JP2008172185A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor increasing capacity by solving the problem wherein large capacity cannot be achieved easily for the electrolytic capacitor used for various kinds of electronic equipment. <P>SOLUTION: The capacitor comprises: a capacitor element 1, where an insulating section is provided at a prescribed position of an anode body, made of aluminum foil for dividing into an anode section and a cathode formation section and a solid electrolyte layer comprising a conductive polymer and a cathode layer are formed and laminated on the cathode formation section successively to form the cathode section; an anode terminal 9 and a cathode terminal 10 jointed to the anode and cathode sections of the capacitor element 1; and an insulating packaging resin 11 for covering the capacitor element 1, excluding one portion of the anode terminal 9 and the cathode terminal 10. In the capacitor, the anode body is constituted by forming a metal oxide layer, such as titanium oxide and zirconium oxide, on the surface of aluminum foil where a dielectric oxide coating layer is formed, thus increasing the capacity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  Among the electrolytic capacitors used in various electronic devices, the present invention is mainly achieved by using an electrode foil in which a metal oxide layer is formed on the surface of a dielectric oxide film formed on the surface of a valve action metal foil. The present invention relates to an electrolytic capacitor with increased capacity.

  FIG. 5 is a cross-sectional view showing a configuration of a solid electrolytic capacitor using a conductive polymer as a solid electrolyte as an example of this type of conventional electrolytic capacitor, FIG. 6 is a perspective view thereof, and FIG. 7 is a solid electrolytic capacitor thereof. 8 is a partially cutaway perspective view showing the configuration of the capacitor element used in FIG. 5. In FIGS. 5 to 7, reference numeral 20 denotes a capacitor element, and the capacitor element 20 is an anode body made of an aluminum foil which is a valve metal. After forming a dielectric oxide film layer (not shown) on the surface of 21, an insulating resist portion 22 is provided to separate the anode portion 23 and the cathode forming portion 24, and the surface of the cathode forming portion 24 has a high conductivity. The cathode portion 27 is formed by sequentially laminating a solid electrolyte layer 25 made of molecules and a cathode layer 26 made of carbon and silver paste.

  Reference numeral 28 denotes an anode comb terminal, 29 denotes a cathode comb terminal, 29a denotes a guide portion formed by bending a part of a connection surface of the cathode comb terminal 29, and the anode portion 23 of the capacitor element 20 is connected to the anode comb terminal. Similarly, the cathode portion 27 is mounted on the connection surface of the cathode comb terminal 29 on the connection surface 28, and the anode portion 23 of the capacitor element 20 is joined by resistance welding by bending the connection portion 28a of the connection surface of the anode comb terminal 28. The cathode portion 27 is joined to the connection surface of the cathode comb terminal 29 via a conductive silver paste (not shown).

  Reference numeral 30 denotes an insulating exterior resin that covers the capacitor element 20 in a state where parts of the anode comb terminal 28 and the cathode comb terminal 29 to which the capacitor element 20 is bonded are exposed on the outer surface. The anode comb terminal 28 and the cathode comb terminal 29 exposed from 30 are each bent from the side surface to the bottom surface along the exterior resin 30 to form external terminals, thereby forming a surface mount type solid electrolytic capacitor. (Patent Document 1).

  Various methods for forming a metal oxide layer on the surface of the anode body 21 constituting the capacitor element 20 have been proposed for the purpose of increasing the capacity of the conventional solid electrolytic capacitor thus configured. As known in the art, CVD, ion plating, sputtering, and other methods are known, but these methods require not only special and expensive manufacturing equipment but also metal oxides for large-area substrates. There is a problem that it is extremely difficult to form a layer with a thin film or to form a metal oxide layer with a thin film on a substrate having a complicated surface shape.

  Therefore, in order to solve these problems, a method using a metal oxide sol formed by hydrothermal treatment has been proposed. For example, a mixed aqueous solution of a zirconium salt and a rare earth yttrium salt is subjected to a saturated water vapor pressure. There has been proposed a method for producing metal oxides, in which the mixed oxide sol obtained by hydrothermal treatment is applied to the surface of a substrate, dried and fired (Patent Documents 2 and 3).

