Reconfigured the PCB to a Standard 2 Layer stackup while preserving the 50 mm × 50 mm board and 2 mm rounded corners.
Set the routing intent to top copper for signal/power and bottom copper as the primary reference/plane layer.
Re-placed the board for the 2-layer strategy: J1 at the left edge, U1 at the top antenna edge, U2 away from the power cluster, and D1/U3/U4 near USB-C input.
Updated the Implementation Notes with the 2-layer stackup, placement strategy, verification status, and remaining work.
Success criteria review
✅ 2-layer stackup is configured and board dimensions are retained.
✅ Component placement is optimized for USB-C access, ESP32 antenna position, power-path compactness, and sensor thermal separation.
❌ Routing is not fabrication-ready yet: the latest check still reports 49 airwires, meaning copper routing remains incomplete.
❌ Final fabrication readiness is blocked until routing is completed and the airwire check is clean.
Next steps
Complete PCB routing next, prioritizing USB D+/D−, VBUS/5V, 3V3, GND, and I2C, then re-run checks before export/manufacturing.