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.
The deposition behavior of electroless nickel on alumina substrate
Abstract The electroless deposition of nickel on alumina substrate was investigated with respect to the deposition behavior. The weight gain of the alumina substrate indicated that a three-stage mechanism exists for the deposition process, namely incubation, nucleation plus growth, and growth. The exclusive growth stage starts around 5 min after reaction. The activation energies as well as the effect of the deposition parameters on the rate of the nucleation and growth stages were investigated. The growth stage has a greater activation energy than the nucleation stage.
Seeing Like a Racial State: the Census and the Politics of Race in the United States, Great Britain and Canada
ii Acknowledgements iv List of Abbreviations vii List of Tables ix List of Appendices x Chapter 1 Invitation 1 Chapter 2 Orientation 26 Chapter 3 Mark One or More: Census Politics in the United States 61 Chapter 4 The Ethnic Question: Census Politics in Great Britain 115 Chapter 5 (In)Visible Minorities: Census Politics in Canada 168 Chapter 6 Seeing Like a Racial State 234 Chapter 7 Alternatives and Outcomes in the Census Policy Sphere 310 Chapter 8 Conclusions 364 Reference List 382