Tin di:oxide etching chamber - with etchant atomising nozzles to dissolve zinc powder and spray nozzles to etch metallic tin

摘要

Thin tin dioxide layers, for use in formed transparent electrodes to produce luminous symbol displays, are etched by wetting in a first zone the substrate, covered with an aqueous zinc powder paste, by a metered supply of hydrochloric acid to keep the hydrogen release and the tin oxide reduction uniform. In a second zone, a copious supply of hydrochloric acid removed the zinc powder residue and cuts short the reduction. This is a simple process to etch the difficult tin dioxide layers and to reduce under-etching to a minimum under optimum conditions.