A System for Depositing Tungsten Coatings Suitable for an Electrical Contact Application

A method was needed for depositing smooth coatings of tungsten at relatively high rates onto the electrodes of a reed switch. A literature survey indicated that the most suitable technique was based on the vapour phase hydrogen reduction of tungsten hexafluoride. A reactor was designed for this purpose on the basis of safety, optimum utilisation of tungsten hexafluoride, and possible adaption to higher throughput. Experience with this reactor indicated that precautions were necessary before good quality coatings could be deposited and suggested that films of an acceptable thickness variation could be produced by using a flow reversal technique.