PCB routing is the core of printed circuit board design, connecting discrete components into functional circuits via rational trace layout. For beginners, mastering basic routing rules and steps is essential to ensure circuit performance, avoid signal interference, and reduce manufacturing defects. This guide systematically sorts out entry-level knowledge to help beginners get started quickly and correctly.

1. Preparations Before Routing

Complete these steps to avoid repeated modifications during routing.

Confirm Schematic and Component Placement

Verify the schematic for correct connections, pin definitions and power circuits.

Place core components (chips, main control modules) centrally; separate analog and digital components to reduce interference; arrange components by signal flow to shorten key trace lengths.

Ensure adequate spacing between components for soldering and debugging, avoiding overlap or overly tight layouts.

Set Routing Design Rules in Advance

In software like Altium Designer or KiCad, set rules based on design requirements:

Trace width: Match current load—1oz copper foil needs at least 0.5mm width for 1A current; widen power and ground traces to reduce resistance.

Clearance: Keep a minimum 0.2–0.3mm distance between traces, pads and vias (increase for high-voltage circuits to prevent breakdown).

Via size: Choose 0.6–0.8mm diameter and 1.2–1.6mm pad size based on board thickness; avoid overly small vias that are hard to process.

2. Basic Routing Operations

Take double-sided PCB as an example for entry-level design scenarios.

Determine Routing Priority

Route power and ground first with wide traces; use a ground plane if possible to enhance anti-interference capability.

Then route key signal lines (clock, SPI, I2C)—keep them short and straight as they are sensitive to interference.

Finally route ordinary signal lines (GPIO, control signals) with lower requirements.

Single-Layer & Cross-Layer Routing

Select signal layer (top/bottom), use the "Trace" tool to connect pads, and follow preset width and clearance rules.

Keep traces short, straight and smooth; use 45° angles or rounded corners instead of right angles to avoid signal reflection.

Use vias only when single-layer routing can’t avoid crossings—minimize via count to reduce parasitic inductance/capacitance and avoid weakening board strength.

Routing Completion Check

Run the software’s Design Rule Check (DRC) to detect violations like incorrect trace width, insufficient clearance and unconnected nets.

Manually inspect key signal lines to ensure they are not overly long, do not pass near interference sources (power transformers, high-frequency oscillators), and avoid long parallel routing to prevent crosstalk.