Permeability and EMI Characteristics of Fe-Si-Al Alloy Flakes-Polymer Composite

摘要

We investigated the magnetic properties of Fe-Si-Al alloy flakes at high frequencies. The flakes were produced by mechanically grinding water-atomized Fe-Si-Al alloy powder in an attriter. These flakes are typically thinner than 1 micron and have a very high aspect ratio. A composite ferromagnetic sheet was fabricated by dispersing the flakes in polymer, oriented with their flat surfaces parallel to the plane of the sheet. It showed high #mu#' and two magnetic resonances at high frequencies. This peculiar behavior is advantageous from the standpoint of EMI suppression. Transparent and coupling attenuation of the sheet in the quasi-microwave range were evaluated using a micro-loop antenna. This new composite as a high-performance EMI suppressor was found superior to the conventional ferrite-rubber composite and that made of Fe-Si-Al alloy teardrop-shaped particles.