A Micromachined Wiring Board With Integrated Microinductor for Chip-Scale Power Conversion

Abstract

This paper presents a multilayer wiring board that integrates a copper air-core microinductor to enable a highly compact, chip-scale power converter module. The wiring board is wafer-level fabricated with three 30-μm-thick electroplated copper layers and is subsequently detached from the fabrication wafer to yield a board that is only 90 μm thick for minimum overall module volume. Within this platform, a stacked-spiral air-core microinductor is designed for high-switching-frequency power conversion and yields high inductance density of 128 nH/mm 2 (100 nH/mm 3 by volume, including 600 μm clearances both above and below the inductor to minimize coupling with external conductors). Although this technology is anticipated to be more appropriate for emerging, experimental converters with switching frequencies >30 MHz, a proof-of-concept, ultraminiature (9 mm 2 footprint, 0.7 mm thick) power converter module is presented that utilizes the microinductor wiring board in conjunction with a commercially available surface-mount boost regulator (∼4 MHz switching frequency). The converter module yielded a maximum output power of 153 mW at 60% efficiency for a volumetric power density of 24 mW/mm 3 based on the physical volume occupied by the module (13 mW/mm 3 based on the volume needing to be kept clear from external conductors).

Power management for small scale systems

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“…If the loa d, so that the w oard can be use Figure 3. Thick-film copper wiring board used to realize integrated power converter module [10].…”

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

“…The central idea of a reduced frequency of operation approach to improve the FOM of proposed inductor can be justified as follows. It is well known that increasing the frequency will reduce the inductance requirement for switching converters [39]- [42]. However, one cannot increase the switching frequency extremely high for the reasons mentioned earlier.…”

Characteristics of Double Planar Micro-Inductor with Patterned NiFe Thin-Films for DC/DC Integration

“…With the decrease of size and weight of portable electronic products, the requirement of a power management chip for internal integration is becoming urgent. For micro-processors and mobile devices, thin film magnetic inductors are useful for integrated power delivery solutions, which will replace conventional wire-wound inductors [ 1 , 2 ]. The miniaturization and integration of the inductor with electronic circuits are the key to realize electronic products with high performance, small size, light weight, high saturation current, high efficiency, and low lost [ 3 , 4 , 5 ].…”