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kicad-zone-resistance/fill_resistance/raster.py
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janik 4ff729e192
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Barrel contacts for vias/THT pads; configurable cap-drill threshold
- Selected vias and through-hole pads inject at the drill-wall ring on
  every spanned layer (both contact models), not the whole pad face,
  so the pad/pour spreading resistance is part of the result. Vias are
  now selectable as contacts.
- Soldered THT joints: the hole is modeled solder-filled (core in
  parallel with the plating, also for stitching THT barrels) and the
  pad face carries an average-thickness solder coat over the modeled
  copper (SOLDER_THICKNESS_UM).
- Vias with drills above a configurable threshold (dialog field,
  default CAP_MAX_DRILL_MM = 0.5) keep open mouths even with capping
  selected - the fab caps only small vias.
- Geometry dump schema v6: electrode barrel fields, cap_max_drill_nm.
- Verified against R = rho/(pi t)*acosh(d/2a) for two circular contacts
  on a sheet (+2.6% at h = 0.15 mm, a = 1 mm; uniform model above the
  equipotential one as required by the contact bracket).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-16 18:28:47 +07:00

530 lines
22 KiB
Python

"""Rasterization of the fill polygons onto a shared multi-layer grid, and
electrode mask construction.
Grid convention: layer l, row i, col j maps to the cell center
x = x0_nm + (j + 0.5) * h_nm
y = y0_nm + (i + 0.5) * h_nm
in KiCad board coordinates (y grows down). Row 0 is the minimum-y row,
the TOP of the board as drawn in the editor; plots use origin='upper'.
All layers share the same frame, so cell (i, j) is vertically aligned
across layers (via links connect equal (i, j) on different layers).
Connectivity restriction lives in solver.py: it needs the via edges.
"""
from __future__ import annotations
import math
from dataclasses import dataclass
import numpy as np
from matplotlib.path import Path as MplPath
from PIL import Image, ImageDraw
from scipy import ndimage
from . import config
from .errors import ElectrodeError, GridSizeError
from .geometry import Electrode, Problem, Rect
# 4-connectivity: matches the in-plane 5-point stencil of the solver
_STRUCT4 = ndimage.generate_binary_structure(2, 1)
@dataclass
class RasterStack:
masks: np.ndarray # bool (L, ny, nx), True = copper
x0_nm: float # grid origin (outer corner of cell [., 0, 0])
y0_nm: float
h_nm: float
layer_names: list[str]
buildup: np.ndarray | None = None # bool (L, ny, nx): solder buildup
# (mask opening ∩ copper)
chain: np.ndarray | None = None # bool (L, ny, nx): cells that are
# copper only through a 1D trace chain
chain_edges: tuple | None = None # (a, b, g_dc, layer, dl_m) arrays:
# explicit DC conductances and link
# lengths of the chain links
thick_scale: np.ndarray | None = None # float (L, ny, nx): per-cell
# copper-thickness factor (via
# mouths: cap-thin or partially
# drilled cells); None = all 1
mesh: np.ndarray | None = None # bool (L, ny, nx): adaptive leaf
# boundaries (drawn on the raster map)
@property
def nlayers(self) -> int:
return self.masks.shape[0]
@property
def shape2d(self) -> tuple[int, int]:
return self.masks.shape[1:]
def cell_centers(self, i0: int, i1: int, j0: int, j1: int):
xs = self.x0_nm + (np.arange(j0, j1) + 0.5) * self.h_nm
ys = self.y0_nm + (np.arange(i0, i1) + 0.5) * self.h_nm
return np.meshgrid(xs, ys)
def cell_of(self, x_nm: float, y_nm: float) -> tuple[int, int] | None:
"""(i, j) of the cell containing the point, or None if outside."""
ny, nx = self.shape2d
j = math.floor((x_nm - self.x0_nm) / self.h_nm)
i = math.floor((y_nm - self.y0_nm) / self.h_nm)
if 0 <= i < ny and 0 <= j < nx:
return i, j
return None
def extent_mm(self) -> tuple[float, float, float, float]:
"""imshow extent (left, right, bottom, top) for origin='upper',
y axis in board orientation (increasing downward)."""
