Patent ID: 7175781

Claim:
A method for producing a solid electrolytic capacitor comprising a valve acting metal having pores, a dielectric film formed on a surface of the valve acting metal, and an electrically conducting polythiophene composition as a solid electrolyte provided on the dielectric film, the method comprising polymerizing a thiophene monomer represented by the following formula (IX): wherein R 4 and R 5 each independently represents a hydrogen atom, a linear or branched, saturated or unsaturated C1–6 alkyl group or a substituent for forming at least one 5-, 6- or 7-membered heterocyclic structure containing two oxygen elements shown in the formula by combining the C1–6 alkyl groups to each other at any position, the ring structure formed in the scope thereof includes a chemical structure such as a vinylene group which may be substituted and a substituted phenylene group which maybe substituted, in the presence of naphthalenesulfonate anion by the action of a persulfate to form a solid electrolyte layer on the dielectric film, wherein the composition has a sulfate ion content of from 0.1 to 10 mol %.