Evaluation of package-level EMI shielding using conformally coated conductive and magnetic materials in low and high frequency ranges

The magnetic permeability and thickness of magnetic films and their effects on the EMI shielding effectiveness at 1 MHz were investigated. Various kinds of magnetic films having a thickness of 100μm~500μm and a permeability of 50μ~300μ were fabricated. 2D and 3D test vehicles were employed for measuring near-field EMI shielding effectiveness under magnetic source condition. By utilizing 2D and 3D test vehicles, the effects of various magnetic materials on the near-field EMI shielding effectiveness under H-field sources were studied at a low frequency of 1MHz. As a result, we found that the reduction rate of H-field SE is 8.57%, which is very similar to the total opening area of the four sides. the near H-field SE is affected as a logarithmic function of permeability and thickness equally.