ny, nx = self.shape2d
return (
self.x0_nm * 1e-6,
(self.x0_nm + nx * self.h_nm) * 1e-6,
(self.y0_nm + ny * self.h_nm) * 1e-6,
self.y0_nm * 1e-6,
)
def choose_cell_size(bbox_nm: tuple[int, int, int, int], nlayers: int) -> float:
"""Pick the cell size h [nm]; TARGET_CELLS counts TOTAL cells across
all layers. Raise if the grid would exceed HARD_MAX_CELLS."""
x0, y0, x1, y1 = bbox_nm
w, ht = float(x1 - x0), float(y1 - y0)
if w <= 0 or ht <= 0:
raise GridSizeError("Copper geometry has a degenerate bounding box.")
if config.CELL_UM_OVERRIDE is not None:
if config.CELL_UM_OVERRIDE <= 0:
raise GridSizeError(
f"Cell size must be positive "
f"(got {config.CELL_UM_OVERRIDE:g} um)."
)
h = config.CELL_UM_OVERRIDE * 1000.0
else:
# the adaptive grid decouples unknowns from the fine cell count,
# so its auto sizing affords a larger fine-cell budget (finer h)
target = (config.TARGET_CELLS_ADAPTIVE if config.ADAPTIVE_CELLS
else config.TARGET_CELLS)
h = math.sqrt(w * ht * nlayers / target)
h = min(max(h, config.MIN_CELL_UM * 1000.0), config.MAX_CELL_UM * 1000.0)
ncells = math.ceil(w / h) * math.ceil(ht / h) * nlayers
if ncells > config.HARD_MAX_CELLS:
raise GridSizeError(
f"Grid would need ~{ncells / 1e6:.1f} M cells over {nlayers} "
f"layer(s) at cell size {h / 1000:.0f} um (limit "
f"{config.HARD_MAX_CELLS / 1e6:.0f} M). Raise MAX_CELL_UM / "
f"CELL_UM_OVERRIDE in config.py, deselect layers, or measure a "
f"smaller region."
)
return h
def _paint_ring(stack: RasterStack, ring: np.ndarray, value: bool,
target: np.ndarray) -> None:
"""Set target (2D) cells whose center lies inside ring to `value`,
working only within the ring's bbox. Hybrid rasterizer: PIL scanline
fill for the bulk (fast, O(vertices + cells)), then the cells within
a ~2 px band around the ring edge are re-tested exactly against the
polygon, so the result is identical to a pure center-in-polygon pass."""
ny, nx = stack.shape2d
h = stack.h_nm
j0 = max(0, int((ring[:, 0].min() - stack.x0_nm) / h) - 1)
j1 = min(nx, int((ring[:, 0].max() - stack.x0_nm) / h) + 2)
i0 = max(0, int((ring[:, 1].min() - stack.y0_nm) / h) - 1)
i1 = min(ny, int((ring[:, 1].max() - stack.y0_nm) / h) + 2)
if i0 >= i1 or j0 >= j1:
return
w, ht = j1 - j0, i1 - i0
# cell (i, j) center <-> pixel (j - j0, i - i0)
px = (ring[:, 0] - stack.x0_nm) / h - 0.5 - j0
py = (ring[:, 1] - stack.y0_nm) / h - 0.5 - i0
pts = list(zip(px.tolist(), py.tolist()))
inside = np.zeros((ht, w), dtype=bool)
band = np.ones((ht, w), dtype=bool)
if len(pts) >= 3:
fill_img = Image.new("1", (w, ht), 0)
ImageDraw.Draw(fill_img).polygon(pts, fill=1)
inside = np.array(fill_img, dtype=bool)
band_img = Image.new("1", (w, ht), 0)
ImageDraw.Draw(band_img).line(pts + pts[:1], fill=1, width=5,
joint="curve")
band = np.array(band_img, dtype=bool)
bi, bj = np.nonzero(band)
if len(bi):
xs = stack.x0_nm + (bj + j0 + 0.5) * h
ys = stack.y0_nm + (bi + i0 + 0.5) * h
# Path(closed=True) treats the LAST vertex as the CLOSEPOLY dummy,
# so the first vertex must be appended or the ring loses its last
# corner
verts = np.vstack([ring, ring[:1]])
inside[bi, bj] = MplPath(verts, closed=True).contains_points(
np.column_stack([xs, ys]))
sub = target[i0:i1, j0:j1]
sub[inside] = value
def rasterize_stack(problem: Problem, h_nm: float) -> RasterStack:
"""Rasterize every included layer onto one shared frame."""
