fix(lga): prevent corner pad overlap with derived body size

src/fn/lga.ts

@@ -51,8 +51,20 @@ export const lga = (
     )
   }
 
-  const width = parameters.w ?? (grid.y - 1) * parameters.p + 2 * parameters.pl
-  const height = parameters.h ?? (grid.x - 1) * parameters.p + 2 * parameters.pl
+  // The default body size must leave room for the pads on the perpendicular
+  // sides: without the corner allowance, the inner edge of the left/right
+  // pads lands exactly on the center line of the outermost top/bottom pads
+  // (and vice versa), so corner pads overlap. Only needed when pads exist on
+  // adjacent sides.
+  const cornerPadClearance = 0.2
+  const cornerAllowance =
+    grid.x > 0 && grid.y > 0 ? parameters.pw + 2 * cornerPadClearance : 0
+  const width =
+    parameters.w ??
+    (grid.y - 1) * parameters.p + 2 * parameters.pl + cornerAllowance
+  const height =
+    parameters.h ??
+    (grid.x - 1) * parameters.p + 2 * parameters.pl + cornerAllowance
   const leftRightX = (width - parameters.pl) / 2
   const topBottomY = (height - parameters.pl) / 2
   const pads: AnyCircuitElement[] = []

tests/lga.test.ts

@@ -63,3 +63,34 @@ test("lga rejects a side grid that does not match its pad count", () => {
     "requires 16 pads, got 14",
   )
 })
+
+const getMinPadToPadClearance = (footprint: string) => {
+  const pads = getPads(footprint)
+  let minClearance = Number.POSITIVE_INFINITY
+  for (let i = 0; i < pads.length; i++) {
+    for (let j = i + 1; j < pads.length; j++) {
+      const a = pads[i]
+      const b = pads[j]
+      if (!a || !b) continue
+      const dx = Math.max(0, Math.abs(a.x - b.x) - (a.width + b.width) / 2)
+      const dy = Math.max(0, Math.abs(a.y - b.y) - (a.height + b.height) / 2)
+      minClearance = Math.min(minClearance, Math.hypot(dx, dy))
+    }
+  }
+  return minClearance
+}
+
+test("lga14 and lga8 keep clearance between corner pads", () => {
+  // Regression test: with the default (derived) body size, the inner edge of
+  // the left/right pads landed exactly on the center line of the outermost
+  // top/bottom pads, so corner pads overlapped with 0mm clearance.
+  expect(getMinPadToPadClearance("lga14")).toBeGreaterThan(0.1)
+  expect(getMinPadToPadClearance("lga8")).toBeGreaterThan(0.1)
+
+  expect(
+    convertCircuitJsonToPcbSvg(fp.string("lga14").circuitJson()),
+  ).toMatchSvgSnapshot(import.meta.path, "lga14")
+  expect(
+    convertCircuitJsonToPcbSvg(fp.string("lga8").circuitJson()),
+  ).toMatchSvgSnapshot(import.meta.path, "lga8")
+})