A process for fabricating a multi-layer circuit assembly is provided. The process includes (a) providing a substrate at least one area of which comprises a plurality of vias area(s) having a via density of 500 to 10,000 holes/square inch (75 to 1550 holes/square centimeter); (b) applying a dielectric coating onto all exposed surfaces of the substrate to form a conformal coating thereon; (c) removing the dielectric coating in a predetermined pattern to expose sections of the substrate; (d) applying a layer of metal to all surfaces to form metallized vias through and/or to the electrically conductive core; (e) applying a resist to the metal layer to form a photosensitive layer thereon; (f) imaging resist in predetermined locations; (g) developing resist to uncover selected areas of the metal layer; and (h) etching uncovered areas of metal to form an electrical circuit pattern connected by the metallized vias.