An exemplary method of making an FPC includes forming a substrate comprising metal foil layers interleaved with intervening layers by: (a) laminating intervening layers with metal foil layers; (b) adhering a covering film to outermost surfaces of the substrate; (c) defining a hole in one side of the substrate through the covering film and at least two metal foil layers and the intervening layer between the at least two metal foil layers by etching or laser technology; and (d) plating a portion of an inner wall of the hole with conductive material to form a via to electrically connect the at least two metal foil layers.