Separately, zirconium oxychloride is suspended in ethanol, and boric acid aqueous solution and then ammonium water is added to hydrolyze zirconium oxychloride to obtain zirconium hydrate containing boron compound. It has been proposed to form a zirconium oxide film by immersing the base material in order to attach the sol, heat-treating and drying the sol (Patent Document 4).
JP 2000-340463 A Japanese Patent Laid-Open No. 63-233088 JP-A-2-38362 JP-A-5-319953

  However, in the above conventional solid electrolytic capacitor, the metal oxide layer is formed on the substrate having a large area even in the manufacturing methods of Patent Documents 2 to 4 in which the metal oxide layer is formed on the surface of the anode body 21 for the purpose of increasing the capacity. The problem that it is difficult to form a metal oxide with a thin film or a metal oxide film on a substrate with a complicated surface shape cannot be solved. For those that require a heat treatment step, the substrate may be deformed, and in any case, it has a common problem that it is difficult to form a metal oxide as a thin film. The problem was that it was extremely difficult to increase the capacity.

  An object of the present invention is to solve such a conventional problem and to provide an electrolytic capacitor capable of realizing a large capacity by using an anode body in which a metal oxide is formed as a thin film. .

In order to solve the above problems, the present invention provides an insulating part at a predetermined position of an anode body made of an aluminum foil to separate the anode part and the cathode forming part, and a solid made of a conductive polymer on the cathode forming part. Capacitor element in which a cathode portion is formed by sequentially laminating an electrolyte layer and a cathode layer, an anode portion of the capacitor element, an anode terminal joined to the cathode portion, a cathode terminal, and a part of the anode terminal and the cathode terminal In the electrolytic capacitor made of an insulating exterior resin covering the capacitor element except for the above, the anode body has a metal oxide layer formed on the surface of the dielectric oxide film layer formed on the surface of the aluminum foil. constructed, the metal oxide layer is caused by the presence of a metal fluoro complex compound and / or metal fluoride in the solution ^{_{M a F b c- + dH 2}} O → M a O d + F ^{- +} 2dH + (M is Ti, Zr, Si, Nb, Ta, Hf, In, Sn, 1 kind selected from the group consisting of rare earth elements, a, b, c, d are coefficients, ma = b -C = 2d, where m is an oxidation number of the metal M, and satisfies the following relationship: a> 0, b> 0, c ≧ 0, d> 0) It is.

  As described above, the electrolytic capacitor according to the present invention can increase the capacity of the electrolytic capacitor by using the aluminum foil in which the metal oxide layer is formed as a thin film on the surface of the dielectric oxide film layer. It is possible to obtain an effect that it is possible to realize a large capacity which has been difficult.

(Embodiment 1)
Hereinafter, the first aspect of the present invention will be described with reference to the first embodiment.

  1A to 1D are a plan view, a side cross-sectional view, a cross-sectional view taken along line AA, and a cross-sectional view, respectively, showing a configuration of a solid electrolytic capacitor as an example of the electrolytic capacitor according to Embodiment 1 of the present invention. FIG. 2 is a partially cutaway perspective view showing the configuration of a capacitor element used in the solid electrolytic capacitor. In FIGS. 1 and 2, 1 is a flat capacitor element. In this capacitor element 1, a dielectric oxide film layer is formed on the surface of an anode body 2 made of an aluminum foil which is a valve metal, and then a metal oxide film is formed as a thin film (details will be described later) and insulated. The conductive resist portion 3 is provided to separate the anode portion 4 and the cathode forming portion 5 from a conductive polymer (for example, polypyrrole) formed on the surface of the cathode forming portion 5 by a technique such as electrolytic polymerization or chemical polymerization. Become a solid Solution electrolyte layer 6, those that are formed by forming the cathode portion 8 by sequentially laminating forming the cathode layer 7 made of carbon and silver paste.

