JP2005064352A - Solid electrolytic capacitor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor having a large capacity. <P>SOLUTION: A valve metal oxide deposition film is formed on the surface of plain (unetched) aluminum foil or etched aluminum foil by a metal organic chemical vapor deposition (MOCVD) method using a valve metal alkoxide solution such as a titanium alkoxide (TiOC<SB>n</SB>H<SB>2n+1</SB>), zirconium alkoxide (ZrOC<SB>n</SB>H<SB>2n+1</SB>) or tantalum alkoxide (TaOC<SB>n</SB>H<SB>2n+1</SB>), and is used as anode foil and/or cathode foil for the solid electrolytic capacitor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

  As solid electrolytes, solid electrolytic capacitors using conductive polymers such as polypyrrole, polythiophene, polyfuran, polyaniline, or TCNQ complex salts have attracted attention. A method for producing a conventional aluminum wound solid electrolytic capacitor using these electrolytes will be described below.

  First, as shown in FIG. 1, an anode foil 1 obtained by subjecting a foil made of aluminum, which is a valve action metal, to an etching process for roughening and a chemical conversion process for forming a dielectric film, and a counter cathode foil 2 Are wound through a separator 3 to form a capacitor element 7. An anode lead wire 51 and a cathode lead wire 52 are attached to the anodized foil 1 and the counter cathode foil 2 via lead tabs 61 and 62, respectively. Reference numeral 4 denotes a winding tape.

  Thereafter, cut formation of the capacitor element 7 and heat treatment at 280 ° C. are performed. Next, the capacitor element 7 is immersed in 3,4-ethylenedioxythiophene as a monomer in a 50 wt% ferric alcohol solution of p-toluenesulfonic acid as an oxidant solution, and then subjected to thermal polymerization to thereby obtain a capacitor element. 7 is formed between the two electrodes.

  Then, as shown in FIG. 2, a sealing rubber packing 9 is attached to the capacitor element 7, and after being stored and fixed in a bottomed cylindrical aluminum case 8, the opening of the aluminum case 8 is curled with a lateral diaphragm. Then, sealing is performed and aging treatment is performed.

  Thereafter, a plastic seat plate 10 is mounted on the curled surface of the aluminum case 8, and the lead wires 51 and 52 are pressed and bent using the electrode terminals 11 to complete a solid electrolytic capacitor.

  In the market, a large capacity / low ESR electrolytic capacitor is required. As a means for increasing the capacity while maintaining the size of the electrolytic capacitor, the surface of the cathode foil is disclosed in Patent Document 1 and Patent Document 2. There is a method of improving the capacity appearance rate by forming a film of metal nitride such as TiN.

However, even if these methods are used, it is not possible to sufficiently cope with the increase in capacity that will be required from the market in the future. Accordingly, an object of the present invention is to provide a large-capacity solid electrolytic capacitor.
Japanese Patent No. 3016421 JP 2000-114108 A

In order to solve these problems, titanium alkoxide (TiOC _n H _{2n + 1} ), zirconium alkoxide (ZrOC _n ) is formed on the surface of plain (unetched) aluminum foil or etched aluminum foil by metal organic chemical vapor deposition (MOCVD). H _{2n + 1),} using a tantalum alkoxide (TaOC _n H _{2n + 1)} valve metal alkoxide solution such as to form a valve metal oxide deposited film is used as the anode foil and / or cathode foil of the solid electrolytic capacitor.

  To form titanium oxide, zirconium oxide, and tantalum oxide having a dielectric constant higher than that of aluminum on the surface of the aluminum foil by forming a valve metal oxide vapor deposition film by metal organic chemical vapor deposition using the above valve metal alkoxide solution. The foil capacitance is improved. Therefore, the capacity of the solid electrolytic capacitor can be increased.

  Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a capacitor element housed in a solid electrolytic capacitor according to the present invention.

  Titanium ethoxide vapor generated by flowing nitrogen gas at a flow rate of 0.6 L / min to the titanium ethoxide solution is introduced onto aluminum foil heated to 350 ° C. for 30 minutes, and titanium oxide is deposited on the aluminum foil. A film is formed. Further, the aluminum foil subjected to the chemical conversion treatment at 5 V is used as the anode foil 1, and the capacitor element 7 is formed by winding the aluminum foil between the cathode foil 2 and the cathode foil 2 via the separator 3. An anode lead wire 51 and a cathode lead wire 52 are attached to the anode foil 1 and the cathode foil 2 via lead tabs 61 and 62, respectively. Reference numeral 4 denotes a winding tape.

