Flexible Ferrite Magnetic Composite Films for Electromagnetic Applications

Anisotropic magnetic composite films composed of MnZn ferrite powders embedded in an epoxy matrix are investigated for flexible thin-film inductor applications. Commercial MnZn ferrites typically contain α-Fe₂O₃ impurities that impair magnetic performance; in this study, these impurities are effectively eliminated by thermal annealing at 600 °C under argon. To improve particle dispersion and processability within the composite, the ferrite is surface-modified with 3-glycidoxypropyltrimethoxysilane and coated with SiO₂, yielding a more dispersible MZ@SiO₂. This treatment enables the formation of well-aligned particle chains under an external magnetic field, resulting in pronounced magnetic anisotropy and stable permeability. Incorporating FeNi alloy particles into the MZ@SiO₂-based films further increases saturation magnetization and permeability, though finite element simulations indicate that the performance of larger FeNi particles is relatively insensitive to orientation. Inductor devices fabricated with the hybrid MZ@SiO₂-FeNi films exhibit improved inductance and quality factor, underscoring their promise for next-generation high-performance magnetic components with tunable anisotropy.