Voltammetric studies of lithium deposition/dissolution on Pt and Mo ultramicroelectrodes have been carried out at various temperatures in 1M LiClO4/PC and PC+EC solutions. Due to the short exposure time at the lithium surface, the influence of the decomposition reaction of the solvents with the deposited lithium could be retarded by applying a high scan rate, and clear sigmoidal CVs were observed for the ultramicroelectrodes. Based on this evidence, the lithium ion diffusion coefficient and kinetic parameters for lithium deposition/dissolution were obtained. The temperature dependence of these kinetic parameters is also discussed.
Chip bumping for flip chip and tape automated bonding (TAB) assembly has become increasingly important in microelectronic devices. Several methods using vapor deposition followed by electrolytic deposition to form bumps on a spattered aluminum electrode have been reported. The metallization process can be simplified by use of the electroless plating process. Generally the zincate process is used for electroless nickel plating on aluminum substrate. However, the process can not be applied to the metallization of fine circuits, pads or microbumps with photoresists because photoresist are attacked by the highly alkaline zincate solution. Accordingly, electroless nickel plating on aluminum substrate by methods other than the zincate process have been investigated. As a result, straight-walled bumps of up to approximately 20μm in height and between 20μm to 80μm in cubic area can be formed without damege to the photoresist by nickel displacement followed by electroless plating. In addition, nickel bumps can be more uniformly fabricated on an aluminum substrate initially accelerated with DMAB and followed by electroless nickel plating.
The deposition mechanism in electroless plating of Ni-B alloys from malonate complex solutions containing dimethylamine borane (DMAB) as a reducing agent was investigated. In all conditions except low pH and low DMAB concentrations, the utilization factor of the DMAB was found to be ca. 8 per cent for Ni deposition, ca. 24 per cent for Ni2B deposition and ca. 70 per cent for H2 deposition. The deposition mechanism can be explained by the electrochemical mechanism, given in reaction equations 1) through 6).
The growth morphologies of electrodeposited silver under potential control on an Au (111) surface from the solutions of 5mM AgNO3/0.5M HNO3 and 5mM KAg (CN)2/0.5M KCN were investigated using Scanning Tunneling Microscopy (STM) in air. The silver films were deposited between 20mV and 100mV overpotential. From 5mM AgNO3/0.5M HNO3, silver was deposited like a single crystal along the gold substrate at 20mV overpotential. At 50mV overpotential large grains (300-500nm) were formed. Finally, at 100mV overpotential rough films were formed. From 5mM KAg (CN)2/0.5M KCN, silver was deposited like a single crystal at 20mV overpotential, and between 50mV and 100mV, smaller grain deposition with 50-100nm particles were clearly deposited compared to the deposit from 5mM AgNO3/0.5M HNO3.
ADC 12 aluminum alloy die castings and aluminum of 99.87% purity were anodized in sulfuric acid and boric acid/sodium tetraborate solution at constant pulse voltage with an on-time of 25ms and off-tims of 1-1000ms. The electrochemical properties of the barrier layer were examined by measuring changes in ionic current and applied voltage during the off-times of the pulse wave. In sulfuric acid solution, ionic current densities increased rapidly for ADC 12 and the change in applied voltage decreased exponentially as the off-time of the pulse wave was lengthened. Barrier layers formed on ADC 12 in sulfuric acid solution had better charging properties than those formed in boric acid/sodium tetraborate solution. Barrier layers formed on ADC 12 in boric acid/sodium tetraborate solution had much poorer charging properties than those formed on 99.87% aluminum.
The acceptor level of phosphorus in vapor phase epitaxial ZnSe films co-doped with phosphorus and lithium was investigated. A new donor-acceptor pair (DAP) emission was observed in the photo-luminescence property. Using DAP analysis, the acceptor level was found to be 0.151eV. It is considered that the acceptor level in ZnSe films co-doped with phosphorus and lithium is due to phosphorus complexes.
Using a ring-on-desk-type wear tester of the authors'own design, observations were made of wear of anodized coatings in the presence of engine oil. It was found that; (1) When ring pressure was 10∼30kgf/cm2, wear proceeded in accordance with a grinding action dependent on the roughness of the ring surface. (2) When ring pressure was 50∼70kgf/cm2, wear proceeded in accordance with a pushing action of loose micro grains formed by the breaking of the anodic oxide film.
Abrasive tests of anodized coatings on alumiunm alloys were studied with lubricating oil, (wet) and no that (dry). It was found that the amount of wear increased with larger abrasive grain and greater load on the wheel, and that wear greater in the wet tests; that is to say, the oil functioned as a grainding agent, increasing grindability. With smaller grain and lighter load, however, the difference in wear between the wet and dry tests was reduced very few and certain conditions the difference in wear was reversed; that is to say, the oil exhibited a lubricating action.