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.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.