JPH06232012A - Laminated solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a solid electrolytic capacitor which has an excellent leakage current, ESR, and impedance characteristics and uses a conductive high polymer layer having a large volume-capacitance ratio as a solid electrolyte. CONSTITUTION:An element-laminated body 22 is manufactured by forming a conductive high polymer layer 20 composed of a chemically polymerized film and electrolytically polymerized film on a dielectric oxide film 1 which is formed by working metallic foil exerting a valve action equipped with six piece sections 12, 13, 14, 15, 16, and 17 connected to a zigzag weld uniting section 11 firmly fixed with an anode line 18 and protruded in the same direction nearly perpendicular to the section 11 at intervals and constitutes the surface of an anode base body and a cathode layer 21 on the external surface of the high polymer layer 20.

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,
Aluminum, tantalum, valve metal such as niobium is used as the anode body, and on the dielectric oxide film formed on this anode body,
Manganese dioxide as a solid electrolyte, for example, 7.7.
8.8. — An organic semiconductor composed of a TCNQ complex of tetracyanoquinodimethane is formed, and a cathode layer is formed on these solid electrolytes, which contributes to miniaturization and high performance of capacitors.

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 stacking and integrating anode bodies have been proposed.

[0006] That is, it is conceivable that the anode bodies that require lamination are laminated in advance and then the conductive polymer layer is formed, but in the case of such a technique, three or more layers of valve action metal foil are formed. It is impossible to perform batch welding, and the number of layers is limited to two.

Therefore, in the case of a laminated structure of three or more layers, an anode wire is connected to an anode substrate which has been roughened in advance, and then a dielectric oxide film layer on the anode substrate and conductivity as a solid electrolyte. A multilayer structure is formed by laminating a plurality of capacitor substrates in which a polymer layer and a cathode layer are sequentially formed.The dielectric oxide film, the conductive polymer layer, and the portion where the cathode layer is formed are formed in the lamination process. Mechanical stress cannot be prevented, and not only the conductive polymer layer and the cathode layer are cracked, but also the anodic oxide film is damaged, but the conductive polymer as a solid electrolyte has no film repairing ability, so the leakage current characteristics , ESR characteristics and impedance characteristics were deteriorated.

[0008]

In the prior art having the above-mentioned structure, two layers are the limit for a multilayer structure having good leakage current characteristics, ESR characteristics, and impedance characteristics, and further increase in capacity per unit volume is required. If this is to be achieved, a conductive polymer layer must be formed in advance, and the capacitor boards must be laminated and integrated, and to the part where the dielectric oxide film, conductive polymer layer, and cathode layer were formed during the integration process of the capacitor boards. Cannot prevent the mechanical stress of the conductive polymer layer,
Since the anodic oxide film is damaged not only by the cracks on the cathode layer but the conductive polymer as a solid electrolyte has no film repair ability, it has a drawback that the leakage current characteristic, ESR characteristic and impedance characteristic are deteriorated.

The present invention was made to solve the above problems, and its purpose is to provide a laminated solid having a laminated structure of three or more layers with stable electric characteristics such as leakage current, ESR, and impedance. An electrolytic capacitor and a method for manufacturing the same are provided.

[0010]

SUMMARY OF THE INVENTION A laminated solid electrolytic capacitor according to the present invention comprises a zigzag-welding integrated portion of at least three sides, in which overlapping surfaces having anode wires fixed to each other are welded together, and the zigzag-folding integrated part. An anode base made of a valve action metal foil that protrudes in the same direction at a distance from each other, and each piece forming each end of each side of the oxidization portion is substantially perpendicular to the above-described folded and welded integrated portion, and this anode Dielectric oxide film formed on substrate surface, conductive polymer layer consisting of chemical polymerization film and electrolytic polymerization film formed on this dielectric oxide film, and formed on outer surface of this conductive polymer layer It is characterized in that it is composed of a cathode layer.

Further, in the method for manufacturing a laminated solid electrolytic capacitor according to the present invention, at least two locations of one valve metal foil are cut from both ends toward the center without being divided into the same length, and the cut is made. Fold along the line connecting the two parts, and weld the zigzag folded surfaces together to form a three-sided zigzag-weld integrated part, and form a zigzag-weld integrated part. Part of the zigzag-welding-integrated part and fixing the anode wire to an arbitrary part of the zigzag-welding integrated part so as to form an anode substrate, and the dielectric part is formed on the one part. The process of forming a body oxide film, and the chemical oxidation polymerization means is formed on this dielectric oxide film to form a chemically polymerized film. Heavy Forming a conductive polymer layer formed of film, and is characterized in successively undergoes that the step of forming a cathode layer on the outer surface on the conductive polymer layer.

