PCB Design Principles for Beginners

Key Takeaways

• Learn why PCB design principles are important.

• Explore crucial PCB design principles.

• Find out how to implement PCB design principles in practice.

Minimize thermal issues by complying with PCB design principles

The key to determining whether a PCB design functions reliably in the field or fails miserably (and wastes time and money) lies in whether or not your PCB design complies with PCB design principles. 

PCB design isn’t just about routing traces between components and passing the DRC check. It’s about ensuring that a PCB withstands EMI and prevents it from being a source. When you’re following PCB design principles and best practices, you’re also ensuring a PCB’s thermal reliability, manufacturability, and prolonged lifespan. These design principles should serve as a guide to creating quality, reliable PCBs. 

The Most Important PCB Design Principles 

Maximize functionality, reliability, and durability with PCB design principles.

Here are some of the most important design principles that you ought to keep in mind when working on a PCB.

Ground Separation

When working on a mixed-signal design, it’s crucial to keep both analog and digital ground planes apart. Analog components ought to be grouped together on top of a dedicated ground plane. The same applies to their digital counterpart. Both ground planes must only be connected at a single point to prevent ground loops.

EMI Mitigation

Every PCB can potentially suffer from EMI or become a source of interference. As a designer, you’ll need to be cautious when working on a PCB layout. Some best practices include:

• Increasing clearance between high-frequency traces and low-frequency or analog traces.

• Minimizing the return path of high-speed signals and ensuring they are not crossing over a split-plane. A smaller current loop reduces the strength of EMI radiation.

• High-speed differential signals should be routed beside each other and be equal in length, otherwise, it would negate the noise-suppression nature of differential pairs.  

• Avoiding the use of vias on high-speed traces, as they might contribute to EMI emission.

PDN Stability

A circuit on a PCB is only as good as its power delivery network. This means you’ll need to ensure that the voltage regulator module is capable of supplying the maximum current required by the load. 

Besides that, the supply voltage needs to be stable and free from electrical interference from noisy components. Include a low-pass filter at the regulator’s output to help suppress high-frequency noise and add a bypass capacitor close to components like microcontrollers to prevent unwanted disruptions.

Thermal Management

With components and PCBs getting smaller, thermal management is an area that demands a designer’s attention. The use of thermal vias, heatsinks, and the placement of temperature-sensitive components are crucial to ensure thermal reliability. 

Design Manufacturability

If you want to avoid issues at the assembly stage, you’ll want to ensure that the PCB is designed for manufacturability. Ensure that the component pad size is correct and fiducial markers and tooling strips are present for surface-mount designs. 

Putting PCB Design Principles into Practice

Good PCB design software makes complying with PCB design principles easier.

You’ll have your hands full trying to put the above principles into practice. It’s going to be a challenge to ensure that your PCB design adheres to all of those PCB design principles and guidelines. There’s also a need to strike a balance between correctness and execution, as companies are pressured with shorter time-to-market.

Your attempts to comply with PCB design principles will be more successful if you’re using the right PCB design tools. OrCAD has a range of features and tools that make compliance easier. If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.