The invention uses a programmable interconnect substrate having a plurality of conductive and interconnectable vias located on one or both surfaces thereof. A customised pattern of bonding pads is then formed over the one or both surface of the substrate which correspond to the terminal footprints of specific surface mounted packages intended to be mounted on the substrate. A generalised pattern of bonding pads may also be formed on the surface of the substrate for electrically connecting terminals of bare dice thereto by means of thin wire. All bonding pads are electrically connected to one or more vias by direct electrical contact or by a conductive trace extending from the bonding pad to a nearly via.