Files
kicad-zone-resistance/fill_resistance/board_io.py
T
janik 9e307f2818
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Solder cone around protruding THT leads (tent structure)
The clipped lead of a soldered THT contact protrudes
THT_LEAD_PROTRUSION_MM (1.5 mm default, 0 disables) out of the hole on
the side opposite the component, and a solder cone wraps it: full
protrusion height at the drill wall, tapering linearly to zero at the
pad edge. Painted as per-cell extra conduction-equivalent copper via
stack.thick_scale - the tall solder column at the wall pulls the joint
vicinity to lead potential (equivalent to extending the barrel wall
vertically), the taper carries the radial spreading. DC-exact additive
conductance; at f > 0 the factor multiplies the skin-corrected sheet
conductance like the via mouths (documented approximation).

The protrusion side is looked up from the owning footprint (pads store
absolute positions; component on F.Cu -> lead tents on B.Cu), with a
logged B.Cu fallback. Dump schema gains protrusion_side and
tht_protrusion_nm (defaults keep older v6 dumps loading).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-16 18:47:10 +07:00

631 lines
25 KiB
Python

"""All KiCad IPC access. This is the ONLY module that imports kipy;
everything downstream works on plain geometry dataclasses.
Run `python -m fill_resistance.board_io dump.json [net]` against a live
KiCad to extract without the dialog (all layers of the net, defaults).
"""
from __future__ import annotations
from dataclasses import dataclass, field
from pathlib import Path
from kipy import KiCad
from kipy.board import Board
from kipy.board_types import ArcTrack, BoardRectangle, Pad, Via
from kipy.proto.board.board_pb2 import BoardStackupLayerType
from kipy.proto.board.board_types_pb2 import ZoneType
from kipy.util.board_layer import (canonical_name, is_copper_layer,
layer_from_canonical_name)
import numpy as np
from . import config
from .errors import ApiVersionError, CandidateError, SelectionError
from .geometry import (Electrode, LayerFill, Polygon, Problem, Rect,
SurfaceBuildup, TrackSeg, ViaLink,
contact_solder_buildups, linearize_ring)
MASK_TO_COPPER = {"F.Mask": "F.Cu", "B.Mask": "B.Cu"}
# zone fills are polygonal in practice; tolerance only guards arc nodes
ARC_TOL_NM = 10_000
def connect() -> tuple[KiCad, Board]:
try:
kicad = KiCad()
kicad.ping()
except Exception as e:
raise ApiVersionError(
f"Could not connect to KiCad's IPC API: {e}\n"
f"Is KiCad running with the API server enabled "
f"(Preferences > Plugins > Enable KiCad API)?"
)
try:
print(f"connected to KiCad {kicad.get_version()}")
except Exception:
pass
try:
board = kicad.get_board()
except Exception as e:
raise SelectionError(
f"Could not get the open board from KiCad: {e}\n"
f"Open the PCB in the board editor and run again."
)
return kicad, board
def board_dir(board: Board) -> Path:
# document.board_filename is a bare file name (no directory) in
# KiCad 10.0.1; the project path is the reliable location
try:
path = board.get_project().path
if path and Path(path).is_dir():
return Path(path)
except Exception:
pass
try:
filename = getattr(board.document, "board_filename", "") or ""
if Path(filename).is_absolute():
return Path(filename).parent
except Exception:
pass
return Path.cwd()
# --- stackup geometry --------------------------------------------------------
@dataclass
class StackupInfo:
names: list[str] # copper layers, top to bottom
thickness_nm: dict[str, int]
z_nm: dict[str, int] # copper center depth
z_bot_nm: int # total stack thickness
def get_stackup_info(board: Board) -> StackupInfo:
names: list[str] = []
thickness: dict[str, int] = {}
z_center: dict[str, int] = {}
z = 0
for sl in board.get_stackup().layers:
t = int(sl.thickness or 0)
if sl.type == BoardStackupLayerType.BSLT_COPPER:
name = canonical_name(sl.layer)
if t <= 0:
t = int(config.FALLBACK_THICKNESS_UM * 1000)
print(f"warning: stackup gives no thickness for {name}; "
f"assuming {config.FALLBACK_THICKNESS_UM} um")
names.append(name)
thickness[name] = t
z_center[name] = z + t // 2
z += t
if not names:
raise CandidateError(
"Could not read any copper layer from the board stackup."
