JPS6060710A - Method of producing solid electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid electrolytic capacitor.

In general, solid electrolytic capacitors are made by forming an oxide film on the surface of a gold mist electrode such as AZs Ta to form a dielectric, a solid electrolyte is attached to this, and a conductive layer such as gelaphite or silver is used to form a dielectric. It is constructed by deriving the poles. This type of capacitor generally uses manganese dioxide as the solid electrolyte in many cases. A method is used in which this material is immersed in a manganese nitrate solution and then subjected to a thermal decomposition treatment to form manganese dioxide and adhere to the electrode. According to this method, during thermal decomposition treatment, for example, in the case of AJ, the AlzOs film, which is an @electric body, is damaged, resulting in a large drop in breakdown voltage. In any case, this method involves dissolving the dielectric film (with nitric acid) and attaching manganese dioxide to it, which works to firmly bond the electrode and manganese dioxide and lower the contact resistance between solids. I'm also doing it. Therefore, various methods have been investigated to improve the manganese dioxide method, particularly to improve the film deterioration and the drop in pressure resistance, but no fundamental solution has been found in any of them.

In other words, it is necessary to improve the method of adhering the solid electrolyte to the electrode.However, adhering the solid electrolyte to the electrode while degrading the film with a nitric acid-based metal salt will result in good adhesion between the dielectric film and the solid electrolyte. Melting the film itself is not a good idea because it greatly reduces the performance characteristics of the capacitor.

As a result of various studies, the inventors of the present invention have found a method for strongly adhering to the dielectric film without deteriorating the film. The point of the present invention is that Sn, 09 or ZnO
Alternatively, a metal oxide powder such as MnOt, which can be used as a solid electrolyte, is sintered with a low melting point oxide. Naturally, the low melting point oxide must be one that does not deteriorate the dielectric film on the electrode, and is most desirable if it has the ability to repair the A12 oz film, which is the most susceptible to deterioration. From this point of view, it was easily determined that CrO3 is the most suitable material having a low melting point and film repair ability.

5nu2 or ZnO or MnO in Crys aqueous solution
2 powders are dissolved in a supersaturated state, an electrode with a dielectric film is immersed in the solution, and then heat treatment is performed. However, since the melting point of CrOx is 196°C, it cannot be used at higher ambient temperatures. CrO3 is melted and acts as a strong binder between the Altos film and SnO2, ZnO2 or Mn02 to provide adhesion.

In addition, after this immersion, in the heat treatment process, 5nu2
is S nOz ・nH2O, and ZnO is Zn(lnH2
0, and MnO2 changes to an oxide having adsorbed water or crystallized water like MnO2.nH2O, so the solid electrolyte function increases.

That is, adsorbed water or crystal water causes a water utilization reaction with the defective parts of the dielectric film, and the protons released by the reaction M(HzO)n+M(OH)n+nH are 5n02, Zn0%.
By electrophoresis in MnO2, dilatation progresses and the so-called aging ability increases.

Furthermore, regarding the reduction in film withstand voltage due to dissolution of the anodic oxide film, which has been a major problem in the past, the method of the present invention hardly causes any reduction in film withstand voltage.

Hereinafter, specific examples of the present invention will be described.

A chemically formed foil obtained by anodizing 99.99% high purity A, ff foil to 150 V with an ammonium borate solution is used.

Sn0w powder with an average diameter of 0.1 μm was used, and Cr
The Os solutions had the concentrations shown in Table 1, and were dissolved and dispersed in a supersaturated state. After immersing the A7 chemically formed foil in the solution,
Heat treatment was performed at 250''C for 10 minutes, and the process was repeated three times.

Table 1 could not.

Further, a solid capacitor sample was prepared by coating hecolloidal carbon on the solid electrolyte produced by the method of the present invention, applying silver paste treatment, and soldering lead wires.

Figure 1 shows the aging characteristics when a constant current of 0.5 mA/cd was applied. ■, ■, ■, ■, ■ in the figure are samples A L 2.3.4. in Table 1, respectively. 5, and the breakdown voltage was up to 150 ■, but the aging characteristics worsened as the CrO3 concentration increased.

Further, the capacitance and -δ characteristics of the same sample were consistent with those shown in Table 1. According to this, the lower the CrO3 concentration, the better the characteristics. Further, if the concentration of Crys is less than 1%, the adhesion to the dielectric material is extremely poor, and the characteristics cannot be sufficiently confirmed. Also, the concentration of Crys is 70
% or more, the insulating properties of CrOx rapidly increase, the electrical conductivity becomes extremely low, and it is difficult to provide an electrolytic function. These things j2
The concentration of the cro3 solution is suitably 1.0 wt% to 70 wt%, and can be controlled by setting an appropriate concentration according to each specification.

As mentioned above, it has been found that even if ZnO powder is supersaturated dispersed in the Crys solution and the same treatment is performed, it has good solid electrolyte function.The present invention has been found to be useful in industrial and practical applications as a method for manufacturing solid electrolytic capacitors. It is of high value.

[Brief explanation of drawings]

FIG. 1 is an aging characteristic diagram of solid electrolytic capacitors manufactured by varying the concentration of Cr OH solution. Patent applicant Nippon Capacitor Industry Co., Ltd.

Claims (2)

[Claims] (1) When forming an oxide film on the surface of the gold electrode and attaching the solid electrolyte to it, 5n02, znαMnO2
After dispersing metal oxide powder such as in a Crys solution and immersing a film-forming entertainment electrode with an anodic oxide film in the solution, heating in an atmosphere within a temperature range of 190'C or more and less than the melting temperature of the electrode metal. A method for manufacturing a solid electrolytic capacitor, which comprises performing a treatment and repeating this operation multiple times to generate a solid electrolyte. (2) The concentration of the above Cr Os solution is 1.0 to 70 wt%
A method for manufacturing a solid electrolytic capacitor according to claim 1, wherein a solid electrolytic capacitor is used.