Corning Incorporated
ETCHING GLASS AND GLASS CERAMIC MATERIALS IN HYDROXIDE CONTAINING MOLTEN SALT

Abstract:

A method of etching a substrate comprises: contacting a substrate having a thickness with an etchant disposed in a vessel for a period of time until the thickness has reduced by at least 2 .mu.m and at an average rate of 1 .mu.m per minute to 6.7 .mu.m per minute, the etchant having a temperature of 170.degree. C. to 300.degree. C. and comprising a molten mixture of two or more alkali hydroxides; and ceasing contacting the substrate with the etchant. The etchant in some instances comprises a molten mixture of NaOH and KOH. For example, the etchant in some instances includes a molten mixture of 24 wt. % to 72 wt. % NaOH, and 76 wt. % to 28 wt. % KOH. In some instances, the method alters the weight percentage of Na.sup.+, K.sup.+ and Li.sup.+ in the composition of the surface of the substrate by less than 1%.