| abstract |
To achieve a large thickness of conductive metal-containing material in a feature of a product unit processed with a liquid-based etch process, the desired thickness of material is apportioned to the two opposing surfaces of a substrate to create a two-part feature. Conventional features are made by identically patterning two same-thickness metal-containing layers and electrically connecting the resulting patterned parts in any suitable manner. However, features may also be made that do not have identical parts on opposite sides of the substrate, the two parts being electrically connected but differing in thickness, in shape, or both. Moreover, having two metal-containing layers separated by an insulator is also useful for allowing different sections of the same feature or circuit to cross one another without shorting, or to overlap in whole or in part without shorting. A polymer substrate (1004), e.g. polyethlyene terepthalate, is covered on the top and bottom surfaces by a metal- containing layer, e.g. aluminium or copper foil, which are in turn covered by etch masks (1110, 1120, 1130, 1140, 1150, 1160, 1180), e.g. a resin formed by gravure printing or photoresist. The web is immersed in a bath or sprayed with an etchant, e.g. NaOH, to form the metal-containing web (1115, 1125, 1135, 1145, 1155, 1165, 1175, 1185). |