JP2014192231A - Method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solid electrolytic capacitor capable of obtaining a solid electrolytic capacitor with low leakage current and ESR, and downsizing a device.SOLUTION: A method for manufacturing a solid electrolytic capacitor 1 comprises the steps of: forming a dielectric coating layer 13 on a surface of an anode body 12 made of valve action metal; forming a conductive precoat layer 14 on the dielectric coating layer 13; and immersing an element intermediate 20 in which the precoat layer 14 is formed in an electrolytic polymerization solution H, feeding power from a feeding point 32a in contact with or adjacent to an external electrode 32 to the element intermediate 20, and forming a conductive polymer layer 15 on the precoat layer 14 by electrolytic polymerization (electrolytic polymerization step). The feeding point 32a is provided on an edge line 20d between two adjacent surfaces of the element intermediate 20.

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor in which a conductive polymer layer is formed using electrolytic polymerization.

  A conventional solid electrolytic capacitor is disclosed in Patent Document 1. This solid electrolytic capacitor has a capacitor element covered with an exterior material. The capacitor element is formed by laminating a dielectric coating layer, a precoat layer, and a conductive polymer layer on the surface of the anode body.

  The anode body is formed of a sintered body of valve action metal such as tantalum. The dielectric coating layer is formed by anodizing a porous anode body made of a sintered body. The precoat layer is made of conductive polypyrrole or the like, and is formed by chemical polymerization in which a monomer such as a precursor pyrrole and an oxidizing agent are reacted.

  The conductive polymer layer is made of polypyrrole or the like and is formed by electrolytic polymerization. That is, the element intermediate on which the precoat layer is formed is immersed in an electrolytic polymerization solution, and an external electrode is brought into contact with the peripheral surface of the element intermediate. Then, power is supplied to the element intermediate using the contact region of the external electrode as a feeding point, and a conductive polymer layer is formed on the precoat layer.

  Since the anode body is formed of a valve action metal sintered body and the cathode is formed of a conductive polymer layer, a solid electrolytic capacitor having a small size, a large capacity, and a low ESR (equivalent series resistance) can be obtained.

  Moreover, since the conductive polymer layer is formed by electrolytic polymerization, the mechanical strength and electrical conductivity are high and leakage current and ESR can be further reduced as compared with the case of forming by chemical polymerization. At this time, since a conductive polymer layer cannot be directly formed on the dielectric coating layer by electrolytic polymerization, a conductive precoat layer is formed to enable electrolytic polymerization. The precoat layer may be formed of manganese dioxide as disclosed in Patent Document 2.

  When the external electrode is buried in the conductive polymer layer formed on the surface of the element intermediate, the conductive polymer layer and the precoat layer are lost when the external electrode is removed. As a result, the dielectric film layer fixed to the precoat layer may be damaged or a thin portion may be formed in the conductive polymer layer. For this reason, the yield of a solid electrolytic capacitor falls due to an increase in leakage current or a short circuit.

  In order to solve this problem, in Patent Document 1, the feeding point is varied when feeding power to the element intermediate through the external electrode. That is, a pair of external electrodes are provided with the element intermediate body interposed therebetween, and can be moved horizontally. The pair of external electrodes alternately supply power by contacting the opposing side surfaces of the element intermediate body. In another embodiment of Patent Document 1, the external electrode is movable in the vertical direction from the lower part to the upper part along the side surface of the element intermediate body during power feeding. As a result, the external electrode can be prevented from being buried.

Japanese Patent Laid-Open No. 11-283878 (pages 3 to 4, FIGS. 1 and 3) JP-A-2-219211 (pages 4-5, FIG. 2)

  However, according to the method for manufacturing a solid electrolytic capacitor disclosed in Patent Document 1, the pair of external electrodes that sandwich the element intermediate body move horizontally. The external electrode moves in the vertical direction over a long distance from the lower part to the upper part of the element intermediate. For this reason, there existed a problem that the apparatus which forms a conductive polymer layer by electrolytic polymerization enlarged.

