Comparison of low-melting lead-free solders in tensile properties with Sn–Pb eutectic solder

The tensile properties of Sn–8 mass % Zn–3 mass % Bi and Sn–58 mass % Bi low-melting lead-free solders were investigated and compared with those of a Sn–Pb eutectic solder. The tensile strength decreases with decreasing strain rate and increasing temperature. The tensile strength of each solder is approximately double that of the Sn–Pb solder at room temperature (RT). The ductility of each solder is inferior to that of the Sn–Pb solder. From the results of strain-rate-change tests, the stress exponents and the activation energies for creep of Sn–58Bi and Sn–8Zn–3Bi were also examined.     

Effect of thermal treatment on catalytic properties of La0.9Ce0.1 0003

The effect of thermal treatment on the catalytic properties of methane oxidations and the surface chemical states of La_0.9Ce_0.1CoO₃ have been investigated using X-ray photoelectron spectroscopy (XPS). The catalytic activity reached a maximum in the sample calcined at 1123 K. With further increase in the calcination temperature, the surface chemical states of cobalt seemed to shift from perovskite phase to CoO, and the catalytic activity decreased.[/p]     

Nanoscale operation of a living cell using an atomic force microscope with a nanoneedle

We have developed a tool for performing surgical operations on living cells at nanoscale resolution using atomic force microscopy (AFM) and a modified AFM tip. The AFM tips are sharpened to ultrathin needles of 200-300 nm in diameter using focused ion beam etching. Force-distance curves obtained by AFM using the needles indicated that the needles penetrated the cell membrane following indentation to a depth of 1-2 microm. The force increase during the indentation process was found to be consistent with application of the Hertz model. A three-dimensional image generated by laser scanning confocal microscopy directly revealed that the needle penetrated both the cellular and nuclear membranes to reach the nucleus. This technique enables the extended application of AFM to analyses and surgery of living cells.     

Tetragonal-to-Cubic Structural Phase Transition in Pollucite by Low-Temperature X-ray Powder Diffraction

The tetragonal-to-cubic structural phase transition in pollucite (CsAlSi₂O₆) was investigated using low-temperature X-ray powder diffraction in the temperature range of 93 to 298 K, and the lattice constants were refined with Rietveld analysis. It was found that CsAlSi₂O₆ had a tetragonal phase with a space group of I 4₁/acd in the temperature range of 93 to 248 K, a = 1.36337(4) nm, c = 1.36988(6) nm at 248 K, and underwent a phase transition from tetragonal to cubic with a space group of Ia-3 in the temperature range of 248 to 273 K, a = 1.36645(3) nm at 273 K.     

聚对苯二甲酸丁二酯/热塑性聚酰胺弹性体合金的抗冲击强度和破坏机理

聚对苯二甲酸丁二酯（ＰＢＴ）与在ＰＢＴ中添加了热塑性聚酰胺系弹性体（ＴＰＡＥ）的ＰＢＴ合金相比，前者的抗冲击强度低，后者的抗冲击强度高，通过偏光显微镜和扫描电镜的观察，在Ｕ型缺口前部区域内的塑性束缚下，ＰＢＴ呈脆性破坏；ＰＢＴ的合金因塑性区域内的空穴化和空穴的变形及空穴之间区域的颈缩和纤维化，有效的吸收了冲击能量，使塑性束缚得到缓解，促进了平面应变状态向平面应力状态转变，最终呈半韧性或韧性破坏。     

Morphologies and tensile properties of elastomer-modified epoxy and polycarbonate blended systems

The morphologies and tensile properties of an elastomer-modified epoxy (EME)/polycarbonate (PC) binary system and an EME/diglycidyl ether of bisphenol A (DGEBA)/PC ternary system were examined. In the EME system, a continuous elastomer-rich phase formed, while in the EME/DGEBA systems (unblended with PC), a continuous epoxy-rich phase formed. In both of these systems, two-phase structures were observed. In contrast, a microdispersed structure was observed when the PC was blended with either the EME or with the EME/DGEBA systems. It is suggested that blending of the epoxy with PC caused an increased solubility of the former into the elastomer phase. The tensile strength and tensile elongation of both the EME and EME/DGEBA systems were improved by blending with PC. In the EME/PC blend, the tensile elongation reached its maximum value (60%) at a PC content of approximately 10 p.h.r. (parts per hundred resin by weight), with this maximum being approximately one and a half times higher than that of the unblended EME. Tensile strength was also clearly increased by blending with small amounts of PC, but soon reached a steady value. In the EME/DGEBA/PC blends, the tensile properties were dependent on the weight ratio of EME to DGEBA. In the absence of PC, as this ratio increased, the tensile elongation also increased, while at the same time the tensile strength decreased. The tensile properties were also improved in this system, by blending with PC. From the results obtained, it was clear that the improvement in tensile properties was closely related to the changes in morphology. Therefore, blending of the PC induced a microdispersed structure and improved the elongation of the epoxy resin.     

The relationship between moisture resistance and epoxy molding compounds in integrated circuits

The influence of epoxy molding compounds on metallized aluminum corrosion in a Pressure Cooker Test (P.C.T.) was investigated by a monitor chip encapsulated in a dual in-line package (D.I.P.). The monitor chip is composed of a leakage current measuring part which has opposite metallized aluminum tracks and an aluminum corrosion measuring part which has metallized fine aluminum tracks. The formulation of the epoxy molding compound was changed for the average particle size of fillers, the internal release agents, and the coupling agents. The relationships between the stress of the epoxy molding compounds and moisture resistance was also investigated by using epoxy molding compounds which had different characteristics of stress.     

Homogeneous graft copolymerization of styrene onto cellulose in a sulfur dioxide–diethylamine–dimethyl sulfoxide cellulose solvent

Graft copolymerization of styrene onto cellulose was studied in a homogeneous system (SO₂–DEA–DMSO medium) by γ-ray mutual irradiation technique. At the same time, homopolymerization of styrene was also examined separately in DMSO, SO₂–DMSO, DEA–DMSO, and SO₂–DEA–DMSO media by the same technique. Polymerization of styrene hardly occurs on concentrations above 10 mole SO₂–DEA complex per mole glucose unit. Maximum percent grafting was obtained in concentrations of 4 mole, after which it decreased rapidly. Total conversion and percent grafting increased with the irradiation time. The value (=0.55) of the slope of the total conversion rate plotted against the dose was only a little higher than the 1/2 which was expected from normal kinetics. No retardation in homopolymerization of styrene in DMSO, SO₂–DMSO, and DEA–DMSO was evident, while the retardation of homopolymerization in the SO₂–DEA–DMSO medium was measurable. Sulfur atoms were detected in the polymers obtained in both of SO₂–DMSO and SO₂–DEA–DMSO solutions. All of the molecular weights of polymers obtained in the present experiment were very low (3.9 × 10³?1.75 × 10⁴).