JPH06204097A - Layered solid-state electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a solid-state electrolytic capacitor by using a conductive high-molecular layer excelling in leakage current characteristic, ESR characteristic and impedance characteristic and having a high volume-to-capacitance factor for its solid-state electrolyte. CONSTITUTION:A dielectric oxide film 1 is formed on the surface of an anode plate 1 which comprises a valve action metal foil having four leaves 6, 7, 8, and 9 which are concatenated to an overlapped weld part to which an anode line 10 is fixed, and which protrude approximately perpendicular to the overlapped weld part 5, while mutually maintaining a spacing, in the same direction. Over the dielectric oxide film 1, a conductive high-molecular layer 12 comprising a chemical polymer film and an electrolytic polymer film is formed. A cathode layer 13 which is formed on the external surface of the conductive high- molecular layer 12 is formed to provide an element laminate 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor having a conductive polymer layer as a solid electrolyte and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, as a solid electrolytic capacitor,
A valve metal such as aluminum, tantalum, or niobium is used as an anode body, and an organic semiconductor composed of manganese dioxide or TCNQ complex as a solid electrolyte is formed on the dielectric oxide film formed on the anode body. It is formed by forming a cathode layer on the cathode and plays a part in miniaturization and high performance of the capacitor.

Further, in recent years, solid electrolytic capacitors using a conductive polymer such as polypyrrole, polythiophene and polyfuran as a solid electrolyte have been attracting attention in order to meet further demands for miniaturization and high performance of capacitors.

This conductive polymer has an electric conductivity of about 10
² S / cm and manganese dioxide (10 ^-2 S / cm),
Compared with TCNQ complex (10 S / cm), it is very high and has excellent thermal stability. Therefore, by using this conductive polymer as a solid electrolyte,
It is possible to obtain a solid electrolytic capacitor having excellent electrical characteristics such as impedance frequency characteristics and leakage current characteristics and excellent temperature characteristics in a wide range.

However, as electronic parts have become lighter, thinner, shorter, and smaller,
Even in a solid electrolytic capacitor using a conductive polymer as a solid electrolyte, for the purpose of increasing the capacity per unit volume,
Various techniques for laminating and integrating anode bodies have been proposed. These techniques involve connecting an anode wire to a pre-roughened anode substrate, and then forming a dielectric oxide film layer and a solid layer on the anode substrate. A laminate is formed by laminating a plurality of capacitor base plates on which a conductive polymer layer as an electrolyte and a cathode layer are sequentially formed.

[0006]

However, since the above technique is a technique for laminating and integrating the anode substrate having the conductive polymer layer formed thereon, the dielectric oxide film and the conductive polymer are formed in the integration process. Layer, it is not possible to prevent the mechanical stress to the part where the cathode layer is formed, the conductive polymer layer, the cathode layer as well as damage to the anodic oxide film, the conductive polymer as a solid electrolyte film Since it has no repair ability, it has a drawback of degrading leakage current characteristics, ESR characteristics, and impedance characteristics.

The present invention has been made to solve the above problems, and its object is to provide a laminated solid electrolytic capacitor having stable electric characteristics such as leakage current, ESR, and impedance, and a method for manufacturing the same. It is a thing.

[0008]

SUMMARY OF THE INVENTION A laminated solid electrolytic capacitor according to the present invention has a fold-weld portion in which an anode wire is fixed at an arbitrary position, and is connected to the fold-welded portion and is substantially connected to the fold-welded portion. An anode base made of a valve metal foil having at least four pieces vertically and spaced from each other and protruding in the same direction, a dielectric oxide film formed on the surface of the anode base, and this dielectric oxidation. It is characterized by comprising a conductive polymer layer composed of a chemically polymerized film and an electrolytic polymerized film formed on the film, and a cathode layer formed on the outer surface of the conductive polymer layer.

Further, the method of manufacturing a laminated solid electrolytic capacitor according to the present invention includes at least one valve-action metal foil.
Cut from both ends toward the center without dividing into the same length, fold along the line connecting the cuts, and weld the fold center to form the fold weld. Each piece constituting both ends of the lap weld is projected perpendicularly to the fold weld with mutual spacing and protruding in the same direction, and an anode wire is fixed at an arbitrary position of the fold weld to form an anode. A step of forming a substrate, a step of forming a dielectric oxide film on the one part, a chemical oxidation polymerization means is formed on the dielectric oxide film to form a chemical polymerization film, and then an electrolytic oxidation polymerization means is formed. Take the steps of sequentially forming an electrolytically polymerized film to form a conductive polymer layer composed of a chemically polymerized film and an electrolytically polymerized film, and a step of forming a cathode layer on the outer surface of the conductive polymer layer. It is a feature.

