Electromagnetic Interference Shielding
20 April 2009 | Green Technology | No Comments
The high demand on the reliability of electronics and the rapid growth of radiofrequency radiation sources have rapidly increased the importance of electromagnetic interference (EMI) shielding due to the interference of radiofrequency radiation with digital electronics.
To solve this problem , the radiation sources and electronics are shielded by materials which reflect or/and absorb radiation.
The electromagnetic interference refers to the reflection and/or absorption of electromagnetic radiation by a material that acts as a shield again the penetration of electromagnetic waves.
EMI shielding is distinguished from magnetic shielding, which refers to the shielding of magnetic fields at low frequencies.Materials for EMI shields are different from those for magnetic shielding.Electromagnetic shielding is realized through reflection, absorption and/or multiple relfections.
The absorption mechanism of EMI shielding is due to the presence of electric and magnetic diapoles that interact with the electromagnetic fields in radiation.BaTiO3 or other materials, having a high electrical permittivity, may provide the electric dipoles.Fe3O4 or other materials with high magnetic permeability may provide the magnetic dipoles.The increasing of the volume concentration of magnetic dipoles is possible by reducing the number of magnetic domains through the use of multilayer magnetic films.
Tags: electromagnetic, electromagnetic fields, electromagnetic interference, Electromagnetic shielding, electromagnetic waves, EMI shielding