Makoto Sonehara

Preparation and characterization of Mn-Ir/Fe-Si exchange-coupled multilayer film with Ru underlayer for high-frequency applications

Fe-Si magnetic film and Mn-Ir/Fe-Si exchange-coupled film with an Ru underlayer were fabricated and evaluated. Both coercivity and anisotropy dispersion were reduced due to the Ru underlayer effect on the magnetic properties of Fe-Si magnetic film and Mn-Ir/Fe-Si exchange-coupled film. Even in the Mn-Ir/Fe-Si exchange-coupled multilayer film with an Ru underlayer, the coercivity of the upper Fe-Si layer was reduced.

Development of an Electromagnetic Wave Shielding Textile by Electroless Ni-Based Alloy Plating

A polyester nonwoven textile with Ni-based alloy coating was fabricated, and the effect of electromagnetic wave shielding was evaluated. The Ni-based was coated by electroless plating on the textile. The electromagnetic wave shielding effect of the textile with Ni-B coating was about 99.98% over the induction range of 6-13 GHz. Because the textile has thin, light, flexible, and breathable characteristics, it will be versatile for the various electromagnetic wave shielding applications.

Preparation and Characterization of Nanofiber Nonwoven Textile for Electromagnetic Wave Shielding

A nanofiber nonwoven textile with metallic magnetic material coating was fabricated, and the effect of electromagnetic wave shielding was evaluated. The nanofiber nonwoven textile with an average diameter of about 500 nm was spun by electrospinning. The metallic magnetic material was coated by sputtering on the textile surface. EMI shielding effect of the textile with metallic magnetic material coating was about 90% in the GHz band. Because the textile has thin, light, flexible, and breathable characteristics, it will be versatile for various electromagnetic wave shielding applications.

Carbonyl-Iron/Epoxy Composite Magnetic Core for Planar Power Inductor Used in Package-Level Power Grid

Our research objective is to realize the basic technology for a next generation package-level power grid (PLPG) for plural application large scale integrated circuits (LSIs). In this study, a carbonyl-iron powder (CIP)/epoxy composite magnetic core, for large-current power inductor used for the main dc-dc converter in the PLPG, has been fabricated and evaluated. 54 vol.%-CIP/epoxy composite core made by screen-printing had a relative permeability of 7.5 and loss tangent of about 0.03 at 100 MHz. The planar power inductor using composite core was fabricated and evaluated, which had a quasi closed magnetic circuit consisting of low permeability composite core and embedded 35-μm-thick, two-turn copper spiral coil. The fabricated inductor with a 1-mm-square in size had 5.5 nH inductance, Q-factor of 15 at 100 MHz, and 18 mΩ dc coil resistance. Inductance was constant even when the superimposed dc current increased up to around 5.5 A.

Increase of

In order to increase Q -factor of radio-frequency (RF) magnetic thin film inductor integrated in chip-size-package RF-ICs, two schemes have been investigated experimentally. For suppressing the in-plane eddy current of the magnetic thin film, a slit-patterned structure was introduced, and it was found that the slit-patterned magnetic thin film is very effective for increasing Q-factor. On the other hand, for suppressing alternating current (ac) copper loss, a multiline-conductor spiral coil was introduced, and it was found that the multiline coil is effective for improving decrease of inductance at high frequencies. By introducing the two schemes, a maximum Q-factor of 18 at 1.5 GHz was obtained in a spiral inductor with a bottom slit-patterned CoFeSiO/SiO2 granular multilayer film and triple-line-conductor spiral coil.

Q

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 850×850 μm2, 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.

-Factor of RF Magnetic Thin Film Inductor by Introducing Slit-Patterned Magnetic Thin Film and Multiline-Conductor Spiral Coil

Mn-Ir/Fe-Si exchange-coupled films with an Ru underlayer for high frequency applications were fabricated, and their microwave permeability was evaluated. Both exchange bias field and ferromagnetic resonance frequency increased with decreasing Fe-Si thickness. For example, Mn-Ir (10 nm)/Fe-Si (10 nm)/Ru (1 nm) exchange-coupled film deposited on SiO 2 had a static relative permeability of about 180 and a ferromagnetic resonance (FMR) frequency of about 4.3 GHz. The microwave properties such as permeability and FMR frequency can be controlled by changing Fe-Si thickness

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

To realize the basic technology of a package-level dc power grid for the next generation power delivery to large scale integrated circuits (LSIs), two types of planar spiral inductors embedded in an organic interposer, for several tens of megahertz switching power supply integrated in LSI package, have been proposed. One is a Zn-Fe ferrite core spiral inductor, and another is a hybrid core spiral inductor, with quasi closed magnetic circuit consisting of the bottom Zn-Fe ferrite core and top carbonyl-iron/epoxy composite core. In this paper, the two types of planar spiral inductors have been fabricated and evaluated. From the experimental results, it was found that the hybrid core planar spiral inductor exhibited higher Q-factor and larger rating dc current than the Zn-Fe ferrite core inductor.

Relation Between Microwave Complex Permeability and Ferromagnetic Fe-Si Layer Thickness in Mn-Ir/Fe-Si Exchange-Coupled Film

A novel microelectromechanical systems (MEMS) Fabry-Perot tunable filter (FPTF) and calibration system for accurately controlling the wavelength of the transmission peak in the wide wavelength range of visible light are reported. The MEMS FPTF consists of a Fabry-Perot filter having Ag alloy mirrors, an electrostatic actuator, and a capacitive gap sensor. The calibration system consists of the capacitive gap sensor, a capacitance measurement circuit, and a voltage controller. Through introducing the calibration system to MEMS FPTF, wavelength accuracy of more than ±1 nm is achieved. This is the accuracy level required for high-accuracy spectrum measurement in the range from 400 to 700 nm.

Embedded Planar Power Inductor in an Organic Interposer for Package-Level DC Power Grid

A strain sensor using a stress-magnetoresistance effect of a Ni–Fe/Mn–Ir exchange-coupled magnetic film was fabricated and evaluated. The stress magnetoresistance is used in the inverse magnetostrictive effect and the magnetoresistance effect in the magnetic film since an external stress is changed into an electric resistance in it. A compressive stress was measured by the strain sensor with a Mn–Ir (10 nm)/Ni–Fe (50 nm)/Ru (1 nm) exchange-coupled film. The change in resistivity Δρ/ρ is proportional to the applied compressive stress σ for σ≦50 MPa in the strain sensor. When increasing Ni–Fe layer thickness in the strain sensor, a gauge factor increased.