Initial import: KiCad zone resistance plugin

DC/AC resistance, power dissipation, and via/injection-area currents of copper zone fills. KiCad 10 IPC-API plugin (kicad-python/kipy): multi-layer via-coupled FDM solver, multi-part terminals via User.1/User.2 marker layers, pads as contacts, uniform-injection and equipotential contact models, per-foil skin effect, optional solder/copper buildup on mask openings. 54-case test suite incl. exact analytic references. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-14 17:22:00 +07:00
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+"""All tunable constants. v1 has no GUI dialog: edit here, re-run.
+
+A future version may read overrides from <project>/fill_res_config.json.
+"""
+
+# --- Grid sizing ---
+# Benchmarked on the VOUT+ plane (147x59 mm): R changes < 0.3% from
+# 150 um cells down to 50 um; 1.7M unknowns direct-solve in ~17 s
+# (raster ~20 s). Accuracy is feature-limited (slots/necks narrower than
+# one cell), not plane-limited - override CELL_UM_OVERRIDE for boards
+# with sub-cell slots.
+TARGET_CELLS = 2_000_000        # auto cell size aims for roughly this many cells
+HARD_MAX_CELLS = 16_000_000     # abort above this (see GridSizeError message)
+MIN_CELL_UM = 25.0              # clamp for auto cell size
+MAX_CELL_UM = 500.0
+CELL_UM_OVERRIDE: float | None = None   # force a cell size, bypasses auto (not HARD_MAX)
+MARGIN_CELLS = 2                # empty guard cells around the copper bbox
+
+# --- Physics ---
+RHO_CU_OHM_M = 1.68e-8          # copper resistivity at 20 degC
+COPPER_THICKNESS_UM: float | None = None  # None -> stackup, fallback 35.0 with warning
+FALLBACK_THICKNESS_UM = 35.0
+TEST_CURRENT_A = 1.0            # default injected current (dialog/CLI-selectable)
+VIA_PLATING_UM = 18.0           # barrel plating thickness (always plated).
+                                # Capped vs uncapped vias do not change the
+                                # layer-to-layer DC path: the >=5um cap sits
+                                # over the hole mouth in parallel with the
+                                # annular-ring contact, not in series.
+INCLUDE_TH_PADS = True          # plated through-hole pads stitch layers too
+SKIN_SIDES = 1                  # skin-effect field config: 1 = plane facing a
+                                # return plane (conservative), 2 = isolated foil
+
+# --- Solder / mask-opening buildup ---
+INCLUDE_MASK_BUILDUP = False    # OFF by default; dialog-toggleable. Zones on
+                                # F.Mask/B.Mask = mask openings that collect
+                                # solder on the pour underneath
+SOLDER_THICKNESS_UM = 50.0      # solder height over opened copper
+SOLDER_RHO_OHM_M = 1.32e-7      # SAC305, ~7.9x copper
+BUILDUP_EXTRA_CU_UM = 0.0       # optional user-added copper (busbar/wire
+                                # soldered into the opening); dialog-settable
+
+# --- Zone / layer selection ---
+LAYER_HINT: str | None = None   # e.g. "F.Cu" to disambiguate candidate fills
+ELECTRODE_POS_LAYER = "User.1"  # rectangles on this layer mark V+ contact parts
+ELECTRODE_NEG_LAYER = "User.2"  # rectangles on this layer mark V- contact parts
+ALWAYS_REFILL = False           # refill zones even if KiCad says they are filled
+
+# --- Solver ---
+CONTACT_MODEL = "uniform"       # "uniform": conductor pressed on top injects
+                                # orthogonally with uniform surface density
+                                # (J ramps across the contact); "equipotential":
+                                # ideal bonded lug (Dirichlet). The two bracket
+                                # a real contact: R_equi <= R_real <= R_uniform.
+SPSOLVE_MAX_UNKNOWNS = 2_500_000  # above this, use CG (Jacobi) instead of
+                                  # direct solve (measured: direct is ~14x
+                                  # faster at 1.7M unknowns, ~3 GB peak)
+CG_TOL = 1e-8
+CG_MAXITER = 50_000             # CG iterations are cheap; large grids need many
+
+# --- Geometry ---
+ARC_TOL_FRACTION = 0.5          # arc sagitta tolerance as a fraction of cell size
+
+# --- Plots / output ---
+CMAP_POTENTIAL = "viridis"
+CMAP_CURRENT = "inferno"
+CMAP_POWER = "magma"
+POWER_DYNAMIC_RANGE = 1e4       # LogNorm span for the power map (power ~ J^2)
+LOG_CURRENT_SCALE = True
+CURRENT_DYNAMIC_RANGE = 1e3     # LogNorm vmin = vmax / this
+DPI = 150
+INTERACTIVE = True              # False -> save PNGs only, never open windows
+OUTPUT_DIRNAME = "fill_res_results"