Abstract
Generally, Flexible Printed Circuits (FPCs) are made of polyimide (PI), because of its excellent heat resistance, flexibility, size stability, and surface smoothness. Metallization on PI substrate are used for high density flexible printed circuit formation. In this study, we have focused on how to achieve good adhesion between the PI and the electrolessly deposited copper without micro-roughening. Adhesion strength between PI and plated copper showed about 1.0kN/m by UV irradiation for one to three minutes. A modified layer of a depth of about 150nm was formed on the PI surface by the irradiation of UV light. Adhesion was derived from the nano-level anchor effect by the formation of co-existed layer between the modified PI surface and the deposited copper. Moreover, selective and fine copper patterns were also obtained using selective UV light irradiation and conventional copper plating.
