Radial-Anisotropy Thin-Film Magnetic Material for High-Power-Density Toroidal Inductors

Conference: CIPS 2012 - 7th International Conference on Integrated Power Electronics Systems
03/06/2012 - 03/08/2012 at Nuremberg, Germany

Proceedings: CIPS 2012

Pages: 6Language: englishTyp: PDF

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Qiu, Jizheng; Sullivan, Charles R. (Thayer School of Engineering at Dartmouth, Hanover, NH, USA)

Thin-film nanogranular magnetic materials are attractive for micro-fabricated high-frequency power magnetics, but their anisotropy makes them difficult to use in toroidal geometries. A method to deposit magnetic materials with the radial anisotropy required for high-power-density and high-quality-factor toroidal inductors is discussed in this paper. The radial anisotropy is induced during sputter deposition of magnetic thin films by an applied radial magnetic field. A magnetic field orientation fixture including a permanent magnet and carefully shaped iron pieces for fabricating smaller toroidal cores with down to 1.6-mm inner diameter and up to 5.7-mm outer diameter has been designed and fabricated. Radial-anisotropy toroidal cores with 1.7-mm inner diameter, 5.6-mm outer diameter, 10-µm thickness have been fabricated. Hysteresis measurements of fabricated samples showed desired radial anisotropy. Magnetic field orientation fixtures with shared magnets enabling fabricating even smaller toroidal cores are proposed. High-power-density and high-quality-factor toroidal inductors using the radial-anisotropy thin-film magnetic material are optimized for a high-frequency power converter.