  An object of the present invention is to provide a method of manufacturing a solid electrolytic capacitor that can obtain a solid electrolytic capacitor having a small leakage current and ESR, and that can reduce the size of the device.

  In order to achieve the above object, the present invention provides a dielectric coating layer forming step of forming a dielectric coating layer on the surface of an anode body made of a valve metal, and forming a conductive precoat layer on the dielectric coating layer. A precoat layer forming step, and an element intermediate on which the precoat layer is formed is immersed in an electrolytic polymerization solution, and an electric power is supplied from a feeding point where an external electrode is in contact with or close to the element intermediate. In the method of manufacturing a solid electrolytic capacitor comprising an electropolymerization step of forming a conductive polymer layer on the element, the feeding point is provided on a ridge line between two adjacent surfaces of the element intermediate.

  According to this configuration, in the dielectric film layer forming step, a dielectric film layer such as an oxide film is formed on the surface of the anode body made of a valve metal such as tantalum. Next, in the precoat layer forming step, a conductive precoat layer is formed on the surface of the dielectric film layer. Next, in the electrolytic polymerization step, a conductive polymer layer is formed on the precoat layer. At this time, the element intermediate on which the precoat layer is formed is immersed in the electrolytic polymerization solution, and a feeding point where the external electrode is in contact with or close to the ridge line between two adjacent surfaces of the element intermediate is provided. The element intermediate is fed from a feeding point, and a conductive polymer layer is formed by electrolytic polymerization.

  In the method for manufacturing a solid electrolytic capacitor having the above configuration, the present invention includes a vertical portion in which the external electrode extends in the vertical direction, and a bent portion that is bent at the lower end of the vertical portion and is disposed on the ridgeline. A plurality of the element intermediates are arranged in parallel and immersed in the electrolytic polymerization solution.

  According to the present invention, in the method of manufacturing a solid electrolytic capacitor having the above-described configuration, the external electrode is retracted from the ridge line every predetermined time in the electrolytic polymerization step.

  According to the present invention, in the method for manufacturing a solid electrolytic capacitor having the above-described configuration, the feeding point is formed on a peripheral edge of the lower surface of the element intermediate body immersed in the electrolytic polymerization solution or on a lower end of the side surface.

  According to the present invention, in the method for producing a solid electrolytic capacitor having the above-described configuration, the precoat layer is manganese dioxide or a conductive polymer formed by chemical polymerization.

  According to the present invention, since the feeding point of the external electrode is provided on the ridge line between two adjacent surfaces of the element intermediate in the electrolytic polymerization process, damage to the dielectric oxide film is reduced and the conductive polymer layer is made uniform. It can be formed to a thickness. Therefore, a solid electrolytic capacitor with low leakage current and ESR and high yield can be obtained. Further, since the feeding point of the external electrode is not changed, the apparatus for the electrolytic polymerization process can be downsized.

Side surface sectional drawing which shows the solid electrolytic capacitor of 1st Embodiment of this invention Process drawing which shows the manufacturing process of the solid electrolytic capacitor of 1st Embodiment of this invention The front view which shows the outline of the electrolytic polymerization process of the solid electrolytic capacitor of 1st Embodiment of this invention The perspective view which shows the outline of the electrolytic polymerization process of the solid electrolytic capacitor of 1st Embodiment of this invention The front view which shows the outline of the electrolytic polymerization process of the solid electrolytic capacitor of 2nd Embodiment of this invention The perspective view which shows the outline of the electropolymerization process of the solid electrolytic capacitor of 2nd Embodiment of this invention The perspective view which shows the outline of the electropolymerization process of the solid electrolytic capacitor of a comparative example

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the solid electrolytic capacitor of the first embodiment. The solid electrolytic capacitor 1 has a capacitor element 10 covered with an exterior material 3 such as an epoxy resin. Lead frames 11 and 18 are connected to the capacitor element 10, and a part of the lead frames 11 and 18 is exposed from the exterior material 3.

