Effects of ultrasonic process on the adhesion of Cu/non-conductive PCB substrate in electroless copper plating

Electroless Cu plating has been used in PCB industry when circuit was made upon non-conductive substrate. Adhesion is getting important since the size of L/P is reduced. The adhesion of copper on substrate is mainly dependent on Pd activation and copper seeding. In this study the methods of Pd activation were varied and the effects of ultrasonic process were investigated. The thickness of copper layer with activation process was analyzed. The adhesion of copper layer was increased as much as 80% after ultrasonic process applied.