JP4325354B2 - Manufacturing method of solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a method for producing a solid electrolytic capacitor using a conductive polymer used in various electronic devices as a solid electrolyte.

  In recent years, there has been a demand for miniaturization and large capacity of electronic devices, and there is an increasing demand for solid electrolytic capacitors that have good characteristics up to the high frequency region and that are small in size and large in capacity. In order to meet such demands, solid electrolytic capacitors using a conductive polymer having high electrical conductivity such as polypyrrole as a solid electrolyte have been put into practical use.

  FIG. 5 is a cross-sectional view showing a general configuration of a conventional solid electrolytic capacitor using such a conductive polymer as a solid electrolyte. In FIG. 5, 20 indicates a capacitor element, and the capacitor element 20 is tantalum. After the valve action metal powder such as tantalum or niobium having the anode lead wire 21 made of metal is press-molded into a desired shape and sintered, a porous anode body 22 is produced. Dielectric oxide film layer 23 on the outer surface, thin underlayer 24 made of conductive polymer, solid electrolyte layer 25 made of conductive polymer such as polypyrrole, polythiophene or polyaniline, cathode made of carbon layer 26 and silver paint layer 27 The layer 28 is formed by sequentially stacking layers.

  29 is an anode lead terminal connected by welding to the anode lead-out line 21 of the capacitor element 20, 30 is a cathode lead terminal connected to the cathode layer 28 of the capacitor element 20 via a conductive adhesive, and 31 is an anode lead terminal. 29 and an insulating exterior resin in which the capacitor element 20 is integrally covered with a part of the cathode lead terminal 30 exposed on the outer surface.

  The solid electrolyte layer 25 made of a conductive polymer constituting the capacitor element 20 is formed by polymerization. This polymerization method generally includes chemical polymerization and electrolytic polymerization. The solid electrolyte layer 25 It is known that the solid electrolyte layer 25 is preferably formed by electrolytic polymerization in which the formed polymer film becomes dense in order to improve the electrical conductivity of the conductive polymer constituting the anode. Since the body 22 is insulated by the dielectric oxide film layer 23, it is difficult to perform electrolytic polymerization using the conductor portion of the anode body 22 as the anode at the polymerization start point.

  Therefore, conventionally, before the electrolytic polymerization is performed, a base layer 24 made of a thin conductive polymer is formed on the dielectric oxide film layer 23 by a method such as chemical polymerization, and the anode body on which the base layer 24 is formed. 22 is immersed in an electrolytic polymerization solution, and an anode (for example, an external electrode such as stainless steel whose tip is formed in a needle shape) is brought into contact with a part of the anode body 22 from the outside. The solid electrolyte layer 25 made of a conductive polymer was formed by conducting electropolymerization by energizing a cathode disposed therein.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

  As a method for improving the drawbacks of the technique described in Patent Document 1, a large number of defects are generated in the dielectric layer formed on the surface of the capacitor element to which the anode lead wire is joined. A method of polymerizing has been proposed. That is, the capacitor element on which the dielectric layer is formed is immersed in water, and ultrasonic vibrations are applied to the dielectric layer to cause a number of defects, and then the conductive polymer is pre-coated on the dielectric layer by chemical polymerization. By forming a layer, and then applying a positive voltage to the anode lead wire of the capacitor element in the electrolytic polymerization solution, the defect portion can be energized to conduct electrolytic polymerization, thereby making the conductive layer conductive on the dielectric layer. A polymer film is formed.

As prior art document information related to the invention of this application, for example, Patent Document 2 is known.
Japanese Patent Laid-Open No. 62-165313 JP 2003-86462 A

  However, in the above-described conventional method for manufacturing a solid electrolytic capacitor, in the technique described in Patent Document 1, it is necessary to install and remove the external electrode, so that the material cost and the manufacturing cost increase, and the manufacturing process becomes complicated. . Furthermore, when it is automated, the entire manufacturing apparatus becomes large and complicated.

