Printed Circuit Board (PCB) design has to be considered as a critical part of any electronic project, whether it’s a consumer gadget or a cutting-edge communication device.
There is no question that a well-designed PCB helps deliver optimal performance, reliability, and efficiency. However, even experienced designers can fall into common traps that compromise both functionality and manufacturability.
In this blog, we’ll explore some of the most common mistakes to avoid in PCB design, including material selection, such as when to choose a Rogers PCB instead of an FR-4 PCB for high-frequency applications.
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Poor Material Selection for High-Frequency Applications
Your choice of PCB material plays a vital role in determining a circuit’s performance, especially in high-frequency applications like RF and microwave systems.
A classic mistake would be opting for the commonly used FR-4 PCB material for applications although it cannot handle high-frequency signals effectively. FR-4 is certainly affordable and versatile, but has limitations in terms of signal loss and dielectric constant consistency at high frequencies.
The solution for high-frequency applications would be to choose Rogers PCB materials. Rogers materials. These offer lower dielectric loss, to help boost signal integrity. They also have a consistent dielectric constant (Dk) across a wide frequency range. In addition, they offer minimal signal distortion and crosstalk, making them ideal for applications like antennas, radar systems, and 5G devices.
Neglecting Power and Ground Planes
Failing to dedicate proper power and ground planes can lead to electromagnetic interference (EMI), voltage drops, and noise in the circuit.
A practical solution to this issue would be to use solid and contiguous power and ground planes. Avoid splitting the ground plane unnecessarily, as this can create loops and increase EMI, and place the power plane close to the ground plane to create natural decoupling capacitance.
Overlooking Trace Width and Spacing
A common mistake with this scenario is to use inadequate trace widths for power and signal lines. This leads to excessive resistance, heat buildup, and signal loss.
To counteract this problem, use a PCB trace width calculator to determine the required width based on current, voltage, and power requirements. Be sure to follow design rules for spacing to prevent arcing or short circuits, especially in high-voltage circuits.
Ignoring Signal Integrity in High-Speed Designs
The mistake you often witness here is a failure to account for signal integrity issues such as reflection, noise, and crosstalk in high-speed designs.
The solution involves impedance matching and minimizing crosstalk. Aim to design traces with consistent impedance for high-speed signals, and maintain adequate spacing between high-speed traces and avoid parallel runs.
Don’t forget to use termination resistors too. These reduce reflection and stabilize signal integrity.
Poor Via Placement
Overusing or poorly placing vias can lead to signal degradation. This can lead to increased parasitic inductance, and difficulty in manufacturing.
Ways to address this problem would be to use vias strategically, and avoid excessive via stitching. Minimize the number of vias on high-frequency signal paths to maintain signal quality, and opt for microvias in designs with tight space constraints or high-density interconnections.
Inadequate Heat Dissipation
This happens when you don’t give enough consideration to thermal management. This then leads to components overheating and can reduce its lifespan, or induce failure.
A good way around this issue would be to use thermal vias, copper pours, and heat sinks to dissipate heat efficiently. Also, place high-power components in areas with adequate ventilation. Finally, simulate thermal performance during the design phase to identify hot spots.
Poor Component Placement
The mistake often made here is when you randomly place components without considering signal flow, accessibility, or thermal requirements.
You can counteract this problem by grouping components by function, (e.g., power, analog, digital) to reduce noise and improve signal integrity.
Group components by function. This involves placing components with high thermal output near heat dissipation areas. Also, make sure critical components like oscillators and regulators are placed away from noise sources.
Overcomplicating the PCB Design
It’s all too easy to overcomplicate things when it comes to PCB design. Adding unnecessary layers, excessive vias, or complex routing, can increase manufacturing costs and introduce potential design flaws.
Aim to keep the design as simple as possible while meeting performance requirements. Work with your manufacturer to understand their capabilities and limitations, avoiding features that unnecessarily complicate production.
Skipping Design Rule Checks
Failing to perform thorough Design Rule Checks before sending the design for manufacturing can result in costly errors.
That’s why you need to use PCB design software to run automated DRCs for trace width, spacing, via size, and other parameters. Again, collaborate with your manufacturer to ensure their specific design rules are incorporated into your checks.
Ignoring the Importance of Prototyping
Last but not least, sending a design directly to production without prototyping can result in expensive rework if issues are discovered later.
You should always create a prototype PCB and test it thoroughly before moving to full-scale production. Use prototyping to validate signal integrity, power distribution, and thermal performance.
Designing a PCB is as much about avoiding pitfalls as it is about innovation and creativity. Avoidable mistakes like poor material selection, neglecting signal integrity, or inadequate thermal management can quickly compromise your project’s success.
Choosing the right materials, such as Rogers PCB for high-frequency applications, and adhering to best practices for layout, component placement, and thermal design are crucial to creating a reliable and efficient PCB.
Now that you are more aware of the typical design errors and mistakes that tend to be repeated more often than they should be, you can avoid the impact of these common errors. This will allow you to have confidence that your PCB design is going to be properly optimized for performance, manufacturability, and longevity.
Regardless of whether you’re working on a simple project or a complex high-frequency system, attention to detail and a commitment to best practices will always pay off.
We all understand the importance of correct PCB design and the role it plays in the design and manufacturing process. Avoid these classic mistakes and you will find the transition to a finished product, smoother and less stressful.