[0012]

According to this structure, since the zigzag-welding integrated portion is formed by welding the zigzag folded surfaces together, a multi-layered structure having three or more layers can be easily obtained, and the anode base body can be easily obtained. The anode wire is fixed at one place with respect to, and only one anode wire is required, and since there is no need to weld a plurality of anode wires as in the prior art, it contributes to the improvement of impedance characteristics, and after forming the anode substrate, By performing re-formation, the dielectric oxide film can be repaired, and since mechanical stress is not applied to the anode substrate after that, it contributes to the improvement of leakage current characteristics, and furthermore, a cathode layer is provided between each part of the laminated structure. Since it is a structure that is not formed, the space between each piece can be made as narrow as possible, which greatly contributes to the reduction in size and weight.

[0013]

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

As shown in FIGS. 2 (A) and 2 (a), after a known means is used to roughen the surface, a voltage is applied in, for example, an aqueous solution of ammonium adipate to form a dielectric oxide film 1, which is a valve action. Cut the metal foil 2 from two ends toward the center to the same length, and make cuts 3, 4, 5, 6 without being divided,
In addition, a welding hole 10 is provided on one side 7 of the sides 7, 8, 9 divided by the cut lines 3, 4, 5, 6.
As shown in (B) and (b), the side 7 is bent along the line connecting the cuts 3 and 4, the side 8 and the side 7 are folded and welded together, and then, as shown in FIG. As shown in c), the side 9 is bent along a line connecting the cuts 5 and 6 in a direction opposite to the folding direction of the side 7, and the side 9 and the side 8 are overlapped and the side 9 is passed through the welding hole 10. And the side 8 are welded together to form the fold-welding integrated portion 11 which is formed by joining the sides 7, 8 and 9, and then, as shown in FIG.
Each piece 12, 13, 14, 15, 1 that constitutes one end
6 and 17 are protruded in the same direction at intervals substantially perpendicular to the zigzag fold-welding integrated part 11, and the anode wire 18 is fixed to an arbitrary part of the zigzag fold-welding integrated part 11 to form an anode substrate 19. To form.

Next, re-formation is carried out in order to repair the damage of the dielectric oxide film 1 generated in the process of forming the anode substrate 19, and 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 20 composed of a chemically polymerized film and an electrolytic polymerized film is formed on the dielectric oxide film 1 of the anode substrate 19, and the conductive polymer layer 2 is formed.
On the outer surface of No. 0, a cathode layer 21 is formed by sequentially forming a graphite layer and a silver paste layer for drawing out a cathode, thereby forming an element stack 22.

As shown in FIG. 4, the cathode layer 21 of the element laminate 22 is connected to the cathode electrode terminal 23, and the anode wire 18 is connected to the anode electrode terminal 24. After that, as shown in FIG. As shown, for example, transfer molding is used to form a resin body 25 to form a capacitor body 26, and the cathode electrode terminal 23 and the anode electrode terminal 24 led out from the side surface of the capacitor body 26 are connected to the capacitor body 2.
The finished product is formed by bending along the six side surfaces to reach the bottom surface of the capacitor body 26.

According to the laminated solid electrolytic capacitor having the above-mentioned structure, the element laminated body 22 is formed by one piece of the valve action metal foil 2, and the zigzag folded and welded integrated portion 11 and the side 8 are formed. Side 7 is folded and welded together, side 9
Along the line connecting the cuts 5 and 6 in the direction opposite to the folding direction of the side 7, fold the side 9 and the side 8 and weld the side 9 and the side 8 through the welding hole 10 to form a zigzag folded surface. Since it is formed by welding,
A multilayer structure of three or more layers can be easily obtained, and the anode wire 18 can be fixed to the anode substrate 19 only at one place of the zigzag-welded integrated portion 11 so that only one anode wire 18 is required. As described above, there is no welding for integrating a plurality of anode wires, and the factor of impedance characteristic deterioration is eliminated.

Further, the dielectric oxide film 1 can be repaired by re-forming after the formation of the element laminate 22, and no mechanical stress is applied thereafter, so that the dielectric oxide film 1 is not destroyed and leaks. The cause of current characteristic deterioration is eliminated.

Further, the cathode layer 21 is formed on the outer surface of the conductive polymer layer 20 after the element laminate 22 is formed.
Each piece 12, 13, 14, 15, 16, which has a laminated structure,
Since the cathode layer 21 is not formed between the layers 17, the space between the individual pieces 12, 13, 14, 15, 16, 17 can be made as small as possible, which is extra compared to the prior art in which the cathode layers are laminated. There is no cathode layer portion 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 the surface was roughened by etching, a zigzag fold welding integrated portion formed by the above-mentioned means was used by using a 6 mm × 7 mm aluminum foil having a dielectric oxide film formed by chemical conversion treatment in an aqueous solution of ammonium adipate. An anode wire having a diameter of 0.2 mm is ultrasonically fixed to an arbitrary portion of the above to form an anode base having six layers on one side, and then re-formation is performed, and the dielectric oxide film is formed by the above-mentioned means. An element laminate obtained by forming a conductive polymer layer on the conductive polymer layer, and forming a cathode layer by sequentially forming a graphite layer and a silver paste layer on the outer surface of the conductive polymer layer for drawing out a cathode. , The cathode layer is a conductive adhesive or soldering,
After connecting the anode wire to each terminal by electric welding,
A laminated solid electrolytic capacitor having a chip structure manufactured by the above-mentioned means.