  Capacitor element 10 is formed by laminating dielectric film layer 13, precoat layer 14, conductive polymer layer 15, carbon layer 16, and silver coating layer 17 on the surface of anode body 12. An anode lead wire 12a is implanted at one end of the anode body 12, and one end of the lead frame 11 forming the anode terminal is welded to the anode lead wire 12a. The lead frame 18 forming the cathode terminal is adhered to the surface of the silver coating layer 17 through an adhesive such as a conductive resin paste.

  FIG. 2 is a process diagram showing the manufacturing process of the solid electrolytic capacitor. The anode body 12 is made of a valve metal such as tantalum, niobium, or aluminum. In the sintering process, a metal or oxide powder having a valve action is formed and vacuum sintered at high temperature. Thereby, a rectangular parallelepiped porous anode body 12 is formed. The anode body 12 may be formed in another polygonal column shape or a cylindrical shape.

  In addition, an anode lead wire 12 a is implanted at one end of the anode body 12 when the anode body 12 is formed. The anode lead wire 12a is generally formed of the same material as the anode body 12. The anode lead wire 12a may be electrically welded to the end surface of the sintered anode body 12.

  Next, in the dielectric film forming step, the porous anode body 12 is anodized (formed). Thereby, the dielectric film layer 13 made of an oxide film is formed on the entire surface up to the inside of the anode body 12.

  Next, in the precoat layer forming step, a conductor precoat layer 14 is formed up to the inside of the anode body 12 so as to cover the entire surface of the dielectric coating layer 13. The precoat layer 14 is made of a conductive polymer formed by manganese dioxide or chemical polymerization.

  The precoat layer 14 made of manganese dioxide is obtained by immersing the anode body 12 on which the dielectric film layer 13 is formed in an aqueous manganese nitrate solution, and then thermally decomposing it at 200 to 400 ° C.

  The precoat layer 14 made of a conductive polymer can be obtained by reacting a precursor monomer with an oxidizing agent. As the monomer, pyrrole, thiophene, aniline, or a derivative thereof is used. As the oxidizing agent, ammonium persulfate, ferric paratoluenesulfonate, ferric nitrate, cupric sulfate, sulfur trioxide, nitrogen dioxide, hydrogen peroxide, peracetic acid and the like are used.

  Next, an electrolytic polymerization process is performed. If necessary, the element intermediate 20 (see FIG. 3) in which the dielectric coating layer 13 and the precoat layer 14 are formed on the anode body 12 is re-formed before the electrolytic polymerization step. By re-chemical conversion, the dielectric coating layer 13 damaged by the formation of the precoat layer 14 can be repaired.

  3 and 4 are a front view and a perspective view showing an outline of the electrolytic polymerization process. In the element intermediate 20 on which the precoat layer 14 is formed, the anode lead wire 12 a led out from the terminal lead-out surface 20 a is held by the holding jig 31. The holding jig 31 is configured to be movable up and down, and the element intermediate 20 is immersed in the electrolytic polymerization solution H when the holding jig 31 is lowered. At this time, the plurality of element intermediates 20 are arranged in parallel at a predetermined pitch P1 and are immersed in the electrolytic polymerization solution H at the same time.

  As the electrolytic polymerization solution H, a supporting electrolyte containing a monomer that is a precursor of a conductive polymer and a dopant of the conductive polymer is used. As the monomer, pyrrole, thiophene, aniline or a derivative thereof is used. 3,4-ethylenedioxythiophene, which is a derivative of thiophene, is more preferable from the viewpoints of conductivity and stability. A sulfonic acid compound, a carboxylic acid compound, or the like is used as the dopant. Thereby, the conductive polymer layer 15 is formed of polypyrrole, polythiophene, polyaniline, or the like.

  In the electrolytic polymerization solution H, the external electrode 32 is inclined and the element intermediate 20 descends and contacts or approaches the external electrode 32. Then, the external electrode 32 feeds power to the element intermediate 20 from the feeding point 32a in contact with or close to the element intermediate 20 to perform electrolytic polymerization. Thereby, the conductive polymer layer 15 is formed on the precoat layer 14.

