Nanoimprinting using release-agent-coated resins

A fluorinated self-assembled monolayer (F-SAM) is mainly used as the antisticking layer. To prevent the F-SAM coated on the nanoimprint lithography (NIL) mold from deteriorating, we propose a new form of nanoimprinting using a release-agent-coated resin. The results from measuring the surface free energy and observations by scanning probe microscopy (SPM) confirmed that the surface free energy, frictional force, and adhesion force of the release-agent spray-coated polymethylmethacrylate (PMMA) were lower than those of PMMA. To prove the release-agent spray-coated PMMA had a releasing effect, we tried to undertake thermal nanoimprinting on it using a mold without F-SAM. The pattern was clearly imprinted on the resin without any signs of adhesion.     

Preliminary Study of Single Phase Preparation and Doping Effect of <Emphasis Type="Italic">β</Emphasis>-Zn<Subscript>4</Subscript>Sb<Subscript>3</Subscript>

Single phase β-Zn₄Sb₃ was prepared by the application of a two-stage heat treatment, and impurity elements were doped. The undoped and doped samples were prepared by direct melting followed by two-stage heat treatment at 450°C and 400°C after solidification of the samples in sealed quartz ampoules. Impurity doping of the samples was performed by the addition of 1 at.% of Se, In, Pb, Te, or Bi. The resulting samples were characterized by x-ray diffraction (XRD), differential thermal analysis (DTA), optical microscopy, and electron probe microanalysis, and their Seebeck coefficients were determined at room temperature. The undoped samples were determined by XRD and DTA to comprise single phase β-Zn₄Sb₃, while the doped samples were composed of multiple phases. From the measurements of the Seebeck coefficient, all samples were found to be p-type and all were found to have almost the same values. These results indicate that β-Zn₄Sb₃ has limited solubility for these impurity elements.     

Thermal Conductivity of Bi<Subscript>0.5</Subscript>Sb<Subscript>1.5</Subscript>Te<Subscript>3</Subscript> Affected by Grain Size and Pores

A fine measurement system for measuring thermal conductivity was constructed. An accuracy of 1% was determined for the reference quartz with a value of 1.411 W/m K. Bi_0.5Sb_1.5Te₃ samples were prepared by mechanical alloying followed by hot-pressing. Grain sizes were varied in the range from 1 μm to 10 μm by controlling the sintering temperature in the temperature range from 623 K to 773 K. The thermal conductivity was 0.89 W/m K for the sample sintered at 623 K, while a grain size of 1.75 μm was measured by optical microscopy and scanning electron microscopy. The thermal conductivity increased on the sample sintered at 673 K because of grain growth and decreased on those sintered at the temperatures from 673 K to 773 K because the increase of pore size caused to decrease thermal conductivity. The increase of thermal conductivity for the samples sintered at temperatures above 773 K was affected by the increase of carrier concentration.     

New high-resolution positive and negative photoresist method for ?/4-shifted DFB lasers

High-resolution positive and negative photoresists were used to fabricate ?/4-phase-shifted corrugations by holographic exposure. To avoid mixing these photoresists, cyclised polyisoprene was used as a midlayer. The shape and depth of the corrugations on the positive and negative photoresist regions were almost the same. Single-mode operation at the Bragg wavelength was confirmed in lasers with the corrugation.     

A Barium-Titanate-Ceramics Capacitive-Type EEG Electrode

A capacitive-type electrode using barium titanate ceramics is described. This electrode is not affected by the polarization potential. Because its surface is chemically inactive and mechanically strong, its noise voltage is minimum from the beginning of its installation. This device is especially suitable for EEG recording.     

Osteogenic activity of human periosteal sheets cultured on salmon collagen-coated ePTFE meshes

Our animal implantation studies have demonstrated that, after osteogenic processing, cultured human periosteal sheets form osteoid tissue ectopically without the aid of conventional scaffolding materials. To improve the osteogenic activity of these periosteal sheets, we have tested the effects of including a scaffold made of salmon collagen-coated ePTFE mesh. Periosteal sheets were produced with minimal manipulation without enzymatic digestion. Outgrown cells penetrated into the coated mesh fiber networks to form complex multicellular layers and increased expression of alkaline phosphatase activity in response to the osteoinduction. In vitro mineralization was notably enhanced in the original tissue segment regions, but numerous micro-mineral deposits were also formed on the coated-fiber networks. When implanted subcutaneously into nude mice, periosteal sheets efficiently form osteoid around the mineral deposits. These findings suggest that the intricate three-dimensional mesh composed of collagen-coated fibers substantially augmented the osteogenic activity of human periosteal sheets both in vitro and in vivo.     