  In addition, in the technique described in Patent Document 2 proposed to improve this problem, the capacitor element manufactured when the defect is large because the defect increased and increased in the dielectric layer is used as the anode of the polymerization start point. If the leakage current of the polymer increases, and the defects are small, the polymerization current that flows during the electropolymerization is not sufficiently supplied, and a new problem arises in that a poor formation of the conductive polymer occurs. Since the defect of the body layer is increased, the process of aging the solid electrolytic capacitor that has been assembled to reduce the defect by applying a constant voltage to both electrodes at a high temperature is an essential condition. There was a problem that this resulted in high costs.

  The present invention solves such conventional problems and provides a method for producing a solid electrolytic capacitor that can be easily and inexpensively formed when the conductive polymer constituting the solid electrolyte layer is formed by electrolytic polymerization. It is intended to do.

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is as follows: (a) sintering a molded body made of a valve action metal powder implanted so that one end of the anode lead-out wire is exposed. Forming a porous anode body ; (b) forming a dielectric oxide film layer on the outer surface of the anode body; and (c) forming on the outer surface of the anode lead-out line derived from the anode body. Removing a part of the formed dielectric oxide film layer to form an exposed portion; and (d) a solid electrolyte layer of a conductive polymer by electrolytic polymerization using the exposed portion where the anode lead-out line is exposed as a polymerization start point. A step of forming a cathode layer on the dielectric oxide layer , and (e) a portion of the dielectric oxide layer between the exposed portion of the anode lead-out line and the lead-out surface of the anode lead-out line , Removing the solid electrolyte layer and the cathode layer and separating the anode and the cathode to form the anode take-out part (F) cutting a part of the anode lead- out portion of the anode lead- out line, (g) connecting an anode lead terminal and a cathode lead terminal to the anode lead- out portion and the cathode layer, and (h) This is a method of manufacturing a solid electrolytic capacitor in which a part of the anode lead terminal and the cathode lead terminal is exposed on the outer surface, and the capacitor element is covered with an insulating exterior resin. Not only does it need to be used, but it also creates a number of defects in the dielectric layer by immersing the capacitor element in water and applying ultrasonic vibrations, and further reduces the number of defects generated in the dielectric layer. In addition, since it is not necessary to perform aging after assembly, a solid electrolyte layer made of a conductive polymer can be stably formed by electrolytic polymerization at a low cost by a simple method. It has the effect that that.

  According to the second aspect of the present invention, the conductive polymer layer by chemical polymerization or the manganese dioxide layer by thermal decomposition is removed before removing a part of the dielectric oxide film layer formed on the outer surface of the anode lead-out line. The exposed layer is formed by removing a portion of the underlying layer and the dielectric oxide film layer at the same time to form an exposed portion. There is an effect that the formation efficiency of the solid electrolyte layer made of a polymer can be improved and the capacity appearance rate can be improved.

  According to a third aspect of the present invention, a precoat layer using a silane coupling agent is formed before forming the underlayer, and a part of the precoat layer, the underlayer, and the dielectric oxide film layer is simultaneously removed. In this way, the exposed portion is formed, whereby the formation efficiency of the first solid electrolyte layer to be formed later by chemical polymerization can be improved and the capacity appearance rate can be improved. Has a working effect.

According to a fourth aspect of the present invention, an area for removing a part of the dielectric oxide film layer formed on the outer surface of the anode lead-out line is 1 mm ² or more, and a scanning YAG laser is used as a removing means. This has the effect of being able to perform stable work efficiently.

  As described above, the method for manufacturing a solid electrolytic capacitor according to the present invention does not require the use of an external electrode, but generates numerous defects in the dielectric layer by immersing the capacitor element in water and applying ultrasonic vibration. In addition, since it is not necessary to perform aging after assembly in order to reduce many defects generated in this dielectric layer, a solid electrolyte layer made of a conductive polymer can be stabilized by electropolymerization at a low cost by a simple method. As a result, it is possible to provide a solid electrolytic capacitor capable of achieving a small size and large capacity and exhibiting good characteristics up to a high frequency region. It is.

