Process of forming multilayer circuit boards

A process for forming a multilayer laminated circuit board, the process comprising the steps of:

• providing a first uncured dielectric layer bonded to a first conductive foil to form a first ply, and a second uncured dielectric layer bonded to a second conductive foil to form a second ply;
• forming vias through the first and second plies so as to extend through the first and second conductive foils;
• filling the vias with a conductive material such that the conductive material electrically contacts the first and second conductive foils;
• providing a cured core laminate having a dielectric core between a pair of patterned conductive claddings each of the patterned conductive claddings defining at least one conductive runner;
• and then
• laminating the first and second plies to opposing surfaces of the cured core laminate such that the first and second dielectric layers overlay the pair of patterned conductive claddings and flow into voids adjacent the conductive runners, the conductive material within the vias electrically contacting the pair of patterned conductive claddings of the cured core laminate.

A process for forming a multilayer laminated circuit board, the process comprising the steps of:

• providing a first uncured dielectric layer bonded to a first conductive foil to form a first ply, and a second uncured dielectric layer bonded to a second conductive foil to form a second ply, the first and second uncured dielectric layers being formed from an epoxy resin and having thicknesses of about twenty-five to about one hundred seventy-five micrometers, the first and second conductive foils having thicknesses of at least about eighteen micrometers;
• drilling vias through the first and second plies so as to extend through the first and second conductive foils, the vias having diameters of about one hundred to about three hundred micrometers;
• filling the vias with a conductive material containing a metal chosen from the group consisting of silver, gold, nickel and copper, the conductive material electrically contacting the first and second conductive foils;
• providing a cured core laminate having a dielectric core between a pair of patterned conductive claddings, each of the patterned conductive claddings defining at least one conductive runner;
• and then
• laminating the first and second plies to opposing surfaces of the cured core laminate such that the first and second dielectric layers overlay the pair of patterned conductive claddings and flow into voids adjacent the conductive runners, the conductive material within the vias electrically contacting the pair of patterned conductive claddings of the cured core laminate while simultaneously preventing flow of the first and second uncured dielectric layers into the vias.