  9 is an anode terminal in which the anode part 4 of the capacitor element 1 is bonded to the upper surface in a state where a plurality of the capacitor elements 1 are laminated (six in the first embodiment), and 10 is a laminate of the capacitor elements 1 similarly. The cathode terminal to which the cathode portion 8 of the capacitor element 1 is joined in the state, 11 is an insulating exterior resin that covers the capacitor element 1 with the bottom surfaces of the anode terminal 9 and the cathode terminal 10 exposed, respectively. In Embodiment 1, an epoxy resin is used as the exterior resin 11.

The metal oxide film formed on the surface of the dielectric oxide film layer of the anode body 2 on which the dielectric oxide film layer is formed is titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) or zircon ammonium fluoride ( (NH ₄ ) ₂ ZrF ₆ ) A reaction such as an aqueous solution is used, that is, M _a F _b ^c− + dH ₂ O produced by the presence of a fluorometal complex compound and / or a metal fluoride in the solution → ^{_{M a O d + bF - +}} 2dH + (M is Ti, Zr, Si, Nb, Ta, Hf, in, Sn, 1 kind selected from the group consisting of rare earth elements, a, b, c, d is a factor , Ma = b−c = 2d, where m is the oxidation number of the metal M, and satisfies the relationship of a> 0, b> 0, c ≧ 0, d> 0), and the dielectric oxide film layer Of metal oxides such as titanium oxide and zirconium oxide Film is obtained so as to form a thin film.

Specifically, 0.04 g of ammonium titanium fluoride ((NH ₄ ) ₂ TiF ₆ ) was added to 100 ml of pure water, stirred, and completely dissolved to obtain an aqueous solution. In this aqueous solution, an aluminum foil on which a dielectric oxide film layer was formed by anodic oxidation after etching was immersed and left at 30 ° C. for 2 hours.

  Subsequently, the immersed aluminum foil was taken out and the cross section was observed with a transmission electron microscope. As a result, it was confirmed that a titanium oxide film was uniformly formed on the surface of the dielectric oxide film layer. Moreover, when the capacity | capacitance of the aluminum foil in which this titanium oxide film was formed was measured, it was 700 micro F. Compared with the capacity of the aluminum foil in which the dielectric oxide film layer which does not process anything was formed is 390 micro F, A capacity nearly 1.8 times larger can be obtained. In addition, these capacity | capacitance measurements were measured using the LCR meter in 15 weight% ammonium adipate aqueous solution at room temperature.

The capacity of the aluminum foil is usually inversely proportional to the thickness of the dielectric oxide film layer, but in the first embodiment, the amount of titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) increases, and the capacity increases as the TiO ₂ film thickness increases. Is something that grows. This is because the fluoride ion contained in titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) partially dissolves the aluminum oxide film formed on the surface of the aluminum foil. This is because an aluminum oxide film of about 9 has been replaced with a titanium oxide film having a relative dielectric constant of about 40 in an amorphous state.

  FIG. 3 is a perspective view showing the configuration of the anode terminal and the cathode terminal, and a plurality of anode terminals 9 and cathode terminals 10 are continuously provided at predetermined intervals on a hoop-shaped substrate (not shown). The substrate is formed by punching and subsequently bending, and then cutting is performed leaving only the necessary portions of the anode terminal and the cathode terminal, and unnecessary portions are discarded.

  The details of the anode terminal 9 will be described. Reference numeral 9a denotes a mounting portion which becomes a mounting surface on the substrate, and both end portions excluding the mounting portion 9a are bent upward in a step shape so as to be covered with the exterior resin 11 It is. Reference numeral 9b denotes a joint surface on which the anode portion 4 of the capacitor element 1 is mounted and joined. This joint surface 9b further folds the portion where both end portions excluding the mounting portion 9a are bent upward in a step shape. Thus, two substrates are formed so as to overlap each other.

