Effects of Composition on the Electromagnetic Wave Shielding/Absorption and Corrosion in Zn-Ni Alloy Thin Film

Abstract

In the Fourth industrial age, there is increasing use of electronic devices with high frequency (GHz) operating circuits for radio wave transmission/reception. This can lead to electromagnetic noise, and malfunctions in nearby devices. Electromagnetic shielding technology has emerged as an important way of preventing device malfunctions due to noise, and interest in shielding materials for electromagnetic waves has also increased. To allow compact integration and light weight electronic devices, highly efficient, thin and multifunctional film materials are required. This study selected the Zn-Ni alloy, which has adequate corrosion resistance, to protect the metal parent material of electronic components. Various compositions of the alloy were deposited using magnetron sputtering. Phase formation and composition were confirmed through XRD and SEM and EDS. The surface resistance of the thin films was measured using the 4point probe method, to calculate the shielding rate of the thin films. The electromagnetic wave shielding/absorption rate then measured according to frequency and the results compared with the calculated values. Corrosion resistance was evaluated with a polarization test. The far field electromagnetic shielding/absorption rate increased as the Zn content increased, up to 52 dB in a film with 70 at% of Zn. Corrosion resistivity behavior was the opposite. However, the Ni5Zn21 phase formation, which occurred in films with lower Zn composition, helped to improve electromagnetic absorption in the near field as well as corrosion resistivity. Therefore, the optimum composition of the Zn-Ni films was provisionally determined to be around Ni: Zn = 43:57 for electronic devices using electromagnetic waves in the near field range.