High resistive ferrite films by a solution process for electromagnetic compatible (EMC) devices

• Published in: Journal of magnetism and magnetic materials 2009-12, Vol.321 (24), p.3979-3983
• Main Authors: Subramani, A.K., Kondo, K., Tada, M., Abe, M., Yoshimura, M., Matsushita, N.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Ferrite film; Insulators; Low-field transport and mobility; piezoresistance; Magnetic material; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Resistivity; Solution process
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2009.07.036

Mn–Zn ferrite films with high resistivity and good noise suppressing ability for use as ‘coupling-type noise suppressors’ have been prepared by the spin-spray ferrite plating. The as-prepared films were crystalline and exhibited single-phase spinel structure. The films had an ‘integrated nano-columnar’ morphology that resulted in a very high resistivity. Further, by varying the chemical composition, films with varying resistivity were prepared and then heat treated at 260 °C for 3 min, similar to that of the reflow soldering process. The reflection and transmission coefficients, S 11 and S 21 parameters, on coplanar micro-strip line (50 Ω) were measured for the as-prepared and heat-treated films in order to study the effect of heat treatment. When the resistivity was above 2×10 5 Ω/sq, S 11 and S 21 exhibited uniform profiles throughout the measurement frequency (50 MHz–10 GHz), which is ideal for the ‘coupling-type’ noise suppressor. These films retain a moderately high resistivity and hence do not show the downshift in the stopband frequency even after the heat treatment (reflow soldering process).