Electromagnetic Interference Shielding Effectiveness of Silver Thin Films Fabricated By Dry Plasma Reduction

Abstract

Owing to the wide use of commercial, military, and scientific electronic devices and communication instruments, electromagnetic interference (EMI) shielding of radio frequency radiation is becoming a serious global problem. In general, light weight, high conductivity and excellent adhesion are required for EMI shielding materials. Metals and their composites are the most popular materials for EMI shielding effectiveness. Currently, they are usually deposited by sputtering and electrodeposition. However, there are some inconvenience for their wide application such as expensive vacuum equipment, or high voltage and small cell used for deposition method. Recently, we developed a new process for efficiently synthesizing supported metal, core-shell, bimetallic nanoparticles by using dry plasma reduction (DPR) near room temperature under atmospheric pressure. The aim of this technique was to overcome the previous mentioned process restrictions. We present, for the first time, here the use of DPR to fabricate silver thin film on PET substrate under atmospheric pressure, without using any toxic chemicals, near room temperature for EMI shielding applications. The morphology and silver film thickness are characterized through HRSEM. The formation of silver nanoparticles are examined using TEM, XRD and XPS measurements. Silver film conductivities are measured by four point probe. The results show that silver thin films are successfully fabricated by DPR. EMI shielding effectiveness is measured in the frequency range from 0.045 to 1 GHz. As the results, the silver thin films have significant shielding effectiveness of more than 55 dB at 0.1 GHz with near 600 nm thickness and sheet resistance of 0.087 Ω/□. Furthermore, the increase in silver film thickness resulted in decreasing sheet resistance and increasing EMI shielding effectiveness.