Method of etching, as well as frame element, mask and prefabricated substrate element for use in such etching

Abstract

In a method of etching a substrate having a surface layer of conductive material, a circuit pattern is transferred to the surface layer in a central surface area portion of the substrate by electrochemical etching. To prevent excessive current densities from forming at the periphery of the central surface area portion during the etching step, a frame adapted to attract electrical field is provided adjacent to the central surface area portion. The frame can be part of a separate frame element which is placed on the substrate before the etching step, or be incorporated in a resist coating on the substrate. The frame can be transferred to the resist coating by any suitable means, for example by photolithographic exposure through a mask with a suitable frame pattern. Alternatively, the frame can be incorporated in a prefabricated substrate element, to which the circuit pattern is transferred in the etching step.

Dependencies are inferred from the claim text.