)
return StackupInfo(names=names, thickness_nm=thickness, z_nm=z_center,
z_bot_nm=z)
# --- electrodes from selection ----------------------------------------------
def _box2_to_rect(box, layer_name: str) -> Rect:
try:
pos, size = box.pos, box.size
return Rect.normalized(pos.x, pos.y, pos.x + size.x, pos.y + size.y,
layer_name)
except AttributeError:
c, s = box.center, box.size
return Rect.normalized(c.x - s.x // 2, c.y - s.y // 2,
c.x + s.x // 2, c.y + s.y // 2, layer_name)
def _convert_poly(poly_with_holes) -> Polygon:
def ring(polyline):
nodes = []
for node in polyline.nodes:
if node.has_point:
nodes.append(("pt", (node.point.x, node.point.y)))
elif node.has_arc:
arc = node.arc
nodes.append(("arc", ((arc.start.x, arc.start.y),
(arc.mid.x, arc.mid.y),
(arc.end.x, arc.end.y))))
return linearize_ring(nodes, ARC_TOL_NM)
return Polygon(outline=ring(poly_with_holes.outline),
holes=[ring(h) for h in poly_with_holes.holes])
def _pad_drill_nm(pad_or_via) -> int:
try:
return int(pad_or_via.padstack.drill.diameter.x)
except Exception:
return 0
def _pad_default_contact(pad: Pad) -> str:
if _pad_drill_nm(pad) > 0:
return "all" # through-hole: contacts the stack
try:
copper = [canonical_name(l) for l in pad.padstack.layers
if is_copper_layer(l)]
if len(copper) == 1:
return copper[0] # SMD: its own layer
except Exception:
pass
return "all"
def _pad_polygons(board: Board, pad: Pad, contact: str) -> list[Polygon] | None:
layer_ids = []
if contact != "all":
try:
layer_ids.append(layer_from_canonical_name(contact))
except Exception:
pass
for name in ("F.Cu", "B.Cu"):
try:
layer_ids.append(layer_from_canonical_name(name))
except Exception:
pass
for lid in layer_ids:
try:
shape = board.get_pad_shapes_as_polygons(pad, layer=lid)
if shape is not None:
return [_convert_poly(shape)]
except Exception:
continue
return None
def _tht_protrusion_side(pad: Pad, footprints) -> str:
"""Outer layer where the clipped THT lead protrudes (tent + solder
cone): the side OPPOSITE the component. Footprint pads are stored
with absolute positions, so the owning footprint is matched by pad
number + position. Unknown owner -> assume the component sits on
F.Cu (lead tents on B.Cu)."""
try:
for fp in footprints or []:
for fpad in fp.definition.pads:
if fpad.number == pad.number \
and fpad.position.x == pad.position.x \
and fpad.position.y == pad.position.y:
side = canonical_name(fp.layer)
return "F.Cu" if side == "B.Cu" else "B.Cu"
except Exception:
pass
print(f"note: no footprint found for pad {pad.number} - assuming its "
f"lead protrudes on B.Cu")
return "B.Cu"
def _to_electrode(board: Board, item, stackup: StackupInfo | None = None,
footprints=None) -> Electrode:
if isinstance(item, BoardRectangle):
tl, br = item.top_left, item.bottom_right
rect = Rect.normalized(tl.x, tl.y, br.x, br.y,
canonical_name(item.layer))
cx = (rect.x0 + rect.x1) / 2e6
cy = (rect.y0 + rect.y1) / 2e6
return Electrode(rect=rect, contact="all",
label=f"rect({cx:.1f},{cy:.1f})")
if isinstance(item, Via):
via: Via = item
x, y = via.position.x, via.position.y
drill = int(via.drill_diameter or 0) or _pad_drill_nm(via)
if drill <= 0:
raise SelectionError(
f"Selected via at ({x / 1e6:.2f}, {y / 1e6:.2f}) mm has no "
f"drill diameter - cannot use it as a contact.")
