Sandwich-type bis(phthalocyaninato)lanthanide complexes, [Ln(Pc)2]z, exhibit intriguing characteristics which stem from the interactions between the two π-conjugated phthalocyanine rings held by the central metal ion in close proximity, and they have been explored as materials for electrochromic displays, molecular semiconductors, gas-sensors and for nonlinear optical applications. This article reviews some topics on their structural, electrochemical, chemical, and spectral characteristics.
The structural parameters of molten PbCl2 have been re-examined by EXAFS spectroscopy. The analysis of the experimental results has been performed, by using a combination of molecular dynamic (MD) simulations and multiple scattering code (FEFF). It is found that in molten PbCl2 each Pb atom is surrounded by near six Cl atoms at an average distance of 0.283 nm.
Electron transfer of indigotetrasulfonate ion at 4-aminothiophenol (ATP) monolayer-modified electrode was examined in the pH range of 2 to 6 by cyclic voltammetry and ac impedance spectroscopy. By changing up the pH of electrolyte from 2 to 6, the redox process of indigotetrasulfonate becomes reversible in the presence of ATP monolayer-modified electrode. While the electron-transfer rate constant of indigotetrasulfonate for bare gold was decreased from 2.5×10−3 cms−1 at pH 2 to 4.7×10−5 cms−1 at pH 6, that for ATP monolayer-modified electrode was increased from 3.2×10−5 cms−1 to 1.6×10−2 cms−1. Reversible redox reaction of indigotetrasulfonate were also observed at cystamine and 4-mercaptopyridine modified electrodes at pH 6, but were not observed at 3-mercaptopropanesulfonic acid, 1-butanthiol and 4-hydoroxythiophenol at pH 6. Our results suggest that the electron transfer rate of indigotetrasulfonate ion is controlled by a specific interaction between the amine groups of the thiol monolayer and indigotetrasulfonate ion.
The compatibility of flip chip fluxes, underfill epoxies and solder resists on printed circuit boards (PCB) was compared by using a single lap shear test.1-3,15) The underfill adhesion to the plain solder resist was generally good, but in flip chip assembly, a flux for joining the connections of flip chips is used. Therefore, the PCB samples coated with different solder resists were fluxed and reflowed to simulate the real production environment. The underfill was applied on these residues and another piece of PCB, treated in same way was attached on it maintaining a consistent gap between two pieces. The underfill was cured according to each manufacturer's specification and a single lap shear test was carried out. The correlation of the variable results was verified by assembling a test flip chip using some of the tested materials and subjecting them into temperature cycling. The adhesion strength was verified by investigating underfill delamination by scanning acoustic microscopy (SAM).
Current-voltage characteristics of aluminum, tantalum and platinum contacted to a pellet of chemically polymerized polypyrrole were investigated. A typical passivation curve was observed for both an anodic and a cathodic polarizations of aluminum and tantalum, which means a formation of an insulated layer at a contact surface, and there was a resemblance in the I-V curves between the anodic and the cathodic polarization curves of aluminum and tantalum. The current in the I-V characteristics was influenced by ambient moisture, decreasing with increases in relative humidity. Similar behavior has been found for a non-valve metal of platinum, which indicates the passivation is due to a transformation of conductive polypyrrole to an insulator. The deterioration of polypyrrole is assumed to be caused by a synergetic effect of oxygen and water. The self-healing behavior in a solid electrolytic capacitor with polypyrrole electrolyte would be caused mainly by a transforming reaction of a conductive polypyrrole electrolyte to an insulator occuring at the contact surface under applied voltage.