CopperPilotDrone

CopperPilot Drone Hardware: PCB Specifications & Manufacturing Guide

This directory contains the complete electronic design files, manufacturing rules, test suites, and component specifications for the CopperPilot 2-layer micro quadcopter flight controller and airframe.

1. Board Specifications & Geometry

2. Fabricator Selection & JLCPCB DFM Rules

The board has been engineered from the ground up to match JLCPCB Standard 2-Layer PCB & SMT Assembly processes with high yield and zero manufacturing fee penalties.

2-Layer Stackup

Layer Name           Material        Thickness     Copper Weight   Dielectric Constant
--------------------------------------------------------------------------------------
Top Solder Mask      LPI Green       10 - 25 µm    -               -
Layer 1 (F.Cu)       Copper (Signal) 35 µm (1 oz)  1.0 oz/ft²      -
Dielectric Core      FR-4 Core       1.50 mm       -               εr ≈ 4.5 @ 1 MHz
Layer 2 (B.Cu)       Copper (GND/PWR)35 µm (1 oz)  1.0 oz/ft²      -
Bottom Solder Mask   LPI Green       10 - 25 µm    -               -
--------------------------------------------------------------------------------------
Total Finished Thickness: 1.60 mm ± 10%

Design Rule Margins vs. JLCPCB Capabilities

3. Power Distribution & Thermal Architecture

Motor Drive Current Regimes

Standard 8520 brushed coreless DC motors (8.5 mm x 20 mm) operate at:

• Hover Current: 1.0 A to 1.2 A per motor (4.0 A to 4.8 A total continuous draw).
• Punch-Out Burst: 2.0 A to 2.5 A per motor (8.0 A to 10.0 A total peak draw for $< 3\text{ seconds}$).
• Locked-Rotor Stall: Up to 3.0 A per motor (12.0 A transient).

Battery Power Bus Routing (+BATT)

• Main power distribution runs along dedicated wide copper corridors (1.016 mm to 1.524 mm) on both top and bottom layers.
• Traces are stitched through 19 power vias (0.8 mm pad / 0.4 mm drill), providing an aggregate current-carrying capacity exceeding 40 A continuous with less than $50\text{ mV}$ DC voltage drop at full throttle.

Low-Side Switching MOSFETs (T1–T4)

• Component: PUOLOP / Vishay SI2302DS-T1 N-channel MOSFET in SOT-23 ($V_{DS} = 20\text{ V}$, $I_D = 2.8\text{ A}$).
• On-Resistance: $R_{DS(on)} = 55\text{ to }65\text{ m}\Omega$ at $V_{GS} = 3.3\text{ V}$.
• Thermal Dissipation:
  • Hover ($1.0\text{ A}$): $P = I^2 \times R_{DS(on)} = 1.0^2 \times 0.056 = 56\text{ mW}$. Junction temperature rise: $\Delta T \approx 8.4^\circ\text{C}$ over ambient.
  • Full Throttle ($2.2\text{ A}$): $P = 2.2^2 \times 0.056 = 271\text{ mW}$. Junction temperature rise: $\Delta T \approx 40.6^\circ\text{C}$ over ambient, well within the $150^\circ\text{C}$ maximum junction rating.

Inductive Flyback Protection (D2–D5) & Snubbers (C15–C18)

• Each motor channel is protected by a 1N5819WS 40 V 1 A Schottky diode in a compact SOD-323 package, clamping inductive turn-off voltage spikes to $V_{BATT} + 0.45\text{ V} \approx 4.65\text{ V}$ (providing a 425% safety margin below the MOSFET's 20 V breakdown).
• 22 nF 0603 MLCC snubber capacitors across each motor terminal eliminate high-frequency brush commutation arcing and RF interference without causing the destructive 52 A inrush current pulses exhibited by legacy 1.0 µF snubber values.

Linear Regulators & Battery Charging

• 3.3V LDO (U3): TPS79633DCQR / ME6211C33M5G-N provides 3.3V regulated output with 51 µF of distributed ceramic decoupling (C3, C4, C9, C10, C14) to buffer 500 mA ESP32-S3 Wi-Fi calibration bursts.
• Li-Po Charger (IC1): Microchip MCP73833T-AMI/UN standalone linear charger in MSOP-10 set to 303 mA constant-current rate via $3.3\text{ k}\Omega$ Rprog1 and $10\text{ k}\Omega$ R33 THERM bias resistor, with dedicated +5V input decoupling (C6 100 nF + C7 10 µF), ensuring safe charging for 300–600 mAh 1S cells with minimal thermal dissipation ($\sim 242\text{ mW}$ peak).
• Power Mux (U2): AO3401A P-channel MOSFET ideal diode circuit automatically disconnects the battery from the load rail when USB-C 5V is plugged in, preventing reverse charging into the cell.

4. Complete Bill of Materials (BOM)

All 69 components (29 unique BOM lines) use surface-mount packages compatible with LionCircuits Turnkey PCBA and JLCPCB SMT Assembly.

BOM Sourcing Metrics:

• Total Components: 69 (66 Top SMT + 3 Bottom SMT)
• Unique Part Types: 29 (100% Turnkey Available on LionCircuits)
• Through-Hole Soldering: 0 pins (100% SMT assembly)

5. JLCPCB Fabrication & Assembly Ordering Guide

When ordering PCBs and PCBA through the JLCPCB online portal:

1. Board Settings:
   • Dimensions: 100.64 mm x 100.00 mm
   • Layers: 2 Layers
   • PCB Thickness: 1.6 mm
   • PCB Color: Green (or desired color)
   • Surface Finish: ENIG (strongly recommended due to 0.50 mm pitch QFN-24 MPU-6050 and USB-C pads; Lead-Free HASL is acceptable)
   • Copper Weight: 1 oz
2. Panel By JLCPCB:
   • Because the drone chassis has irregular arm profiles and motor cutouts, select "Panel by JLCPCB" with 5.0 mm tooling rails on 2 sides (stamp holes / mouse-bites) so the automated SMT pick-and-place conveyor can clamp the board.
3. SMT Assembly:
   • Choose "Top Side" SMT assembly (all 64 components are on F.Cu).
   • Upload the generated CPL file (build/CopperPilotDrone-cpl.csv) and BOM file (build/CopperPilotDrone-bom.csv).
   • In the JLCPCB component alignment preview, confirm orientation of the MPU-6050 (Pin 1 dot), diodes (cathodes), and polarized ICs.

6. Build, Verification & Export Commands

All PCB verification checks, rule validation, and fabrication exports are automated via make inside pcb/:

# Run automated 32-point hardware test suite (PyTest)
make test

# Run KiCad CLI Electrical Rule Check (asserts 0 errors)
make erc

# Run KiCad CLI Design Rule Check with zone refill & parity (asserts 0 errors, 0 unconnected)
make drc

# Generate complete JLCPCB manufacturing release bundle (Gerbers, Drill, CPL, BOM, PDFs, Release Zip)
make fab

# Generate individual manufacturing deliverables
make gerbers       # RS-274X Gerbers for top/bottom copper, mask, silk, and Edge.Cuts
make drill         # Excellon NC drill files (metric, PTH + NPTH)
make cpl           # SMT pick-and-place component centroid file (CPL)
make bom           # Manufacturing BOM with 100% LCSC part mappings
make pdf           # Full schematic and PCB layer documentation PDFs
make d356          # IPC-D-356 electrical test netlist

# Clean intermediate build outputs and caches
make clean