  At this time, since the dielectric coating layer 13 and the precoat layer 14 are very thin, the element intermediate body 20 maintains the same shape as the anode body 12. The feeding point 32a is provided on the ridge line 20d between the side surface 20c and the bottom surface 20b of the element intermediate body 20 having a polygonal column shape or a cylindrical shape. Thereby, the feeding point 32a is formed at the lower end of the side surface 20c and the periphery of the bottom surface 20b. That is, the element intermediate 20 is supplied with power on the ridge line 20d between two adjacent surfaces as a power supply point 32a.

  In the conductive polymer layer 15 formed by electrolytic polymerization, the growth speed of growth is increased at the protruding portion. For this reason, the conductive polymer layer 15 having a larger layer thickness than the other flat portions is formed on the ridge line 20d forming the protruding portion. Thereby, even if the conductive polymer layer 15 is missing when the external electrode 32 is removed, damage to the dielectric coating layer 13 can be suppressed.

  The external electrode 32 only needs to be conductive, and a metal such as stainless steel, conductive rubber, a member obtained by coating a base material with plating or a conductive material, or the like is used. The external electrode 32 is formed of a wire or a thin plate, and is in contact with or close to the precoat layer 14 on the ridge line 20d with a point or a line.

  For this reason, the contact area of the external electrode 32 can be made smaller than that of planar contact. Thereby, the burying of the external electrode 32 when the conductive polymer layer 15 grows can be reduced, and the adhesive force between the external electrode 32 and the conductive polymer layer 15 can be reduced. As a result, when the external electrode 32 is removed, the loss of the conductive polymer layer 15 can be reduced, and damage to the dielectric coating layer 13 and the precoat layer 14 can be further suppressed. Therefore, since it is not necessary to change the feeding point 32a with which the external electrode 32 is brought into contact during feeding as in the conventional example, the apparatus for performing the electropolymerization can be configured in a small and simple manner.

  The contact length when the external electrode 32 is in line contact with the ridge line 20d is preferably 3 mm or less. When the contact length is longer than 3 mm, the contact area increases, and the conductive polymer layer 15 is likely to be lost. Further, when the external electrode 32 has elasticity due to a wire or a thin plate, the external electrode 32 can be reliably brought into contact with the element intermediate 20. An elastic member may be connected to the external electrode 32 so that the external electrode 32 is in contact with the element intermediate 20.

  In addition, the current supplied from the external electrode 32 spreads from the two adjacent surfaces of the element intermediate body 20 constituting the ridge line 20 d to the entire precoat layer 14 including the inside of the anode body 12. For this reason, the conductive polymer layer 15 has a uniform thickness as a whole as compared with the case where the external electrode 32 is in contact with one flat surface, and the ESR of the solid electrolytic capacitor 1 can be reduced. Further, it is not necessary to perform extra electrolytic polymerization for forming a thin portion of the conductive polymer layer 15 with a sufficient thickness, and the capacitor element 10 can be formed slim.

  The two surfaces forming the ridgeline 20d where the feeding point 32a of the external electrode 32 is provided may be any surface, and may be a flat surface or a curved surface. In other words, the feeding point 32 a may be provided on the ridge line between the peripheral surface and the bottom surface of the cylindrical element intermediate 20. Further, the feeding point 32 a may be provided on the ridge line between the terminal lead-out surface 20 a and the side surface 20 c of the element intermediate 20. The feeding point 32a may be provided on a ridge line between two adjacent side surfaces 20c of the element intermediate body 20 formed of a polygonal column.

  At this time, it is more desirable to provide the feeding point 32a on the ridge line 20d between the bottom surface 20b and the side surface 20c of the element intermediate 20 as in the present embodiment. Thereby, since the element intermediate 20 can be brought into contact with or close to the external electrode 32 only by lowering the holding jig 31, the apparatus can be configured simply. Further, the contact pressure between the element intermediate 20 and the external electrode 32 can be easily adjusted.