pad_nm = _padstack_pad_nm(via)
r = max(pad_nm, drill) // 2
rect = Rect.normalized(x - r, y - r, x + r, y + r, "via")
return Electrode(
rect=rect, contact="all", label=f"via({x / 1e6:.1f},{y / 1e6:.1f})",
drill_nm=drill, pad_nm=pad_nm, center=(x, y),
barrel_z=(_padstack_span(via.padstack, stackup)
if stackup is not None else None))
# Pad
pad: Pad = item
contact = _pad_default_contact(pad)
net = pad.net.name if pad.net is not None else "?"
label = f"pad {pad.number}@{net}"
box = board.get_item_bounding_box(pad)
if box is None:
raise SelectionError(f"Could not get the bounding box of {label}.")
rect = _box2_to_rect(box, "pad")
drill = _pad_drill_nm(pad)
return Electrode(rect=rect, contact=contact,
polygons=_pad_polygons(board, pad, contact), label=label,
# through-hole pad: current enters at the soldered
# barrel; the joint is solder-filled + pad-coated,
# with a solder cone around the protruding lead
drill_nm=drill, pad_nm=_padstack_pad_nm(pad),
center=(pad.position.x, pad.position.y),
solder=drill > 0,
protrusion_side=(_tht_protrusion_side(pad, footprints)
if drill > 0 else None))
def _net_hint_of(items: list) -> str | None:
for item in items:
if item.net is not None:
return item.net.name
return None
def get_electrodes(board: Board, stackup: StackupInfo | None = None
) -> tuple[list[Electrode], list[Electrode], str | None]:
"""Terminals from the selection. Each terminal may have MULTIPLE parts
(all merged into one externally-bonded contact):
- rectangles on ELECTRODE_POS_LAYER -> V+ parts, on ELECTRODE_NEG_LAYER
-> V- parts; selected pads/vias fill a side that has no rectangles;
- no marker rectangles selected: legacy mode, exactly 2 items
(rects/pads/vias, any layer) -> one part each;
- empty selection: board-wide scan of both marker layers.
Selected vias and through-hole pads become BARREL contacts: current
enters at the drill-wall ring (the soldered lead/wire), not the pad
face. Draw a marker rectangle over the pad instead to model a probe
pressed onto the pad face.
"""
pos_l = config.ELECTRODE_POS_LAYER
neg_l = config.ELECTRODE_NEG_LAYER
scheme = (f"Draw V+ rectangle(s) on {pos_l} and V- rectangle(s) on "
f"{neg_l} (axis-aligned), and/or select pads/vias for a side "
f"without rectangles.")
selection = list(board.get_selection())
rects = [s for s in selection if isinstance(s, BoardRectangle)]
pads = [s for s in selection if isinstance(s, (Pad, Via))]
# protrusion-side lookup needs the owning footprints (THT pads only)
footprints = (board.get_footprints()
if any(isinstance(s, Pad) and _pad_drill_nm(s) > 0
for s in pads) else None)
if not selection:
allr = [s for s in board.get_shapes() if isinstance(s, BoardRectangle)]
pos = [r for r in allr if canonical_name(r.layer) == pos_l]
neg = [r for r in allr if canonical_name(r.layer) == neg_l]
if pos and neg:
print(f"selection empty - using {len(pos)} rectangle(s) on "
f"{pos_l} as V+ and {len(neg)} on {neg_l} as V-")
return ([_to_electrode(board, r) for r in pos],
[_to_electrode(board, r) for r in neg], None)
raise SelectionError(
f"Nothing selected, and the board-wide scan found "
f"{len(pos)} rectangle(s) on {pos_l} / {len(neg)} on {neg_l} "
f"(need at least one on each).\n{scheme}"
)
pos = [r for r in rects if canonical_name(r.layer) == pos_l]
neg = [r for r in rects if canonical_name(r.layer) == neg_l]
other = [r for r in rects if canonical_name(r.layer) not in (pos_l, neg_l)]
if pos or neg:
if other:
raise SelectionError(
f"{len(other)} selected rectangle(s) are on neither marker "
f"layer ({pos_l} = V+, {neg_l} = V-). {scheme}"
)
es1 = [_to_electrode(board, r) for r in pos]
es2 = [_to_electrode(board, r) for r in neg]
if pads and es1 and es2:
raise SelectionError(
f"Cannot assign the {len(pads)} selected pad(s)/via(s): both "
f"marker layers already provide rectangles. Use pads/vias "
f"only for a side that has none."
