Substrate Embedded, Low-Resistance Solenoid Inductors for Integrated Voltage Regulators

Integrated power conversion and delivery are the key to achieve high-efficiency and high-performance data processing. Power inductors with high power density and low dc resistance are the key enabler to realize miniaturized voltage regulators (VRs) with high efficiency. With the integrated voltage regulators (IVRs), interconnection length from the battery to the loads can be dramatically reduced, resulting in lower conduction loss and higher power efficiency. This article demonstrates substrates with embedded high-power-density solenoid inductors with an ultralow dc resistance for the IVRs. By incorporating advanced metal–polymer magnetic composites as the cores, the inductors show a high inductance density of 7 nH/mm ² with an ultralow dc resistance of 10 $\text{m}\Omega $ . With a low thickness of $< \!\!500~\mu \text{m}$ , the power inductors can be embedded into substrates and positioned close to the loads to realize the IVRs. A substrate-compatible panel-level process was developed to embed the magnetic-core inductors with high throughput and low cost. Compared with the air-core inductors, the magnetic core achieved four times improvement in inductance for the same dc resistance, indicating substantial footprint reduction and improvement in efficiency.