Demetallizing procedure

Abstract

Selective demetallization of an etchable metal layer supported on a polymeric material or other microwave transparent material, or a self-supporting etchable metal layer, particularly aluminum of thickness at least about 1 micron adhesively joined to a flexible polymeric material substrate, is described. A web of polymeric material bearing the etchable metal layer, or an unsupported etchable metal layer, has a pattern of etchant-resistant material first applied and then the web is immersed in and passed through a bath of aqueous etchant, particularly hot aqueous sodium hydroxide solution, for a time at least sufficient to completely remove the etchable metal from non-protected areas of the web. The demetallized web is washed and dried. Specific structure incorporating the selectively demetallized etchable metal layer also are described.

Dependencies are inferred from the claim text.