A method includes forming a first electrically conductive layer on a first side of a dielectric insulation layer, forming a structured mask layer on a side of the first electrically conductive layer that faces away from the dielectric insulation layer, forming at least one trench in the first electrically conductive layer, said at least one trench extending through the entire first electrically conductive layer to the dielectric insulation layer, forming a coating which covers at least the bottom and the side walls of the at least one trench, and removing the mask layer after the coating has been formed.