  Hereinafter, the invention according to the first to seventh aspects of the present invention will be described with reference to embodiments.

  FIG. 1 is a manufacturing process diagram showing a method of manufacturing a solid electrolytic capacitor according to an embodiment of the present invention, and FIGS. 2A to 2C and 3A to 3C are methods of manufacturing the capacitor element. 4 is a cross-sectional view showing a solid electrolytic capacitor produced by the method of manufacturing the solid electrolytic capacitor. In FIG. 4, 1 is a capacitor element, 2 is an anode body, and 3 is this anode body 2. 4 is a dielectric oxide film layer, 5 is a precoat layer, 6 is a thin underlayer made of a conductive polymer, 7 is a solid electrolyte layer made of a conductive polymer, and 10 is a carbon layer. 8 is a cathode layer comprising silver paint layer 9; 11 is an anode lead terminal connected to the anode lead wire 3 by welding; 12 is a cathode lead terminal connected to the cathode layer 10 via a conductive adhesive; Is shaded with the anode lead terminal 11 Part of the lead terminal 12 is insulating outer resin coated integrally the capacitor element 1 in a state of being exposed to the respective outside.

  Next, a method for manufacturing the solid electrolytic capacitor according to the present embodiment configured as described above will be described. First, as shown in FIG. 2A, an anode lead wire 3 made of a tantalum wire having a diameter of φ0.4 mm is provided. Implanted tantalum metal powder (CV product; 80000 / g) is molded using a press mold and sintered to form a rectangular parallelepiped having a thickness of 1.25 mm, a width of 2.10 mm, and a length of 1.60 mm. A dielectric oxide film layer 4 was formed on the outer surface of the sintered body by applying a voltage of 20 V at about 80 ° C. using a 9 vol% phosphoric acid aqueous solution. An anode body 2 was obtained (FIG. 2B).

  Subsequently, the anode body 2 on which the dielectric oxide film layer 4 was formed was treated with a silane coupling agent “KBE603” (N-2 (aminoethyl) 3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. A precoat layer 5 was formed on the dielectric oxide film layer 4 by immersing it in a 3 wt% aqueous solution for 10 minutes and then pulling it up and drying at 110 ° C. for 10 minutes (FIG. 2C). In the present invention, the type of the silane coupling agent that forms the precoat layer 5 is not particularly limited, but the structure having an amino group in the functional group has the best wettability. It can be said that

  In addition, although it is possible to form the solid electrolyte layer 7 made of a conductive polymer by electrolytic polymerization described later without forming the precoat layer 5 with the silane coupling agent, the step of forming the solid electrolyte layer 7 is possible. In the case where the thin underlayer 6 made of a conductive polymer is formed by chemical polymerization before the step, the chemical polymerization liquid for forming the underlayer 6 is formed by forming the precoat layer 5 using the silane coupling agent. Since the wettability is improved and the capacity appearance rate can be increased, the formation of the precoat layer 5 with a silane coupling agent is important.

  Subsequently, the anode body 2 in which the precoat layer 5 is formed on the dielectric oxide film layer 4 is composed of 2 wt% of 3,4-ethylenedioxythiophene and 28 wt% of a 30 wt% aqueous solution of ferric p-toluenesulfonate. %, Isopropyl alcohol is 16 wt%, ethylene glycol is 23 wt%, and pure water is 31 wt% soaked in a chemical polymerization solution at about 15 ° C. for 10 minutes and then pulled up and placed in a dryer for 30 minutes at 40 ° C. Chemical polymerization was carried out by drying at 130 ° C. for 30 minutes. In addition, the immersion position of the anode body 2 in the chemical polymerization liquid at this time was immersed to a position of 1.25 mm from the upper surface of the anode body 2 (the lead-out surface of the anode lead-out line 3).