)
if pads:
pad_parts = [_to_electrode(board, p, stackup, footprints)
for p in pads]
if not es1:
es1 = pad_parts
else:
es2 = pad_parts
if es1 and es2:
return es1, es2, _net_hint_of(pads)
raise SelectionError(
f"Only one terminal defined: V+ has {len(es1)} and V- has "
f"{len(es2)} contact(s). {scheme}"
)
items = rects + pads
if len(items) == 2:
return ([_to_electrode(board, items[0], stackup, footprints)],
[_to_electrode(board, items[1], stackup, footprints)],
_net_hint_of(pads))
raise SelectionError(
f"The selection has {len(rects)} rectangle(s) (none on the marker "
f"layers) and {len(pads)} pad(s)/via(s); without marker layers "
f"exactly 2 contacts are needed.\n{scheme}"
)
# --- fills -------------------------------------------------------------------
def gather_net_fills(board: Board) -> dict[str, dict[str, list[Polygon]]]:
"""net -> layer_name -> merged fill polygons (non-empty only)."""
fills: dict[str, dict[str, list[Polygon]]] = {}
for zone in board.get_zones():
# teardrop fills are conducting copper too, but KiCad types them
# ZT_TEARDROP instead of ZT_COPPER
if zone.type not in (ZoneType.ZT_COPPER, ZoneType.ZT_TEARDROP):
continue
net = zone.net.name if zone.net is not None else "<no net>"
for layer, polys in zone.filled_polygons.items():
if not is_copper_layer(layer) or not polys:
continue
fills.setdefault(net, {}).setdefault(
canonical_name(layer), []).extend(
_convert_poly(p) for p in polys)
return fills
def gather_net_tracks(board: Board) -> dict[str, dict[str, list[TrackSeg]]]:
"""net -> layer -> TrackSeg (centerline + width). Traces conduct
together with the zone fills; the raster decides per run whether a
trace is rasterized from its outline or becomes a 1D chain."""
out: dict[str, dict[str, list[TrackSeg]]] = {}
for t in board.get_tracks():
if not is_copper_layer(t.layer):
continue
width = int(t.width or 0)
if width <= 0:
continue
if isinstance(t, ArcTrack):
pts = np.array([[t.start.x, t.start.y], [t.mid.x, t.mid.y],
[t.end.x, t.end.y]], dtype=np.int64)
else:
pts = np.array([[t.start.x, t.start.y], [t.end.x, t.end.y]],
dtype=np.int64)
net = t.net.name if t.net is not None else "<no net>"
layer = canonical_name(t.layer)
out.setdefault(net, {}).setdefault(layer, []).append(
TrackSeg(layer_name=layer, points=pts, width_nm=width))
return out
def tracks_as_polygons(tracks: dict) -> dict:
"""net -> layer -> outline polygons of the tracks (for the bbox-based
candidate detection; the Problem keeps the TrackSegs themselves)."""
return {
net: {layer: [Polygon(outline=seg.outline(ARC_TOL_NM))
for seg in segs]
for layer, segs in per_layer.items()}
for net, per_layer in tracks.items()
}
def merge_copper(fills: dict, tracks: dict) -> dict:
"""net -> layer -> fill + track polygons, for candidate detection
and the dialog's layer lists (build_problem merges the same way)."""
out: dict[str, dict[str, list[Polygon]]] = {}
for src in (fills, tracks):
for net, per_layer in src.items():
for layer, polys in per_layer.items():
out.setdefault(net, {}).setdefault(layer, []).extend(polys)
return out
def _rect_overlaps(rect: Rect, polygons: list[Polygon]) -> bool:
for p in polygons:
px0, py0 = p.outline.min(axis=0)
px1, py1 = p.outline.max(axis=0)
if rect.x0 <= px1 and rect.x1 >= px0 and rect.y0 <= py1 and rect.y1 >= py0:
return True
return False
def nets_overlapping(fills: dict, es1: list[Electrode],
es2: list[Electrode]) -> list[str]:
"""Nets whose fills overlap both terminals (any part, any layer each -
the connection may go through vias). Permissive bbox prefilter."""
