Hydrophobic coatings are used in various fields. A technology of constructing hydrophobic surfaces is proposed using a combination of roughness structures via electroplating and an extremely thin organic layer. This study verified the relation between the roughness and hydrophobicity of an obtained nickel film by changing the current density, bath pH, bath temperature, and boric acid concentration using a nickel chloride plating bath. Results confirmed that the surface morphology and orientation change depending on the plating conditions. Moreover, the contact angle tends to increase under conditions in which the surface roughness increases. Specifically, the surface roughness and contact angle are high for a low current density (1.0 A / dm2), weak acidity(pH 3-5), and high bath temperature (70-80 ℃). These results are useful as basic data for future production of a complex roughness structure that supports hydrophobicity.
Effects of crystals of the electrodeposited copper film and additive species of the etching solution on etching behavior were investigated to improve the etching factor during wet etching using the subtractive method. Regarding the crystal plane of the copper electrodeposited film, the crystal orientation of the electrodeposited copper film showed random orientation when the current density was swept from 100 mA to 10 mA. The crystallite became smaller. Effects of etching factor improvement were found by using FeCl3 (aq)as an etchant and by adding azoles, especially triazoles. Triazoles were adsorbed onto the specific lattice. Etching was controlled to improve the etching factor.
Electroless deposition of nickel-tin(Ni-Sn)layers on iron(Fe)substrates from baths containing sodium hypophosphite(NaH2PO2)as a reducing agent was examined. In a bath containing both sodium citrate(Na3C6H5O7)and sodium gluconate(HOCH2 (CHOH)4COONa)as com plexing agents, the Ni-Sn layer having 1 μm thickness and atomic Sn content of 30-40 at.% was formed. The bath stability was maintained until the 10th deposition process. Optimizing the concentration ratios of sodium citrate to sodium gluconate and to sodium stannate(Na2SnO3)was important to ascertain the Ni-Sn layer properties for this study. The main component of the Ni-Sn layer was found to be Ni1.5Sn. A small amount of the Ni layer was included in the layer. Results confirmed that the Ni-Sn layer formed from the optimized bath with NaH2PO2/ Na3C6H5O7/ HOCH2 (CHOH)4COONa had nearly perfect chemical resistance properties against hydrogen peroxide and sodium hydroxide aqueous solutions.