Influence of particle size on dynamic magnetic properties of tape-casting NiCuZn ferrite sheets

Recently, mobile data wireless transmission has been increasingly draw attention in the electronics industry, especially for the applications of the near field communication (NFC) system operating at 13.56MHz. In order to avoid performance degradation of NFC antenna due to the eddy current in the mobile phone battery, the electromagnetic (EM) shielding sheet is usually attached between the NFC antenna and the battery metal ^[1,^2]. NiCuZn ferrite is an ideal material used for high frequency EM shielding sheet due to its high electrical resistivity, high permeability, and chemical stability. In this experiment, high quality NiCuZn ferrite sheets with a large area (10×10 cm²) and thickness of 60 μm were fabricated by tape-casting technique requiring ferrite slurry. Enhancement of mechanical property of the large-area ferrite sheets is crucial and challenging for practical applications, considerably depending upon the size of the ferrite particles used in ferrite slurry and final sintering conditions. Therefore, the effect of ferrite particle size on microstructure, magnetic permeability and magnetic loss of the NiCuZn ferrite sheets was systematically investigated.