Study of the chemical polymerization of pyrrole onto printed circuit boards for electroplating applications

Abstract

AbstractWe have studied the deposition of thin films of a conducting polymer, polypyrrole, onto printed circuit boards (PCBs). Film formation occurs as a result of the in situ polymerization of pyrrole monomer using a 1 : 1 FeCl3/5‐sulfosalicylic acid oxidant complex in aqueous solution. We have optimized the polymerization conditions in order to coat a large number of PCBs with a single polymerization bath, while at the same time maintaining the quality of the conducting polymer coating (i.e., keeping its surface resistance below 104 Ω per square). These improvements were achieved simply by controlling the initial oxidant–monomer mole ratio such that the oxidant is always present in significant excess. We have also examined the formation of thick polypyrrole layers obtained from the progressive buildup of thin layers. The morphology and film thickness of these polypyrrole coatings have been studied by scanning electron microscopy. Some preliminary electroplating experiments using these polypyrrole–PCB composites are also described. © 1995 John Wiley & Sons, Inc.