Thick films for multilayer substrates

Abstract

Low temperature fired ceramics based on alumina/glass added oxide ceramics have been developed and are being used by several companies as substrates for high density assembled modular packaging.^1–3 The features of low temperature fireable substrates are the cofireability with highly conductive metals such as Ag, Ag-Pd, or Cu, and the cofireability with other passive component materials for L, C, R and relatively low dielectric constant elements. But most of these substrates have the disadvantage that their thermal expansion coefficient is not perfectly compatible with Si or GaAs. This paper reports the results of a newly developed cordierite/glass based substrate employing Cu as the surface and internal conductors and having the freedom of tuning the thermal expansion coefficient by changing the composition. The ceramic composition with adjustable thermal expansion coefficient value of 3 to 7 ppm/°C can be manufactured and easily matched with the thermal expansion coefficient of Si or GaAs without a big change of electrical performance.     

Radiation-induced bystander effects induce radioadaptive response by low-dose radiation

When normal human fibroblast cells (MRC-5) received a priming irradiation of 3-20 mGy 4 h prior to irradiation with 1000 mGy, the number of DNA double-stranded breaks (DSBs) decreased significantly to 18.2-18.7 per cell compared with 21 per cell when there was no priming irradiation. This result indicates that a priming irradiation of 3-20 mGy induces a radioadaptive response in MRC-5. The authors' previous study had indicated that DSBs induced by ≤ 20 mGy are due to a radiation-induced bystander effect. These findings suggest that radiation-induced bystander effects might contribute to induction of the radioadaptive response. To test this hypothesis, MRC-5 were suspended in lindane, an inhibitor of radiation-induced bystander effects, which was added to the medium for the priming irradiation of 3-20 mGy. Lindane inhibited the protective effect of priming irradiation on DSBs caused by subsequent irradiation with 1000 mGy. Thus, radiation-induced bystander effects may play a role in radioadaptive responses.     

Characterization of silicon dioxide films on a 4H-SiC Si(0001) face by fourier transform infrared (FT-IR) spectroscopy and cathodoluminescence spectroscopy

We used Fourier transform infrared (FT-IR) spectroscopy to characterize silicon dioxide (SiO(2)) films on a 4H-SiC(0001) Si face. We found that the peak frequency of the transverse optical (TO) phonon in SiO(2) films grown on a 4H-SiC substrate agrees well with that in SiO(2) films grown on a Si substrate, whereas the peak frequency of the longitudinal optical (LO) phonon in SiO(2) films on a 4H-SiC substrate is red-shifted by approximately 50 cm(-1) relative to that in SiO(2) films on a Si substrate. We concluded that this red-shift of the LO phonon is mainly caused by a change in inhomogeneity due to a decrease in density in the SiO(2) films. Furthermore, cathodoluminescence (CL) spectroscopy results indicated that the channel mobility of the SiC metal-oxide-semiconductor field-effect transistor (MOSFET) decreases roughly in proportion to the increase in the intensity of the CL peak at 460 and 490 nm, which is attributed to the increase in the number of oxygen vacancy centers (OVCs). FT-IR and CL spectroscopies provide us with a large amount of data on OVCs in the SiO(2) films on a 4H-SiC substrate.     

Differing Escape Responses of the Marine Bacterium Marinobacter adhaerens in the Presence of Planktonic vs. Surface-Associated Protist Grazers

Protist grazing pressure plays a major role in controlling aquatic bacterial populations, affecting energy flow through the microbial loop and biogeochemical cycles. Predator-escape mechanisms might play a crucial role in energy flow through the microbial loop, but are yet understudied. For example, some bacteria can use planktonic as well as surface-associated habitats, providing a potential escape mechanism to habitat-specific grazers. We investigated the escape response of the marine bacterium Marinobacter adhaerens in the presence of either planktonic (nanoflagellate: Cafeteria roenbergensis) or surface-associated (amoeba: Vannella anglica) protist predators, following population dynamics over time. In the presence of V. anglica, M. adhaerens cell density increased in the water, but decreased on solid surfaces, indicating an escape response towards the planktonic habitat. In contrast, the planktonic predator C. roenbergensis induced bacterial escape to the surface habitat. While C. roenbergensis cell numbers dropped substantially after a sharp initial increase, V. anglica exhibited a slow, but constant growth throughout the entire experiment. In the presence of C. roenbergensis, M. adhaerens rapidly formed cell clumps in the water habitat, which likely prevented consumption of the planktonic M. adhaerens by the flagellate, resulting in a strong decline in the predator population. Our results indicate an active escape of M. adhaerens via phenotypic plasticity (i.e., behavioral and morphological changes) against predator ingestion. This study highlights the potentially important role of behavioral escape mechanisms for community composition and energy flow in pelagic environments, especially with globally rising particle loads in aquatic systems through human activities and extreme weather events.     

