Electroless nickel-phosphorus alloy was plated on steels, and tin plated on top of these. Double-plating films were analyzed by glow discharge emission spectrometry (GDS) before and after heat treatment. Effects of heat treatment on X-ray diffraction patterns, anodic polarization curves, and corrosion resistance were investigated compared to electroless nickel-phosphorus alloy films. Anodic polarization currents for tin/electroless nickel-phosphorus alloy double-plating films were greatly suppressed by heat treatment at 400°C. X-ray diffraction measurements confirmed the formation of intermetallic tin-nickel compounds after heat treatment. Current values were assumed suppressed due to formation of these compounds. GDS results showed that film surfaces were blue due to nickel oxides forming on them in heating electroless nickel-phosphorus alloy films at 400°C in an atmosphere. Electroless nickel-phosphorus alloy films with a tin overlayer did not show this color, however, because intermetallic tin-nickel compounds formed on the film surface. CASS tests showed that electroless nickel-phosphorus alloy films with a tin overlayer were superior in corrosion resistance to films without this overlayer.
Electroless Co-Fe alloy deposition on the substrate of amorphous ribbon in a bath containing DMAB as a reducing agent was studied using an electrochemical polarization curve. The deposition rate was predicted by anodic and cathodic polarization curves for electrolessly-deposited Co-Fe alloy electrodes in the plating bath. The catalytic activity sequence of Co-Fe alloy electrode for anodic oxidation of DMAB was estimated from the current density-potential curve in an anodic partial bath not containing metal ions, and led to clarification of the relationship between the deposition rate of Co-Fe and the alloy composition of the deposit. The catalytic activity sequence of amorphous ribbon electrode depending on its alloy composition for anodic oxidation of DMAB was itself found to significantly affect the deposition rate in the initial stage.
Acceleration was investigated using high-resolution TEM to clarify the direct copper plating mechanism on nonconductive substrates catalyzed by treating in a Pd-Sn solution and accelerating in a solution containing copper ion. After catalyzation, catalyst colloids adsorbed on the resin substrate were about 2nm, had low crystallinity, and consisted of 20nm clusters. The composition ratio of Pd:Sn in catalysts was 4:6. After acceleration by dipping in an alkaline solution including copper ions, the Pd:Sn:Cu ratio became 6:1:3 through tin dissolution and copper deposition. Catalyst colloid particle size showed no substantial change after acceleration, but an fcc Pd-Sn solid-solution having improved crystallinity was identified. Dispersed copper crystals occurred in acceleration on the catalyst layer. The catalyst layer on the acetylcellroce substrate surface was 40nm and on the ABS substrate was 15nm. Cross-sectional observation showed that the deeply etched ABS surface was filled with copper deposit anchoring the plated layer. Copper deposition propagation was about 3mm/s in the presence of Cu(II) and 0.1mm/s in its absence. The catalyst layer increases surface conductivity and dispersed copper crystals are assumed to speed up direct copper plating.
Corrosion characteristics of a bright Ni-Cr electroplating system on steel were statistically evaluated. For three thicknesses of Ni, a set of fifteen panels was subjected to outdoor exposure tests. Variation in the corrosion characteristics was based on a probabilistic feature, and may be caused by electrochemical noise and nonequilibrium fluctuations. The time to failure for each panel was estimated from the smoothed curves of the percent area of corrosion. To sample life distribution of individual Ni thicknesses, a Weibull distribution was fitted. The failure mode of the bright Ni-Cr electroplating system was wear-out type of failure. The maximum service life, B10 life, increased logarithmically with increasing Ni thickness.
Polyimide film was studied as a resist for ceramic etching in condensed phosphoric acid. Resist films were formed with three different polyimide precursors developed as materials for passivation, insulation, or protective layers on LSIs. After etching alumina ceramic from 260°C to 320°C, we measured changes in resist thickness, resist film breakdown ratio, and etch factors. Resist film chemical resistance depended strongly on the type of polyimide precursor. Photosensitive polyimide, Photoneece UR-3140®, showed superior resistance to phosphoric acid at up to 320°C The etch factor was relatively low, around 1, however, regardless of resist film formation conditions, indicating that some further process, e. g., application of an adhesion promoter, was needed to enhance resist adhesion to substrates.
The large specific surface area on a low voltage-use aluminum electrolytic capacitor electrode was produced by alternating-current etching in a chlorine solution. The effect of sulfuric acid added to the 3.6% hydrochloric acid solution etchant on etch morphology was examined by Auger spectroscopy, electron microscopy, and galvanovoltammetry. Electrostatic capacitance, pit size, and amount of aluminum hydroxide formed during etching at 1∼50Hz in 3.6%HCl/n%H2SO4(n=0∼1) solution at 333K were determined. A deeper etched porous layer was produced in a 3.6%HCl/0.25%H2SO4 solution than in a 3.6%HCl solution, with general dissolution prevented and surface film formation facilitated by the additive. The atomic ratio O/Al as calculated from the O (507eV) and Al-O (55eV) peaks of the surface film developed in a 3.6%HCl/0.25%H2SO4 solution is 1.8∼2.0 higher than 1.5 for the etched film in a 3.6%HCl solution.
Aluminum was anodized in propylenediamine baths and choline baths containing ammonium fluoride, ammonium tartrate, and ammonium carbonate or ammonium tetraborate, at a bath temperatures of 10°C, 20°C, and 30°C, and at constant bath voltages of 30V, 50V, and 80V. Anodized films thus formed were compared by hardness, alkaline dropping test, dyeing affinity, and pore diameter. Marten's scratch hardness test showed that the hardest films was obtained in low-temperature baths. Films formed in a high-temperature and high-voltage bath were highly corrosion-resistant. In dyeing affinity, films formed in propylenediamine baths and choline baths containing fluoride and tartrate at 20°C and 30V were superior to films formed in the same baths at 30°C and 80V. SEM of the film surface and cross-sections showed that the film formed in propylenediamine baths containing fluoride, tartrate, and carbonate had larger pores (about 150nm) than these formed in bath containing fluoride and tartrate (about 110nm) at 30°C and 80V. Films formed in choline baths containing fluoride, tartrate, and tetraborate had larger pores (about 90nm) than those formed in baths containing fluoride and tartrate (about 60nm). Large pores were assumed formed by the dissolution of pore walls at higher temperatures and voltages.