x0, y0, x1, y1 = problem.copper_bbox()
m = config.MARGIN_CELLS
nx = math.ceil((x1 - x0) / h_nm) + 2 * m
ny = math.ceil((y1 - y0) / h_nm) + 2 * m
stack = RasterStack(
masks=np.zeros((len(problem.layers), ny, nx), dtype=bool),
x0_nm=x0 - m * h_nm,
y0_nm=y0 - m * h_nm,
h_nm=h_nm,
layer_names=problem.layer_names,
)
for li, layer in enumerate(problem.layers):
for poly in layer.polygons:
if poly.holes:
pmask = np.zeros((ny, nx), dtype=bool)
_paint_ring(stack, poly.outline, True, pmask)
for hole in poly.holes:
_paint_ring(stack, hole, False, pmask)
stack.masks[li] |= pmask
else:
# hole-less (e.g. a track outline): paint the layer mask
# directly, skipping the full-frame temp
_paint_ring(stack, poly.outline, True, stack.masks[li])
# via ring/pad copper BEFORE tracks, so 1D chains see it as regular
# copper; drill mouths AFTER tracks, so drills go through trace copper
_paint_via_rings(stack, problem)
# traces: wide ones are rasterized from their outline, sub-resolution
# ones become exact 1D resistor chains along their centerline
index = {name: li for li, name in enumerate(stack.layer_names)}
narrow = []
for seg in problem.tracks:
li = index.get(seg.layer_name)
if li is None:
continue
if seg.width_nm >= config.TRACK_1D_FACTOR * h_nm:
_paint_ring(stack, seg.outline(config.ARC_TOL_FRACTION * h_nm),
True, stack.masks[li])
else:
narrow.append((li, seg))
if narrow:
n_links = _build_chains(stack, problem, narrow)
print(f"{len(narrow)} trace(s) narrower than "
f"{config.TRACK_1D_FACTOR:g} cells modeled as 1D resistor "
f"chains ({n_links} links)")
_apply_via_mouths(stack, problem)
if problem.buildups:
stack.buildup = np.zeros_like(stack.masks)
index = {name: li for li, name in enumerate(stack.layer_names)}
for b in problem.buildups:
li = index.get(b.layer_name)
if li is None:
continue
for poly in b.polygons:
pmask = np.zeros((ny, nx), dtype=bool)
_paint_ring(stack, poly.outline, True, pmask)
for hole in poly.holes:
_paint_ring(stack, hole, False, pmask)
stack.buildup[li] |= pmask
stack.buildup &= stack.masks # solder wets exposed copper only
return stack
def _via_span(problem: Problem, via) -> list[int]:
return [li for li, layer in enumerate(problem.layers)
if via.spans(layer.z_nm)]
def _paint_via_rings(stack: RasterStack, problem: Problem) -> None:
"""Annular-ring / via-pad copper: a full-thickness disc of the pad
diameter on every layer the barrel spans (kind='via' only - THT pad
copper stays outside the model). The drill mouth re-opens the disc
center in _apply_via_mouths."""
