Solenoid-Type PCB-Integrated Inductors Based on Embedded Multilayer Magnetic Thin Films

The increasing demand for miniaturized and highly efficient power management solutions in portable electronic devices has driven the miniaturization and integration of passive components, particularly inductors. This paper presents the design, fabrication, and characterization of an ultra-thin solenoid-type PCB-integrated inductor based on a multilayer laminated Ni50Fe50magnetic thin-film core. By combining magnetic thin film lamination with standard PCB manufacturing processes, the inductors with a thickness of only 0.37 mm are achieved. The study investigates three inductor prototypes: 5-turn coils with closed cores, 3.5-turn coils with non-closed cores, and 4.5-turn coils with non-closed cores. The respective areas of these inductors are 6.7 mm²,6.5 mm², and 7.0 mm², with inductance values at 10 MHz of 30.4 nH, 32.1 nH, and 35.0 nH. The achieved quality factors (Q) are 13.39, 9.40, and 15.39, respectively. Electrical characterization and performance analysis reveal that the inductors exhibit high inductance-to-DC resistance ratios, superior Q-factors, and exceptional performance compared with previously reported PCB-integrated inductors. The electrical performance of these inductors is further demonstrated in a 10 MHz buck converter. These results demonstrate that the proposed method is a commercially viable approach to deliver ultra-thin, high-performance inductors suitable for high-frequency power supply applications.