair a power plane against GND where the stackup allows (interplane capacitance; e.g. VCC on In2.Cu against GND on In1.Cu).
• High-speed content raises the stakes: reference-plane adjacency for the layers carrying fast signals comes first, rail convenience second.
• Outer layers (F.Cu/B.Cu): pick the flood net by same-layer SMD pad count. An outer pour reaches its own-layer SMD pads by fill contact — zero vias for every such pad (the fanout's pour-direct drop skips the barrel when fill reaches the ball). list_nets.py --power prints per-net (F.Cu n SMD, B.Cu n SMD, TH n) for exactly this decision: between candidate nets for an outer flood, the one with the most SMD pads on that layer saves the most vias and escape congestion. TH-heavy nets gain nothing from layer choice (barrels connect everywhere), so don't let TH counts sway it.
• Mention existing zones that already cover a recommendation instead of repeating them. Pouring the same net on that layer REPLACES the existing zone with the run's own settings (solid pad connection unless --thermal-relief, the run's clearance and width, a board-sized outline). Say whether to keep it (--skip-existing-zones, Planes tab: Skip existing zones) or replace it. A multi-layer existing zone is replaced only when every one of its layers is in the assignment.