  Reference numeral 9c denotes a wall portion for positioning the anode portion 4 of the capacitor element 1, and the tip portion of the wall portion 9c is bent so as to contact the upper surface of the anode portion 4 of the capacitor element 1 and is joined by resistance welding. It is what. 9d is a shielding part provided so as to extend obliquely upward from the mounting part 9a toward the cathode terminal 10, and 9e is provided at the tip of the shielding part 9d. The anode part 4 of the capacitor element 1 is mounted and bonded. It is a part used as the joining surface. Reference numeral 9f denotes an external terminal provided so as to be exposed from the side surface of the exterior resin 11 by bending the end portion vertically, and all the parts other than the external terminal 9f and the mounting portion 9a are covered with the exterior resin 11. It is configured so as not to appear in the appearance.

  The details of the cathode terminal 10 will be described. Reference numeral 10a denotes a mounting portion that becomes a mounting surface on the substrate, and both end portions excluding the mounting portion 10a are bent upward in a step shape to be covered with the exterior resin 11 It is. 10b and 10c are joint surfaces to which the cathode portion 8 of the capacitor element 1 is mounted and joined, and the joint surfaces 10b and 10c are portions obtained by bending the both end portions excluding the mounting portion 10a upward in a stepped manner. Two base materials are formed so as to overlap each other by folding back.

  10 d is a wall portion for positioning the cathode portion 8 of the capacitor element 1, 10 e is a shielding portion provided so as to extend obliquely upward from the mounting portion 10 a toward the anode terminal 9, and 10 f is provided at the tip of the shielding portion 10 e. It is a portion that is provided and serves as a joint surface on which the cathode portion 8 of the capacitor element 1 is mounted and joined. 10 g and 10 h are external terminals provided so as to be exposed from the side surface of the exterior resin 11 by bending the end portion vertically, and all except for the external terminals 10 g and 10 h and the mounting portion 10 a are attached to the exterior resin 11. It is covered so that it does not appear on the appearance.

  The capacity of the solid electrolytic capacitor according to the first embodiment thus configured is shown in Table 1 together with the capacity of the conventional product (without the metal oxide layer) as a comparative example, and the capacity of each electrode foil. .

  As is apparent from Table 1, the capacity of the aluminum foil is reduced to 1 of the conventional product by the configuration in which the metal oxide layer of titanium oxide is formed as a thin film on the surface of the dielectric oxide film layer formed on the surface of the aluminum foil. Thus, even in the solid electrolytic capacitor according to the first embodiment using the aluminum foil, the capacity of the product can be greatly improved.

  Further, the above-described structure of the solid electrolytic capacitor has an effect that the ESL can be greatly reduced since the capacitor element 1 can be drawn out from each terminal at the shortest distance. In addition, the anode part 4 and the cathode part 8 of the capacitor element 1 are mounted and joined to each other, and the joining parts of the anode terminal 9 and the cathode terminal 10 are configured so that two substrates overlap each other. Since the distance from the mounting surface of the resin 11 to the substrate, which is the exposed portion, to the capacitor element 1 can be secured within a necessary minimum range, during surface mounting to the substrate, By being exposed to high temperature, the hermeticity of the exterior resin 11 is lowered, and moisture and oxygen can be prevented from entering from the interface between the capacitor element 1 and the terminal and damaging the capacitor element 1, and as a result, It will be able to demonstrate excellent reliability.

(Embodiment 2)
The second aspect of the present invention will be described below with reference to the second to seventh aspects of the present invention.

  FIG. 4 is a partial cross-sectional perspective view showing the configuration of an aluminum electrolytic capacitor as an example of an electrolytic capacitor according to Embodiment 2 of the present invention. In FIG. 4, 19 indicates a capacitor element, and this capacitor element 19 is etched. After the surface is roughened by treatment, a dielectric oxide film layer is formed by anodizing treatment, and a metal oxide layer film is formed as a thin film on the surface of the dielectric oxide film layer (details will be described later) An anode foil 12 made of a foil and a cathode foil 13 obtained by etching at least an aluminum foil are wound with a separator 14 interposed therebetween.

