Microwave Processing of Multilayer Chip Inductors Using MgCuZn Ferrites

MgCuZn ferrites are synthesized by the microwave-hydrothermal method and are processed with varying concentrations of PbO. The nanocrystalline ferrites are sintered using microwaves at a temperature of 900 °C for 30 min. SEM pictures reveal that the grains are uniformly distributed and the addition of PbO causes a small amount of grain growth. The radio frequency behaviors (μ* and a*) of the ferrite samples are tested in the frequency range of 1 MHz to 1.8 GHz. The well-densified MgCuZn ferrite with good electromagnetic properties at high frequency is prepared by incorporation of 0.6 wt% PbO. Using this ferrite powder, the multilayer chip inductors (MLCIs) are prepared by the screen printing method. The inductors of 0.56, 0.88, and 1.44 μH that exhibit self-resonant frequency of 260-600 MHz are made. The size of these inductors is 2 mm × 1.2 mm × 0.8 mm. The inductance and resonant frequency of MLCIs can be adjusted by changing the number of ferrite layers.