Even with the increasing integration of semiconductors and the widespread availability of system-on-chip solutions, there remains a strong demand for custom printed circuit boards (PCBs) in many electronic product applications. Despite the availability of powerful, off-the-shelf development boards, custom PCBs play a critical role, especially in projects requiring tailored solutions. PCB design serves as the core platform for creating electronic systems, allowing for flexible layouts that meet specific project needs.
What Are the Golden Rules of PCB Design?
In this article, Arshon Technology will explore ten key principles that electronics design engineers should remember and apply when working on PCB layout and manufacturing. These rules, which have remained largely unchanged since the commercialization of PCBs, are relevant across a wide range of PCB design projects. By following these golden guidelines, both new electronics designers and seasoned PCB developers can enhance their designs and improve overall product quality.
1. Optimal Grid Selection for PCB Design
Choosing the right grid and spacing is essential for effective PCB design. While multi-grid systems offer flexibility, selecting a grid that fits most components can prevent spacing issues and optimize circuit board functionality. Many devices come in various package sizes, so engineers should pick a grid that aligns with their design needs. Polygonal copper fills are crucial, but multi-grid designs may lead to deviations in polygonal filling. Despite this, multi-grid systems can enhance the circuit board’s lifespan. Careful grid selection and early layout planning are key to achieving a reliable and efficient PCB.
2. Shortest Path for Efficient PCB Design
Keep the circuit paths as short and direct as possible. This principle may seem straightforward, but it is crucial to remember throughout every stage of design. Even if it requires altering the PCB layout to minimize wiring length, the performance benefits are significant. For high-speed digital circuits, short and direct paths are particularly important as they reduce impedance and parasitic effects, ultimately enhancing system performance.
3. Incorporate Decoupling Capacitors for Stability
Decoupling capacitors are essential components that help stabilize voltage levels and filter out noise. Placing these capacitors close to the power supply pins of integrated circuits (ICs) ensures that they can effectively buffer power supply fluctuations. In most cases, a 0.1 μF ceramic capacitor is recommended for decoupling purposes, as it can quickly respond to high-frequency noise and stabilize the power supply.
4. Ensure Proper Ground Plane Design
A solid ground plane is one of the most important aspects of PCB design. It provides a low-impedance path for return currents, reduces electromagnetic interference (EMI), and ensures better signal integrity. Ideally, the ground plane should cover as much of the board as possible, providing a reference point for all signals. Splitting or interrupting the ground plane can create noise issues, so maintaining a continuous ground plane across the entire PCB is critical.
5. Maintain Adequate Trace Width and Spacing
Trace width and spacing are key factors in determining the current-carrying capacity of a PCB. If traces are too narrow, they may not be able to handle the required current and could overheat, leading to board failure. To avoid this, designers should calculate the correct trace width based on the current load and ensure there is sufficient spacing between traces to prevent short circuits and arcing. IPC-2221 standards provide valuable guidelines for selecting trace width and spacing based on current requirements and voltage levels.
6. Steer Clear of 90-Degree Trace Angles
While it may seem like a minor detail, using 90-degree trace angles can cause signal integrity issues. These sharp angles can lead to signal reflection, impedance mismatches, and increased capacitance, all of which can affect the PCB’s performance, especially in high-frequency circuits. Instead, opt for 45-degree trace angles, which allow for smoother transitions and maintain signal integrity.
7. Plan for Effective Power Distribution
Proper power distribution is vital for maintaining stable circuit operation. Using a power plane, similar to the ground plane, ensures that the power is delivered uniformly to all components. If using a power plane isn’t possible, you should use wide traces to distribute power, minimizing voltage drops and ensuring adequate current supply. Planning power distribution early in the design phase can prevent voltage fluctuations and ensure reliable circuit operation.
8. Isolate High-Speed Signals
High-speed signals are prone to generating electromagnetic interference (EMI) and can disrupt nearby signals if not properly managed. To prevent interference, it is essential to isolate high-speed signals by routing them away from other sensitive traces or components. Additionally, shielding these signals by running them over a solid ground plane can help reduce EMI and improve signal integrity. In critical applications, differential pairs may be used to further reduce noise and enhance performance.
9. Consider Heat Dissipation
Effective heat management is crucial, especially in designs where power-hungry components are used. Overheating can lead to reduced component lifespan, board warping, or even catastrophic failure. To combat this, ensure that heat-generating components like power ICs and regulators have adequate ventilation, heatsinks, or thermal vias. PCB layout techniques such as spreading heat-generating components across the board or using copper pours can also help in dissipating heat effectively.
10. Design for Manufacturability (DFM)
Even the most well-designed PCB will fail if it cannot be easily manufactured. Designing for manufacturability (DFM) is about ensuring that your PCB can be produced reliably and cost-effectively. This means adhering to manufacturing tolerances, minimizing the use of fine-pitch components, avoiding vias under components like BGAs, and ensuring clear labeling for components. Working closely with your PCB manufacturer during the design phase can help prevent costly redesigns and ensure a smooth transition from design to production.
Arshon Technology’s Approach to PCB Design
At Arshon Technology, we understand the importance of following best practices in PCB design. Our team adheres to these golden rules to ensure that our designs are robust, reliable, and optimized for performance. We specialize in offering end-to-end PCB design services, from concept to manufacturing, ensuring that your project benefits from our years of experience in the industry. Whether you’re looking for high-speed PCB designs or multi-layer boards, Arshon Technology has the expertise to deliver high-quality solutions tailored to your needs.
Conclusion
Adhering to the golden rules of PCB design is essential for creating functional, reliable, and efficient PCBs. From proper power distribution to ensuring effective heat dissipation, these guidelines serve as the foundation for successful PCB projects. Whether you’re working on simple designs or complex multi-layer boards, following these rules will help you avoid common pitfalls and ensure the best possible outcome for your project. Partnering with experienced professionals, like those at Arshon Technology, can also streamline the process and ensure that your PCB design meets both performance and manufacturability standards.
