Basic Measures to Control EMI

Basic Measures to Control EMI

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Electromagnetic interferences are invisible ghosts that tend to plague the performance of the best electrical devices. Electromagnetic interferences hamper the functionality of the electronic devices. Hence it becomes necessary to guard the electrical appliances against these harmful electromagnetic waves.

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EMI shielding is a mechanism to protect the electronics from electromagnetic interferences. In order to maintain the smooth performance of the electronics, it is essential to prevent them from damages caused by variant electromagnetic frequencies.

Electromagnetic interferences not only disrupt the circuits in which they originate but also affect the nearby circuits. Substantially the electrical engineers are working towards lessening the impact of EMI, yet they face a threat of electromagnetic energy leaks that tend to glow to other parts of the circuits.

Here are stated some of the measures that help in controlling the electromagnetic interferences and improve the functioning of the electrical circuits and systems.

Broad-Level Shielding:

Broad-level shielding is often viewed as a five-sided can that is available in various shapes and heights. They are placed on the circuit over the printed board that requires shielding. Broad-level shielding restricts to acceptable levels of energy propagation between the source and the receptor. BLS is manufactured in various configurations to achieve various levels of effectiveness as stated below:

  • Near Field Effects – shielding performance is likely to be affected by the frequency of the electromagnetic interferences, the position of the source and the field configuration. Other factors to be considered are shield grounding and termination techniques, the coupling of the source to the shield and the mutual effect of coupling between the elements.
  • Layout Considerations – proper design of printed circuit board highly affects the effectiveness of BLS. Also, the number and spacing of traces between the holes of shielded areas of the circuit board determine the effectiveness of the broad-level shielding.

Gasket Shielding:

Through proper seam treatments, gasketing helps to maintain the effectiveness of the shielding. Gasket shielding is a way to deal with the leaks in the enclosed circuit designs. Gaskets are helpful in maintaining the contact between the mating surfaces and are highly dependent on the materials, contact pressures and surface areas. Gasket shielding is generally used where there is no continuity between the metal pieces and apertures. Depending on the suitability, there are two types of gaskets as follow:

  • Metalized Fabric Gaskets – they are made of conductive fabric material and offer a high attenuation.
  • Beryllium Copper Gaskets – these gaskets offer the highest level of attenuation amongst various usable compressions and shear applications. These finger-shaped gaskets offer greater cross-sectional area and higher conductivity.

Thermal Management:

When the devices become fast, they tend to generate more heat. Thermal management being an essential factor of design and layout can be achieved through proper use of thermal pads and heat sinks.

These forms of EMI shielding are highly important to avoid any damages caused by different frequencies of electromagnetic waves. Not only have the measures carried an importance in EMI shielding, basic principles equally carry their importance.


EMI shielding is essential to avoid any encumbrances caused due to varied electromagnetic frequencies of electrical devices. The EMI’s not only affect the circuits in which they originate but also affect the neighboring circuits. To know about the measures to control the EMI, read here.