Dark brown oxyhydroxide films were formed on aluminum, copper, and, ITO glass by cathodic pulse electrolysis in a 0.016mol L-1(NH4)6Mo7O24-0.32molL-1MgSO4 solution of pH 5 at 50°C. The XPS and ICP-AES analyses indicated that the films were composed of mixed valence molybdenum ions of Mo (IV) to Mo (VI), Mg (II) ions, and small amounts of sulfate ions. The MgSO4 is a necessary component in the solution to obtain uniform and adhesive films. The NH4+, Na+ or Zn (II) ions substituted for Mg (II) ions, and acetate, nitrate or phosphate ions substituted for sulfate ions in the solution adversely affected the formation of uniform and adhesive films. Though the decrease of Mg (II) ions in the solution increased the amount of Mo ions in the film, it also showed adverse effects. The films were amorphous by XRD even after drying at 200°C for 12h. Diffuse reflectance spectra of films showed that transmittance is about 15% in the UV-VIS region of 200-700nm in wavelength and increases to 70-80% in the near IR region of 1.5-2μm. Spectrophtometric emissivity measurements at 100°C indicated that emissivity in the IR region of 4-10μm is around 40% and increases drastically to over 90% for wave length longer than 10μm. It indicaates that the film is a selective emitter/absorber for the far IR region. The film also showed electric conductivity.
The mechanism of direct copper plating on nonconductive resin substrates was studied using high-resolution TEM, SEM and XPS. Substrates were catalyzed by Pd/Sn catalyst and subsequently immersed in alkaline solution containing either copper ions or sulfide ions before electroplating. After conversion in the alkaline solution containing copper ions, catalyst colloid particles formed clusters and crystallinity improved. Sulfide compounds, however, formed by conversion in alkaline solution containing sulfide ions. Both conversion techniques markedly promoted propagation in electroplating. The effect is explained by propagation in which improved palladium colloid crystallinity and palladium sulfide formed in conversion play a critical role in determining the propagation rate.
Electrodeposited tin-copper alloys show promise as lead-free alternatives to solder coatings. Eutectic tincopper alloy film was deposited at 0.5∼5A/dm2 and 25°C in the following bath composition: 0.1974mol/L (CH3SO3)2Sn, 0.0026mol/L CuSO4, 2.0mol/L CH3SO3H, 0.01mol/L 2, 2'-dithiodianiline and 5g/L polyoxyethylene-α-naphthol. The coexistence of 2, 2'-dithiodianiline and polyoxyethylene-α-naphthol markedly inhibited preferencial deposition of copper over a noble potential range. The eutectic tin-copper alloy film consists of β-Sn and η(Cu6Sn5) phases, and its solidus temperature was 227°C. Tin and copper ions in the effluent were separated as hydroxide, and the residual concentration of tin and copper ions decreased to less than 0.01mg/L.
The significance of the electroless silver plating bath using ethanethiol derivatives as reducing and complex agents lies in it being noncyanide, having near by neutral pH, and providing good storage stability. This is achieved by plating in a composition that is neither immersion for coating electroless nickel substrates nor autocatalytic. Anodic polarization curves of 2-aminoethanethiol (cysteamine) and N-acetyl-L-cysteine in a basic electrolyte showed that 2-aminoethanethiol acts as a reducing agent and that N-acetyl-L-cysteine is not easily oxidized on silver electrodes. Experiments in polarization confirmed the mixed potential theory including local potentialcurrent relationships for silver deposition. Based on information available on oxidation of the reducing agent, we propose the following partial anodic and cathodic reactions: Anodic partial reaction 2HSCH2CH2NH2→H2NCH2CH2SSCH2CH2NH2+2H++2e- (Cysteamine) (Cystamine) Cathodic partial reaction Ag++e-→Ag
A gold organic compound coated on glazed alumina substrates was thermally decomposed by irradiation of a continuous-wave argon ion laser, and the effects of laser power density and scan speed on formed gold line features, geometry, and electrical resistivity were studied. Laser irradiation at a power density of 0.9-1.9kW/cm2 and a scan rate of 25μm/s produced a smooth, flat gold line. Lines were about 0.3μm thick, whereas the initial compound layer was about 7μm thick. Electrical resistivity was about 10μΩ·cm, which was a little higher than that of bulk gold, probably due to a small amount of additive impurities for promoting adhesion. Even under these optimum power densities, when the scan rate exceeded 100μm/s, a flow pattern appeared on the line surface. When the scan rate was increased and substrates ware heated and cooled more quickly, cracks were induced in the glaze layer due to thermal expansion. At power densities higher than 2kW/cm2, severe cracking occurred and gold vaporized.