Controlling properties of metal-polymer soft magnetic composites through microstructural deformation for power inductor applications

We studied the effect of microstructural deformation on soft magnetic metal powders in a power inductor operating above 1 MHz. In this study, an inductor core was fabricated using Fe-6.5Si powders that exhibit a high electrical resistance and a large magnetic saturation value. This core was formed with a high-density microstructure using nano Fe powders synthesized via pulsed wire evaporation. The permeability was maximized at the content ratio for which the maximum density and packing fraction were observed according to the relationship between permeability and packing fraction outlined in Ollendorff's equation. Experimentally, the highest packing fraction and permeability were observed in the core containing 20 wt% nano Fe powder. Further, the sample with the highest packing fraction showed a relatively low core loss, compared to the other samples. Thus, the inductor core is affected by the intrinsic properties and microstructure of the soft magnetic material used.