  When the feeding point 32a is provided on the ridge line between the terminal lead-out surface 20a and the side surface 20c or on the ridge line between the adjacent two side surfaces 20c, a holding jig is used to bring the external electrode 32 into contact or close proximity. It is necessary to move 31 in the horizontal direction. At this time, the horizontal gap between the element intermediate 20 that moves up and down and the external electrode 32 can be arranged small, and the amount of horizontal movement of the holding jig 31 can be reduced to prevent the apparatus from becoming large.

  Further, the angle formed by the two surfaces constituting the ridge line 20d is preferably about 90 °, but the same effect can be obtained in the range of 60 ° to 150 °. For example, when a predetermined corner of the element intermediate 20 is chamfered with a flat surface, the feeding point 32a may be provided on the ridge line between the chamfered surface and a surface adjacent thereto.

  In addition, when a predetermined corner of the element intermediate 20 is chamfered with a curved surface having a small curvature radius, the chamfered arc-shaped surface can be regarded as a ridge line. Therefore, the feeding point 32a may be provided on the arcuate surface. Note that the external electrode 32 may be brought into contact with or close to a corner where the three ridge lines of the element intermediate 20 intersect.

  Further, it is more preferable that the external electrode 32 is retracted from the ridgeline 20d every predetermined time (for example, 5 minutes to 90 minutes) while the external electrode 32 is energized. The external electrode 32 can be easily retracted from the element intermediate body 20 by raising the holding jig 31, lowering the external electrode 32, or horizontally moving the external electrode 32.

  Thereby, the embedding of the external electrode 32 in the conductive polymer layer 15 can be further reduced. Further, since the loss of the conductive polymer layer 15 when the external electrode 32 is removed is reduced, the thickness of the conductive polymer layer 15 can be formed more uniformly.

  When the external electrode 32 is moved, the external electrode 32 may be separated from the conductive polymer layer 15 grown on the ridgeline 20d. For this reason, the movement amount of the external electrode 32 can be made small, and the enlargement of an apparatus can be suppressed.

  In FIG. 2, in the carbon layer forming step, the element intermediate 20 is immersed in a carbon suspension and dried, and the surface of the conductive polymer layer 15 is covered with the carbon layer 16. Next, in the silver coating layer forming step, an epoxy resin paste containing silver powder is applied on the carbon layer 16. Then, the epoxy resin paste is cured at a predetermined temperature (for example, 180 ° C.) to form the silver coating layer 17. A cathode lead layer is formed by the carbon layer 16 and the silver coating layer 17.

  Next, in the assembly process, the lead frames 11 and 18 (see FIG. 1) are attached by welding or a conductive adhesive, and are covered with an exterior material 3 such as an epoxy resin. In the aging process, an aging process for applying a voltage to the solid electrolytic capacitor 1 is performed. Then, the solid electrolytic capacitor 1 is inspected in the inspection process, and the solid electrolytic capacitor 1 is completed.

  According to the present embodiment, since the feeding point 32a of the external electrode 32 is provided on the ridge line 20d between two adjacent surfaces of the element intermediate 20 in the electrolytic polymerization process, the ridge line 20d having a large layer thickness of the conductive polymer layer 15 is provided. The external electrode 32 is in contact with or close to the top. For this reason, even when the conductive polymer layer 15 is missing on the ridgeline 20d when the external electrode 32 is removed, damage to the dielectric coating layer 13 can be suppressed.

  Further, it is possible to reduce the burying of the external electrode 32 in the conductive polymer layer 15 and to reduce the adhesive force between the external electrode 32 and the conductive polymer layer 15. For this reason, when the external electrode 32 is removed, the loss of the conductive polymer layer 15 can be reduced, and damage to the dielectric coating layer 13 can be further reduced.

  Further, the current supplied from the external electrode 32 spreads from the two surfaces constituting the ridge line 20d to the entire anode body 12. Thereby, the conductive polymer layer 15 can be formed in a uniform thickness. Therefore, the solid electrolytic capacitor 1 having a low leakage current and low ESR and a high yield can be obtained. Further, since the feeding point 32a of the external electrode 32 is not changed, the apparatus for the electrolytic polymerization process can be reduced in size.