  15a and 15b (not shown) are anode leads and cathode leads for external lead connected to the anode foil 12 and the cathode foil 13, respectively, and 16 is a bottomed housing containing the capacitor element 19 together with a driving electrolyte not shown. A cylindrical aluminum metal case 17, a sealing member 17 having a hole through which the anode lead 15a and the cathode lead 15b are inserted to seal the opening of the metal case 16, and 18 an anode lead 15a and a cathode lead 15b A seat plate made of an insulating resin having a hole to be inserted and mounted on the sealing member 17 side. The anode lead 15a and the cathode lead 15b are bent along a groove provided on the outer surface of the seat plate 18. Thus, a surface mount type aluminum electrolytic capacitor is constructed.

Further, the metal oxide film formed on the surface of the anode foil 12 on which the dielectric oxide film layer is formed is titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) or zircon ammonium fluoride ((NH ₄ ) ₂ ZrF _6. ) It utilizes a reaction such as an aqueous solution, that is, M _a F _b ^c− + dH ₂ O → M _a O _d + bF ⁻ + 2dH generated by the presence of a fluorometal complex compound and / or a metal fluoride in the solution. ⁺ (M is one selected from the group consisting of Ti, Zr, Si, Nb, Ta, Hf, In, Sn, and rare earth elements, a, b, c, and d are coefficients, and ma = bc = 2d, m is the oxidation number of metal M, satisfying the relationship of a> 0, b> 0, c ≧ 0, d> 0), on the aluminum foil on which the dielectric oxide film layer is formed Thin film of titanium oxide, zirconium oxide, etc. It is in that in order to form.

Specifically, 0.04 g of ammonium zircon fluoride ((NH ₄ ) ₂ ZrF ₆ ) was added to 100 ml of pure water, stirred and completely dissolved to obtain an aqueous solution. To this aqueous solution, 0.001 g of boron oxide (B ₂ O ₃ ) was added as a fluoride ion scavenger and completely dissolved. In this aqueous solution, an aluminum foil on which a dielectric oxide film layer was formed by anodic oxidation after etching was immersed and left at 30 ° C. for 2 hours.

  Subsequently, the immersed aluminum foil was taken out and the cross section was observed with a transmission electron microscope. As in the first embodiment, a zirconium oxide film was uniformly formed on the surface of the dielectric oxide film layer. Was confirmed. This is considered to indicate that the fluoride ion scavenger added to the aqueous solution has an effect of uniformly forming a metal oxide film.

  Further, when the capacity of the aluminum foil on which the zirconium oxide film was formed was measured, it was 620 μF, and compared with the capacity of the aluminum foil without any treatment being 390 μF, a capacity nearly 1.6 times greater was obtained. It is what In addition, these capacity | capacitance measurements were measured using the LCR meter in 15 weight% ammonium adipate aqueous solution at room temperature.

The capacity of the aluminum foil is usually inversely proportional to the thickness of the dielectric oxide film layer, but in the second embodiment, zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) increases and the ZrO ₂ film thickness is thick. The capacity increases. This is because the fluoride ions contained in zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) partially dissolve the aluminum oxide film formed on the surface of the aluminum foil. This is because an aluminum oxide film having a thickness of about 9 was replaced with a zirconium oxide film having a relative dielectric constant of about 20 in an amorphous state.

  The capacity of the aluminum electrolytic capacitor according to the second embodiment configured as described above is shown in Table 2 together with the conventional product (without the metal oxide layer) as a comparative example, and the capacity of each electrode foil. .

  As can be seen from Table 2, the capacity of the aluminum foil is reduced to 1 of the conventional product by the structure in which the metal oxide layer of zirconium oxide is formed as a thin film on the surface of the dielectric oxide film layer formed on the surface of the aluminum foil. .6 can be increased, so that even in the aluminum electrolytic capacitor according to the second embodiment using this aluminum foil as an anode foil, the capacity of the product can be greatly improved. It is.

  In the second embodiment, the formation of the metal oxide layer of zirconium oxide has been described by taking an example in which the formation is performed only on the anode foil. However, the present invention is not limited to this, and the present invention is not limited to this. Similarly, a metal oxide layer of zirconium oxide may be formed.

