Organic package substrate embedded coupled magnetic core inductors using lithographic via technology for power supply in package

Abstract

In this work, a cost-effective organic package substrate embedded coupled magnetic core inductor technology is proposed and demonstrated for power supply in package applications. Based on a novel lithographic via process, it involves a solid copper pillar electroplating step for creating a groove and integration of the vertical interconnects of the inductor. The primary and secondary windings of the coupled inductor are interleaved on the rectangular magnetic composite core which is accommodated within the groove. The coupled inductor combines solid vertical interconnecting with low loss magnetic composite core, therefore bringing together tight process tolerances and superior current capability. Experimental results show that the 2.9-mm2 coupled inductor achieves a high inductance to resistance ratio of 0.28 nH/mΩ, and a coupling factor of 0.57. In addition, the proposed inductor achieves an ultra-high saturation current of 16.52 A that is the highest reported value for a high-frequency integrated magnetic core inductor to the best of our knowledge. The performance of the coupled inductor has been calculated for a standard 1.8 to 1 V interleaved converter. Notably, it demonstrated a remarkable efficiency exceeding 95% across a wide range of phase currents between 0.11 and 2.32 A.