NOVELTY - Etching a conductive substrate, involves providing a conductive substrate with an etch-resist layer pattern deposited on conductive substrate resulting in spaces defining an exposed part of the substrate, providing a counterelectrode, interposing a non-active electrolyte solution between and in contact with the substrate and counterelectrode, applying an electric current between the substrate and counterelectrode and maintaining the substrate predominantly anodic with respect to counterelectrode, and etching the exposed portion of the substrate electrochemically.    USE - The methods are useful for etching a conductive substrate, removing metal from a metal substrate and forming etch patterns on a metal substrate (all claimed). Can also be used in manufacture of devices e.g. stents, fuel nozzles, cooling channels, bipolar plates for fuel cells, microchannels for sensors, microfluidic devices, chemical reactors, and dialysis.    ADVANTAGE - The method can etch conductive substrate with minimal undercutting and without use of caustic chemicals.    DETAILED DESCRIPTION - Method (M1) for etching a conductive substrate, involves (a) providing a conductive substrate with an etch-resist layer pattern deposited on the conductive substrate resulting in spaces defining an exposed portion of the conductive substrate, (b) providing a counterelectrode, (c) interposing a non-active electrolyte solution between and in contact with the conductive substrate and counterelectrode, (d) applying an electric current between the conductive substrate and counterelectrode and maintaining the conductive substrate predominantly anodic with respect to the counterelectrode, and (e) etching the exposed portion of the conductive substrate electrochemically, thus forming an etched pattern from the etch-resist layer pattern. INDEPENDENT CLAIMS are included for the following:    (1) process (M2) for removing metal from a metal substrate, involves (a) providing a metal substrate, (b) providing counterelectrode, (c) interposing a non-active electrolyte solution between and in contact with the substrate and the counterelectrode, and (d) applying a pulse/pulse reverse electric current comprising an anodic on-time and a cathodic on-time electric current between the substrate and the counterelectrode and maintaining the substrate predominantly anodic with respect to the counterelectrode; and    (2) process (M3) for forming etch patterns on a metal substrate, involves (a) providing a metal substrate having a predetermined pattern of covered metal portions and exposed metal portions, (b) providing a counterelectrode, (c) interposing a non-active electrolyte solution between and in contact with the substrate and the counterelectrode, and (d) applying an electric current between the substrate and the counterelectrode and maintaining the substrate predominantly anodic with respect to the counterelectrode to remove the exposed metal portions from the metal substrate and to form an etch pattern.