The use of glyoxylic acid as an alternative reducing agent to formaldehyde for electroless copper plating was investigated. Plating rates were considerably faster and bath stability was superior to formaldehyde baths under standard operating conditions. The morphologies of the deposited copper were not greatly affected by EDTA concentration, and good mechanical properties of the deposition were obtained. The rate of the Cannizaro reaction with glyoxylate ions was faster than that with formaldehyde, but could be reduced by 10 to 40% using KOH in place of NaOH. It was confirmed that deposition unformity of hole wall coverage was superior to that of the formaldehyde bath. Glyoxylic acid is a nonvolatile chemical that showed good reducing power in electroless copper plating, and can therefore replace formaldehyde, alleviating environmental problems.
In recent years, electroless nickel coatings have been extensively used for various purposes in many fields of industry and a wide variety of functions have been required of the electroless nickel deposits. In this study, an electroless nickel plating bath operated at relatively low temperature has been developed, and the effects of certain factors (temperature, pH, and concentration of acetate and hypophosphite) on the deposition rate and phosphorous content of the electroless nickel deposits have been investigated in some detail. Deposits with phosphorus contents higher than 9wt% were found to be amorphous and to have improved properties with respect to tensile strength and corrosion resistance. The addition of an unsaturated compound such as maleate having a double bond will reduce the molar ratio of hydrogen gas to deposited Ni-P alloy, and also increase the phosphorus content of the deposits.
TiN films have been formed by dynamic mixing (DM) process, in which N ions are implanted during Ti evaporation or TiN reactive evaporation under low or high N2 gas pressure. Structure and wear characteristics of the films have been investigated by comparison with TiN films formed by the conventional reactive evaporation process. Rutherford backscattering spectroscopy and electron probe microanalysis showed that the composition ratio (N/Ti) of the TiN films formed by DM process is above 1.5, and that oxygen concentration is lower than in films formed by conventional reactive evaporation. In DM process, the N/Ti ratio of films formed under high N2 gas pressures was slightly larger than that of films formed under low pressures. Transmission electron microscopy showed that the grain of the films produced by DM process were coarser than those of the films formed by reactive evaporation. In a dry reciprocating rubbing test vs SUJ 2 steel, films produced by reactive evaporation were easily worn out and it is thought that the wear resistance of films made by DM process is superior to that of films made by reactive evaporation. With DM process, no matter how N2 gas pressure varies, there are no large differences in the wear characteristics of the films.
The effect of such variables as etchant concentration, bath temperature, current density and current sweep rate on the cubic pit propagation and porous etch structure formation is discussed by means of electron microscopy and galvanovoltammetry. Maximum values of electrostatic capacitance were obtained under conditions for the formation of a deep porous etched layer. The formation of such a layer was found to be due to the formation and breakdown of a thin anodic film covering the inner surface of the cubic pits during etching. As indicated by the shape of cyclic polarization curves, the breakdown of the anodic film was facilitated by increases in the concentration and temperature of the etching solution, and suppressed by increases in the current sweep rate. This is explained by the rate at which Cl- ions are supplied to the bottoms of cubic etch pits.
ADC12 aluminum die casting alloy was heat-treated for various periods, th' at different temperatures, Th' and anodized in 10wt% sulfuric acid solution at 20°C by applying a constant current density, ia' of 100A/m2. The film formation behavior and film properties were examined as functions of Th'th and the abrasion thickness, X, of specimens by scanning electron microscopy (SEM), chemical analysis, and diffuse reflectance spectroscopy (DRS). The steady value of anode potential, Ea*, was found to decrease with increasing Th'th' and X. The ratio of dissolution current to ia decreased with Th and th, and was independent of X. Oxide films formed after anodizing for 40min showed thickness differences on all specimens, and the variation in film thickness decreased with increasing Th'th' and X. The value of average film thickness, δ, increased with Th'th' and X and this is expected to be due to an contribution of oxygen gas evolutions. DRS showed that the degree of film coloration decreases with increasing Th'th and X. The film formation mechanism is discussed with reference to structural change in the metal substrate due to heat treatment.
The structure of composite oxide films on aluminum has been investigated by scanning electron microscopy (SEM) of fractured sections and by transmission electron microscopy (TEM) of ultramicrotomed sections. It was found that TEM of ultramicrotomed sections is an extremely powerful technique for structural examination of the composite oxide films at high resolution. Voids and cracks, which are responsible for an electrical instability so-called “relaxation”, could be observed clearly within the composite oxide films. Although, the voids and cracks could not be observed readily by SEM of fractured sections due to the limited resolution, SEM has an important advantage that it allows ready examination over wide areas of the specimen. Various types of defects, introduced during relaxation, could be observed readily by SEM. Thus, the combination of the both techniques allows a more complete picture to be obtained on the structure of the composite oxide films of practical importance for capacitor applications.