  Subsequently, the anode body 2 was immersed in an ethanol solution at about 40 ° C. for 1 hour, and then a dielectric oxide was oxidized by applying a voltage of 12 V at about 80 ° C. for 40 minutes using a 0.1 wt% aqueous solution of ammonium dihydrogen phosphate. The defect of the coating layer 4 was repaired, followed by washing with pure water at room temperature for 15 minutes and then drying at 105 ° C. for 10 minutes. Furthermore, after the anode body 2 was once again immersed and dried using the above chemical polymerization solution, a higher concentration chemical polymerization solution (3,4-ethylenedioxythiophene was 4 wt%, p-toluenesulfonic acid second A thin underlayer 6 made of a conductive polymer was formed by chemical polymerization using a 30 wt% aqueous solution of 60 wt% of iron, 19 wt% of isopropyl alcohol, 12 wt% of ethylene glycol, and 5 wt% of pure water (see FIG. 2 (c)).

  The underlayer 6 may be a thermal decomposition manganese dioxide layer instead of the chemically polymerized conductive polymer layer, and the method for forming the underlayer 6 made of a conductive polymer is limited to the method by chemical polymerization. Instead, it can be formed by applying a polymer solution in which a conductive polymer is dispersed to the anode body 2 and curing it.

  Subsequently, the anode lead-out line 3 at a position of 1.25 mm to 1.70 mm from the lead-out surface of the anode lead-out line 3 of the anode body 2 in which the precoat layer 5 and the underlayer 6 are laminated on the dielectric oxide film layer 4. A YAG laser oscillator ML-7061A manufactured by Miyachi Technox Co., Ltd. was used to irradiate the front and back surfaces twice with a laser beam having a Q switch frequency of 15 kHz and a current value of 20 A, and was formed on the outer surface of the anode lead-out line 3. By removing the dielectric oxide film layer 4, the precoat layer 5 and the underlayer 6, the anode lead-out wire 3 was exposed to form an exposed portion 14 (FIG. 3A).

  As a method for removing the dielectric oxide film layer 4, the precoat layer 5 and the base layer 6 formed on the outer surface of the anode lead-out line 3, there are laser irradiation and mechanical scraping methods. It is the most stable in terms of accuracy, and the laser type is larger than the general pulse YAG laser, so the laser output per irradiation area is large because of the smaller spot diameter, and the removal accuracy of the precoat layer 5 is very high. It is preferable to use a scanning YAG laser exhibiting stable performance. However, since the scanning YAG laser has a large laser output per unit area, the leakage current increases when the laser is irradiated twice or more at the same position. It is important to make the part not used in the product as 1. Further, the laser irradiation conditions depend on the amount of the precoat layer 5 to be removed, so that it is necessary to change the conditions of the Q switch frequency and the current value each time. Absent. Note that the laser current value must be 30 A or less in order to suppress the deterioration of the leakage current.

  Further, the removal area of the precoat layer 5 is sufficient if a polymerization current necessary for performing the electropolymerization described later can be supplied, and an area having a diameter of 0.1 mm or more is sufficient. In order to uniformly form the polymer solid electrolyte layer 7 on the outer surface of the anode body 2, the dielectric oxide film layer 4, the precoat layer 5 and the underlayer 6 formed on the outer surface of the anode lead-out line 3 are formed. Even better results can be obtained if it is removed over the entire circumference.

  Subsequently, the anode body 2 in which the exposed portion 14 is formed on the anode lead-out line 3 is composed of 2.4 wt% of 3,4-ethylenedioxyethylene, 24 wt% of a 40% aqueous solution of sodium butylnaphthalenesulfonate, and isopropyl phosphate. Is immersed in an electropolymerization solution at about 25 ° C. consisting of 0.2 wt% of ethanol, 5.4 wt% of ethanol, and 68 wt% of pure water, and the exposed portion 14 where the anode lead-out line 3 is exposed is defined as a polymerization start point of electropolymerization. A solid electrolyte layer 7 made of a conductive polymer by electrolytic polymerization is formed by applying a voltage of 1.4 V as an anode to be formed for 50 minutes, and this is washed with pure water at about 40 ° C. for 10 minutes, and then at 60 ° C. The film was dried for 10 minutes and further at 105 ° C. for 10 minutes (FIG. 3B).

