Abstract: There is a solid electrolytic capacitor having a low ESR characteristic. In accordance with the solid electrolytic capacitor using an capacitor element wherein solid electrolyte is formed, the post-etching void factor of the anode foil used for the capacitor element is set at not more than 51% or the post-etching void factor of the cathode foil used for the capacitor element is set at not more than 44%, so that an electrode foil increases in conductivity and decreases in resistivity, to thereby obtain, coupled with the solid electrolyte of a low resistivity, a solid electrolytic capacitor having a lower ESR characteristic.

Abstract: There are provided a solid electrolytic capacitor having a low ESR characteristic and an electrode foil to be used for this electrolytic capacitor. In accordance with the present invention, a capacitor element uses an anode foil with a post-etching void factor of not more than 51% or a cathode foil with another post-etching void factor of not more than 44%, wherein the capacitor element contains a solvent consisting mainly of a water and a water-soluble metal complex being bonded with phosphoric acid ions, whereby the electrode foil increases in conductivity and decreases in resistivity, while an electrolytic solution thereof has a low resistivity, to thereby obtain the solid electrolytic capacitor having the low ESR characteristic and the electrode foil to be used therefor.

Abstract: An electrolyte for electrolytic capacitor containing within an aprotic solvent a fluorocomplex acid salt of a N-heterocyclic compound as solute.An electrolyte for electrolytic capacitor according to the invention may conveniently be prepared by adding to an aqueous solution of fluorocomplex acid salt an equivalent amount of N-heterocyclic compound for reaction with subsequent dryness at reduced pressure to obtain an anhydrous salt which is then added to the aprotic solvent to prepare the resultant electrolyte having desired conductivity.

Abstract: An electrolyte for electrolytic capacitor containing within an aprotic solvent a tetrafluoroborate of an organic amine compound as solute.An electrolyte for electrolytic capacitors according to the invention may conveniently be prepared by adding to an aqueous solution of tetrafluoroborate an equivalent amount of organic amine compound for reaction with subsequent reduction and dryness to obtain an anhydrous salt which as an approximately 10% by weight solution is then added to the aprotic solvent to prepare the resultant electrolyte.