Preparation Of Electromagnetic Shielding Fabric By Magnetron Sputtering

Electronic products are more and more widely used in People's daily life, while electromagnetic wave has disadvantage to health of people, therefore, how to reduce the harm caused by electromagnetic radiation has drawn more and more attention by people. In this paper, harm to people caused by electromagnetic radiation and research status quo of electromagnetic shielding fabric both at home and abroad was introduced. Main research achievements of electromagnetic shielding fabric, such as blended fabric made from metal fibers and dressed fibers, chemical coated fabrics, metal-plating fabrics, multi-iron fabrics, nano-material finished fabrics were presented. However, electromagnetic shielding fabrics prepared by these ways have lots of defects, such as poor handle, low shielding efficiency, pollution on environment and caducous agent. In the paper, a Physical Vapor Deposition technique - magnetron sputtering, which was a dry processing method without any pollution, was applied to deposit nano-thickness films on the surfaces of fabrics to obtain the electric conductivity and electromagnetic shielding properties.Parameters of film thickness, sputtering power and pressure of argon were changed in the process of depositing nano-film on nonwoven by magnetron sputtering. In the meanwhile, Atom force microscope (AFM) was applied to observe the effect of technical parameters on film structure and sputtering speed. Results showed that film thickness, sputtering speed and argon pressure had influence on film structure and physical performance of the films. The process of Nano silver depositing and forming film on non-woven fabric with magnetic sputter is introduced. Four-probe tester was used to test the foursquare resistances of the films, and influences of parameters on conductivity were analyzed. It showed that when the film thickness reached to a certain degree, conductivity increased as the film thickness increased. When coated with silver films of the same thickness, the conductivity decreased as the increase of sputtering power and first decreased then increased with the increase of argon pressure. Electromagnetic shielding efficiency(SE)of the coated fabrics was tested according to ASTM D4935-99, it showed that SE increased with the increase of film thickness, and when thickness is 100nanon, SE value reached 26dB or above(that is shielding proportion over 99.7%). Based on the SE(shielding efficiency) tested, a regression equation of film thickness and SE is obtained, which can be used to forecast the SE. According the equation, the SE of non-woven fabric deposited with nano-silver film of 500nm will come to 56.46dB.Qualitative and quantitative analysis of optical performance and surface element of the coated fabric was also carried out. Analysis of surface elements shows that along with the increase of the film, the silver content on the non-woven fabric will increase.