Review on recent progress in epoxy-based composite materials for Electromagnetic Interference(EMI) shielding applications

The densely packed electronic components in electronic devices emit electromagnetic (EM) radiations, and the interaction of the emitted EM radiations with external EM signals of neighboring components leads to device malfunctions and also creates health issues in human beings. Particularly, in aircraft, EM interference is a serious threat that leads to disastrous outcomes. The shielding of electronic components is an ideal way to reduce the pollution of electromagnetic interference (EMI). The mechanism of EMI shielding efficiency is discussed elaborately in this article. The factors associated with the EMI shielding of materials are discussed in detail. The EMI shielding by reflection and absorption are two possible routes to improve the shielding performance of the shielding materials. This article also highlights the EMI shielding mechanisms by reflection and absorption. However, the risk of secondary EM pollution is associated with the reflection of EM waves. This review also outlines the methods to improve the absorption-based shielding performance of the materials. The significance of the microstructure of the shielding materials in enhancing the absorption-dominant shielding efficiency is also presented with a detailed analysis. This helps to fabricate the absorption-dominant EMI shielding materials with suitable microstructures. The EM loss is associated with the magnetic, dielectric, and conduction losses according to EM theory.