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How to Overcome the PCB Electromagnetic Problems

2022-11-21

Electromagnetic problems are a problem that PCB designers must face. Simply put, even small design issues can lead to electromagnetic problems, and system design engineers must always monitor electromagnetic compatibility and interference.

What are the PCB electromagnetic problems?

PCB electromagnetic problems relate to EMI and EMS, which usually includes the generation, propagation, and reception of electromagnetic energy processes.

EMI (Electromagnetic Interference)

Refers to the work of electronic products that will cause interference with other electronic products in the vicinity, with which there are EMC specifications.

EMC (Electro Magnetic Compatibility)

It means that the electromagnetic energy generated by the device neither interferes with other devices, nor the ability to interfere with the electromagnetic energy of different devices.

Any PCB designer should follow the EMC design rules to minimize the number and impact of EMI.

Classification of electromagnetic interference sources

With the development of modern electronic technology, electromagnetic interference has become ubiquitous, we can classify it from the following aspects.

  • Sources

They are divided into man-made interference and natural causes. Man-made electromagnetic interference from electronic circuits, natural effects may come from the universe, atmospheric lightning,  and other environmental factors.

  • Duration

Continuous interference emits a constant signal, it is also a source of EMI, usually manifested as background noise. Pulse interference is intermittent, usually caused by switching systems, lightning, and other non-constant sources.

  • Bandwidth

Narrowband signals used by radio may encounter interference from oscillators and transmitters, broadband interference affects high data signals such as television and can come from many sources, including arc welders and solar noise.

What are the effects of electromagnetic interference´╝č

Whether human or environmental, EMI can be dangerous. For example, in the medical field, the use of wireless devices is being born, unfortunately, EMI can affect the function of medical equipment such as ventilators, ECG monitors, and heart monitors.

In other industries, EMI can break the loop of sensors and navigation systems, causing data to be biased and thus leading to the wrong results.

The most common source of EMI is the internal design, poor PCB design can lead to incompatible signals on the board, which may eventually lead to board failure

How to prevent and solve electromagnetic problems?

To minimize EMI, PCB designers must follow EMC design principles. EMC problems are mainly related to design flaws that cause interference between alignments, circuits, vias, PCB coils, and other components.

Grounding plane

The design of the grounding layer is critical to reducing EMI. This is because all circuits need to be grounded in order to work.

  • Maximize the grounding area within the PCB
  • Use a solid ground plane
  • Connect each component to a ground plane or point
  • Use split planes carefully
  • Connect bypass or decoupling capacitors
  • Minimize signal length

Alignment layout

Proper use of traces ensures proper propagation of current. Traces are essentially conductive paths that contain flowing electrons when the circuit is active, and simple bends or crossings can cause PCB EMI.

  • Avoid right-angle designs
  • Separate signals
  • Shorten the current return path
  • Keep spacing between traces to a minimum
  • Be careful with vias design

Component Alignment

Some best practices for component layout in PCB design include:

  • Separate analog and digital components
  • Separate analog circuits and high-speed trace sections
  • Beware of high-speed components

EMI shielding

Small, high-speed components will always generate some EMI; fortunately, shielding and filtering can minimize the impact of this EMI.

  • Component and board physical shielding
  • Low-pass filtering
  • Cable shielding

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