A method for forming an electrolytic capacitor is disclosed. The method
includes forming a conductive polymer coating by polymerizing a monomer
in the presence of less than a stoichiometric amount of an oxidative
polymerization catalyst. The present inventor has found that the use of
less than the stoichiometric amount of the oxidative polymerization
catalyst per mole of monomer can slow the polymerization of the monomer,
creating oligomers that are shorter in length than if fully polymerized
into a polymer. Without wishing to be bound by theory, it is believed
that these shorter oligomers provide better penetration into the porous
anode. Thus, the resulting conductive polymer layer can be more
intimately positioned with respect to the anode. As a result, the formed
capacitor can exhibit better performance.