Method of manufacturing a solid electrolytic capacitor with a sufficiently low impedance in a high frequency range

Abstract

In a method of manufacturing a solid electrolytic capacitor in which an electrolyte layer containing a conductive polymer is formed by chemical oxidative polymerization on a dielectric oxide film layer formed by anodizing surfaces of a valve metal, an ammonium peroxodisulfate solution adjusted to pH 6 to 8 is used as an oxidant in forming the conductive polymer layer.

1 . A method of manufacturing a solid electrolytic capacitor which comprises:
 a valve metal;   a dielectric oxide film layer formed by anodizing a surface of the valve metal; and   an electrolyte layer containing a conductive polymer and being formed on the dielectric oxide film layer by chemical oxidative polymerization,   wherein a solution containing ammonium peroxodisulfate and adjusted to pH 6 to 8 is used as an oxidant for causing the chemical oxidative polymerization.   
     
     
         2 . The method according to  claim 1 , wherein the solution contains, as a dopant, at least one selected from p-toluenesulfonic acid, phenolsulfonic acid, naphthalenesulfonic acid, and aromatic derivatives each having sulfonic groups. 
     
     
         3 . The method according to  claim 2 , wherein a concentration of the ammonium peroxodisulfate in the solution is 1 to 50 mass %. 
     
     
         4 . The method according to  claim 1 , wherein a concentration of the ammonium peroxodisulfate in the solution is 1 to 50 mass %. 
     
     
         5 . A method of manufacturing a solid electrolytic capacitor, the method comprising:
 preparing a valve metal;   forming a dielectric oxide film layer by anodizing a surface of the valve metal; and   forming an electrolyte layer containing a conductive polymer on the dielectric oxide film layer by chemical oxidative polymerization using an oxidant,   wherein a solution containing ammonium peroxodisulfate and adjusted to pH 6 to 8 is used as the oxidant.   
     
     
         6 . The method according to  claim 5 , wherein the solution contains, as a dopant, at least one selected from p-toluenesulfonic acid, phenolsulfonic acid, naphthalenesulfonic acid, and aromatic derivatives each having sulfonic groups. 
     
     
         7 . The method according to  claim 5 , wherein a concentration of the ammonium peroxodisulfate in the solution is 1 to 50 mass %. 
     
     
         8 . The method according to  claim 5 , further comprising:
 forming a cathode layer on the electrolyte layer; and   connecting external electrodes to the valve metal and the cathode layer, respectively.   
     
     
         9 . The method according to  claim 8 , further comprising covering, with a packaging resin, all portions except a part of each of the external electrodes. 
     
     
         10 . The method according to  claim 9 , further comprising extending a part of each of the external electrodes along a surface of the packaging resin.