  In addition, although the example using 3, 4- ethylenedioxythiophene was described about the conductive polymer material which comprises the solid electrolyte layer 7 which consists of the said conductive polymer, this invention is not limited to this. As for the conductive polymer material and the dopant material, any material can be applied as long as it is a polymer compound having a π-electron conjugated system, and among them, polypyrrole, polythiophene, polyaniline or derivatives thereof that are easy to produce industrially. It is preferable that Similarly, all materials can be applied as long as the dopant material is doped with a polymer compound having a π-electron conjugated system and has an electric conductivity of 10 S / cm or more, and various tests such as a reliability test are possible. In view of deterioration in electrical conductivity due to dedoping from a conductive polymer, at least one of alkyl naphthalene sulfonate and alkyl benzene sulfonate is preferable. In addition, it is not necessarily limited to the above conditions because it varies depending on the conductive polymer and the dopant material in the conditions such as the solvent type of the electrolytic polymerization liquid, the additive, the polymerization liquid composition, the polymerization temperature, the time, and the polymerization voltage. Further, the same can be said for repair conditions, cleaning conditions, and the like.

  Next, the cathode layer 10 is formed by forming the carbon layer 8 and the silver paint layer 9 on the anode body 2 on which the solid electrolyte layer 7 made of the conductive polymer is formed, and the upper surface (anode) of the anode body 2 is further formed. Dielectric oxide film layer 4 formed on the outer surface of anode lead-out line 3 by irradiating laser light to anode lead-out line 3 at a position of 0.35 mm to 1.25 mm from lead-out line 3 of lead-out line 3. By removing the precoat layer 5, the underlayer 6 and the solid electrolyte layer 7 at the same time, the anode lead-out wire 3 was exposed to form the anode lead-out portion 15, thereby obtaining the capacitor element 1 in which the anode and the cathode were separated ( FIG. 3 (c)).

  The laser irradiation condition for separating the anode and the cathode is not only to remove the solid electrolyte layer 7 made of a conductive polymer, but also to the base layer 6, the precoat layer 5 and the dielectric oxide film layer 4 simultaneously. Since it is necessary to remove and expose the anode lead-out line 3, a laser current value equal to or higher than the condition for obtaining the exposed portion 14 which is the starting point of the electrolytic polymerization is required. To be closer to the capacitor element 1 than the portion 14 and have a laser irradiation area that is larger than the area necessary for connection with the lead terminal 11 on the anode side, and to prevent the anode and the cathode from being separated so as not to be short-circuited The anode lead-out line 3 must be exposed over the entire circumference, and in this way, connection with the anode lead terminal 11 described later can be performed reliably and without short-circuiting. It is made to be able to.

  Subsequently, after the anode lead-out line 3 was cut at a position of 1.10 mm from the upper surface (the lead-out surface of the anode lead-out line 3) of the capacitor element 1 with the anode and the cathode separated in this way, the anode lead-out line 3 was connected to the anode lead. After being connected to the terminal 11 by resistance welding and connecting the cathode lead terminal 12 to the cathode layer 10 of the capacitor element 1 through a conductive adhesive, the anode lead terminal 11 and a part of the cathode lead terminal 12 are external surfaces. The capacitor element 1 is sealed with an exterior resin 13 made of an insulating epoxy resin in a state exposed to the above, and after aging for 20 minutes by applying a voltage of 8 V at a high temperature of 125 ° C., The anode lead terminal 11 and the cathode lead terminal 12 exposed from the exterior resin 13 are bent along the exterior resin 13 from the side surface to the bottom surface, so that the surface mount type solid electrolytic core of the present embodiment is used. To produce a capacitor.

