抄録
Methods for prediction of gold plating characteristics by numerical analysis were investigated. The gold plating bath for the evaluation contains 5,5-dimethylhydantoin (DMH) as the complexing agent. HAuCl4 was used as the gold source, and phosphate salt was contained as a pH buffer. Thallium ion was added to refine the deposited grains. The concentration of Au([Au]), the pH, and the temperature were manipulated to determine the composition and conditions of the plating bath. The appearance of gold films was evaluated by color measurement using the L*a*b* color system. This method of evaluation is advantageous in terms of quantification of the appearance. Values of the color measurement tended to change depending on the various compositions and conditions of the plating bath. The brightness of the color L* obtained as a result of the color measurement was analyzed numerically with a statistical technique. The following experimental formulas were established by the numerical analysis.
L*(−) = K0{1−exp(−K1C)}−K2C
K0(−) = 73.9−2180exp(−0.125T)
K1(M−1) = 178
K2(M−1) = 338−323exp[−{(pH−7.18)/1.17}2]
[C : [Au] (M = mol/dm3), T : temperature(ºC)]
