Electroless Plating on Plastic Induced by Selective Laser Activation

This paper presents a new method for selective micro metallization of polymers. A Nd:YAG laser is employed to draw patterns on polymer surfaces that are submerged in a liquid (usually water). After subsequent activation with palladium chloride and followed by auto-catalytic electroless plating, copper deposit only on the laser tracks. The mechanism of the palladium activation step is analyzed based on experimental results and theoretical calculations. It is believed that the laser introduces porous and rough structures on the surface, which favours the palladium attachment. Looking from the surface property’s point of view, the basic polymer surface tends to attract palladium in an acidic solution. Using the laser treatment mentioned above, standard grades of thermoplastic materials such as ABS, SAN, PE, PC and others have been successfully metalized. The metalized tracks are down to 300 μm in width with 50μm between two tracks, but further optimization is expected in this field. Due to the porous and rough structure of the laser track, excellent adhesion between metallization and substrate is obtained. On top of the first copper layer, additional metal such as nickel, gold, palladium or tin can be deposited.