  Thereafter, cut formation of the capacitor element 7 and heat treatment at 280 ° C. are performed. Next, the capacitor element 7 is impregnated with 3,4-ethylenedioxythiophene as a monomer and 50 wt% of a ferric butyl alcohol solution of p-toluenesulfonic acid as an oxidant solution, and then thermally polymerized to thereby impregnate the capacitor. A conductive polymer layer is formed between both electrodes of the element 7. And, after mounting the rubber packing 9 for sealing on the capacitor element 7 and storing and fixing it in the bottomed cylindrical aluminum case 8, sealing is performed by curling the opening of the aluminum case 8 with a horizontal aperture, Perform an aging process. Thereafter, a plastic seat plate 10 is mounted on the curled surface of the aluminum case 8, and the anode lead wire 51 and the cathode lead wire 52 are pressed and bent using the electrode terminals 11 to complete a solid electrolytic capacitor.

  Zirconium ethoxide vapor generated by flowing nitrogen gas at a flow rate of 0.6 L / min into the zirconium ethoxide solution is introduced onto the aluminum foil heated to 350 ° C. for 30 minutes, and zirconium oxide is deposited on the aluminum foil. A film is formed. Further, the aluminum foil subjected to the chemical conversion treatment at 5 V is used as the anode foil 1 to complete a solid electrolytic capacitor in the same manner as in Example 1.

  Tantalum ethoxide vapor generated by flowing 0.6 L / min of nitrogen gas through the tantalum ethoxide solution is introduced onto aluminum foil heated to 350 ° C. for 30 minutes, and tantalum oxide is deposited on the aluminum foil. A film is formed. Further, the aluminum foil subjected to the chemical conversion treatment at 5 V is used as the anode foil 1 to complete a solid electrolytic capacitor in the same manner as in Example 1.

  Table 1 shows electrical characteristics (average values of n = 20, respectively) of capacitors (outside diameter φ6.3 mm × H6.0 mm, rated 2.5 V−180 μF) prototyped in the conventional examples described in Examples 1 to 3 and ). The capacitance was measured at 120 Hz, and the ESR was measured at 100 kHz.

表１を見てわかるように、有機金属化学蒸着法によって酸化アルミニウムより高誘電率を有する弁金属酸化物蒸着膜を形成させた電極箔を陽極として使用することによって、大容量化を達成することが可能となった。以上のように、本発明によれば、固体電解コンデンサの大幅な大容量化を実現することができる。従って、今後市場で要求されるであろう大容量の固体電解コンデンサを市場に供給することが可能となる。

As can be seen from Table 1, a large capacity can be achieved by using as the anode an electrode foil in which a valve metal oxide deposition film having a higher dielectric constant than aluminum oxide is formed by metal organic chemical vapor deposition. Became possible. As described above, according to the present invention, a large capacity of the solid electrolytic capacitor can be realized. Therefore, a large-capacity solid electrolytic capacitor that will be required in the market in the future can be supplied to the market.

In the embodiment of the present invention, the electrode foil uses an etched aluminum foil only for the anode foil and the polythiophene-based conductive polymer for the electrolyte. The same effect can be obtained by using etched or unetched aluminum foil for both. In the electrolyte, the same effect can be obtained even when a conductive polymer such as polypyrrole or polyaniline is used.

It is a disassembled perspective view of the electrolytic capacitor element which concerns on a prior art example and the Example of this invention. It is sectional drawing of the electrolytic capacitor which concerns on a prior art example and the Example of this invention.

Explanation of symbols

1 Anode foil 2 Cathode foil 3 Separator 4 Winding tape 7 Capacitor element 8 Aluminum case 9 Rubber packing 10 Seat plate 11 Electrode terminal 51 Anode lead wire 52 Cathode lead wire 61 Lead tab 62 Lead tab

Claims (4)

  In a solid electrolytic capacitor containing therein a capacitor element in which an anode foil obtained by anodizing a metal having a valve action and a cathode foil are wound via a separator, the valve is provided on the anode foil and / or the cathode foil. A solid electrolytic capacitor, wherein a valve metal oxide deposition film is formed by metal organic chemical vapor deposition (MOCVD) using a metal alkoxide solution.   2. The solid electrolytic capacitor according to claim 1, wherein any one of polythiophene-based, polypyrrole-based, polyaniline-based conductive polymer, and TCNQ complex salt is used as the electrolyte. Titanium alkoxide (TiOC _n H _{2n + 1} ), zirconium alkoxide (ZrOC _n H _{2n + 1} ), tantalum alkoxide (TaOC _n H _{2n + 1} ) is used as the valve metal alkoxide solution in the metal organic chemical vapor deposition method. A method for producing a solid electrolytic capacitor. Steam of the valve metal alkoxide generated by flowing nitrogen gas through the valve metal alkoxide solution is introduced onto a heated metal foil to form an oxide vapor deposition film of the valve metal on the metal foil, 4. The method for producing a solid electrolytic capacitor according to claim 3, wherein a metal foil on which a valve metal oxide deposition film is formed is used for an anode foil and / or a cathode foil.

Images