AnasSarkiz/NEMA14_RP2040

docs/jlcpcb-order-review.md

# NEMA14_RP2040: JLCPCB engineering review

This handoff is prepared for order review. It is not JLCPCB approval or a production release. No order or payment has been submitted.

Upload `JLCPCB-Gerbers.zip` for the PCB, `JLCPCB-BOM.csv` and `JLCPCB-CPL.csv` for SMT assembly. The BOM contains exact source MPNs and LCSC part numbers. The default `artifacts/nema14-gerbers.zip` applies the same reviewed fabrication and assembly policies. The upstream CLI export is retained under `artifacts/engineering-fixes/upstream-native-gerbers.zip` for diagnosis. `review-cam.zip` contains the exact CAM and detailed source-identity tables used by the independent audit.

Select 4 layers, 35 × 35 mm, 1.6 mm board thickness, and ENIG for the separate bare top-side test-point pads. Request at least 35 um outer copper, 17.5 um inner copper and 20 um plated via barrels. Copper layer order is F_Cu / In1_Cu / In2_Cu / B_Cu. Both drill files are required: plated drills/slots and NPTH. The four mounting holes are Ø3.2 mm at (±13, ±13), with board-center origin.

The 100 um stencil has independently screened fine-pitch apertures and four windows totaling 60% exposed-pad coverage for the MCU, PD controller and A4988. `Thermal-Via-Process.csv` identifies the actual exposed-pad via positions and drill sizes that require filling, copper capping and planarization. Confirm the supplier's paste/reflow and via-in-pad processes before releasing assembly; these capabilities and costs have not been quoted.

SMT fitted parts: 82. Bottom SMT references: none. Separate bare top-side `TP_*` test points have no purchased component or stencil paste. JST `J_MOTOR` is native SMT BM04B-SRSS-TB(LF)(SN), C160390, and is included in the top-side SMT BOM and CPL. No bottom-side fitted components or JST through-hole leads are present. The functional order is pin 1 A+, 2 A−, 3 B+, 4 B−. The JST mates vertically from +Z.

The **eight USB-C shell tabs require supplier-approved TOP-side secondary soldering**. Their 0.7 mm stakes do not protrude through the 1.6 mm board; do not assume a bottom-wave or ordinary through-hole process is suitable. `Through-Hole-Joint-Plan.csv` lists the actual eight joint coordinates for supplier quotation or manual soldering. USB signal pads receive stencil paste; shell slots do not. Do not assume an SMT-only quote includes these joints or that the unsoldered USB tabs provide a qualified cable-retention or shield-ground connection.

CPL coordinates are millimeters about board center, unmirrored board XY for both sides. Rotation is the native imported footprint orientation plus component placement rotation. **Check every polarized part and pin 1 in JLCPCB's placement preview.** `placement-orientation-review.json` lists each actual numbered pad, center, side and rotation; source agreement is not proof of supplier pickup convention. Upright USB-C CPL coordinates use the imported land-pattern datum. The CAD body alignment and manufacturer pickup datum are separate conventions; supplier pickup confirmation remains required. Do not substitute a body bounding-box center for the native CPL datum.

The preview images show actual corrected mask and silkscreen Gerbers, not the native CAD captions. Dense silkscreen omits captions that cannot fit safely; all fitted references remain in the assembly maps and placement tables. Inspect assembly maps together with the pad-orientation manifest.

Software verification covers source nets, all saved traces/segments/vias, physical connectivity, actual CAM shorts/opens and clearance, pad/mask/drill agreement, stencil geometry, assembly identities, exact outline and mounts, and nominal native STEP mechanical checks. **USB impedance/reference paths, switching loops, sense/ground return behavior, firmware and thermal performance still require engineering and hardware validation.** A working reference board does not prove this implementation works.

Both upright USB-C sockets occupy opposite edges (+Y and −Y), with cable insertion from +Z. The defined 10 × 7 × 30 mm housings have 23.300 mm nominal separation. The model screens maximum Ø6 × 3 mm heads within a Ø6.4 mm envelope and an Ø6 mm vertical tool path. Verify actual plugs, fasteners, tool tolerances, JST mating cable, thread engagement and the mounting stack. Rear-motor compatibility has not been verified.

Economic versus Standard PCBA service and panelization are unconfirmed. Require supplier acceptance of the eight short USB shell stakes and the three filled/capped exposed-pad vias before choosing the assembly service. If the accepted service requires a panel, obtain its approved rail, tooling-hole and fiducial requirements; no factory panel is released in this package. Panel/process acceptance is a supplier-review blocker. The functional PCB remains 35 × 35 mm.

Supplier review still must confirm exact stock and quote, pickup orientation, via-in-pad and stencil/reflow process, specified stackup/copper, and assembly sides/THT plan. Do not authorize substitutes. Prototype bring-up must verify USB data, 15 V PD, regulator isolation, phase current/thermal behavior, motor, temperature sensor, LEDs and buzzer before production approval.

Every native and order-source record passes its installed Circuit JSON schema. Display offsets are canonical strings, optional null IDs are omitted, and the buzzer uses a generic pinout record with its real MPN and pin identities retained. See `native-json-compatibility.json`. The actual coupled USB copper and adjacent grounded references are checked separately; fabricator stackup/impedance and bench USB operation remain unverified.

Board source SHA-256: `16a605a565a272ce12a5194f28e1d9d8359c183d6110d117a4771d2b8ec91d2d`. Corrected CAM audit: PASS, zero findings. Electrical source, placement, native footprints/courtyards, copper, masks, drills and outline are preserved.

CH224A revision 1.13.0: the electrical migration intentionally changes the PD supply/configuration circuit while preserving every existing placement and land pattern. The fixed request remains 15 V. See ch224a-migration.md for the 56 kohm configuration, 0 ohm supply feed and VBUS rating confirmed by WCH V2.1. Live stock, supplier process approval and hardware validation remain outstanding; this package is for engineering review, not manufacturing release.