Ultra Low Profile Power Inductor Integrated in Wafer Level Package

Abstract

An ultra-low profile power inductor solution with wafer level package has been demonstrated. The proposed power inductor is formed by high aspect ratio Cu pillar with embed high permeability bulk magnetic material. By adding proper bulk magnetic material into 3D inductor with tall Cu pillar, the inductance value can be increased significantly for DC-DC converter. In this paper, we presented solenoid and toroid type power inductor; Solenoid inductor presents 10 times inductance enhancement, 365 for L/DCR (nH/Ohm) and 950mA for saturation current with 10.5 turns. Toroid inductor presents 33 times inductance enhancement, 888 for L/DCR (nH/Ohm) and 120mA for saturation current with 22 turns on 2x1.7mm2 area, almost all of index can be match expectation.