Selective electroless copper plating micro-coil assisted by 248 nm excimer laser
In the study, template of micro-coil patterns created by the excimer laser and activated by reactants for electroless copper plating is described. The generated micro-coil patterns are transformed into copper patterns on the substrate and formed copper microstructures. This method simplifies the manufacturing process of making circuits on boards comparing with the conventional lithography process of forming copper patterns on the substrate. Micro-patterns generated by the excimer laser result in the change of surface electric properties and activation selectively. A chemical reaction through the selective activated area may deposit metal, such as copper. The kryptonfluoride excimer laser (KrF, 248 nm in wavelength) not only provides simple and fast machining patterns, but also uses its high energy density to drill holes and circuits directly. Palladium ions are added as mediators in the electroless plating solution to enable a continuous electroless copper deposition. According to the experiment of excimer laser assisted electroless copper plating, the procedures of pretreatment and post cleaning are key factors resulted in excellent selective plating. The samples were pretreated by sodium dodecyl sulfate (SDS) and post cleaned by acetone and diluted nitric acid resulting in distinct micro-patterns. The deposition area is confined in the excimer laser ablated portion resulting in well selective plating.
selective electroless copper micro-coil excimer laser palladium