Effect of pH on electroless nickel deposition on alumina substrates for chip resistor application
Alumina has been used widely in electronics industry specifically for chip resistor application. Currently, the deposition of nickel on alumina surface using electrodeposition method suffered from the insufficient bonding between the metallic coating (nickel) and the ceramic substrate (alumina). Electroless deposition method however can produce strong adhesion between the metallic coating and ceramic substrate. In this research, the effect of pH on the electroless nickel on alumina substrate was investigated. The electroless deposition of nickel on alumina substrate was conducted at pH 4.0, 5.6 and pH 10.0 for 3, 5, 10, 20 and 30 minutes at constant temperature. The crystal structure of the substrate and coating was characterized by using X-ray diffraction (XRD). The surface morphology of the coating was observed by using scanning electron microscopy (SEM) and the coating thickness was measure by X-ray fluorescence (XRF). The coating performance was tested by using Standard ASTM D3359 (Tape-Test). It was found that the optimum pH of plating solution was 10.0 with the maximum thickness was obtained at 30 minutes of deposition with thickness of 1.15 μm. These optimum coating parameters shows homogeneous and uniform nickel deposition on the alumina surface as observed by SEM. Nickel deposition by electroless method at pH 4.0, 5.6, and 10.0 have excellent bonding with alumina substrate as shown by tape test analysis.
Influence of pH Solution on Electroless Copper Plating Using Sodium Hypophosphite as Reducing Agent
The effect of pH solution on the electroless deposition of copper-rich Cu–Ni–P alloys, using hypophosphite as reducing agent, has been carried out. The deposition rate increased obviously with the increase of pH. The surfaces morphology, the roughness and the cristallinity depend many of pH. The kinetics of copper electroless was investigated by means of cyclic voltammetry and electrochemical impedance spectroscopy. The shape of voltammogramms and impedance diagram depend also of the pH solution.
Influence of electroless Ni-P deposits on the corrosion-fatigue properties of an AISI 1045 steel
Abstract Electroless nickel (EN) deposits containing approximately 10% phosphorous and about 20 μ m thickness are shown to increase the corrosion-fatigue properties of the AISI 1045 steel in the stress amplitude range of 221–331 MPa, in the presence of an aqueous solution of 3% NaCl. Such an increase is enhanced if the coating is in the as-deposited condition rather than post-heat treated at 473 K for 4 h, despite the fact that such a treatment produces an increase in hardness. The improvement observed in corrosion-fatigue properties is also more pronounced as the stress amplitude decreases. The monotonic mechanical properties determined under tensile conditions are not affected by the presence of the coating. The inadequate agitation of the bath has given rise to microporosities and `orange-peel' type effects associated with the deposit which are believed to be related to the trapping of hydrogen bubbles.