  In addition, since the external electrode 32 is retracted from the ridgeline 20d every predetermined time in the electrolytic polymerization process, the burying of the external electrode 32 in the conductive polymer layer 15 can be further reduced. In addition, since the loss of the conductive polymer layer 15 when the external electrode 32 is detached is further reduced, the thickness of the conductive polymer layer 15 can be formed more uniformly.

  In addition, a feeding point 32 a is formed on the periphery of the lower surface (bottom surface 20 b) of the element intermediate 20 immersed in the electrolytic polymerization solution H. Thereby, electrolytic polymerization can be performed only by moving the element intermediate 20 up and down, and the apparatus can be further simplified. When a flat chamfer is formed at the corner between the bottom surface 20b and the side surface 20c of the element intermediate 20, a feeding point 32a may be provided at the lower end of the side surface 20c.

  Further, since the precoat layer 14 made of manganese dioxide or a conductive polymer formed by chemical polymerization is provided, a conductive polymer layer 15 having high mechanical strength and electrical conductivity is formed on the precoat layer 14 by electrolytic polymerization. can do.

  Next, FIGS. 5 and 6 are a front view and a perspective view showing an outline of the electrolytic polymerization process of the solid electrolytic capacitor 1 of the second embodiment. For convenience of explanation, the same reference numerals are given to the same parts as those in the first embodiment shown in FIGS. In the present embodiment, the shape of the external electrode 32 is different from that of the first embodiment. Other parts are the same as those in the first embodiment.

  The external electrode 32 has a vertical portion 32b extending in the vertical direction and a bent portion 32c bent at the lower end of the vertical portion 32b. The bent portion 32c is arranged in contact with or close to the ridge line 20d between the bottom surface 20b and the side surface 20c of the element intermediate 20. Thereby, the feeding point 32a of the external electrode 32 is provided on the ridgeline 20d.

  A plurality of element intermediates 20 are arranged in parallel at a predetermined pitch P <b> 2, and the element intermediates 20 are immersed in the electrolytic polymerization solution H by the lowering of the holding jig 31. At this time, since the external electrode 32 is bent and the vertical portion 32b extends in the vertical direction, the pitch P2 of the element intermediate 20 can be made narrower than the pitch P1 (see FIG. 3) of the first embodiment. Thereby, the apparatus which performs electropolymerization can be reduced in size. Moreover, more capacitor elements 10 can be electrolytically polymerized at the same time, and production efficiency can be improved.

  Examples of the solid electrolytic capacitor 1 will be described below. In the solid electrolytic capacitor 1 of Example 1, the anode body 12 is formed of a niobium sintered body of 4.2 mm × 3.4 mm × 1.6 mm. Next, the anode body 12 was immersed in an aqueous phosphoric acid solution, and anodization (chemical conversion) was performed by applying a direct current voltage of 32 V to form the dielectric film layer 13. Next, a precoat layer 14 was formed on the surface of the dielectric film layer 13 by chemical polymerization using a thiophene monomer and an oxidizing agent.

  Next, the element intermediate 20 is immersed in an electrolytic polymerization solution H composed of an aqueous solution in which thiophene monomer and sodium dodecylbenzenesulfonate as a dopant component are dissolved. The linear external electrode 32 shown in FIG. 3 was brought into contact with the precoat layer 14 on the ridge line 20d between the two surfaces of the element intermediate 20, and a constant current of 0.5 mA per capacitor element 10 was applied for 3 hours. Thereby, electropolymerization was performed to form the conductive polymer layer 15.

  Next, the element intermediate 20 was immersed in the carbon suspension and then dried to form the carbon layer 16. Next, the epoxy resin paste containing silver powder was apply | coated to the surface of the element intermediate body 20, and the silver coating layer 17 was formed by hardening at 180 degreeC.

  Thus, the capacitor element 10 was prepared, and the lead frames 11 and 18 were attached to the capacitor element 10 and then covered with the exterior material 3 made of epoxy resin. And the aging process was performed and the solid electrolytic capacitor 1 was created.