(Conventional example) After roughening by etching, an aluminum foil on which a dielectric oxide film has been formed by chemical conversion treatment in an aqueous solution of ammonium adipate is used, and is 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 6 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. 6 were obtained.

The sample is rated 1 in both the embodiment and the conventional example.
It is 0V-6.8 μF, and the quantity is 100 pieces each.

[0026]

[Table 1]

As is clear from Table 1 and FIG. 6, the conventional example shows deterioration of the leakage current characteristic, ESR characteristic, and impedance characteristic, which is because of the mechanical effect when laminating the capacitor base plates. 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, cracks did not occur 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 was eliminated, and all characteristics were stable. The state was demonstrated, and the excellent effect of the present invention was demonstrated in a laminated solid electrolytic capacitor having a chip structure in which this kind of conductive polymer layer was used as a solid electrolyte.

Although not specifically shown here,
Compared with the conventional example in which the conductive polymer layer and the cathode layer are formed on the aluminum foil are laminated, the example is one in which the conductive polymer layer and the cathode layer are formed after lamination, so that the cathode layer Can be kept to the minimum necessary and the size can be greatly reduced with the same rating, and it is possible to meet the recent demand for light, thin, short and small products.

In the above-mentioned embodiment, the structure in which the cuts on the valve action metal foil are provided in two straight lines and six pieces are laminated is explained, but the invention is not limited to this. Rather than making more cuts than the number of the folded and welded integrated part, the welding holes necessary for welding the overlapping surfaces are provided at any place that is the folded and welded integrated part. Needless to say, the number may be eight or more.

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

In the above-mentioned embodiment, the laminated solid electrolytic capacitor having a chip structure is illustrated. 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, for example, 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.

[0034]

As described above, according to the present invention, it is possible to form a laminated structure from a single piece of valve action metal foil, and therefore leakage current characteristics, ESR characteristics and impedance characteristics are remarkably improved. Further, it is possible to obtain a laminated solid electrolytic capacitor having a large volume capacity ratio and a high practical value, and a method for manufacturing the same.

[Brief description of drawings]

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

FIG. 2 is an explanatory view showing a manufacturing process of an anode substrate according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an anode substrate according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state in which electrode terminals are connected to the element laminate according to the embodiment of the present invention.

FIG. 5 is a front view showing a laminated solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 6 is a frequency-impedance characteristic curve diagram.

[Explanation of symbols]

 1 Dielectric oxide film 2 Valve metal foil 3, 4, 5, 6 Cuts 7, 8, 9 Sides 10 Weld holes 11 Spiral-welding integrated part 12, 13, 14, 15, 16, 17 One part 18 Anode wire 19 Anode base 20 Conductive polymer layer 21 Cathode layer 22 Element laminate 23 Cathode electrode terminal 24 Anode electrode terminal 25 Resin exterior 26 Capacitor body

Claims (2)

[Claims] 1. A zigzag fold-welding integrated portion of at least three sides in which lapped surfaces having anode wires fixed to each other are welded to each other, and each zigzag fold of the zigzag fold-welding integral part on each side. An anode base made of a valve action metal foil which is substantially perpendicular to the welded integrated portion and which is spaced apart from each other and protrudes in the same direction, a dielectric oxide film formed on the surface of the anode base, and this dielectric. A conductive polymer layer formed of a chemical polymerization film and an electrolytic polymerization film formed on the oxide film,
A laminated solid electrolytic capacitor comprising a cathode layer formed on the outer surface of the conductive polymer layer. 2. A valve-action metal foil is cut at least at two locations from both ends toward the center without being divided into the same length, and is folded along the line connecting the cuts, and is folded over. The surfaces are welded together to form a three-sided zigzag fold-weld integrated part, and the pieces forming the two ends of each zigzag fold-weld integrated part are spaced approximately perpendicular to the zigzag fold-weld integrated part. A step of projecting in the same direction and fixing an anode wire to an arbitrary portion of the above-mentioned zigzag-welding integrated portion to form an anode substrate; a step of forming a dielectric oxide film on the one portion; A step of forming a chemically polymerized film by taking a chemical oxidative polymerization means on the film, and then forming an electropolymerized film by taking an electrolytic oxidative polymerization means to form a conductive polymer layer consisting of the chemical polymerized film and the electrolytic polymerized film. And this high conductivity A method for manufacturing a laminated solid electrolytic capacitor, which comprises sequentially forming a cathode layer on an outer surface of a molecular layer.