Designing Your First Custom PCB: From KiCad Schematic to Gerber Files

Why Custom PCBs Over Breadboards

Breadboard prototypes are essential for rapid iteration, but they are unreliable for deployments. Loose jumper wires fall off, stray inductance corrupts high-frequency signals, and breadboard power rails cannot handle more than ~200mA safely. A custom PCB solves all three problems — it is your hardware, permanently.

The KiCad Workflow

KiCad is a free, open-source EDA (Electronic Design Automation) suite used for professional PCB design. The workflow has five stages:

1. Schematic Capture (Eeschema)
2. Footprint Assignment
3. PCB Layout (PCBnew)
4. Routing
5. Gerber Export

Stage 1: Schematic Capture

The schematic is the logical blueprint — it shows component relationships, not physical placement. Wire ESP32 power rails first:

VIN (5V) → AMS1117-3.3 LDO → 3.3V rail
3.3V rail → ESP32 VCC
3.3V rail → 100nF decoupling cap → GND (place cap physically near ESP32 pin)

Decoupling capacitors (100nF) next to every power pin are critical — they suppress high-frequency noise from switching events.

Stage 2: Footprint Assignment

Every schematic symbol needs a physical footprint — the copper pads and silkscreen on the board. For an ESP32-WROOM-32 module, use the RF_Module:ESP32-WROOM-32 footprint from KiCad's library.

Stage 3: PCB Layout Principles

• Keep analog and digital ground planes separate, joining at a single point.
• Place decoupling caps within 1-2mm of the power pin they serve.
• High-current traces (e.g. motor drivers, 500mA+) need wider copper: use the PCB trace width calculator (W = I / (k × ΔT^0.44)).
• Antenna keepout zones: Keep all copper away from the ESP32 PCB antenna area.

Stage 4: Design Rules Check (DRC)

Before routing, set your manufacturer's DRC constraints (e.g. JLCPCB minimums: 0.2mm trace width, 0.2mm clearance, 0.3mm drill). Run DRC after routing to catch violations.

Stage 5: Gerber Export

Generate: F.Cu, B.Cu, F.Mask, B.Mask, F.Silks, B.Silks, Edge.Cuts, and the drill file (.drl). Zip these and upload to JLCPCB or PCBWay for a 5-unit prototype batch for around $10–$20.

Need a custom PCB designed for your IoT product? Let's talk →