Ferrite polymer composite for improving the electromagnetic compatibility of semiconductor packaging

The complex permittivity and permeability of ferrite-filled polymer composites were studied at 50 MHz to 1 GHz, and their effects on the electromagnetic compatibility (EMC) of an integrated circuit (IC) package mounted on a printed wiring board (PWB) in the far- and near-field modes were investigated. Incorporating the ferrite particles into the polymer increased the real part of the complex permeability to 10-11 at 50 MHz, and the real part exhibited a frequency dependency over the applied frequency range (50 MHz to 1 GHz). The ferrite particle increased the magnetic loss (μ″ = 3-5) as well, which can absorb the magnetic energy of the incident electromagnetic wave. By coating the test IC package with the ferrite-polymer composite materials, the EMC level of the PWB was dramatically improved. This improvement may be due to the high magnetic loss of the ferrite-polymer composite.