Microscale magnetic components for the application of DC-DC converters operating in the 1-10 MHz range

A novel method to manufacture and assemble a microinductor that is based on flip-chip bonding is described in this article. The microinductor is developed for DC-DC converters operating in the MHz switching frequency. The fabricated inductors have an inductance ranging from 0.3μH to 180μH. An optimum Q-factor of 14 was attained at 1 MHz. Cobalt-copper-iron cores maintained a constant inductance across a 1 kHz-1MHz bandwidth. The thin film laminate minimizes the eddy current loss and the hysteresis loss was negligible. Impedance increases linearly with frequency indicating that parasitic capacitance effects in this frequency range are negligible. The microinductor operated at an efficiency of 92% at 1MHz achieving a power density of 3.75 W/mm³.