out = []
for net, per_layer in fills.items():
hit1 = any(_rect_overlaps(e.rect, polys) for e in es1
for polys in per_layer.values())
hit2 = any(_rect_overlaps(e.rect, polys) for e in es2
for polys in per_layer.values())
if hit1 and hit2:
out.append(net)
return sorted(out)
def gather_mask_buildups(board: Board) -> dict[str, list[Polygon]]:
"""Zones on F.Mask/B.Mask (mask openings) -> fill polygons keyed by
the outer copper layer they expose."""
out: dict[str, list[Polygon]] = {}
for zone in board.get_zones():
try:
filled = zone.filled_polygons
except Exception:
continue
for layer, polys in filled.items():
copper = MASK_TO_COPPER.get(canonical_name(layer))
if copper and polys:
out.setdefault(copper, []).extend(
_convert_poly(p) for p in polys)
return out
def any_zone_unfilled(board: Board) -> bool:
return any(z.type in (ZoneType.ZT_COPPER, ZoneType.ZT_TEARDROP)
and not z.filled for z in board.get_zones())
def refill(board: Board) -> None:
print("refilling zones - this modifies the open document ...")
board.refill_zones(block=True)
# --- barrels -----------------------------------------------------------------
def _padstack_pad_nm(item) -> int:
"""Largest copper pad diameter of a via/pad padstack; 0 if unknown.
Used to bound the barrel-to-fill connection search in the solver."""
try:
sizes = [max(int(l.size.x), int(l.size.y))
for l in item.padstack.copper_layers]
return max(sizes) if sizes else 0
except Exception:
return 0
def _padstack_span(padstack, stackup: StackupInfo) -> tuple[int, int]:
"""(z_top, z_bot) of the barrel; falls back to the full stack."""
try:
copper = [canonical_name(l) for l in padstack.layers
if is_copper_layer(l)]
zs = [stackup.z_nm[c] for c in copper if c in stackup.z_nm]
if len(zs) >= 2:
return min(zs) - 1, max(zs) + 1
except Exception:
pass
return -1, stackup.z_bot_nm + 1
def gather_barrels(board: Board, net_name: str,
stackup: StackupInfo) -> list[ViaLink]:
barrels = []
for via in board.get_vias():
if via.net is None or via.net.name != net_name:
continue
drill = int(via.drill_diameter or 0) or _pad_drill_nm(via)
if drill <= 0:
continue
z_top, z_bot = _padstack_span(via.padstack, stackup)
barrels.append(ViaLink(x=via.position.x, y=via.position.y,
drill_nm=drill, z_top_nm=z_top,
z_bot_nm=z_bot, kind="via",
pad_nm=_padstack_pad_nm(via)))
if config.INCLUDE_TH_PADS:
for pad in board.get_pads():
if pad.net is None or pad.net.name != net_name:
continue
drill = _pad_drill_nm(pad)
if drill <= 0:
continue
barrels.append(ViaLink(x=pad.position.x, y=pad.position.y,
drill_nm=drill, z_top_nm=-1,
z_bot_nm=stackup.z_bot_nm + 1, kind="pad",
pad_nm=_padstack_pad_nm(pad)))
return barrels
# --- top level ----------------------------------------------------------------
def build_problem(board: Board, net: str, layer_names: list[str],
es1: list[Electrode], es2: list[Electrode],
stackup: StackupInfo, fills: dict,
buildups: dict[str, list[Polygon]] | None = None,
extra_cu_um: float | None = None,
tracks: dict | None = None,
vias_capped: bool | None = None,
cap_max_drill_mm: float | None = None) -> Problem:
per_layer = fills.get(net, {})
per_layer_tracks = (tracks or {}).get(net, {})
layers = []
segs: list[TrackSeg] = []
for name in stackup.names: # keep stackup order
if name not in layer_names:
continue
polys = list(per_layer.get(name, []))
layer_segs = per_layer_tracks.get(name, [])
if not polys and not layer_segs:
print(f"note: net {net} has no copper on {name} - layer skipped")
continue
if config.COPPER_THICKNESS_UM is not None:
t = int(config.COPPER_THICKNESS_UM * 1000)
else:
t = stackup.thickness_nm[name]
layers.append(LayerFill(layer_name=name, thickness_nm=t,
z_nm=stackup.z_nm[name], polygons=polys))
segs.extend(layer_segs)
if not layers:
raise CandidateError(
f"Net {net} has no fill on any of the selected layers "
f"({', '.join(layer_names)})."
