PREFAB-HW v12 — 4-layer laser-ablation substrate
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100 x 80 mm · 4 layers · 1.6 mm · 479 plated vias + 4 plated M3 mounts

READ THIS BEFORE CAM. Several things below look like errors and are not.
Please do not "correct" them — query us instead.


ORDER SETTINGS
  Layers ............ 4
  Dimensions ........ 100 x 80 mm
  Thickness ......... 1.6 mm
  Outer copper ...... 1 oz      Inner copper ...... 1 oz
  Surface finish .... OSP       (declared in the .gbrjob as Finish: OSP)
  Soldermask ........ NONE, BOTH SIDES
  Silkscreen ........ NONE, BOTH SIDES
  Min track/space ... 0.2 mm (no tracks are present; this is the ablation rule)
  Min hole .......... 0.30 mm
  Min annular ring .. 0.15 mm


INTENTIONAL — DO NOT CORRECT
  1. NO SOLDERMASK. The mask gerbers are negative-polarity with a single
     aperture covering the whole 100x80 board, i.e. fully open. The board must
     arrive as bare OSP-coated copper on both outer faces. A mask would block
     both the laser and later soldering.

  2. NO SILKSCREEN. No silk files are supplied. Nothing should be printed.

  3. ALL FOUR LAYERS ARE COMMON. The board ships deliberately shorted: the
     outer copper fields, the L2 ground plane and the L3 rail islands are all
     joined through the via barrels. Netlist/electrical test will report the
     board as a single net. That is correct. E-test may be skipped.

  4. THE OUTER LAYERS ARE SOLID COPPER FIELDS. There is no circuit pattern on
     L1/L4 — the customer laser-ablates the circuit after delivery.

  5. INNER LAYERS ARE PRE-STRUCTURED. L2 carries 6 ground islands, L3 carries
     10 rail islands, each with fabbed antipads. These are permanent and are
     the only part of the design a laser can never reach. Please hold the
     inner-layer registration to your normal 4-layer tolerance.


FILES
  *-F_Cu.gtl        L1  solid copper field
  *-GND_PLANE.g2    L2  ground plane (6 islands)
  *-PWR_PLANE.g3    L3  power rail islands (10 islands)
  *-B_Cu.gbl        L4  solid copper field
  *-F_Mask.gts      top soldermask — FULLY OPEN (= no mask)
  *-B_Mask.gbs      bottom soldermask — FULLY OPEN (= no mask)
  *-Edge_Cuts.gm1   board outline, single 100x80 rectangle
  *-PTH.drl         483 plated holes: 479 x 0.30 mm vias + 4 x 3.20 mm mounts
  *-NPTH.drl        empty by design (no unplated holes on this revision)
  *-job.gbrjob      job file, 4 layers, 1.6 mm, OSP


NOTES
  · The four M3 corner holes are PLATED and tied to the outer copper.
  · The three 1.5 mm copper dots per side are optical fiducials. They sit in
    cleared 1.25 mm moats and must not be tented or covered.
  · Hole-to-hole minimum is 2.00 mm. Copper-to-edge minimum is 0.50 mm.
