Ni-P alloys were electrodeposited using simple chloride baths containing 0 to 0.24 mol/L of phosphorus acids (H3PO2, H3PO3 and H3PO4). In the case of baths containing H3PO4, pure Ni was plated with hydrogen gas evolution, while the H3PO2 and H3PO3 baths yielded the corresponding Ni-P alloy at various current efficiencies and with a phosphorus content of 0 to 17 weight percent. As a result of electrochemical experiments and thermodynamic analysis involving the Gibb's free energy change in the deposition process, equations (1)-(3) were developed for alloy deposition in the phosphorous acid baths. 2H++2e-→H2……(1) Ni2++2e-→Ni……(2) 3Ni2++H3PO3+3H+6e-→Ni3P+3H2O……(3) The calculated values of the Gibb's free energy change for equation (3) showed that the induced co-deposition mechanism with phosphorus and nickel metal was reasonably explained by the strong atomic interaction between Ni and P.
The effects of additives and pH on electroless copper plating from EDTA baths were investigated by the interfacial AC impedance method and mixed potential measurement. When pH rose, the mixed potential fell and the value of charge transfer resistance RP decreased. In this condition, the plating process was enhanced. When the additives were added to the solution, they inhibited the cathodic reaction more strongly than the anodic reaction. This increased the RP value and the whole reaction was inhibited.
Chemical etching of Al in an acidic bath was studied by measuring the etching rate and the AC impedance of Al in the bath. The etching rate increased with increasing bath temperature. Moreover, the rate was significantly increased by the addition of Fe3+ ions and phosphoric acid into the bath. The mechanism of the etching reaction was then studied. In the case of the Fe3+ ion additive, it was found that the Fe3+ ion not only oxidize the Al, but also accelerate the reaction rate of H+ reduction. Changes in bath temperature mainly affected the reduction rate of H+ ions, which made up 82% of the etching reduction rate, while that of Fe3+ ions made up 18%. In the case of the phosphoric acid additive, the enhancement mechanism of etching rate acceleration was attributed to a dissolution reaction of the Al oxide film.
The dependence of drying temperature on changes in the composition of dry-in-place type chromate composed of Cr3+, Cr6+ and PO43-, has been investigated based on the results of thermal analysis assuming its drying process at actual application. Using a differential thermal analysis, an endothermic reaction was observed between 85°C and 200°C, while an exothermic reaction peaking at 300°C was observed between 200°C and 400°C. Further, the influence of these endothermic and exothermic reactions on the composition of dry-in-place type chromate has been investigated by XPS analysis. The thermal reaction has been also analyzed by the separation of chromate into water-insoluble constituents and soluble constituents, assuming the participation of water in the actual corrosion environment. The water-insoluble constituents form the polymer structures with Cr3+, Cr6+ and PO43- after endothermic reaction. In the exothermic reaction following the endothermic reaction, decrease of Cr6+ and increase of Cr3+, were caused by a reduction of deoxidization. It is considered that Cr3+, which is produced by a reduction of deoxidation, forms CrPO4. No composite difference is discernible in water-dissoluble constituents before and after the endothermic reaction, and they were composed of CrO3, CrPO4, Cr2O3 and Cr(OH)3·nH2O. The composition after the exothermal reaction is a mixture of CrO3 and small amounts of Cr2O3 and Cr(OH)3·nH2O. CrPO4 was not detected in this case. It is concluded that increase in PO43- fixed in water-insoluble constituents follows the increase in Cr3+ caused by a reduction of deoxidization.
The effects of plating conditions on the thermal peeling of tin or solder plated phosphor-bronze were examined. Main findings are summarized as follows. 1. The resistance to thermal peeling of reflowed tin films with 0.5μm copper undercoat was highest when plated in a phenolsulfonate bath, while that of reflowed tin films with no undercoat was highest when plated in a sulfate bath. 2. Thermal peeling took place more readily and was less sensitive to plating bath composition for bright solder films than for reflowed tin films. In phosphor-bronze that was bright solder plated in a methanesulfonate bath, thermal peeling was observed after aging at room temperature for 16, 000h. 3. An arrhenius type relation was obtained between the aging time to peeling and aging the temperature.
Pink light emission from the Al electrode has been observed during AC anodizing at 10∼60Hz, 50∼65V of Al in aqueous solutions containing Eu3+ ion. The emission peaks at 590, 612, 653, 703nm were assigned respectively to the 5D0-7F1, 5D0-7F2, 5D0-7F3 and 5D0-7F4 transitions of the Eu3+ activator, and appeared only during cathodic half periods. It is concluded that the pink emission is electroluminescence caused by the excitation of cathodically injected Eu3+ accompanying hydrogen evolution due to the electrolytic rectification into the thin barrier Al2O3 layer to which high electric field was applied.
A simple method of preparing a powder ACEL device using an alumina dielectric formed by sol-gel method have been investigated. Device emission occurred from 30V, and luminance at 200V was 40cd/cm2. It was concluded that the alumina formed by the sol-gel method can be used as the dielectric material for powder ACEL devices.