Method and apparatus for preparing conductive screened through holes employing metalli-plated polymer thick films

摘要

An apparatus and method for preparing conductive bridges to electrically couple discrete electrical conductors arranged on opposed surfaces of a common substrate, with the conductive bridge extending uniformly along and through the walls of a bore formed through the substrate. The method and apparatus utilized includes the preparation of a conductive bridge extending along and through the walls of a bore formed through the substrate, with the bore or opening in the substrate being subjected to the force of vacuum applied through a vacuum diffusion barrier. The substrate is exposed to the vacuum source through a plurality of spaced-apart bores of relatively small diameter, with the vacuum diffusion layer being in the form of a web of filter paper tracking and moving in synchronism with the substrate. Conventional silk screening techniques are utilized to form the conductors and bridges, with polymer thick conductive fluids being employed as the printing medium. Multiple layers of conductors may be formed, with dual-sided circuitry being applied to the substrate. The multiple layers are fabricated by initially plating a layer of metal upon the exposed surface of the polymer thick conductive films, and thereafter printing a defined pattern of dielectric upon the electroplated copper. Subsequently, a second polymer thick conductive fluid is employed as a printing medium upon the surface of the dielectric, with contact to the copper being available through vias formed in the dielectric layer. Following cure of the second layer of polymer thick conductive film, the exposed surfaces may be plated with a film of copper, nickel or other suitable metal.