Fabrication of Planar Power Inductor for Embedded Passives in LSI Package for Hundreds Megahertz Switching DC-DC Buck Converter

Recently, research and development of integrated low-voltage dc-dc converter to LSIs has been active. In order to realize such integrated dc power supply, power magnetic devices must be integrated in it. The authors have fabricated planar power inductor embedded in LSI package for hundreds megahertz switching dc-dc buck converter. In this study, two types of planar power inductors have been fabricated: one was spin-sprayed Zn-ferrite thick film magnetic core inductor, and the other was composite magnetic core (Fe-based amorphous/polyimide) inductor. Footprint of the fabricated inductors was 850 x 850 mu m(2), their inductance was about 10 nH, and the quality factor Q was about 20 at 100 MHz. The rating current which depends on the superimposed dc characteristic was at least up to 2 A.ArticleIEEE TRANSACTIONS ON MAGNETICS. 47(10):3204-3207 (2011)journal articl

The road to fully integrated DC-DC conversion via the switched-capacitor approach

This paper provides a perspective on progress toward realization of efficient, fully integrated dc-dc conversion and regulation functionality in CMOS platforms. In providing a comparative assessment between the inductor-based and switched-capacitor approaches, the presentation reviews the salient features in effectiveness in utilization of switch technology and in use and implementation of passives. The analytical conclusions point toward the strong advantages of the switched-capacitor (SC) approach with respect to both switch utilization and much higher energy densities of capacitors versus inductors. The analysis is substantiated with a review of recently developed and published integrated dc-dc converters of both the inductor-based and SC types. © 2012 IEEE

Micro-Fabrication of Planar Inductors for High Frequency DC-DC Power Converters

International audienc

PCB embedded bondwire inductors with discrete thin film magnetic core for power supply in package

This paper details the design, assembly, and detailed characterization of Printed Circuit Board (PCB) embedded thin magnetic film inductor for Power Supply in Package applications. Solenoidal inductors were assembled on copper tracks printed on PCB with wire bonds to complete the copper loop. Further, the solenoid inductors have laminated amorphous soft magnetic thin films embedded between the two conductor layers. The devices have chemically thinned Vitrovac films laminated as core material. Three different designs of solenoid inductors with different number of turns, are assembled and characterized. The assembled PCB inductor measured a highest Quality factor of 8.5 for a 3 turn device at 10 MHz

Doctor of Philosophy

dissertationMicroelectromechanical systems (MEMS) resonators on Si have the potential to replace the discrete passive components in a power converter. The main intention of this dissertation is to present a ring-shaped aluminum nitride (AlN) piezoelectric microreson

Metal-embedded SU-8 Slab Techniques for Low-resistance Micromachined Inductors

This work presents a new fabrication technique for micro power inductors by using metal-embedded SU-8 slab molding techniques. The proposed technique uses X-ray lithography to fabricate high-aspect-ratio LIGA-like microstructures in form of embedded structures in the SU-8 slab. This process was applied to fabricate an inductor’s windings with an aspect ratio of 10, which can provide very low resistance but still preserve a small form factor and low profile. Inductors were designed as pot-core structures with overall heights of 370 μm and embedded with 250-μm-thick windings. From the advantage of metal embedded SU-8 slab techniques, 8 μm-thick permalloy core could be fabricated by electroplating around the winding in a single step that could help simplify the process. Four types of inductors were fabricated with 3, 5, 10, and 16 turns in the area of 1.8 to 9.5 mm2. The measured inductance was in the range of 70 nH to 1.3 μH at 1 MHz and DC resistance of 30–336 mΩ for 3–16 turns, respectively. The DC resistance of fabricated inductor was low, as expected, and showed good result compared with the results in literature

Design, modelization and realization of integrated inductive components for low power supplies and microsystems

Full integration of energy conversion devices for compact power supply circuits is still encountering strong technological locks, especially to integrate passive inductive and capacitive components. The increasing working frequency of those devices, which already reaches 1 Megahertz, would enable the size reduction of passive components and then their integration. Nevertheless, losses, which highly depend on frequency and technology, may complicate or even stop this increase.\ud The objective of this thesis is the systematic study of integrated inductors structures through the developing of precise modeling and simulating methods on the frequency range from 0Hz to 1GHz. First, an analytic model based on PEEC (Partial Element Equivalent Circuit) method has been developed. This modeling approach has been adapted to the studied components: rotational symmetry, not negligible section conductors, inhomogeneous media, etc… The final model splits the physical study of the component into two steps: electromagnetic computations on subparts of the set (partial elements) and global frequency response calculus with the equivalent electrical models of the subparts. A full process for the technological realization of inductive components has also been achieved in order to experimentally verify the modeling. The improvement of design resolution and increase of copper electroplating thickness, as planarization of conductor levels with SU8 resin have been specifically studied. Those overhangs have permitted the realization of multilevel and multiconductor inductors which present good features at high frequency. Finally, the characterization of prototypes at low frequency has been enabled by the realization of an impedance measurement bench we developed for the range from 40Hz to 110MHz and high frequency characterizations have been performed with a network analyzer. This work has been completed by the development of a very fast computing analytical model for the calculus of the magnetic field in integrated inductors. This method has been used to find the repartition of the magnetic field generated by integrated planar magnetic actuators excited by a DC current for a microsystems and microfluidics application.---------------------------------------------------------------L’intégration complète des dispositifs de conversion d’énergie destinés à créer des circuits d’alimentation compacts se heurte encore aujourd’hui à des contraintes technologiques fortes sur l’intégration des composants passifs inductifs et capacitifs. La fréquence de fonctionnement de ces dispositifs, d’ores et déjà de l’ordre du MHz, en augmentant pourrait réduire la taille de ces composants passifs et donc permettre leur intégration. Cependant, les pertes fortement liées à la fréquence et à la technologie, freinent encore cette augmentation.\ud Cette thèse a pour objectif l’étude systématique de structures d’inductances intégrées à travers le développement d’une modélisation accompagnée de simulations précises pour le développement d’une méthodologie de simulation valable sur la plage de fréquence de 0Hz à 1GHz. Pour cela, un modèle analytique basé sur la méthode PEEC (Partial Element Equivalent Circuit) a d’abord été développé. Ce type de modèle a du être adapté aux topologies des composants étudiés : symétrie cylindrique, conducteurs de section non négligeable, milieux non homogènes… Ce modèle décompose l’étude du composant en deux étapes : calculs électromagnétiques menés sur des sous-parties du composant (éléments partiels) et calcul de la réponse fréquentielle globale à partir de modèles électriques des éléments partiels. Un procédé complet de réalisation technologique des composants inductifs a également été mis au point en parallèle afin de valider expérimentalement la modélisation. L’amélioration de la résolution des motifs et l’augmentation de l’épaisseur des dépôts lors des étapes de croissance électrolytique du cuivre, ainsi que la planarisation des niveaux de conducteurs avec de la résine SU8 ont fait l’objet d’études spécifiques. Ces avancées ont permis la réalisation de selfs multibrin et multiniveau qui présentent des caractéristiques électriques intéressantes en haute fréquence. Enfin, la caractérisation des prototypes en basse fréquence a été rendue possible par la mise en oeuvre d’un banc de mesure d’impédance pour la gamme de fréquence de 40 Hz à 110MHz et des caractérisations en haute fréquence effectuées à l’aide d’un analyseur de réseau. Ces travaux ont été complétés par la mise au point d’une méthode analytique de calcul du champ magnétique. Les calculs permettent de prédire la répartition du champ magnétique généré par des actionneurs magnétiques planaires intégrés excités en courant continu