Design, Fabrication, and Characterization of Package Embedded Solenoidal Magnetic Core Inductors for High-Efficiency System-In-Package Integrated Voltage Regulators

Abstract

In this paper, we discuss the design, fabrication, and characterization of package embedded solenoidal inductor using a NiZn ferrite magnetic core material based on the novel fabrication process. The process relies on stencil printing of the magnetic core material along with the photolithography and copper electroplating of the inductor’s traces. The electrical parameters of the fabricated inductors were extracted using a pi-equivalent circuit and showed an average dc resistance of 29 $\text{m}\Omega $ , an inductance of 26 nH, and an ac resistance of $2.62~\Omega $ at 100 MHz, which represents the targeted switching frequency of the system-in-package integrated voltage regulator. The organic substrate parasitic effects were accounted for through the extraction of an average shunt capacitance of 1.2 pF and an average parasitic conductance of 0.12 mS at 100 MHz. The measured 10% saturation current of the inductor was 9.6 A. The electrical parameters of the fabricated inductors were modeled and showed a good agreement with the measured data.