)
vias = gather_barrels(board, net, stackup) if len(layers) > 1 else []
included = {l.layer_name for l in layers}
buildup_list = [
SurfaceBuildup(layer_name=name, polygons=polys)
for name, polys in (buildups or {}).items() if name in included
]
print(f"net {net}: {len(layers)} layer(s) "
f"({', '.join(l.layer_name for l in layers)}), "
f"{len(segs)} track(s), {len(vias)} via/pad barrel(s)"
+ (f", solder buildup on "
f"{', '.join(b.layer_name for b in buildup_list)}"
if buildup_list else ""))
problem = Problem(
board_path=board.name or "",
net_name=net,
rho_ohm_m=config.RHO_CU_OHM_M,
plating_nm=int(config.VIA_PLATING_UM * 1000),
layers=layers,
vias=vias,
electrodes1=es1,
electrodes2=es2,
thickness_source=("override" if config.COPPER_THICKNESS_UM is not None
else "stackup"),
buildups=buildup_list,
solder_thickness_nm=int(config.SOLDER_THICKNESS_UM * 1000),
solder_rho_ohm_m=config.SOLDER_RHO_OHM_M,
extra_cu_nm=int((extra_cu_um if extra_cu_um is not None
else config.BUILDUP_EXTRA_CU_UM) * 1000),
tracks=segs,
vias_capped=(vias_capped if vias_capped is not None
else config.VIAS_CAPPED),
cap_plating_nm=int(config.CAP_PLATING_UM * 1000),
cap_max_drill_nm=int((cap_max_drill_mm if cap_max_drill_mm is not None
else config.CAP_MAX_DRILL_MM) * 1e6),
tht_protrusion_nm=int(config.THT_LEAD_PROTRUSION_MM * 1e6),
)
solder_layers = contact_solder_buildups(problem)
if solder_layers:
sides = sorted({e.protrusion_side
for e in problem.electrodes1 + problem.electrodes2
if e.solder and e.protrusion_side})
cone = (f", {config.THT_LEAD_PROTRUSION_MM:g} mm lead + solder cone "
f"on {', '.join(sides)}"
if sides and problem.tht_protrusion_nm > 0 else "")
print(f"THT contact(s): solder-filled hole + "
f"{config.SOLDER_THICKNESS_UM:g} um average solder coat on the "
f"pad face ({', '.join(solder_layers)}){cone}")
return problem
if __name__ == "__main__":
import sys
from .geometry import save_problem
out = Path(sys.argv[1]) if len(sys.argv) > 1 else Path("geometry_dump.json")
_, board = connect()
stackup = get_stackup_info(board)
es1, es2, net_hint = get_electrodes(board, stackup)
if any_zone_unfilled(board):
refill(board)
fills = gather_net_fills(board)
tracks = gather_net_tracks(board) if config.INCLUDE_TRACKS else {}
copper = merge_copper(fills, tracks_as_polygons(tracks))
nets = nets_overlapping(copper, es1, es2)
if len(sys.argv) > 2:
net = sys.argv[2]
elif net_hint in nets:
net = net_hint
elif len(nets) == 1:
net = nets[0]
else:
print(f"candidate nets: {nets}; pass one as second argument")
sys.exit(1)
problem = build_problem(board, net, list(copper.get(net, {})), es1, es2,
stackup, fills, tracks=tracks)
save_problem(problem, out)
print(f"wrote {out}")