Fe/Submicron FeNi Soft Magnetic Composites with High Working Frequency and Low Loss

Application of high-power electronic equipment requires inductors with greater high-frequency performance and higher energy efficiency than ever, and thus it is urgent to develop new soft magnetic composites to meet these requirements. To reduce the eddy current loss of soft magnetic composites and obtain molded inductors with high working frequency, low loss and high power, high purity submicron FeNi particles were prepared by plasma torch, and effect of these particles on eddy current loss of soft magnetic composites was examined by simplified finite element model. Soft magnetic composites and molded inductors were prepared by mixing carbonyl iron powder and submicron FeNi particles with different mass fractions. The influence of submicron FeNi particles on the properties of soft magnetic composites and molded inductors is analyzed emphatically. With 30% of mass fraction of submicron FeNi particles, the imaginary part of permeability (mu") mu" ) of the ring core decreases from 1.57 to 1.36 (reduced by 13.4%), compared with that of the soft magnetic composite made by only pure carbonyl iron powder. The quality factor Q of the molded inductors at 10 MHz increases from 13 to 20 (increased by 53.8%), while the self-resonance frequency increases by 12.7% and the saturation current increases from 2.148 A to 2.352 A. Submicron FeNi particles can effectively reduce eddy current loss and improve stability of the high frequency permeability of soft magnetic composites by increasing the internal resistance of materials and reducing the size of eddy current flow region. Therefore, this study demonstrates that compounding submicron FeNi particles is a promising method to obtain molded inductors with high frequency, low loss, and good comprehensive performance at low cost on a large scale.