ny, nx = stack.shape2d
h = stack.h_nm
for via in problem.vias:
if via.kind != "via" or via.pad_nm <= 0:
continue
r = via.pad_nm / 2.0
j0 = max(0, math.floor((via.x - r - stack.x0_nm) / h))
j1 = min(nx, math.floor((via.x + r - stack.x0_nm) / h) + 1)
i0 = max(0, math.floor((via.y - r - stack.y0_nm) / h))
i1 = min(ny, math.floor((via.y + r - stack.y0_nm) / h) + 1)
if i0 >= i1 or j0 >= j1:
continue
xs = stack.x0_nm + (np.arange(j0, j1) + 0.5) * h - via.x
ys = stack.y0_nm + (np.arange(i0, i1) + 0.5) * h - via.y
disc = (ys[:, None] ** 2 + xs[None, :] ** 2) <= r * r
for li in _via_span(problem, via):
stack.masks[li, i0:i1, j0:j1] |= disc
def _apply_via_mouths(stack: RasterStack, problem: Problem) -> None:
"""Drill-mouth treatment, area-weighted per cell (4x4 supersampling):
capped vias carry a cap_plating-thin copper cap over the mouth on the
OUTER layers, uncapped vias (and inner layers either way) get an open
hole. The fab caps only small vias: drills above cap_max_drill_nm
stay open even with vias_capped. Fully swallowed cells leave the
mask; partially covered cells keep a thickness-scaled sheet
conductance via stack.thick_scale."""
ny, nx = stack.shape2d
h = stack.h_nm
outer = {li for li, n in enumerate(stack.layer_names)
if n in ("F.Cu", "B.Cu")}
sub = (np.arange(4) + 0.5) / 4.0
for via in problem.vias:
if via.kind != "via" or via.drill_nm <= 0:
continue
r = via.drill_nm / 2.0
j0 = max(0, math.floor((via.x - r - stack.x0_nm) / h))
j1 = min(nx, math.floor((via.x + r - stack.x0_nm) / h) + 1)
i0 = max(0, math.floor((via.y - r - stack.y0_nm) / h))
i1 = min(ny, math.floor((via.y + r - stack.y0_nm) / h) + 1)
if i0 >= i1 or j0 >= j1:
continue
xs = stack.x0_nm + (np.arange(j0, j1)[:, None] + sub[None, :]) * h \
- via.x
ys = stack.y0_nm + (np.arange(i0, i1)[:, None] + sub[None, :]) * h \
- via.y
cov = ((ys[:, None, :, None] ** 2 + xs[None, :, None, :] ** 2)
<= r * r).mean(axis=(2, 3))
if not (cov > 0).any():
continue # mouth far smaller than h
if stack.thick_scale is None:
stack.thick_scale = np.ones(stack.masks.shape)
for li in _via_span(problem, via):
if problem.vias_capped and li in outer \
and via.drill_nm <= problem.cap_max_drill_nm:
ratio = min(problem.cap_plating_nm
/ problem.layers[li].thickness_nm, 1.0)
else:
ratio = 0.0
s = 1.0 - cov * (1.0 - ratio)
gone = s <= 1e-9
stack.masks[li, i0:i1, j0:j1] &= ~gone
stack.thick_scale[li, i0:i1, j0:j1] *= np.where(gone, 1.0, s)
def _build_chains(stack: RasterStack, problem: Problem,
narrow: list) -> int:
"""Sub-resolution traces as 1D resistor chains: mark the cells their
centerline crosses as copper and record one explicit conductance per
pair of consecutive cells, allocating the trace's TRUE arc length to
each link (a diagonal trace is not staircase-inflated). Links whose
cells are already regular copper AND face-adjacent are skipped there
(the trace merges into the pour: union, not sum). Returns the number
of links."""
