Copper patterned polystyrene panels by reducing of surface bound Cu (II)-sulfonyl hydrazide complex

A modified electroless metal deposition method has been developed for copper plating of polystyrene (PS) surfaces. The modified procedure avoids the plasma conditioning and surface activation steps in the classical electroless metal plating process. First step of the present procedure is chlorosulfonation of PS surface by soaking into chlorosulfonic acid, yielding chlorosulfonated surface with density of 0.046-0.110 mmolcm^{- 2} depending on contact time (10-60 min). In the second step chlorosulfone groups on the surface are converted to sulfonyl hydrazides almost quantitatively by reaction with hydrazine solution (80%). Green Cu (II)-sulfonylhydrazide complex is formed at the surface, in the third step, by interaction with ammoniacle Cu (II) solution at room temperature. The copper in the complex is reduced rapidly in the fourth step, by immersing the specimen into 5% of hydrazine solution. The elemental copper deposited onto the surface serves activating sites to accumulate more (5-7 mg per cm²) elemental copper from electroless copper solutions in the final step. The present method avoids the surface activation with palladium and allows preparing copper patterns with reasonably high pull-off strengths (3.77 Nmm^{- 2}) on PS panels. In the study the copper deposition has been investigated using standard analytical procedures, X-ray photoelectron spectrometry (XPS) and Scanning Electron Microscopy.