  As described above, the method for manufacturing a solid electrolytic capacitor according to the present invention does not require the use of an external electrode, but generates a large number of defects in the dielectric layer by immersing the capacitor element in water and applying ultrasonic vibration. In addition, since it is not necessary to perform aging after assembly in order to reduce a large number of defects generated in the dielectric layer, a solid electrolyte layer made of a conductive polymer can be stabilized by electrolytic polymerization at a low cost by a simple method. As a result, it is possible to stably manufacture a solid electrolytic capacitor capable of achieving a small size and a large capacity and exhibiting good characteristics up to a high frequency region. is there.

  The method for producing a solid electrolytic capacitor according to the present invention can easily form a solid electrolyte layer made of a conductive polymer by electropolymerization in a simple and inexpensive manner. It has a feature that it can exhibit the characteristics, and is useful as a method for producing a solid electrolytic capacitor using a conductive polymer as a solid electrolyte layer.

Manufacturing process diagram showing a method of manufacturing a solid electrolytic capacitor according to an embodiment of the present invention (A)-(c) Sectional drawing which showed the manufacturing method of the capacitor | condenser element (A)-(c) Sectional drawing which showed the manufacturing method of the capacitor | condenser element Sectional drawing which showed the solid electrolytic capacitor produced by the manufacturing method of the same solid electrolytic capacitor Sectional view showing the configuration of a conventional general solid electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode body 3 Anode lead-out line 4 Dielectric oxide film layer 5 Precoat layer 6 Underlayer 7 Solid electrolyte layer 8 Carbon layer 9 Silver paint layer 10 Cathode layer 11 Anode lead terminal 12 Cathode lead terminal 13 Exterior resin 14 Exposed part 15 Anode extraction part

Claims (4)

(A) a step of sintering a molded body made of a valve action metal powder implanted so that one end of the lead-out line of the anode is exposed to form a porous anode body; and (b) an outside of the anode body. Forming a dielectric oxide film layer on the surface; and (c) removing a portion of the dielectric oxide film layer formed on the outer surface of the anode lead-out line derived from the anode body to form an exposed portion. And (d) forming a solid electrolyte layer of a conductive polymer on the dielectric oxide film layer by electrolytic polymerization using the exposed portion where the anode lead-out line is exposed as a polymerization start point , and then forming a cathode layer. (E) removing a portion of the dielectric oxide film layer, solid electrolyte layer, and cathode layer between the exposed portion of the anode lead-out line and the lead-out surface of the anode lead-out line, separating the anode and cathode, and taking out the anode Forming a portion; and (f) cutting a part of the anode lead-out portion of the anode lead-out line. A degree, a step of respectively connecting the anode lead terminal and the cathode lead terminal (g) the anode terminal portion and a cathode layer, (h) a state in which a part of the anode lead terminal and the cathode lead terminal are exposed to the respective outer surface A method for producing a solid electrolytic capacitor in which the capacitor element is covered with an insulating exterior resin. Before removing a part of the dielectric oxide film layer formed on the outer surface of the anode lead-out line, a base layer composed of a conductive polymer layer by chemical polymerization or a manganese dioxide layer by thermal decomposition is formed. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein a part of the dielectric oxide film layer is simultaneously removed to form an exposed portion. A precoat layer using a silane coupling agent is formed before forming the underlayer, and the exposed portion is formed by simultaneously removing a part of the precoat layer, the underlayer and the dielectric oxide film layer. 2. A method for producing a solid electrolytic capacitor as described in 2. ^2. The solid according to claim 1, wherein an area for removing a part of the dielectric oxide film layer formed on the outer surface of the anode lead-out line is 1 mm ² or more, and a scanning YAG laser is used as the removing means. Manufacturing method of electrolytic capacitor.

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