5 Common PCB Design Mistakes and How to Avoid Them

In the world of electronics engineering, PCB design is where theory meets reality. A schematic may look perfect on paper, yet a tiny oversight in the layout can cause EMI issues, overheating, unstable power delivery, or complete system failure. Even experienced designers fall into subtle PCB design mistakes that only reveal themselves during testing or, worse, in production.

For the Voltix community, here are the five most common PCB design mistakes and the practical steps you can take to avoid them—ensuring reliable, manufacturable, and high performance boards.

1. Poor Signal Return Paths (The Unseen Noise Generator)

The Mistake

Focusing only on the signal trace and ignoring the return current path. Every signal forms a loop. When you place a split or gap in the ground or power plane under a high speed trace, you break that loop.

The Consequence

The return current is forced into a longer, detoured route, dramatically increasing loop area and inductance. This creates unwanted antennas that radiate EMI, generate crosstalk, and degrade signal integrity.

How to Avoid It

• Treat the signal and its return path as a paired system.
• Use continuous, unbroken ground planes.
• Never route high speed traces across plane gaps.
• If crossing is unavoidable, add stitching vias or bridge capacitors to provide a proper local return path.

2. Undersized Trace Width and Copper Weight (The Hidden Heat Problem)

The Mistake

Routing power traces too thin or using insufficient copper weight. Many designers prioritize routing convenience instead of calculating the actual current requirements.

The Consequence

Thin traces have higher resistance, causing voltage drops and excessive Joule heating. Over time, this can burn traces, damage nearby components, or create reliability problems under load.

How to Avoid It

• Use a reliable trace width calculator (IPC-2221 or online tools).
• Input maximum expected current, allowable temperature rise, and copper weight (1 oz, 2 oz, etc.).
• Use copper pours for high current nets to improve thermal performance and reduce resistance.
• For anything over 1 A, consider using 2 oz copper or an inner layer power plane.

3. Incorrect Use of Decoupling/Bypass Capacitors (The Transient Bottleneck)

The Mistake

Placing decoupling capacitors too far from IC power pins, or using incorrect values. Decoupling capacitors act as small energy reservoirs for fast switching events.

The Consequence

If the capacitor is too far, the inductance of the trace prevents fast current delivery. The result: voltage dips, unstable operation, data errors, noise spikes, or system resets.

How to Avoid It

• Place a 0.1 µF ceramic capacitor as close as physically possible to each VCC pin.
• Keep traces short and connect directly to the ground plane.
• Use multiple values (e.g., 10 µF + 0.1 µF) for components like MCUs and FPGAs to cover different frequency ranges.
• Select low ESR, high quality MLCC capacitors.

4. Poor Thermal Management (The Fast Track to Failure)

The Mistake

Clustering high power components—regulators, MOSFETs, drivers—in tight spaces without adequate heat dissipation or thermal relief.

The Consequence

High junction temperatures reduce component lifespan, cause thermal throttling, trigger shutdowns, or lead to complete system failure.

How to Avoid It

• Use thermal vias beneath exposed pad packages to move heat to inner or bottom layers.
• Connect these pads to large copper pours for effective heat spreading.
• Follow manufacturer recommendations for pad size and via density.
• Choose components with safe thermal resistance (θJA) and ensure the PCB layout helps them dissipate heat.

5. Incorrect Component Footprints (The Assembly Killer)

The Mistake

Using incorrect footprints—wrong pad sizes, misaligned spacing, or incorrect pin numbering. Often caused by relying on unverified libraries or rushing custom footprints.

The Consequence

Wrong footprints lead to solder bridging, weak joints, misalignment, or total assembly failure. Fixing this after production is expensive and time consuming.

How to Avoid It

• Always follow the manufacturer’s recommended land pattern from the datasheet.
• Use IPC-7351B standards when creating custom footprints.
• Before manufacturing, print a 1:1 scale layout and place the real component on it for a final alignment check.

Build Reliable PCBs by Avoiding These Classic Pitfalls

Great PCB design is a combination of engineering knowledge, attention to detail, and practical experience. By understanding these five common PCB design mistakes—signal return issues, incorrect trace sizing, improper decoupling, poor thermal management, and flawed footprints—you significantly increase the reliability and manufacturability of your designs.

For more electronics engineering tutorials and PCB design insights, stay tuned to Voltix—your gateway to sharper, smarter hardware design.