Process for manufacturing a multi-layer circuit board

Abstract

A circuit board having a structure including a permanent photoimageable dielectric material suitable for fabrication of vias both by laser ablation, plasma ablation, or mechanical drilling techniques and by photoimaging techniques. A process is also disclosed for the manufacture of a multi-level circuit on a substrate having a first-level circuitry pattern on at least one side. The process comprises applying a permanent photoimageable dielectric over the first-level circuitry pattern; exposing the permanent photoimageable dielectric to radiation; laminating a conductive metal layer to the dielectric; making holes in the conductive metal layer and dielectric by mechanical drilling or by laser or plasma ablation; and making a second-level circuitry pattern and filling the holes with a conductive material to electrically connect the first and second layers of circuitry. A further process is claimed for designing a multi-level circuit board product comprising making a prototype having the above structure in which the holes are manufactured by mechanical drilling or by laser or plasma ablation, evaluating the prototype, and then manufacturing a commercial circuit board having essentially the same structure and materials of construction as the prototype, but wherein the holes are manufactured by photoimaging techniques.