JP6519982B2 - Method of manufacturing capacitor - Google Patents

Description

The present invention relates to a method of manufacturing a capacitor such as a solid electrolytic capacitor.

  In a capacitor such as a solid electrolytic capacitor, an element body is formed, and a solid electrolyte layer is generated in the element body.

It is known that a conductive polymer layer is formed in a capacitor element using a conductive polymer dispersion solution in a capacitor including a capacitor element in which the solid electrolyte layer is formed (for example, Patent Document 1).

JP, 2011-199086, A

  By the way, in a capacitor including a capacitor element in which such a conductive polymer layer is formed, it is possible to increase the withstand voltage. For this reason, it is suitable for various uses, such as a car-mounted use and an inverter etc. whose working voltage is rising from 20 [WV] to 35 [WV].

  However, since the concentration of the conductive polymer microparticles in the dispersion solution of the conductive polymer is low, the solid electrolyte layer may not be sufficiently filled in the capacitor element, and the shape retention property of the capacitor element can not be maintained, It has been confirmed that the leakage current is increased by the deformation.

  FIG. 4 shows a capacitor in which the capacitor element is deformed by resin molding. In the capacitor 102, after the formation of the capacitor element 104, the solid electrolyte layer is formed of the dispersion solution of the conductive polymer, and then the resin mold layer 106 is formed by molding. A void 108 is generated between the electrode foils in the capacitor element 104 in which the solid electrolyte layer is formed of the dispersion solution of the conductive polymer.

  When the capacitor element 104 having such an air gap 108 is placed in the cavity of a molding die and a mold resin is injected, the pressure for injection molding of the mold resin acts on the capacitor element 104. The pressure of the injection molding is large and exceeds the shape retention pressure of the capacitor element 104. For this reason, the capacitor element 104 can not withstand the injection molding pressure, and as shown in FIG. 4, element deformation occurs such that a bent portion 110 is produced in a cylindrical body close to a perfect circle.

  Such deformation changes the leakage current characteristics of the capacitor element 104, such as distortion of the distance between the electrode foils. The capacitor 102 having such a capacitor element 104 has problems such as an increase in leakage current.

Then, in view of the above-mentioned subject, the object of the present invention is to improve shape retention of a capacitor element in which a solid electrolyte layer is formed, and to prevent deterioration of the element due to resin molding.

In order to achieve the above object, the method for producing a capacitor according to the present invention comprises the steps of winding an electrode foil and a separator to form a device body, a dispersion solution of a conductive polymer in the device body or a soluble conductive polymer shape retention for holding and forming a capacitor element solution was impregnated to form a solid electrolyte layer, the element shape in the gap generated between the said electrode foil and between the electrode foil of the capacitor element separator The steps of: filling the material; and forming a resin mold layer on the outer periphery of the capacitor element filled with the shape-retaining material .

  According to the present invention, the following effects can be obtained.

  (1) Since the shape retaining material is filled in the air gap of the capacitor element, the shape retaining property of the capacitor element can be enhanced, and element deformation due to resin mold pressure can be prevented.

  (2) Element deformation is suppressed, leakage current can be reduced, and capacitor characteristics can be improved.

  (3) Since the shape retention property of the capacitor element is improved by filling the shape retaining material in the capacitor element, the capacitor element is unlikely to be large, and the demand for miniaturization can be met.

And, other objects, features and advantages of the present invention will become more apparent by referring to the attached drawings and the respective embodiments.

It is a flowchart which shows an example of the manufacturing process of the capacitor | condenser which concerns on one Embodiment. It is sectional drawing which shows a capacitor | condenser. It is a flowchart which shows the manufacturing process of the capacitor | condenser which concerns on an Example. It is sectional drawing which shows the capacitor | condenser containing the capacitor | condenser element which produced the conventional element deformation | transformation.

  FIG. 1 shows a manufacturing process of a capacitor according to an embodiment of the present invention. This manufacturing process is an example of the method of manufacturing the capacitor of the present invention.

  The manufacturing process includes the element forming process (S11), the solid electrolyte layer forming process (S12), the glass filling process (S13), and the resin molding process (S14).

  The element formation process forms a wound element including an anode foil and a cathode foil. In the formation of the wound element, for example, the separator is sandwiched between the anode foil and the cathode foil and wound to form a cylindrical wound element. The anode foil and the cathode foil are formed of, for example, aluminum foil.

