Electroplating pulse plating

Puippe, J. C. and Leamon, F., Theory and Practice of Pulse Plating, Amer. Electropl. Soc., Orlando (1986)... 

The more positive electrochemical values favor the formation of reduced species. For example, the Nemst equation predicts that thorium with a half cell potential of E Th = -1.9 V, would have to be at a concentration of over 10 M before it would plate out at the half-cell potential of copper, E° Cu = 0.34 V. Even when a reverse pulse plating process is employed to create level, and polycrystalline, copper, the Nemst equation predicts thorium would still have to be at a concentration of over 10 M before it would plate out at -0.34 V. One would expect to obtain extreme copper purity from contaminants such as Th when electroplating at the voltages required for copper plating. 

Plating rate as a function of pulse cycle is plotted in Fig. 5 for various pulse peak potentials. In the plating range, the pulse plating rate was not much different from that of DC plating. The potentials more positive to -0.8V vs SCE were not considered for electroplating as copper deposition rate was very low. 

Puippe JC, Leaman E (eds) (1986) Theory and practice of pulse plating. American Electroplate and Surface Finishing Society, Orlando... 

Pulse plating of zinc, cadmium, nickel, chromium and precious metals in aqueous media and molybdenum, chromium, tungsten, niobium and titanium in fused salts improves the properties of the deposits [1,15]. Dense, not dendritic coatings can be obtained because concentration polarization is minimized by the use of pulse current (PC) [16]. Moreover, other pulse plating effect can improve the surface roughness and morphology of the electroplated coatings [17, 18],... 

This paper studies the effects of the addition of ethylene diamine to the Au-Sn plating solution reported in ref.[7]. The changes in the composition and microstructure of the Au-Sn solder coating produced by pulsed current electrodeposition are noted. The electroplating solution developed for the co-deposition of Au and Sn is slightly acidic so that it can be used in conjunction with alkaline-developable photoresists. 

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