Electrodeposition constant voltage

The poly(oxyphenylene) was electrodeposited from freshly prepared solution containing 0.23 M of 2-allylphenol, 0.4 M of allylamine, 0.2 M of butylcellosolve (ethyleneglycol monobutylether) in water/methanol mixture (1 1 by volume) by applying a constant potential of 4 V from constant voltage power-supply (Zentro-Elektrik, Type LA 15/156 B) between the cathode (a platinum coil of 1.5 cm area) and the substrate (anode). The current was monitored with a Keithley 177 microvoltmeter and recorded with a Metrawatt, Model SE 780 recorder. The electrodeposited films of poly(oxyphenylene) formed within half of an hour (aprox. 1.5 /xm thick) were rinsed with distilled water and cured at 150°C for 30 min. 

Both constant-voltage and constant-current coating methods have been employed, the latter eliminating large current spikes that can occur on switching on the voltage and can cause problems with some resists at the beginning of electrodeposition. 

The analytical electrodeposition that we are discussing, as well as others, can be carried out by maintaining the current, rather than the applied voltage, at a constant level. To maintain constant current, we must increase the applied voltage periodically as the electrolysis proceeds. 

Fatas, et al. (63), have also done a study on the electrodeposition of CdS from nonaqueous solutions, in this case on stainless steel and tin oxide. They studied two solvents DMSOandPC. Thesolutionswere0.19 M sulfur and 0.055 M cadmium chloride in DMSO, and PC saturated with sulfur, cadmium chloride and potassium chloride. The depositions were carried out at a constant current at 120°C. All voltages were referenced to a cadmium/cadmium chloride electrode. 

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