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61.
Flip chip technology with Au bumps on a substrace has been widely applied to electronic equipment such as smart phones. The purposes of this study are to examine the effect of Al pad thickness on the bondability of flip chip using ultrasonic bonding and to clarify interfacial structures between Au alloy bumps and Al pads by ultrasonic bonding compared before and after a thermal cycle test. Suitable Al thickness for excellent initial Au/Al bonding without chip cracking are 0.8 μm because a thin Al layer could not reduce stress to a chip under an Al pad during the ultrasonic bonding process. Intermetallic compounds between the Au alloy bump and chip after reflows consisted of five Au-Al layers, and a pure Al layer remained. On the other hand, after the temperature cycle test at 218/423 K, intermetallic compounds between the Au alloy bump and chip were changed into two kinds of Au-Al layers, so a pure Al layer did not exist. In addition, if thick intermetallic compound layers existed around the bonding region, bondability deteriorated easily by thermal stress due to a thermal cycle test, therefore the open failure rate was rising when the Au thickness was 1.2 μm. 相似文献
62.
A simple screening procedure for heterotrophic nitrifying bacteria with oxygen-tolerant denitrification activity 总被引:4,自引:0,他引:4
Matsuzaka E Nomura N Nakajima-Kambe T Okada N Nakahara T 《Journal of Bioscience and Bioengineering》2003,95(4):409-411
Various naturally occurring strains of heterotrophic nitrifying bacteria were isolated by enrichment culture using acetamide as the C and N source, and 21 strains were identified as heterotrophic nitrifiers. Using a new simple procedure, these 21 strains were also investigated for the ability to carry out denitrifcation in the presence of oxygen. Several of the nitrifying strains were found to exhibit a distinct activity that allows for denitrifcation via nitrite (NO2-) in the presence of oxygen, indicating that they have an oxygen-tolerant denitrifcation system. A wide variety of bacteria possessing both nitrification and denitrifcation capabilities in the presence of oxygen were isolated and partially characterized by using the simple screening combinatorial procedure described in this paper. 相似文献
63.
64.
Yoshihiko Okada Kaori Sasaki Baiqian Zhong Hideki Ishida Takeshi Mitsuda 《Journal of the American Ceramic Society》1994,77(5):1319-1323
A mixture of CaO and silicic acid prepared with a Ca/Si ratio of 2.0 was hydrothermally synthesized at 80° to 200°C, and the thermal decomposition behavior of the products (C-S-H with Ca(OH)2 ) was analyzed using XRD, 29 Si MAS NMR, and the trimethylsililation method (TMS). It was found that the main silicate anion structure of C-S-H was a mixture of a dimer and a single-chain polymer (larger than Si5 O16 ) and that polymerization advanced with an increase of the synthesizing temperature. On heating, the products decomposed to form β-C2 S. It was found that the decomposition was gradual and that the-higher the temperature of hydrothermal synthesis, the lower was the temperature of the decomposition into β-C2 S. Although the decomposition proceeded to form a monomer (β-C2 S) from the polymer and dimer, this dimer was resistant to heat and did not decompose unless heated to above 400°C. 相似文献
65.
66.
We studied the use of poly(ethylene glycol) (PEG)-modified dendrimers as a nanocapsule with a biocompatible surface. We designed PEG-modified dendrimers having a shell of hydrophobic amino acid residues in the peripheral moiety of the dendrimer to increase their encapsulation ability. Subsequently, l-phenylalanine or γ-benzyl-l-glutamate residues were introduced to all chain ends of the poly(amidoamine) G4 dendrimers. Furthermore, PEG (MW 2000) chains were attached to the amino acid residues. These hydrophobic amino acid residues rendered the PEG-modified dendrimers as more compact. After binding of Rose Bengal (RB) guest molecules to dendrimers, an assay using the Klotz plot showed that the hydrophobic amino acid layer slightly affected the guest site number, but significantly increased intrinsic binding of the dendrimers to guest molecules. The PEG-modified dendrimers with the hydrophobic amino acid layer were better able to retain guest molecules than the dendrimer without the layer: they are therefore useful for drug delivery. 相似文献
67.
The thermal stability of a FeF3 cathode was quantitatively studied by differential scanning calorimetry (DSC). The cycled electrode without electrolyte was examined and found to become more thermally stable after Li-ion insertion. On the other hand, mixtures of cycled electrodes and electrolyte were investigated by changing the ratio of cycled electrode to electrolyte. The thermal decomposition of the electrolyte was mainly responsible for the exothermic heat for the discharged electrode and electrolyte combination. Although a reaction between the active materials of the electrode and electrolyte was observed for the mixture of the charged electrode and electrolyte, the exothermic heats were small. In contrast to lithium transition-metal oxide cathodes for lithium-ion batteries, the exothermic heat was suppressed by the FeF3 electrode. Therefore, FeF3 as a cathode for Li-ion batteries shows more thermal stability at elevated temperatures. 相似文献
68.
In the present study, K2S and Bi2S3 were used as additives in electrolytes and electrodes, respectively. The effects of these additives on the electrochemical properties of nano-sized Fe2O3-loaded carbon electrodes were investigated using cyclic voltammetry (CV), galvanostatic cycling performance and scanning electron microscopy (SEM), along with electron dispersive spectroscopy (EDS). The results showed that both K2S and Bi2S3 significantly reduced hydrogen evolution and benefited the Fe2O3-loaded carbon electrode, such as by retarding passivation and improving the discharge capacity. The effects of metal sulfide additives depended on the carbon used. For Bi2S3 additive, all carbons provided larger capacities than acetylene black (AB) while AB gave greater capacity than other carbons when K2S was used. 相似文献
69.
LiMxMn2−xO4 (M=Co, Ni) materials have been synthesized by a melt-impregnation method using γ-MnOOH as the manganese source. Highly crystallized LiMxMn2−xO4 compounds were synthesized at a calcination temperature of 800°C for 24 h in air. All compounds show a single phase except for LiNi0.5Mn1.5O4 based on the X-ray diffraction (XRD) diagram. With the increase of the doping content from 0.1 to 0.5, the capacity of doping materials decreases mainly in the 4 V region.
Although LiM0.5Mn1.5O4 (M=Co, Ni) compound shows a small capacity in the (3+4) V region compared with parent LiMn2O4, it is a very effective material in reducing capacity loss in the 3 V region that is caused by the Jahn–Teller distortion. The doping of Co and Ni ions in the LiMn2O4 cathode material promotes the stability of this structure and provides an excellent cyclability. 相似文献
70.
Kazuki Tajima Yasusei Yamada Shanhu Bao Masahisa Okada Kazuki Yoshimura 《Solar Energy Materials & Solar Cells》2008,92(2):120-125
All-solid-state switchable mirror glass was prepared by magnetron sputtering. The device exhibited the multi-layer structure of Mg4Ni/Pd/Ta2O5 on WO3/ITO/glass substrate. The Mg4Ni, Pd, and Ta2O5 in the device acted as optical switches, proton injector and solid electrolyte, respectively. Reactive DC magnetron sputtering was employed as a new deposition method for Ta2O5 electrolyte thin film for the device. The transmittance of the device, at a wavelength of 670 nm using reactive DC-sputtered Ta2O5 thin film, reached 0.1% (a reflective state) to 48% (a transparent state). The transmittance change occurred in less than 40 s when 5 V was applied, and the switching speed was 60 times faster than that of the device using reactive RF-sputtered Ta2O5 thin film. 相似文献