Current Pumping from Spin Dynamics

We show theoretically that charge and spin currents arise from spin dynamics in the presence of the spin–orbit interaction. The dominant calculation is the inverse spin Hall effect, namely the spin current pumped from precession of local spins is converted into the charge current by the spin–orbit interaction. The conversion mechanism is explained based on the conservation laws of charge and spin.     

RETRACTED ARTICLE: Single-Phase <Emphasis Type="Italic">β</Emphasis>-Zn<Subscript>4</Subscript>Sb<Subscript>3</Subscript> Prepared by a Mechanical Grinding Method

Single-phase β-Zn₄Sb₃ materials were prepared by mechanical grinding (MG). Source materials for the Zn₄Sb₃ ingots were prepared using three different processes after the direct melting of constituent elements. In process 1, the ingot was obtained by quenching the melt in water within an evacuated quartz ampoule. In process 2, the ingot was heat-treated for 100 h at 723 K after process 1. In process 3, the ingot was heat-treated for a total of 200 h in two stages at 723 K and 673 K after process 1. The resultant ingots were mechanically ground and sintered at 623 K by hot pressing. The sintered materials were characterized by x-ray diffraction, differential thermal analysis (DTA), and thermoelectric property measurements. The thermal conductivity of the sintered materials was 0.88 W m⁻¹ K⁻¹ at room temperature, being slightly lower than that reported for the materials prepared by a conventional method. Results indicate that the dimensionless figure of merit of the single-phase β-Zn₄Sb₃ ranged from 1.06 to 1.31 at 573 K.     

Ultra-thin high-density LSI packaging substrate for advanced CSPs and SiPs

An ultra-thin high-density LSI packaging substrate, called multi-layer thin substrate (MLTS), is described. It meets the demand for chip scale packages (CSPs) and systems in a package (SiPs) for use in recently developed small portable applications with multiple functions. A high-density build-up structure is fabricated on a Cu plate, which is then removed, leaving only an ultra-thin, high-density multi-layer substrate. MLTS has (1) excellent registration accuracy, which enables higher density and finer pitch patterning due to the use of a rigid, excellent-flatness Cu base plate; (2) a thinner multi-layer structure due to the use of a core-less multi-layer structure; (3) excellent reliability, supported by the use of an aramid-reinforced epoxy resin dielectric layer; and (4) a cost-effective design due to the use of fewer layers fabricated using a conventional build-up process. A prototype high-density CSP (0.4-mm pitch/288 pins/4 rows/10 mm²) was fabricated using a 90-μm-thick MLTS (with a solder resist layer). Testing demonstrated that it had excellent long-term reliability. A prototype ultra-thin, high-density SiP (0.5-mm pitch/225 pins/11 mm²/0.93 mm thick) was also fabricated based on MLTS. MLTS consists of only two conductor layers (total thickness: 90 μm) while an identical-function build-up printed wiring board needs four conductor layers (total thickness: 300 μm). With its thinner core-less multi-layer structure, MLTS enables the fabrication of ultra-thin, high-density SiPs.     

40 Gbit/s packet bit error ratio and loss real-time measurement for ultrahigh-speed packet switched network

A novel packet bit error rate (BER) and loss measurement method and system is proposed. A proposed 40 Gbit/s packet BER and loss measurement system is expressed in detail. A 40 Gbit/s BER and loss measurement with various conditions is demonstrated experimentally. In real time, only the payload part of a packet and burst stream with fluctuated guard time is evaluated. The BER and packet loss of a randomly received packet sequence due to routing and buffering can be also evaluated by the measurement system. A 10 Gbit/s packet BER and loss measurement with optical label switching, buffering, and preamble-free optical packet 3R are demonstrated experimentally.