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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. [ABSTRACT FROM AUTHOR]

It has been very difficult to develop a miniaturized temperature sensor device using the conventional temperature-sensitive ferrites, such as Mn-Zn ferrite, which is due to difficulty of the high-frequency operation, because of their low natural resonance frequency (below 1 MHz) and low electrical resistivity (around 10[sup2] - 10[sup4] Ω·cm). The authors have recently developed a polycrystalline Mn-substituted Li-Zn-Cu ferrite with a high natural resonance frequency beyond 10 MHz and high resistivity over 10[sup6] Ω·cm, which exhibited strong temperature-dependent magnetic properties. It was considered that the transmission-line device using a new temperature-sensitive ferrite as an electromagnetic-field propagation substrate enables us to obtain a novel chip temperature-sensing micro device, because of the possibility of high-frequency operation due to a high resonance frequency and high resistivity of the new ferrite. We have simulated a quarter-wavelength resonator using the Mn-substituted Li-Zn-Cu ferrite substrate and its temperature-dependent properties. Since the quarter-wavelength transmission-line resonator includes distributed inductance and capacitance depending on the temperature-sensitive electromagnetic property of the ferrite substrate, this type of device operates as an integrated LC resonator-type temperature sensor. In this study, the integrated resonator-type temperature sensor using a spiral strip-line structure with the Mn-substituted Li-Zn-Cu ferrite substrate was fabricated, and its temperature-dependent characteristics were evaluated. [ABSTRACT FROM AUTHOR]

Recently, high-density printed circuit boards (HD-PCBs) with less than 50 μm/50 μm line/space has been developed. In the HD-PCB, since the spacing between adjacent signal lines becomes very small, the crosstalk electromagnetic interference among adjacent lines becomes serious. In general, in order to suppress the crosstalk, the ground line is located at the spacing between signal lines because of the decrease of mutual capacitance among adjacent signal lines. The authors have proposed a magnetic method for reducing the crosstalk. The composite magnetic material was filled in the spacing between signal lines instead of the ground line. The magnetic composite is composed of Fe-Si-B-Cr amorphous particles with a mean diameter of 6 μm and epoxy resin. From the experiments using the PCB-TEG with a 130 μm/50 μm line/space and 25-mm line length, the crosstalk was suppressed in the wide frequency range by using the magnetic composite. In the case of using 51 vol.% amorphous composite, the crosstalk suppression was up to 20 dB around 1 GHz. The influence of the magnetic composite on the transmission and reflection in the main signal line was very small. Therefore, the proposed method is effective for crosstalk suppression without influence on the signal transmission. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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)IRu (1 nm) exchange-coupled film deposited on SiO2 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. [ABSTRACT FROM AUTHOR]

A new planar inductor using a composite magnetic core for low voltage and large current dc-dc converter has been developed. The composite material consisted of a 40% volume fraction of Mn-Zn ferrite particle with a mean diameter of 10 μm and polyimide matrix. The composite magnetic core exhibited a low relative permeability of 6. The fabricated planar inductor with a size of 15 × 15 × 1.4 mm consisted of an inner two-turn copper square spiral coil, a top 350-μm-thick composite magnetic core and a bottom 1-mm-thick Ni-Zn ferrite substrate. The inductor had a dc coil resistance of 15 mΩ and an inductance of 140 nH. The degradation of inductance was below 4% at a superimposed dc current of 10 A. A synchronous rectifier type buck converter with a switching frequency of 1 MHz, an input voltage of 5 V, and an output voltage of 1 V was constituted using a planar inductor, and exhibited a maximum conversion efficiency of 80% at 4 A. [ABSTRACT FROM AUTHOR]

In order to miniaturize the quarter wavelength transmission-line transformer for high frequency impedance matching, a possibility of a spiral microstrip-line structure with a magnetic/dielectric hybrid structure was investigated. For this purpose, the CoZrNb/polyimide hybrid spiral microstrip-lines with various spiral turns were fabricated and evaluated. From the results, the spiral transmission-line structure enabled to miniaturize the quarter wavelength transformer, whose insertion loss was comparable with that of a straight-line structure. [ABSTRACT FROM AUTHOR]

A new wideband common-mode noise filter for switching power supplies has been developed. The filter consisted of an Mn-Zn ferrite core and a copper/polyimide tape wound coil. The tape wound coil had two signal lines, two ground lines, and a poly- imide dielectric film. The filter exhibited a common-mode rejection of over 30 dB in the wide frequency range of 100 kHz to 100 MHz. The wideband common-mode filtering was due to the high-frequency magnetic loss of the Mn-Zn ferrite core and the optimum ground point selection for the ground lines. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The thermal stability and read-write properties of synthetic ferrimagnetic media (SFM) are compared with conventional media (CM) of the same stability factor KuV/kT and Mrδ (remanent magnetization and thickness product). SFM are found to be more stable than the equivalent CM, suggesting that the thermal stability advantage does not arise simply from an "increased effective volume." The overwrite properties (OW) and nonlinear transition shift (NLTS) are better for CM. However, for media with the same signal decay rate, the OW is similar over a wide head field range and the NLTS match at larger fields. [ABSTRACT FROM AUTHOR]