Improvement of Adhesion for Layer-to-Layer Connection for Build-up Printed Circuit Boards

Abstract

SUMMARYThe adhesion strength between the copper conductor and dielectric layer for build-up pcb's is mainly governed by the etching of the dielectric layer. However, high adhesion cannot be obtained consistently. Therefore, the improvement of adhesion strength between dielectric materials and deposited copper has been studied and reported in this paper.The addition of potassium thiocyanate into the electroless copper plating bath compared to other additives was effective in improving the adhesion strength, because the plating reaction on the copper surface was inhibited and the uniformity of deposited copper film at the inside of fine etched holes was improved. However, in the case of the extension of plating time for electroless copper plating in order to bury the etched holes, the adhesion was decreased with the accumulation of hydrogen and water content in the electroless copper film.