Abstract: A method for manufacturing electrical connecting elements or semifinished products. Microvias are formed in a dielectric substrate layer by piercing a substrate layer (1) through a first conducting layer (3), which essentially covers an entire side of the substrate. The perforation depth (d) is at least equal to the total thickness of the substrate and the first conducting layer. The conductor material of the first conducting layer (3), during the piercing step, is deformed so that it partially covers the wall of the hole fabricated by the piercing process. Plating the first conducting layer with additional conductor material bridges the little remaining distance between the conductor material and the opposite side of the substrate layer.

Abstract: The surface of a metal foil to be used as an intermediate layer in printed circuit boards is chemically roughened. In one embodiment, fine depressions are etched out of the metal coating. In another embodiment, protuberances are plated thereon. The use of the method permits the use of the foil in the production of multilayer printed circuit boards with coatings having different thermal expansion characteristics and improves the adhesion with the next conductor layer applied thereto to a significant extent and prevents delamination.