[0010]

According to this structure, the anode wire is fixed to the anode base at one place and only one anode wire is required, and unlike the prior art, a plurality of anode wires are not welded. Deterioration factors are eliminated, and the dielectric oxide film can be repaired by performing re-formation after forming the anode substrate, and since mechanical stress is not applied to the anode substrate, the leakage current characteristic deterioration factor is eliminated. Further, since the cathode layer is not formed between the respective ones of the laminated structure, the distance between the respective ones can be made as small as possible, which greatly contributes to reduction in size and weight.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2 (A), a sheet of valve metal foil 2 having a dielectric oxide film 1 formed by applying a voltage in, for example, an aqueous solution of ammonium adipate after roughening the surface by using known means. Put the cuts 3 and 4 without dividing into the same length from the both ends of the substantially central part toward the center, and fold along the line connecting the cuts 3 and 4 as shown in FIG. 2B. In addition, the folding center portion is welded to form the folding welding portion 5, and each of the piece portions 6, which constitutes both ends of the folding welding portion 5,
Anode wires 10 are fixed to arbitrary portions of the fold-weld portion 5 by projecting 7, 8 and 9 in the same direction with a space therebetween, which is substantially perpendicular to the fold-welded portion 5, and an anode substrate 11 is formed. To form.

Next, re-formation is performed to repair the damage of the dielectric oxide film 1 generated in the process of forming the anode substrate 11, and then, as shown in FIG. After being immersed in a pyrrole / ethanol solution for 5 minutes, it was further immersed in a 0.5M-ammonium persulfate aqueous solution.
Dipping for 1 minute, chemical oxidation polymerization, dielectric oxide film 1
A chemically polymerized film made of polypyrrole is formed on the above, and thereafter, for example, in an electrolytic oxidative polymerization solution containing 0.05 mol / liter of alkylnaphthalene sulfonate and 0.2 mol / liter of pyrrole monomer as a supporting electrolyte, The chemically polymerized film formed by the treatment is used as an anode, and constant current electrolytic oxidation polymerization (1 mA / cm ² , 1
Time) to form an electrolytically polymerized film of polypyrrole. That is, by these treatments, a conductive polymer layer 12 composed of a chemically polymerized film and an electrolytic polymerized film is formed on the dielectric oxide film 1 of the anode substrate 11, and the conductive polymer layer 1 is formed.
A graphite layer and a silver paste layer are sequentially formed on the outer surface of No. 2 for drawing out a cathode to form a cathode layer 13 and an element stack 14.

Then, as shown in FIG. 3, a cathode electrode terminal 15 is connected to the cathode layer 13 of the element laminate 14 and an anode electrode terminal 16 is connected to the anode wire 10, and then, as shown in FIG. As shown, for example, transfer molding is applied to the resin exterior 17 to form the capacitor body 18, and the cathode electrode terminal 15 and the anode electrode terminal 16 led out from the side surface of the capacitor body 18 are connected to the capacitor body 1
The finished product is formed by bending along the eight side surfaces to reach the bottom surface of the capacitor body 18.

According to the laminated solid electrolytic capacitor having the above-mentioned structure, the element laminated body 14 is formed by one piece of the valve metal foil 2, and the anode wire 10 is fixed to the anode base 11. However, since only one anode wire 10 is required at one place of the lap welding portion 5, welding for integrating a plurality of anode wires as in the prior art is not necessary, and the factor of impedance characteristic deterioration is eliminated.

Further, the dielectric oxide film can be repaired by performing re-formation after the element laminate 14 is formed, and mechanical stress is not applied thereafter, so that the dielectric oxide film is not destroyed and the leakage current characteristic is eliminated. The deterioration factor is eliminated.

Further, the cathode layer 13 is formed on the outer surface of the conductive polymer layer 12 after the element laminate 14 is formed,
Since the cathode layer 13 is not formed between the respective piece portions 6, 7, 8, 9 having a laminated structure, the space between the respective piece portions 6, 7, 8, 9 can be made as narrow as possible, and the cathode layer can be formed as in the prior art. There is no extra cathode layer portion as compared with the case of stacking after formation, and the volume capacity ratio is excellent.

Next, a characteristic comparison between the embodiment according to the present invention and the prior art will be described.

(Example) After roughening by etching, a 6 mm × 7 mm aluminum foil on which a dielectric oxide film has been formed by chemical conversion treatment in an aqueous solution of ammonium adipate is used. An anode wire is fixed to a portion to form an anode substrate, and thereafter, re-formation is performed, and a conductive polymer layer is formed on the dielectric oxide film by the above-mentioned means. An element laminate obtained by forming a cathode layer by sequentially forming a graphite layer and a silver paste layer for drawing out the cathode on the surface, the cathode layer being a conductive adhesive or soldering, and the anode wire being electrically welded. Then, the laminated solid electrolytic capacitor having the chip structure manufactured by the above-mentioned means after being connected to the respective terminals.

(Conventional example) After roughening by etching, an aluminum foil on which a dielectric oxide film was formed by chemical conversion treatment in an aqueous solution of ammonium adipate was used, and it was divided into an anode side and a cathode side with an insulating resin to form a cathode. Side effective area 3mm
A conductive polymer layer is formed on the cathode side of an anode substrate having a size of 3 mm by the same method as that of the present invention, and a graphite layer and a silver paste layer are sequentially formed on the conductive polymer layer. The element layer is formed by stacking 4 capacitor base plates with the cathode layer formed on the anode side and the cathode side in correspondence with each other, fixing the cathode layer with a silver adhesive interposed, and integrating the anode side by electric welding. A laminated solid electrolytic capacitor having a chip structure manufactured by forming a body and then performing the same means as in the above-mentioned embodiment.

