A metallized substrate, such as used to make a resonant circuit tag with inductive and capacitive elements in series, has a thin inorganic or polymeric dielectric layer formed on a metal layer. The inorganic layer may be formed by anodizing a surface of the metal layer. The organic layer may be formed by flexographic printing. In both cases, a via hole is formed through the dielectric layer. A second layer of very thin conductive metal is deposited on the dielectric layer and in the via hole. The substrate is subsequently patterned with an etch resist and then etched to form the inductor coil and the capacitor plates, which are interconnected via the metallized via hole.