  In the second embodiment, the surface mount type aluminum electrolytic capacitor using the seat plate 18 has been described as an example. However, the present invention is not limited to this, and the seat plate 18 is not provided. A lead-type aluminum electrolytic capacitor may be used.

  Now, the formation of the metal oxide layer described above will be described in further detail.

The electrode foil used for the electrolytic capacitor of the present invention is a fluoro metal complex compound and / or a metal fluoride represented by titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) or zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ). Is obtained by forming a metal oxide layer such as titanium oxide or zirconium oxide on the surface of the dielectric oxide film layer formed on the surface of the valve action metal foil.

  An important point in forming the metal oxide layer is that a valve action metal foil having a dielectric oxide film layer is used. That is, when a valve action metal foil not formed with a dielectric oxide film layer is used, the metal oxide layer referred to in the present invention cannot be formed, and as a result, the effects of the present invention can be achieved. Is extremely difficult.

  Therefore, as described above, when a metal oxide layer of, for example, zirconium oxide is also formed on the cathode foil, a dielectric oxide film layer must be formed on the surface of the cathode foil in advance.

In this embodiment, titanium fluoride ammonium ((NH ₄ ) ₂ TiF ₆ ) and zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) are used as the fluorometal complex compounds. Ti and Zr are more versatile than other valve metals, and both titanium ammonium fluoride ((NH ₄ ) ₂ TiF ₆ ) and zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) are easily available. There are advantages.

In particular, Ti has a high relative dielectric constant compared to other valve metals, so it has a significant effect on capacity increase. When Zr is used, the dielectric film withstand voltage is improved compared to other valve metals. Therefore, it is desirable to use ammonium titanium fluoride ((NH ₄ ) ₂ TiF ₆ ) or zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) as the fluorometal complex compound.

However, the present invention is not limited to this, and other fluoro metal complex compounds can also be used. The same effect can be obtained by using a metal fluoride (for example, titanium fluoride (TiF ₄ )) instead of the fluoro metal complex compound, and the fluoro metal complex compound and the metal fluoride can be used in combination. Is possible.

  As the fluoride ion scavenger, a boron-containing compound can be used. That is, boron can capture fluoride ions and efficiently form a metal oxide layer on the surface of the dielectric oxide film layer. Examples of the boron-containing compound include ammonium borate, boron oxide, and boric acid. These compounds can be used alone or in combination.

  In addition, by adjusting the pH of the solution containing the fluoride ion scavenger, there is an effect that a high capacity electrode foil can be obtained. Here, in particular, by adjusting the pH of the solution to be higher than 7, a higher capacity electrode foil can be obtained. Although this mechanism has not been clarified at the present time, it is presumed that the rapid reaction is suppressed and the formation of a more uniform metal oxide film is promoted.

  As the pH adjuster for adjusting the pH, at least one of ammonia, hydrazine, amines, basic salts, and hydroxides can be used.

  In addition, ammonium borate, boron oxide and boric acid as fluoride ion scavengers can also be used as pH adjusters, and these ammonium borate, boron oxide and boric acid can be used alone or in combination. Is possible. Thus, by using ammonium borate, boron oxide, or boric acid, there is an effect that a high-capacity electrode foil can be obtained.

  In addition, the composition system of the solution can be further simplified by using the one having both functions of the fluoride ion scavenger and the pH adjuster, and as a result, the solution management in the manufacturing process is facilitated.

  Even when ammonium borate, boron oxide, or boric acid is used alone or in combination, at least one of the above pH adjusters, that is, ammonia, hydrazine, amines, basic salts, and hydroxides is used. It can also be used together. As described above, since there are a plurality of pH adjustment methods, the degree of freedom in process design increases.

