Method for forming titanium oxide film and titanium electrolytic capacitor

a technology of titanium oxide film and electrolytic capacitor, which is applied in the direction of electrolytic capacitor, solid-state diffusion coating, superimposed coating process, etc., can solve the problems of large leakage current, short life of the capacitor, high cost of tetrafluorocarbon, etc., and achieves small leakage current, high dielectric constant, and low cost

Inactive Publication Date: 2003-01-16
TOHO TITANIUM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the tantalum electrolytic capacitor has a problem in that tantalum is expensive.
However, as shown in the partially enlarged view in FIG. 4 showing the case of an aluminum electrolytic capacitor, when a capacitor is prepared, oxygen deficiency occurs in the aluminum oxide film and the film begins to exhibit a semiconducting property, resulting in large leakage current and thus a short life of the capacitor.
In addition, aluminum has a smaller dielectric constant per unit area as compared with tantalum, and hence it is difficult to make a compact type capacitor of large capacitance.

Method used

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  • Method for forming titanium oxide film and titanium electrolytic capacitor
  • Method for forming titanium oxide film and titanium electrolytic capacitor
  • Method for forming titanium oxide film and titanium electrolytic capacitor

Examples

Experimental program
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example 1

[0072] A metal titanium plate was heated in oxygen at 700.degree. C. for 2 hours, thereby obtaining an oxide film having a thickness of 400 nm. Subsequently, the plate was subjected to calcination in vacuum of approximately 1.times.10.sup.-3 Pa at 800.degree. C. for 2 hours, thereby removing the oxide film. The metal titanium plate was used as an electrode, and a voltage of 30 V was applied in an aqueous solution of ammonium adipate (150 g / L) for 5 minutes, thereby obtaining an oxide film. With respect to the resultant oxide film, evaluation of insulation property and measurement of capacitance were made. The results are shown in Table 1.

example 2

[0073] Substantially the same procedure as in Example 1 was repeated except that a metal titanium plate was heated in oxygen at 600.degree. C. for 2 hours, thereby obtaining an oxide film having a thickness of 100 nm. With respect to the resultant oxide film, evaluation of insulation property and measurement of capacitance were made. The results are shown in Table 1.

example 3

[0074] Substantially the same procedure as in Example 1 was repeated except that a metal titanium plate having an oxide film having a thickness of 400 nm was heated in vacuum at 800.degree. C. for 4 hours, thereby obtaining an oxide film. With respect to the resultant oxide film, evaluation of insulation property and measurement of capacitance were made. The results are shown in Table 1.

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Abstract

A compact type large capacity titanium electrolytic capacitor having minimized leakage current is provided by forming a stable oxide film having a large dielectric constant on a titanium surface, wherein a titanium substrate having a titanium oxide film thereon having a thickness of 50 nm or more is subjected to calcination in vacuum or an inert gas atmosphere, thereby reducing the thickness of said oxide film to less than 50 nm and the calcined surface of said metal titanium substrate is subjected to oxidation, thereby re-forming an oxide film on the surface of said metal titanium substrate. The metal titanium substrate having the re-formed oxide film obtained by such method can be used as an anode for a titanium electrolytic capacitor.

Description

APPLICATION FIELD IN INDUSTRY[0001] The present invention relates to a method for forming an oxide film and to an electric capacitor. Particularly, the present invention relates to a method for forming on a metal titanium substrate a dense oxide film having large electrostatic capacitance and excellent insulation property; and to a titanium electrolytic capacitor wherein the metal titanium substrate having a dense oxide film obtained by the method is used as an anode.PRIOR ART[0002] As a compact type electrolytic capacitor having a large capacitance as represented by solid electrolytic capacitor, tantalum electrolytic capacitor and aluminum electrolytic capacitor have been commercially used.[0003] In the tantalum electrolytic capacitor, a porous sintered body of metal tantalum is used as an electrode, and a dielectric oxide film is formed by anodic oxidation of the metal tantalum. The oxide film of tantalum obtained in this manner is extremely stable, and therefore, the resultant ca...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C23C8/10C23C8/80H01G9/04H01G9/042
CPCC23C8/10C23C8/80H01G9/042
Inventor ARAI, YOSHIYUKI
Owner TOHO TITANIUM CO LTD
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