PCB Electromagnetic Compatibility Shielding Design

The existence of electromagnetic interference is the reason for electromagnetic compatibility consideration when designing PCB products. Electromagnetic interference (EMI) is the process by which destructive electromagnetic energy is transmitted from one electronic device to another electronic device by radiation or conduction. In general, EMI refers to radio frequency signals (RF), but electromagnetic interference can occur in all frequency ranges.

Increasing attention is paid to the need for SE/EMC (shielding effectiveness/ electromagnetic compatibility) with more use of electronic components. Electromagnetic shielding is based on the principle of metal isolation to control electromagnetic interference from one area to another area to sense and radiate electricity spread.

Usually includes two kinds: one is electrostatic shielding, mainly used to prevent effects from electrostatic field and constant magnetic field; another is electromagnetic shielding, mainly used to prevent effects from alternating electric field, alternating magnetic field and alternating electromagnetic fields. 

EMI shielding can make the product simple and effective in line with the EMC specification. When the frequency is below 10MHz, most electromagnetic waves are in conductive forms, while most higher frequencies are in the form of radiation.

When designing, solid monolayer shielding material, solid multi-layer shielding material, double shielding or more than double shielding and other new materials are used to shield EMI. Low-frequency electromagnetic interference requires thick shielding layer. To obtain the maximum electromagnetic absorption loss, the most suitable one is the use of high permeability materials or magnetic materials such as nickel-copper alloy, etc. While metal shielding are suitable for high-frequency electromagnetic waves.