Moreover, while continuing research, it discovered that the effect of being able to raise the capacity | capacitance of an electrolytic capacitor was exhibited even if the density | concentration of a fluoro metal complex compound and / or a metal fluoride was very low. In other words, even if the metal oxide is formed in an island shape on the surface of the dielectric oxide film, the capacity is improved. Specifically, the preferable adhesion amount of the metal oxide formed on the electrode foil is 10 to 1000 μg / m ² in terms of the effective surface area of the electrode foil. If it is less than 10 μg / m ² , the above-mentioned effects may not be sufficiently exhibited. On the other hand, when it exceeds 1000 μg / m ² , it is often formed on the entire surface instead of islands. By the way, as a method of measuring the amount of metal oxide, ICP is used to measure the amount of titanium oxide formed on the electrode foil, for example, and convert the amount of titanium to titanium oxide to form the electrode foil. The calculated titanium oxide can be calculated.

In order to form the metal oxide in an island shape, for example, the above-described ammonium titanium fluoride ((NH ₄ ) ₂ TiF ₆ ) or zircon ammonium fluoride ((NH ₄ ) ₂ ZrF ₆ ) is used as the fluorometal complex compound. In this case, the concentration may be 0.0005 mol / l or more and less than 0.01 mol / l.

  This is because if it is less than 0.0005 mol / l, the effect of improving the capacity may not be obtained sufficiently.

  On the other hand, the upper limit concentration is preferably less than 0.01 mol / l. This is because islands may not be formed at 0.01 mol / l or more. Moreover, from the complexity of work, less than 0.01 mol / l is preferable. That is, it is necessary to perform heat treatment after forming the metal oxide in order to fix the generated metal oxide to the substrate. Therefore, if the concentration is less than 0.01 mol / l, it may be air-dried, and a heat treatment step is unnecessary, and the equipment for that purpose and the energy required for the heat treatment are unnecessary.

  In addition, by using such a low concentration, the amount of chemicals used can be greatly reduced, and the environmental load during waste liquid treatment can also be reduced.

  The reason why the capacity is improved at such a very low concentration is unclear, but at the present time, it is presumed as follows.

  Fluoride ions dissolve the dielectric oxide film to form a metal oxide. At that time, it is considered that the weak part of the dielectric oxide film is preferentially dissolved. The weak part may be a structural defect or a recess due to a scratch. It is considered that the metal oxide is preferentially formed at the weak spot of the dielectric film by preferential dissolution. That is, it is considered that the weak part is reinforced with the metal oxide, thereby improving the withstand voltage and increasing the capacity at the part.

  As described above, the fluoride ion scavenger is also effective when the metal oxide is formed in an island shape. That is, the fluoride ion scavenger suppresses the dissolution of the dielectric oxide film, so that the weak part of the dielectric film is more preferentially dissolved than the other parts, and the metal oxide formation reaction proceeds more slowly. As a result, the formation state of the metal oxide can be easily controlled, and as a result, the metal oxide can be easily formed in an island shape.

  Moreover, an island-shaped metal oxide can be easily formed by setting the treatment time longer. This is because the longer the processing time, the larger the metal oxides become larger and the smaller ones become smaller and the particles become unevenly distributed, resulting in the formation of more islands. It is done.

As described above, the present invention is caused by the presence of a metal fluoro complex compound and / or metal fluoride in the solution ^{_{M a F b c- + dH 2}} O → M a O d + bF - + 2dH + (M is Ti , Zr, Si, Nb, Ta, Hf, In, Sn, one selected from the group consisting of rare earth elements, a, b, c, d are coefficients, and ma = bc = 2d, m is a metal An electrode formed by forming a metal oxide layer on the surface of the dielectric oxide film layer using the reaction of the oxidation number of M, satisfying the relationship of a> 0, b> 0, c ≧ 0, d> 0) By using the foil, it is possible to increase the capacity as an electrolytic capacitor, and as a result, it is possible to realize a large capacity that has been difficult to realize in the past.

  The electrolytic capacitor according to the present invention has an effect that the capacity can be increased and the capacity can be reduced, and is useful in a field where a reduction in size and capacity of various electronic devices is required.

