Tuesday, July 17, 2012

Problem on Plastic Electroplating

The basic problem of plastic electroplating is in attempting to electroplate onto plastics substrates is, of course, that they are electrically non-conductive and cannot be immersed in a plating solution and coated in the way that metal objects can. Some method was therefore needed whereby a conductive film could be deposited onto the plastics surface to provide the basis for subsequent electrodeposition. It was, of course, vital that this surface layer, in addition to being electrically conductive, should adhere well to the substrate if the final coating system was to show good adhesion.

Substrate Etching.
Early processes, using conductive paint or chemically reduced silver on surfaces roughened either mechanically or by solvent attack, did not provide adequate adhesion. In the mid 1960s, etching solutions based on chromic acid were developed which could successfully be used with acrylonitrile butadiene styrene (ABS) copolymer. Use of these solutions resulted in selective removal of the butadiene phase from the resin to give a micro-etched surface providing bonding to the subsequent conductive layer.

Electroless Plating
This development came at a time when great improvements were also being made in the technology of electroless nickel and electroless copper deposition. These advances in electroless plating combined with the development of the etching technique gave rise to a system that provided a highly conductive coating exhibiting satisfactory adhesion to the plastics surface.