When the initial characteristics of the above-mentioned embodiment and the conventional example were examined, the results shown in Table 1 below were obtained. In this Table 1, the numerical value in the upper row of each column shows the average value, and the numerical value in the lower row shows the distribution range, and ESR is the frequency 1
It is a resistance value at 00 kHz.

Further, when the frequency-impedance characteristics of each of them were examined, the results shown in FIG. 5 were obtained.

The sample is rated 1 in both the embodiment and the conventional example.
It is 0V-4.7 μF, and the quantity is 100 pieces each.

[0024]

[Table 1]

As is clear from Table 1 and FIG. 5, the conventional example shows deterioration in leakage current characteristics, ESR characteristics, and impedance characteristics. The reason for this is that mechanical properties when laminating the capacitor base plates are laminated. The stress causes cracks in the cathode layer and the conductive polymer layer, and the resistance value increases as a whole in this portion.At this time, cracks in the cathode layer and the conductive polymer layer do not stop and the anodized film is formed. Damage occurs,
It is considered to lead to an increase in leakage current.

On the other hand, in the examples, no cracks are generated in the cathode layer and the conductive polymer layer due to mechanical stress, and, of course, the cause of damage to the anodic oxide film is eliminated and all the characteristics are stable. And demonstrated the excellent effect of the present invention in a laminated solid electrolytic capacitor having a chip structure in which a conductive polymer layer of this kind is used as a solid electrolyte.

In the above embodiments, the cuts on the valve metal foil are linearly provided and four pieces are laminated, but the present invention is not limited to this. Needless to say, it is also possible to provide two or more straight cuts and to make the number of one side more than that in the above-mentioned embodiment.

As the valve action metal foil, tantalum, titanium, niobium or the like can be used in addition to aluminum.

In the above-mentioned embodiment, a laminated solid electrolytic capacitor having a chip structure is exemplified. However, for example, a tin-plated CP wire is used as an external terminal, and a lead wire structure is formed by applying an exterior by a fluid immersion method or a dip method. It is also possible to

Further, the specific method of forming the conductive polymer layer and the cathode layer can be freely selected. Further, the present invention is applicable not only to the above ratings but also to various types of laminated solid electrolytic capacitors having various ratings, and excellent effects can be obtained.

[0031]

As described above, according to the present invention, 1
It is possible to form a laminated structure from a single piece of valve action foil, and therefore leakage current characteristics, ESR characteristics and impedance characteristics are significantly improved, and a laminated solid electrolytic capacitor having a large volume capacitance ratio and high practical value, and the same. A manufacturing method can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an element laminated body according to an embodiment of the present invention.

2A and 2B show a manufacturing process of an anode substrate according to an embodiment of the present invention, FIG. 2A is a plan view of a valve action metal foil, and FIG. 2B is a perspective view of the anode substrate.

FIG. 3 is a cross-sectional view showing a state in which electrode terminals are connected to the element stack body according to the embodiment of the present invention.

FIG. 4 is a front view showing a laminated solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 5 is a frequency-impedance characteristic curve diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric oxide film 2 Valve metal foil 3 Cut 4 Cut 5 Folded welded portion 6 Single piece 7 Single piece 8 Single piece 9 Single piece 10 Anode wire 11 Anode base 12 Conductive polymer layer 13 Cathode layer 14 Element laminate

Claims (2)

[Claims] 1. A fold-welded portion in which an anode wire is fixed at an arbitrary position, and a fold-welded portion which is connected to the fold-welded portion and which is substantially perpendicular to the fold-welded portion and has a space therebetween and projects in the same direction. From an anode substrate made of a valve action metal foil having at least four pieces, a dielectric oxide film formed on the surface of the anode substrate, and a chemical polymerization film and an electrolytic polymerization film formed on the dielectric oxide film. And a cathode layer formed on the outer surface of the conductive polymer layer. 2. A valve-acting metal foil, at least at one location, is cut from both ends toward the center without being divided into the same length and is folded along a line connecting the cuts.
In addition, the fold center is welded to form the fold weld,
Each piece constituting the both ends of the fold-welded portion is projected in the same direction with a space therebetween substantially perpendicular to the fold-welded portion, and an anode wire is fixed to any portion of the fold-welded portion. Forming a positive electrode substrate, a step of forming a dielectric oxide film on the one part, a chemical oxidation polymerization means is formed on the dielectric oxide film to form a chemical polymerization film, and thereafter,
A step of forming an electrolytic polymerization film by taking electrolytic oxidation polymerization means to form a conductive polymer layer composed of a chemical polymerization film and an electrolytic polymerization film, and forming a cathode layer on the outer surface of the conductive polymer layer. A method of manufacturing a laminated solid electrolytic capacitor, which comprises sequentially performing steps.