Abstract: A single sided printed circuit board on a rigid substrate is prepared in a conventional manner, such as etching, with a first circuit including pads at the desired sites of interfacial connections. A rectangular hole is punched through the substrate at each inconnect site. A conductive foil is bonded to the other side of the substrate and a second circuit pattern is etched from the foil with circuit paths overlying the apertures. Then portions of the second circuit are inserted through the apertures by a gang of piercing tools so that the second circuit portions lie adjacent the pads of the first circuit. The interfacial connections are then completed by dip soldering or by welding. Alternatively, the second circuit applied to the substrate may be in the form of a preformed circuit on a flexible substrate.