Pulse electroplating of rich-in-tungsten thin layers of amorphous Co-W alloys

A combination of an improved plating bath and pulsed current was shown to lead to a substantial increase in tungsten content in amorphous Co-W alloys. This increase was associated with selective oxidation of cobalt during the rest times of the deposition process. The tungsten content reached 41.4 at % under the following conditions: current density 35mA cm(-2) ratio of pulse time to rest time 1/1, and pulse frequency 10 Hz. The alloy layers were of similar hardness and of much better smoothness, ductility, adhesion to the substrate, and resistance to corrosion compared to those plated according to the US 4529668 patent.