Money For Lunch – How to Deal with Electromagnetic Compatibility (EMC) While Designing a PCB?

How to Deal with Electromagnetic Compatibility (EMC) While Designing a PCB?

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What is Electromagnetic Compatibility (EMC)?

Electromagnetic Compatibility, in short EMC, is basically tied with the production, locomotion and the receipt of electromagnetic energy; which is a highly undesirable characteristic of a printed circuit board. The energy which is produced is a consequence of so many energy-producing components placed together on a PCB. It is highly necessary that the signals generated by the random mix of different energy-producing components display compatibility and don’t interfere with each other. It is more like a case of unity in diversity.

What is Electromagnetic Interference (EMI)?

The terms Electromagnetic Compatibility (EMC) & Electromagnetic Interference (EMI) come together but they don’t mean necessarily the same. EMI is basically the undesirable and catastrophic effects which arise due to EMC. EMI is a threat which constantly looms over a printed circuit board and the long-term reliability of the PCB is inversely proportional to the amount of EMI in the circuit. A

As the demand for high-speed circuits is increasing; PCB designers are facing more and more challenges in developing the desired design. Apart from EMC, there are several other factors which a PCB designer has to take in consideration like power consumption, size of the PCB etc. Below provided are certain tips which will, undoubtedly, aid and assist PCB designers in dealing with the EMC issues during the design phase itself.

Tips to Get Over the Electromagnetic Compatibility (EMC) Issues during PCB Design Phase

  • Shielding

Shielding is a type of a mechanical solution in an attempt to decrease EMC. Various PCB Shielding Techniques are used to control EMC over a printed circuit board. The most common PCB shielding technique is the usage of metallic enclosures which prevents the energy from escaping the component. These metallic enclosures are either conductive or made up of magnetic materials and are grounded thereby making them effective in significantly reducing the Electromagnetic Interference.

  • Ground Planes

While designing a printed circuit board the phase of designing the ground plane is the most critical. The ground area must be increased till the maximum possible size in between the area of the printed circuit board. Also, it must be checked that each and every component is connected to the ground plane. In this process, care must be taken that components are not connected randomly to the ground plane. Different techniques are present for effectively connecting the components to the ground plane.

Having a full ground plane is desirable and moreover, if each regulated voltage has its own ground plane, EMC will be overcome with utmost ease. However, the same is not practically feasible as if a PCB designer uses multiple ground planes; the cost of fabricating that PCB will easily surpass the allocated budget.

Also, while coming back to the ground; if a signal is following a long path, a ground loop is created, which functions as an antenna and ultimately emits energy. Thus, the very benefit of designing the ground plane is eliminated. That’s why it is recommended that every trace which is taking the current back to the source must have a minimal path length possible.

  • The arrangement of layers in a multi-layered PCB

If we are designing a multi-layered PCB then we can’t just place the layers randomly. A systematic approach needs to be followed. For example, if a PCB with more than two layers is being constructed then it is recommended to keep one full layer as a ground plane. Similar to this there are certain rules and regulations which are set to reduce EMC in PCB design.

  • Decoupling Capacitor

A decoupling or a bypass capacitor is used near the power supply to provide a low impedance pathway for the high-frequency current generated on the power supply.

  • Digital Circuits

If a digital circuit is being designed then signals generated from clocks are relatively high in speed and for these signals, the traces must be kept as a minimum in size as possible and next to the ground plane so as to control radiation as well as crosstalk.

  • No Random Placement of Components

You can’t just place components randomly over a printed circuit board. Components must be divided into different sections such as digital section, analog section, high-speed section, power-supply etc. If a signal has to move from one section to another a filter must be employed at the border.

Conclusion:

Apart from these various other ways are there which a PCB designer must keep in his/her mind, while designing a PCB, to get a quality product which is reliable for long-term.

 

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