Unleashing the Performance of Self-Rolled-Up 3D Inductors via Deterministic Electroplating on Cylindrical Surfaces

Internet-of-Things and Cyber-Physical-System applications demand compact power converters, which require inductors to have small footprints but considerable power handling abilities. 3D air-core tubular inductors fabricated using the self-rolled-up membrane (S-RuM) technology have demonstrated significantly higher inductance density compared to conventional planar structures. However, previous design options and associated performance are constrained by the resistive loss due to the thickness of the metal and magnetic coupling limited by the air core. Here, the study reports a post-rolling electroplating scheme aimed at enhancing the metal conductivity and core magnetic permeability in S-RuM inductors, all while maintaining their compact footprint. A DC resistance improvement of over 10X and an inductance enhancement of over 30X are achieved by the 3D S-RuM inductors, via parallel-processed Cu-electroplated strips on the cylindrical shells and partially permalloy-electroplated core. The improvement is projected to continue to improve as the entire core is filled. This advancement paves the way for scalable applications of this technology in ultra-compact, low-loss passive power electronics, such as converters and filters. The strain-induced self-rolled-up membrane (S-RuM) technology has been demonstrated to be an effective platform for dramatically miniaturizing passive components including inductors. This work introduces the concept and design methodology of a post-rolling electroplating process on the walls and in the core of the curved surfaces of S-RuM inductors, to improve the quality factor (Q) and inductance, respectively, without compromising the footprint. image