L, ny, nx = stack.masks.shape
plane = ny * nx
h = stack.h_nm
regular = stack.masks.copy()
chain = np.zeros_like(stack.masks)
aa, bb, gg, ll, dd = [], [], [], [], []
for li, seg in narrow:
pts = seg.centerline(0.2 * h)
d = np.hypot(*np.diff(pts, axis=0).T)
s = np.concatenate([[0.0], np.cumsum(d)])
length = float(s[-1])
n_samp = max(2, int(math.ceil(length / (h / 3.0))) + 1)
ss = np.linspace(0.0, length, n_samp)
xs = np.interp(ss, s, pts[:, 0])
ys = np.interp(ss, s, pts[:, 1])
jj = np.floor((xs - stack.x0_nm) / h).astype(np.int64)
ii = np.floor((ys - stack.y0_nm) / h).astype(np.int64)
jj = np.clip(jj, 0, nx - 1) # bbox includes all tracks;
ii = np.clip(ii, 0, ny - 1) # clip only guards rounding
first = np.concatenate(
[[True], (ii[1:] != ii[:-1]) | (jj[1:] != jj[:-1])])
ci, cj, cs = ii[first], jj[first], ss[first]
chain[li, ci, cj] = True
g0 = (seg.width_nm * 1e-9
* problem.layers[li].thickness_nm * 1e-9 / problem.rho_ohm_m)
for k in range(len(ci) - 1):
dl = (cs[k + 1] - cs[k]) * 1e-9
if dl <= 0:
continue
adj4 = abs(int(ci[k + 1] - ci[k])) + abs(int(cj[k + 1] - cj[k])) == 1
if adj4 and regular[li, ci[k], cj[k]] \
and regular[li, ci[k + 1], cj[k + 1]]:
continue # pour conducts here already
aa.append(li * plane + int(ci[k]) * nx + int(cj[k]))
bb.append(li * plane + int(ci[k + 1]) * nx + int(cj[k + 1]))
gg.append(g0 / dl)
ll.append(li)
dd.append(dl)
stack.chain = chain & ~regular
stack.masks |= stack.chain
stack.chain_edges = (np.asarray(aa, dtype=np.int64),
np.asarray(bb, dtype=np.int64),
np.asarray(gg, dtype=float),
np.asarray(ll, dtype=np.int64),
np.asarray(dd, dtype=float))
return len(aa)
def _rect_cells(stack: RasterStack, rect: Rect) -> np.ndarray:
"""Bool (ny, nx) mask of cells whose center lies inside the rectangle."""
ny, nx = stack.shape2d
h = stack.h_nm
out = np.zeros((ny, nx), dtype=bool)
j0 = max(0, int(math.ceil((rect.x0 - stack.x0_nm) / h - 0.5)))
j1 = min(nx, int(math.floor((rect.x1 - stack.x0_nm) / h - 0.5)) + 1)
i0 = max(0, int(math.ceil((rect.y0 - stack.y0_nm) / h - 0.5)))
i1 = min(ny, int(math.floor((rect.y1 - stack.y0_nm) / h - 0.5)) + 1)
if i0 < i1 and j0 < j1:
out[i0:i1, j0:j1] = True
return out
def _electrode_cells2d(stack: RasterStack, e: Electrode) -> np.ndarray:
"""2D footprint of the electrode shape (pad polygons or rectangle)."""
if e.polygons:
cells = np.zeros(stack.shape2d, dtype=bool)
for poly in e.polygons:
pm = np.zeros(stack.shape2d, dtype=bool)
_paint_ring(stack, poly.outline, True, pm)
for hole in poly.holes:
_paint_ring(stack, hole, False, pm)
cells |= pm
if not cells.any():
# shape smaller than one grid cell (small pad): use the cell
# containing its center
r = e.rect
c = stack.cell_of((r.x0 + r.x1) / 2, (r.y0 + r.y1) / 2)
if c is not None:
cells[c] = True
return cells
return _rect_cells(stack, e.rect)
def _barrel_ring2d(stack: RasterStack, e: Electrode,
mask2d: np.ndarray) -> np.ndarray:
"""Contact cells of a barrel electrode on one layer: the copper ring
at the drill wall (cell centers within one cell of radius drill/2),
where the lead/wire soldered into the hole actually meets the layer.
If rasterization or an antipad leaves no copper there, fall back to
the nearest copper ring within the pad footprint (+1 cell of slop) -
the same search bound as the solver's barrel attachment."""
