PCB routing guidelines: top 10 practices

Proper routing ensures signal integrity, minimises electromagnetic interference (EMI), and optimises the overall performance of the electronic device.

What is PCB routing?

PCB routing is the process of designing the physical paths, or traces, on a PCB that connect various electronic components. These traces carry electrical signals and power between the components, effectively enabling the PCB to function as intended. PCB routing directly impacts the performance, reliability, and manufacturability of the electronic device.

Here are the top ten best practices for effective PCB routing:

Minimise signal paths

Short and direct signal paths reduce the potential for noise and signal degradation. Avoid unnecessary bends and keep trace lengths as short as possible to maintain signal integrity.

Maintain consistent trace width

Consistent trace width ensures uniform current distribution and reduces the risk of overheating. Calculate the appropriate trace width based on the current carrying capacity and stick to it throughout the design.

Utilise ground planes effectively

A solid ground plane reduces EMI and provides a return path for signals, which improves overall circuit stability. Ensure the ground plane is continuous and not segmented by signal traces or components.

Separate analogue and digital signals

Keep analogue and digital signal paths separate to prevent interference. Use separate ground planes for analogue and digital sections if possible to further minimise noise coupling.

Route differential pairs correctly

For high-speed signals, route differential pairs with equal lengths and close proximity to each other. This practice minimises noise and ensures signal integrity by maintaining the differential impedance.

Implement proper power distribution

Ensure power traces are wide enough to handle the required current. Use power planes or multiple layers to distribute power efficiently and reduce voltage drops across the PCB.

Use decoupling capacitors strategically

Place decoupling capacitors close to the power pins of integrated circuits (ICs) to filter out noise and stabilise the power supply. Ensure the capacitors have low impedance at the operating frequency.

Control trace impedance

Impedance control is essential for high-frequency signals. Use controlled impedance traces for signals that require precise impedance matching, such as RF and high-speed digital signals.

Avoid sharp corners in traces

Sharp corners can cause signal reflections and EMI. Use 45-degree or curved bends instead of 90-degree angles to maintain signal integrity and reduce EMI.

Perform design rule checks (DRC)

Regularly run design rule checks to identify and correct potential issues. DRCs help ensure that the PCB design adheres to the manufacturing capabilities and industry standards.

Additional considerations

• Thermal management: Proper thermal management is crucial for reliable PCB operation. Use thermal vias, heat sinks, and appropriate trace widths to dissipate heat effectively.
• Layer stacking: Multi-layer PCBs offer better routing options and signal integrity. Plan the layer stack-up carefully to separate power, ground, and signal layers effectively.
• Component placement: Optimise component placement to minimise routing complexity. Place related components close to each other to reduce trace lengths and improve performance.
• Signal integrity analysis: Perform signal integrity analysis to detect and mitigate issues such as crosstalk, reflections, and ringing in high-speed designs.

Adhering to these best practices will help ensure a reliable, high-performance PCB design. As PCB technology continues to evolve, staying updated with the latest routing techniques and guidelines is essential for maintaining the quality and efficiency of electronic devices.