Various Frequency Band Electromagnetic Shielding Film by Internal Multi-Reflection Between ITO Nano-Branches

Electromagnetic wave interference (EMI) means that electromagnetic waves generated from the outside interfere with the operation of some device. As various industries develop, the contamination by electromagnetic waves increases and the risk also increases day by day. In particular, such interference in communication equipment or the space industry can lead to failure of huge capital projects from causing inconvenience in daily life. Shielding this interference is called electromagnetic wave interference shielding (EMI shielding), and various materials or processes are being studied. Representative materials studied so far include carbon, ferrite, perovskite, silicon carbide, and conducting polymer series. It is usually in the form of a composite composed of two or more materials without using a single material. What these composites have in common is that they basically use reflection by electron conductivity or absorption by dielectric or magnetic property. In addition, the effect of dielectric properties occurring at interfaces or internal scattering occurring between surface can be expected. For application to various fields, the thickness of the EMI shielding film should be thin, but considering only absorption by dielectric properties, it cannot be thinner than the skin depth, so the aforementioned additional effects are inevitable. In this study, ITO nano branches were used, and a film capable of EMI shielding on various regions was produced by increasing the density of the rods constituting the nano branches. Consequently, 22.31 dB (X band), 21.88 dB (K_u band), 21.09 dB (K band), and 17.81 dB (K_a band) shielding effect were shown for each region at a thickness of about 3um. It has a very high shielding efficiency compared to a very low thickness. Therefore, it is expected that it can be used in various fields.