Production method of a capacitor

[0080] By using and shaping a tantalum powder having CV (product of capacitance and electrochemical voltage) of 140,000 μF·V / g together with a tantalum lead wire of 0.24 mmφ, a sintered bodies in a size of 4.5×1.0×1.5 mm were produced (sintering temperature: 1,300° C., sintering time: 20 minutes, density of sintered body: 6.2 g / cm3; the Ta lead wire was vertically embedded in the center part of the 1.0×1.5 mm face of the sintered body while being buried 4 mm inside the sintered body and protruding 10 mm outside).

[0081] On a separately prepared polyimide-made resin plate having a length of 250 mm, a width of 30 mm and a thickness of 2 mm (There are provided by printed wiring, on the front surface of the plate, a circuit connecting connection terminals for 32 electric conductors and respective anodes of current regulative diodes and reaching the power supply terminal in the left side of plate, and on the back surface, a circuit electrically connected only to the connection terminals ...

[0087] An oxide dielectric film layer comprising Nb2O5 was formed through electrochemical formation at 23 V by using a niobium sintered body (made of powder having CV of 250,000 μF·V / g, nitrided amount: 11,000 ppm, amount of oxygen due to natural oxidation on the surface: 81,000 ppm, sintering temperature: 1,280° C., sintering time: 30 minutes, density of the sintered body: 3.4 g / cm3) and a niobium lead wire in place of the tantalum sintered body and the tantalum lead wire in Example 1. Then, a series of operations, that is, the sintered bodies were dipped in an alcohol solution of 2% ethylenedioxythiophene, pulled up, left standing, dipped in an alcohol solution of 18% iron naphthalenesulfonate, pulled up, left standing at 40° C. for 30 minutes and dipped in alcohol, were repeated seven times. The sintered bodies were then subjected to re-electrochemical formation at 17 V and 80° C. for 30 minutes in an aqueous 0.1% acetic acid solution, washed with water and dried.

[0088] Subseque...