Small-Resistance and High-Quality-Factor Magnetic Integrated Inductors on PCB

We have designed and fabricated both single-coil and parallel-coil magnetic integrated inductors with extremely small resistances and high quality factors on an 8-in-round printed circuit board (PCB) substrate for microprocessor power delivery applications. The dc resistances of these inductors are less than 12 ${hbox{m}} Omega $. Soft magnetic material CoFeHfO was successfully integrated into the inductor fabrication to increase the inductance. The quality factors are more than 80 in a frequency range of 1.5–2 GHz for air-core inductors and more than 23 in a range of 200–300 MHz for magnetic inductors. The net inductance improvement of the magnetic inductor over air-core inductor is about 12%, which could be further enhanced with a thicker magnetic core, according to our theoretic calculation and HFSS simulation. We also characterized the permeability spectra of CoFeHfO material on the PCB substrate, simulated the high-frequency performance of the magnetic integrated inductor by HFSS, and, for the first time, reached a good agreement with the experimental data. The experimental and simulation results of the magnetic inductors as compared to those of the air-core inductors point out the future direction to further optimize magnetic integrated inductors.