(A) The top view which showed the structure of the solid electrolytic capacitor as an example of the electrolytic capacitor by Embodiment 1 of this invention, (b) The side sectional drawing, (c) The sectional view in the AA line, (d) ) Sectional view along line BB Partially cutaway perspective view showing the configuration of a capacitor element used in the solid electrolytic capacitor The perspective view which showed the structure of the anode terminal used for the solid electrolytic capacitor, and a cathode terminal The partial cross-section perspective view which showed the structure of the aluminum electrolytic capacitor as an example of the electrolytic capacitor by Embodiment 2 of this invention Sectional drawing which showed the structure of the solid electrolytic capacitor as an example of the conventional electrolytic capacitor Same perspective view Partially cutaway perspective view showing the configuration of a capacitor element used in the solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 19 Capacitor element 2 Anode body 3 Resist part 4 Anode part 5 Cathode formation part 6 Solid electrolyte layer 7 Cathode layer 8 Cathode part 9 Anode terminal 9a Mounting part 9b, 9e Joint surface 9c Wall part 9d Shielding part 9f External terminal 10 Cathode Terminal 11 Exterior resin 12 Anode foil 13 Cathode foil 14 Separator 15a Anode lead 15b Cathode lead 16 Metal case 17 Sealing member 18 Seat plate

Claims (7)

An insulating part is provided at a predetermined position of an anode body made of aluminum foil, and the anode part and the cathode forming part are separated, and a solid electrolyte layer and a cathode layer made of a conductive polymer are sequentially laminated on the cathode forming part. Capacitor element in which a cathode part is formed by the above, an anode part and a cathode terminal joined to the anode part and the cathode part of the capacitor element, and an insulating property covering the capacitor element except for a part of the anode terminal and the cathode terminal In the electrolytic capacitor made of the exterior resin, the anode body is formed by forming a metal oxide layer on the surface of the dielectric oxide film layer formed on the surface of the aluminum foil. ^{_{M a F b c- + dH 2}} O → M a O d + bF caused by the presence of a metal fluoro complex compound and / or metal fluoride in ^{- + 2dH} + (M is Ti, Zr, i, Nb, Ta, Hf, In, Sn, one selected from the group consisting of rare earth elements, a, b, c, d are coefficients, ma = bc = 2d, m is an oxidation of metal M The electrolytic capacitor is formed by using a reaction of the following formula: a> 0, b> 0, c ≧ 0, d> 0. A capacitor element formed by winding an anode foil and a cathode foil made of aluminum foil with a separator interposed therebetween, a bottomed cylindrical metal case containing the capacitor element together with a driving electrolyte, and In an electrolytic capacitor comprising a sealing member sealing an opening of a metal case, at least the anode foil of the electrode foils constituting the capacitor element is formed on the surface of the dielectric oxide film layer formed on the surface of the aluminum foil. A metal oxide layer is formed, and this metal oxide layer is formed by the presence of a fluorometal complex compound and / or a metal fluoride in a solution. M _a F _b ^c− + dH ₂ O → M _a O ^{_{d + bF - + 2dH + (}} M is Ti, Zr, Si, Nb, Ta, Hf, in, Sn, 1 kind selected from the group consisting of rare earth elements, a, b, c, d is And ma = b−c = 2d, where m is the oxidation number of the metal M and satisfies the relationship of a> 0, b> 0, c ≧ 0, d> 0). Electrolytic capacitors that are things. The electrolytic capacitor according to claim 1, wherein the metal oxide layer is formed in an island shape on the surface of the dielectric oxide film layer. The electrolytic capacitor according to any one of claims 1 to 3, wherein the metal oxide layer formed on the surface of the dielectric oxide film layer is formed in the presence of a fluoride ion scavenger in the solution. . The metal oxide layer formed on the surface of the dielectric oxide film layer is formed by the presence of a fluoride ion scavenger and a pH adjuster in the solution. The electrolytic capacitor as described. The electrolytic capacitor according to claim 1, wherein the metal oxide layer is larger than a dielectric constant of the dielectric oxide film layer. The electrolytic capacitor according to claim 1, wherein titanium oxide or zirconium oxide is used as the metal oxide layer.

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