Calculate EMI shielding effect and skin depth
Countless kinds of EMI shields have different materials and shapes, but in general the ultimate goal is to limit the electromagnetic field.
The shielding element acts as a barrier to block electromagnetic radiation. In fact, the process of this shielding method has a huge attenuation, which will depend on the electromagnetic wave and the material of the shielding element.
When waves hit the shielding material, two new waves are generated, including reflected waves and transmitted waves. Therefore, the energy of the incident wave will split into these two waves. The transmitted component is the key related component, and the wave will pass through the shielding material to the outside. The effectiveness of the shielding will determine its ability to attenuate this component. Skin depth is the distance that a wave can travel before its amplitude is reduced to 1/e. This parameter depends on the material permeability, frequency and resistivity.
The purpose of using shielding material is to reduce the amplitude of the wave as much as possible after the wave passes. Therefore, it is extremely important to select the appropriate material type and its thickness t to ensure that all frequencies of the system are attenuated.
How the shielding material performs in this task depends on the shielding effect (S.E).


Types of EMI shielding

The type of EMI shielding will largely depend on the type of product, electromagnetic requirements and environmental conditions. The most common EMI shielding is as follows:
-EMI gasket.
-EMI shielding tape.
-Metal clip.
-Shielding cabinet.

EMI gasket
EMI gaskets are used to cover the irregular but existing micropores between two mechanical surfaces. These gaskets can also be used to improve the ground connection. They have sticky parts and many contours, so they can be easily installed in different types of mechanical joints.
The gasket can be cut to fit any system.


EMI shielding tape
When you want to make sure that all the micro holes are covered, but there is not much vertical space for options like EMI gaskets, EMC tape is the first choice. These tapes have a highly conductive material (such as nickel or copper) on the top and an adhesive on the other side.
There are many length and width options for EMC shielding tape, the picture is provided by Holland Shielding Systems BV.

Metal clip
Any equipment needs a short, wide, and directly connected ground wire. If this connection is not done well, an unnecessary monopole will be formed, which will generate radiated electromagnetic fields. The metal clip improves this connection and strengthens the mechanical connection.

Shielding cabinet
For interference sources such as CPU, storage IC, and radio frequency (RF) level, it is an excellent choice to use a shielding cabinet on the PCB layer for separate shielding.
The shielding cabinet can be installed on the PCB in conclusion.
All circuits emit electromagnetic radiation and are easily radiated by other circuits. Obtaining the certification needed to bring your product to market can be a painful testing process.
Various forms and types of EMI shielding are the basis for solving EMI problems.