5 Common PCB Design Mistakes to Avoid as a Beginner

However, in technology and science, there are a lot of places for art; we are actually making art while designing, and that is true! A kind of art that needs a lot of mathematics and physics phenomena. Today, we will discuss a similar kind of art, which is known as PCB design. Every electronics engineer at the end of the day wants to implement the circuits on a PCB to solve certain problems. Because it is very common in electronics, the JLCPCB team started these educational blogs. Today, in this guide, we will explore some design mistakes to avoid in PCB designs that are very common as a new designer, and we will look into the science behind these.

1. Poor Planning and Component Placement

Today, because of lots of integration in devices, we are using mixed signal systems, which contain digital and analog parts. Analog parts are a bit slower but prone to noise on the other hand, digital parts work on high frequencies, and they become the main cause of this noise. So when designing such a circuit involving mixed signal parts, we should look into design rules. Place the digital and analog away from each other at least 20H. Where H is the distance between the two layers L1 and L2. placed away to reduce the noise, and also so that tracks will not cross each other from other layers. Bad placement increases trace length (higher loss and EMI) and worsens thermal dissipation. It also complicates power routing and often forces many vias and crossovers during routing.

How to avoid it:

• Group functional blocks (power, analog, digital, RF) and orient them for short connections between related pins.
• Use the 20H rule for mixed signal
• Reserve space for test points, programming headers and polarity markings.

2. Ignoring Power Distribution and Decoupling

Power integrity is the most important factor in multilayer PCBs. If there is an error in the power supply or noise in the power, then the product's quality and performance can be compromised. The two main causes for power supply failure can be the placement of the decoupling capacitor and the distribution. Power distribution issues are there because of improper trace width; thin VIN/VOUT traces heat up and create voltage droop under load. Usually, in power supplies, different value decoupling capacitors are used to eliminate the high-frequency and lower-frequency noises. There are some recommended steps to improve the power integrity of a PCB.

How to avoid it:

• Use wide traces or dedicated power planes for high-current nets. On 4-layer boards, dedicate an inner plane to ground and another to power if needed.
  
• Place at least one 0.1 μF ceramic decoupling cap right beside each power pin. Add 1 μF–10 μF bulk caps near regulators. Keep traces as short as possible (millimeters, not centimeters).
  
• Use ferrite beads or LC filters to isolate noisy domains (e.g., switching regulator to analog).

3. Poor Signal Integrity: Impedance, Return Paths and Crosstalk

Beginners route fast signals like any other wire on random layers, abrupt layer transitions, and long stubs. They also split planes without handling return paths. Let's talk about them one by one. If the impedance of two lines does not match, then the signal will reflect from the discontinuity end, and impedance mismatch will be there. It usually occurs because of vias, trace discontinuity, and component placement in the signal path. Cross-talk is there due to the overlapping of signal magnetic fields with other trace magnetic fields. And return paths are required to ground the signal and complete the path from generation to sinking back. There are all factors that decide the signal integrity of a PCB.

Here are some guidelines to avoid:

• Plan stackup up front. For typical designs, use a 4-layer stackup (Top signal / GND / PWR / Bottom signal) so every high-speed trace has a close reference plane.
  
• Use controlled impedance (50 Ω single-ended, ~100 Ω differential) for high-speed traces and route differential pairs together with consistent spacing.
  
• Avoid splitting ground planes under a signal; a signal's return should be continuous and directly under the trace. If you must split planes, route signals so return currents aren't forced to jump over voids.
  
• Use 45° bends and gentle curves for RF/fast traces rather than 90° turns.

4. Thermal and Power Dissipation Oversight

Beginners rely on copper pours or small copper pads without thermal vias or proper heatsinking. But due to this ICs run hotter, derate or fail.

How to avoid it:

• Identify heat sources (power MOSFETs, linear regulators, processors). Provide adequate copper area and thermal vias beneath power ICs or BGAs to transfer heat to internal planes.
  
• Use thermal reliefs where needed, but avoid isolating thermal pads completely from planes. For BGAs, place an array of thermal vias under the pad and ensure they are plugged or tented if the fab requires it.
  
• Add thermal pads and heatsink mounting if dissipation exceeds what copper planes can handle. Run a quick thermal estimate (power × thermal resistance) to check temperatures.

5. Not Designing for Manufacturability

Clean schematics and finished GERBERs don’t guarantee a manufacturable PCB. Common issues can be wrong footprints and silkscreen over the pads. Sometimes we also have to look for missing fiducials and insufficient clearances for wave/hand soldering. PCB house rejects files, reworks cost time and money, assembly fails, and debugging becomes painful.

How to avoid it:

• Use verified footprints from the vendor or libraries and always check the datasheet if it is matching with the component parameters.
  
• Add fiducials, paste mask openings, and keep component spacing compatible with pick-and-place machines.
  
• BOM (bill of materials) should be included with the placement file.

Conclusion:

So with all this, now the beginner guide has ended here, and we have learnt a lot about what to do and what not to do in this guide. I will be happy to continue based on the response. For more PCB and schematic-related posts, you can see the JLCPCB blog sections. Every trace in the PCB should be calculated, like power traces, for better current handling. Signal traces to reduce reflections. This guide will help you understand a lot more factors about the PCB circuit design.