Synergic effect of Pd/γ-alumina and Cu/ZSM-5 on the performance of NO x storage reduction catalyst

NO _x reduction with a combination of catalysts, Pd catalyst, NO _x storage reduction (NSR) catalyst and Cu/ZSM-5 in turn, was investigated to elucidate for the high NO _x reduction activity of this catalyst combination under oxidative atmosphere with periodic deep rich operation. The catalytic activity was evaluated using the simulated exhaust gases with periodically fluctuation between oxidative and reductive atmospheres, and it was found that the NO _x reduction activity with this catalyst combination was apparently higher than that of the solely accumulation of these individual activities, which was caused by the additional synergic effect by this combination. The Pd catalyst upstream of the NSR catalyst improved NO _x storage ability by NO₂ formation under oxidative atmosphere. The stored NO _x was reduced to NH₃ on the NSR catalyst, and the generated NH₃ was adsorbed on Cu/ZSM-5 downstream of the NSR catalyst under the reductive atmosphere, and subsequently reacted with NO _x on the Cu/ZSM-5 under the oxidative atmosphere.     

Tunable laser for sensing atmospheric transmission in the infrared region of 11 ∼ 16 µm

We succeeded in observing the continuously tunable, pulsed InSb SFR (Spin-Flip Raman) laser emission in the infrared region of 11～16µm (11.4～16.3µm) from only one InSb device, merely by adjusting the pumping wavelength (11 lines from the infrared NH₃ laser) and the applied magnetic field (0～80 kGauss).     

Statistical micromechanical method for dynamic kinetic binary interaction among moderate dense gene-regulating bio-molecules

A statistical thermodynamical approach has been introduced to calculate shear viscosity and thermal flux for interactions among the gene-regulating biomolecular protein particles that operate in moderate density rigid-sphere fluids. Starting from the modified Boltzmann equation with the help of linear perturbation theory, the coefficients of distribution function were determined. On the basis of transport theory, we introduced computational forms of diffusion constant, mass flux, shear viscosity, and thermal flux. We examined the influences of changes in mass, diameter, and magnitude of the pair correlation function. The present method will be available to evaluate the local physical reaction properties of the gene-regulating particles.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

夹杂物及硼对低合金高强钢焊接冷裂纹敏感性的影响

本研究工作采用卧式对接插销试验和定载荷氢脆试验对低合金高强钢冷裂纹敏感性进行了探讨,从试验的结果可以认为:钢中的夹杂物可以作为氢的陷井,吸取更多的氢,因而降低了氢在晶界和局部的集积。所以,在本试验范围内,钢中的夹杂物越多,冷裂纹敏感性越能得到改善。含硼的钢,由于增加钢的淬硬性,因此提高了冷裂纹的敏感性。此外,硼还能促使氢在晶界集积,造成晶界脆弱。由上所述,使晶内存在适量的夹杂物和尽可能降低钢中的含硼量,可以作为改善对冷裂纹敏感性的重要手段。     

NOx reduction behavior on alumina with discharging nonthermal plasma in simulated oxidizing exhaust gas

The NO_x reduction activity on γ‐alumina was significantly improved by discharging nonthermal plasma in a simulated oxidizing exhaust gas under conditions of a high space velocity. On the other hand, those on a Pt‐loaded catalyst and Cu‐ZSM‐5 could not be improved. The discharging nonthermal plasma converted NO to NO₂ and hydrocarbons to partial‐oxidized hydrocarbons, such as aldehydes, under the oxidizing conditions. From the relationship between the NO_x reduction activities and the properties of several alumina catalysts, it was found that the NO_x reduction activity was correlated with the number of acid sites on the alumina based on the NH₃ adsorption measurement. Therefore, it is concluded that the NO_x reduction occurred at the acid sites of the alumina, and the discharging nonthermal plasma improves the NO_x reduction activity by NO₂ formation and partial‐oxidation of hydrocarbons. These results suggest that a catalytic reaction assisted by the discharging nonthermal plasma could be a promising technology for NO_x reduction in lean‐burn and diesel exhaust gases even under the conditions of high space velocity. Copyright © 2006 Society of Chemical Industry