  In the solid electrolytic capacitor 1 of Example 2, the bent external electrode 32 shown in FIG. 5 was brought into contact with the ridge line 20 d of the element intermediate 20. Further, the operation of retracting the external electrode 32 from the element intermediate 20 was performed once every 60 minutes during energization of the electrolytic polymerization. Otherwise, a solid electrolytic capacitor 1 was produced in the same manner as in Example 1.

<Comparative example>
In the solid electrolytic capacitor 1 of the comparative example, as shown in FIG. 7, the external electrode 32 was brought into contact with the precoat layer 14 on the planar side surface 20 c of the element intermediate 20. Otherwise, a solid electrolytic capacitor 1 was produced in the same manner as in Example 1. In FIG. 7, the same parts as those in FIG. 4 are given the same reference numerals.

  Characteristics were measured for the solid electrolytic capacitors 1 of Examples and Comparative Examples prepared as described above. The results are shown in Table 1.

  Here, for each of the examples and comparative examples, a DC voltage of 6.3 V was applied to each of 100 samples to measure a leakage current, and an ESR characteristic of 100 kHz was measured. A sample having a leakage current of 1000 μA or more was determined to be a short product. Note that the ESR and leakage current shown in Table 1 are averages of the samples excluding the shorted product.

  According to Table 1, in the solid electrolytic capacitor 1 of Example 1, one out of 100 shorts occurred, but it was less than the comparative example, and the ESR and leakage current were also low. This is presumed to be because the external electrode 32 is less buried in the conductive polymer layer 15, damage to the dielectric coating layer 13 during removal is reduced, and the conductive polymer layer 15 is formed uniformly. Is done.

  In Example 2 provided with a step of retracting the external electrode 32 during energization of electrolytic polymerization, no short circuit occurred, and ESR and leakage current were lower than in Example 1. It is thought that damage to the dielectric coating layer 13 is suppressed to a minimum because the electropolymerization is performed while eliminating the burying of the external electrode 32 in a short time.

  According to the present invention, it can be used for a solid electrolytic capacitor in which a conductive polymer layer is formed using electrolytic polymerization.

DESCRIPTION OF SYMBOLS 1 Solid electrolytic capacitor 3 Exterior material 10 Capacitor element 11, 18 Lead frame 12 Anode body 13 Dielectric film layer 14 Precoat layer 15 Conductive polymer layer 16 Carbon layer 17 Silver coating layer 20 Element intermediate 20a Terminal lead surface 20b Bottom surface 20c Side surface 20d Ridge line 32 External electrode 32a Feed point 32b Vertical part 32c Bending part

Claims (5)

  A dielectric coating layer forming step of forming a dielectric coating layer on the surface of an anode body made of a valve metal, a precoat layer forming step of forming a conductive precoat layer on the dielectric coating layer, and the precoat layer Electropolymerization in which the formed device intermediate is immersed in an electrolytic polymerization solution and a conductive polymer layer is formed on the precoat layer by electrolytic polymerization by supplying power from a feeding point where an external electrode is in contact with or close to the device intermediate And a step of providing the feeding point on a ridge line between two adjacent surfaces of the element intermediate body.   The electrolytic polymerization solution has a vertical portion in which the external electrode extends in a vertical direction and a bent portion that is bent at the lower end of the vertical portion and is arranged on the ridgeline, and a plurality of the device intermediates are arranged side by side. The method for producing a solid electrolytic capacitor according to claim 1, wherein the method is immersed in the solid electrolytic capacitor.   3. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the external electrode is retracted from the ridge line every predetermined time in the electrolytic polymerization step. 4.   4. The manufacturing of the solid electrolytic capacitor according to claim 1, wherein the feeding point is formed at a peripheral edge of a lower surface of the element intermediate body immersed in the electrolytic polymerization solution or a lower end of a side surface. 5. Method.   The method for producing a solid electrolytic capacitor according to claim 1, wherein the precoat layer is manganese dioxide or a conductive polymer formed by chemical polymerization.