Silver Based Electromagnetic Shielding Coating Glass

With the development of electronic technology and broad application ofelectronic equipment, electromagnetic radiation has an increasing significant impacton the human life. The electromagnetic interference could cause two problems: (1)noise signal and even malfunction of the electronic appliance; (2) radiative damageof the human body. Therefor shielding of electromagnetic radiation is very important.Many electromagnetic shielding materials are used to prevent electromagneticinterference. In many fields such as medical instrument for diagnosis, display screenof personal electronic equipment, windows of aerospacecraft, request the materialswith large shielding effectiveness and high transparency in the visible range.Transparent electromagnetic shielding glasses accord with these requests. Theinnovations in this article are that AZO/Ag/AZO and AZO/Ag/AZO/Ag/AZOmultilayer films are produced by magnetic sputtering at room temperature; throughexperiments and theory calculation, the structure of the multilayer films is fixed whatmake sure the glass has high transparency in the visible range and large shieldingelectromagnetic effectiveness; Oxidizing processes and mechanism of silver thinfilm in atmosphere at room temperature are researched.The main obtained conclusions in this article are as follows:1) For AZO/Ag/AZO multilayer films, when the thickness of silver film andAZO film is 16nm and 45nm respectively, multilayer films show minimum sheetresistance of 5.02Ω/sq, maximum transmittance in the visible of 86%, maximuminfrared reflectivity of 95% and electromagnetic shielding effectiveness of35dB(5.85-8.2GHz).2)For AZO/Ag/AZO/Ag/AZO multilayer films, when the thickness of silver filmand AZO film is 16nm and 92nm respectively, multilayer films show minimumsheet resistance of 2.73Ω/sq, maximum transmittance in the visible of 70%,maximum infrared reflectivity of 99% and electromagnetic shielding effectiveness of40dB (5.85-8.2GHz).3) The silver thin film with thickness of about 16nm deposited by radiofrequency magnetron sputtering will be degraded in atmospheric environment at room temperature and lose good conductivity and high infrared reflectivity. Ag₂Sand Ag₂SO₄ first dot-dispersed over silver film, and then formed continuum compactAg₂S (little Ag₂SO₄) film after the silver film tally oxidized. The mechanism ofoxidation of silver thin film exposed to the room temperature and atmosphericenvironment is as the following: O₂ was first chemically adsorbed on the surface ofthe films and the surface reconstruction was caused; then small molecule gasescontaining S such as H₂S and SO₂ were also chemically adsorbed on the surface ofthe films and the surface reconstruction was caused again; finally, the silver thinfilms were oxidized to a great deal of columnar Ag₂S and a few of Ag₂SO₄ by O₂and small molecule gases containing S; the silver thin films were not oxidized byCO₂ and N₂ in the air.