Mussel inspired polymers for flexible electronics applications*

Electroless plating of solid metals from a solution onto a catalytically active surface has been widely used in the printed circuit board industry for production of wiring layers and inter-layer (via) connections. Smooth substrate surfaces, like polyimide (PI) for flexible electronics applications, are particularly challenging as the electrolessly plated metal tends not to adhere to the surface. It is therefore desirable to develop new chemistries that can be used for adhesion promotion between the polyimide substrate and the deposited copper. Herein, we introduce a mussel-inspired universal adhesive moiety, dopamine, as a side group to a water soluble polymer backbone and demonstrate its application as an adhesion promotion layer for electroless plating of flexible substrates. When the polymer is deposited on a substrate surface, the DOPA moiety reacts with the substrate and adheres to it while the polymer chain extends and folds to generate a smoother outer surface through minimizing the surface energy, creating a smooth and uniform coat of deposited copper.