Batch fabrication of radial anisotropy toroidal inductors

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

“…Figure a compares the performance, inductance density (L/area) vs Q/area, of the S‐RuM power inductors with conventional state‐of‐the‐art (SoA) micro‐inductors with similar sizes, frequencies, and application targets. [ 58–72 ] By this figure of merit, S‐RuM Cu plated inductors achieved very high Q per area due to resistance improvements of over 10x. The Q value of the 2‐cell, 5‐turn S‐RuM inductors (plotted in green) improved from 2 to 15 without changing the physical areal footprint of 0.15 mm 2 , allowing this device design to reach a higher Q per area than all other reported micro‐inductors.…”

“…Benchmark of S‐RuM electroplated inductors with conventional state‐of‐the‐art (SoA) inductors. a) Benchmark chart of L/area vs Q/area for three types of S‐RuM inductors against other SoA micro‐inductors recently reported in the literature: [ 58–72 ] (green) 2‐cell, 5‐turn, Cu plated devices; (yellow) 4‐cell, 15‐turn, Cu plated devices; (red) 4‐cell, 10‐turn, Cu shell and magnetic core plated devices (circle for control/unplated, star for plated). b) Comparison of S‐RuM devices of the same geometries with and without electroplating: (green) 2‐cell, 5‐turn, Cu plated devices showing significant resistance drop; (yellow) 4‐cell, 15‐turn, Cu plated devices showing significant resistance drop; (red) 4‐cell, 5‐turn, and (blue) 4‐cell 10‐turn, Cu shell and magnetic core plated devices, showing both significant resistance drops and inductance increases (circle for control/unplated, triangle for plated).…”

Design, Modeling, and Analysis of a 3-D Spiral Inductor With Magnetic Thin-Films for PwrSoC/PwrSiP DC-DC Converters

“…The Q dc of magnetic-core inductors is better than air-core inductors due to enhanced inductance contributed by the magnetic-core. However, the integration of a magnetic-core has following disadvantages: (a) it involves core loss [24] (b) it is challenging to integrate the core [25], [26], and (c) it is difficult to introduce anisotropy into the core [27], [28]. In the previous research on 3D inductors [5], [29] [see Fig.…”

“…Also, it involves displacement eddy current loss [33]. The second approach degrades the power handling capacity of the film [34]. Finally, the third approach is not suitable for power supply frequency range, which is typically 1-100 MHz, as it suffers from low quality factor [31].…”

“…This novel approach offers a low reluctance path for the flux, resulting in high inductance density. The thin-film magnetic-cores are arranged so that flux travels along the hard axis of the core, which is essential for high-frequency operation [34], and the eddy currents flow in the axial direction, in the direction opposite to the current in the vertical conductors of the winding. More details on the 3-D spiral inductor with magnetic thin-films are given in section III.…”