Design, Fabrication, and Characterization of Flip-Chip Bonded Microinductors

Magnetic core materials of higher performance than ferrite materials in the 0.5-10 MHz frequency range are investigated. The performance characteristics of electrodeposited nickel-iron, cobalt-iron-copper alloys, and the commercial alloy Vitrovac 6025 have been assessed through their inclusion within a custom made solenoid micro-inductor. Inductance values ranging from 0.3 to 120 muH with component power efficiency above 90% have been measured. Two highly laminated prototypes consisting of 70 and 105 laminates of 5 mum thick nickel-iron have achieved a power output efficiency of 92% at 0.5 MHz with power densities of 33 and 49 W/cm³ , respectively. A design methodology based on material properties and device specifications is proposed for the manufacture of performant microinductors. Issues surrounding micro-inductor design and performance are discussed.