PCB Layout Best Practices: Design Guidelines for Reliable Boards

Good PCB layout is the foundation of reliable electronics. Poor layout can cause signal integrity issues, thermal problems, and manufacturing defects. This guide covers essential best practices.

Component Placement Strategy

Group by Function

Keep related components together—power, analog, digital, and RF sections separated.

Consider Signal Flow

Arrange components to minimise trace lengths for critical signals.

Thermal Planning

Place heat-generating components where they can be cooled effectively.

Assembly Access

Ensure adequate spacing for soldering, rework, and test probe access.

Routing Guidelines

Power Distribution

  • Use dedicated power and ground planes where possible
  • Keep power traces short and wide to minimise impedance
  • Place decoupling capacitors close to IC power pins
  • Use multiple vias for plane connections

Signal Integrity

  • Controlled Impedance: Match trace impedance for high-speed signals
  • Length Matching: Match trace lengths for differential pairs
  • Crosstalk Prevention: Maintain spacing between parallel traces
  • Return Paths: Ensure clean return current paths

Thermal Management

Heat is the enemy of reliability. Every 10°C rise roughly halves component lifespan.

  • Use thermal vias under hot components
  • Consider copper pours for heat spreading
  • Leave space for heatsinks and airflow
  • Simulate thermal performance for high-power designs

Design for Manufacturing (DFM)

Minimum Spacing

Respect manufacturer minimums for trace/space, hole size, and annular rings.

Solder Mask

Ensure adequate solder mask dams between pads to prevent bridging.

Silkscreen

Keep silkscreen clear of pads. Use readable text sizes (min 0.8mm).

Test Points

Add test points for critical signals to enable debugging.

Review Checklist

  • ✓ All nets connected (no unrouted connections)
  • ✓ Design rules check (DRC) passes
  • ✓ Correct component footprints verified
  • ✓ Adequate clearances for high-voltage
  • ✓ Mounting holes and board outline correct
  • ✓ Fiducial marks for SMT assembly

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