ny, nx = stack.shape2d
h = stack.h_nm
if e.center is not None:
x, y = e.center
else:
x = (e.rect.x0 + e.rect.x1) / 2.0
y = (e.rect.y0 + e.rect.y1) / 2.0
r = e.drill_nm / 2.0
rw = max(e.pad_nm, e.drill_nm + 300_000) / 2.0 + h
out = np.zeros((ny, nx), dtype=bool)
j0 = max(0, math.floor((x - rw - stack.x0_nm) / h))
j1 = min(nx, math.floor((x + rw - stack.x0_nm) / h) + 1)
i0 = max(0, math.floor((y - rw - stack.y0_nm) / h))
i1 = min(ny, math.floor((y + rw - stack.y0_nm) / h) + 1)
if i0 >= i1 or j0 >= j1:
return out
xs = stack.x0_nm + (np.arange(j0, j1) + 0.5) * h - x
ys = stack.y0_nm + (np.arange(i0, i1) + 0.5) * h - y
d = np.sqrt(ys[:, None] ** 2 + xs[None, :] ** 2)
m = mask2d[i0:i1, j0:j1]
ring = m & (np.abs(d - r) <= h)
if not ring.any():
dc = np.where(m & (d <= rw), d, np.inf)
dmin = dc.min()
if np.isfinite(dmin):
ring = dc <= dmin + h # e.g. thermal-spoke tips
out[i0:i1, j0:j1] = ring
return out
def _part_mask3d(stack: RasterStack, problem: Problem,
el: Electrode) -> np.ndarray:
"""(L, ny, nx) contact cells of one electrode part: the barrel-wall
ring on every spanned layer for via/THT-pad contacts, else the
part's shape ∩ copper on its contact layer(s)."""
part = np.zeros_like(stack.masks)
if el.drill_nm > 0:
for li, name in enumerate(stack.layer_names):
if el.contact not in ("all", name):
continue
if el.barrel_z is not None:
z = problem.layers[li].z_nm
if not (el.barrel_z[0] - 1 <= z <= el.barrel_z[1] + 1):
continue
part[li] = _barrel_ring2d(stack, el, stack.masks[li])
return part
cells2d = _electrode_cells2d(stack, el)
for li, name in enumerate(stack.layer_names):
if el.contact in ("all", name):
part[li] = cells2d & stack.masks[li]
return part
def electrode_masks(stack: RasterStack, problem: Problem
) -> tuple[np.ndarray, np.ndarray]:
"""Terminal mask = OR over its parts; part = shape ∩ copper on the
part's contact layer(s), or the barrel-wall ring for via/THT-pad
contacts (current enters through the soldered barrel, not the pad
face). contact 'all' = every included layer (bolted lug / through
pad); a layer name = that layer only. Every part must individually
land on copper (clear feedback). V+/V- must not overlap; touching is
checked later, only for the equipotential contact model."""
def build(parts: list[Electrode], which: str) -> np.ndarray:
e = np.zeros_like(stack.masks)
for el in parts:
part = _part_mask3d(stack, problem, el)
if not part.any():
where = ("near its barrel (drill-wall ring / pad footprint)"
if el.drill_nm > 0 else
"(or is smaller than one grid cell)")
raise ElectrodeError(
f"A {which} contact part ({el.label}) does not overlap "
f"any copper of the selected fill on contact layer(s) "
f"'{el.contact}' {where}."
)
e |= part
if not e.any():
raise ElectrodeError(f"The {which} terminal has no contact parts.")
return e
e1 = build(problem.electrodes1, "V+")
e2 = build(problem.electrodes2, "V-")
if (e1 & e2).any():
raise ElectrodeError(
"The V+ and V- contact areas overlap on the copper grid. "
"Move them apart."
)
return e1, e2
def electrode_partition(stack: RasterStack, problem: Problem
) -> tuple[list, list]:
"""Per-part cell masks for both terminals, as [(label, mask3d), ...].
Cells covered by several overlapping parts are attributed to the
FIRST part (first-wins partition), so part currents sum exactly to
the terminal current."""
def build(parts: list[Electrode]) -> list:
out = []
claimed = np.zeros_like(stack.masks)
for el in parts:
m = _part_mask3d(stack, problem, el)
m &= ~claimed
claimed |= m
out.append((el.label, m))
return out
return build(problem.electrodes1), build(problem.electrodes2)
def electrodes_touch(stack: RasterStack, e1: np.ndarray,
e2: np.ndarray) -> str | None:
"""Layer name where the terminals are 4-adjacent, or None."""
for li in range(stack.nlayers):
if (ndimage.binary_dilation(e1[li], structure=_STRUCT4) & e2[li]).any():
return stack.layer_names[li]
return None