  In the solid electrolyte layer forming step, a solid electrolyte layer is formed on the surfaces of the anode foil and the cathode foil of the wound element formed in the element forming step to form a capacitor element.

  In the glass filling step, the liquid glass is filled in the space generated in the capacitor element on which the fixed electrolyte layer is formed in the solid electrolyte layer forming step. This liquid glass is an example of a shape-retaining material that retains the element shape of the capacitor element.

  In the resin molding step, a resin mold layer is formed by resin molding on the outer surface of the capacitor element whose shape retention has been enhanced by glass filling.

  FIG. 2 shows a cross section of the manufactured capacitor. This capacitor 2 is, for example, a solid electrolytic capacitor.

  The capacitor 2 is provided with a capacitor element 4 which is a wound element as described above, and a resin mold layer 6 is formed around the capacitor element 4. The capacitor element 4 is wound around the element center 8, and the air gap 10 is filled with liquid glass 12. Thus, the capacitor element 4 holds the original form of the wound element, and in this embodiment, forms a cylindrical body having a circular cross section close to a perfect circle. From the capacitor element 4, external terminals 14-1 and 14-2 on the anode side and the cathode side are drawn out. For example, the external terminal 14-1 on the anode side is connected to the anode foil, and the external terminal 14-2 on the cathode side is connected to the cathode foil.

  In this embodiment, the air gap 10 filled with the liquid glass 12 is clearly shown in the lead portions of the element center 8 and the external terminals 14-1 and 14-2, but it is not limited to this. The liquid glass 12 is similarly filled in the gaps 10 formed between the electrode foils and between the electrode foils and the separators. Thereby, the element shape in the wound state is maintained.

<Effect of one embodiment>

  (1) The capacitor element 4 which is a winding element is held in the original shape as a winding element by filling the liquid glass 12.

  (2) If such a capacitor element 4 is installed in a cavity of a mold, it can withstand the injection pressure of the resin mold, and element deformation of the capacitor element 4 can be prevented.

  (3) In the capacitor 2 provided with the capacitor element 4 having no element deformation as described above, the leakage current due to the element deformation can be reduced.

  (4) Since the capacitor element 4 is filled with the liquid glass 12 as compared with the prior art in which the capacitor element 4 is covered and the coating enhances the hardness of the capacitor element, the shape retention property of the capacitor element 4 is improved. The capacitor element 4 can be made smaller, and the capacitor element 4 and the capacitor 2 can be made smaller.

  FIG. 3 shows a manufacturing process of a capacitor according to an embodiment of the present invention.

  This manufacturing process is a manufacturing process of a solid electrolytic capacitor as an example. The manufacturing process includes a winding process (S21), a solid electrolyte layer forming process (S22, S23), a shape retaining process (S24, S25), a resin molding process (S26) and an aging process (S27).

  In the winding step (S21), an anode foil, a cathode foil and a separator which are element materials are wound. As an example, separators are superimposed on the front and back surfaces of the anode foil, and the cathode foil is placed with the separator interposed. The laminated material is wound. By such a winding process, an element before forming the solid electrolyte layer is formed.

  In the solid electrolyte layer forming step (S22, S23), a solid electrolyte layer is formed on the element body obtained in the winding step. For example, a conductive polymer is used for the solid electrolyte. The formation of the solid electrolyte layer includes an immersion step (S22) and a drying step (S23).

  In the immersion step (S22), the element is immersed in a dispersion solution of a conductive polymer, and the element body is impregnated with a solid electrolyte under a reduced pressure environment. That is, the immersing step is a step of impregnating the dispersion solution. The dispersion solution of the conductive polymer impregnated in the element body of the capacitor element 4 is a solution in which fine particles of the conductive polymer are dispersed in a solvent. Generally, the particle size of the conductive polymer fine particles is as small as 100 nm or less. Examples of the conductive polymer include polypyrroles, polythiophenes, polyacetylenes, polyphenylenes, polyphenylene vinylenes, polyanilines, polyacenes, polythiophene vinylenes, and copolymers of these. Among them, polypyrroles, polythiophenes and polyanilines are preferable from the viewpoint of easiness of polymerization and stability in air. Among polythiophenes, polyethylenedioxythiophene is preferred because it has very high conductivity in the oxidized form. The solvent of the dispersion solution of the conductive polymer includes water and / or an organic solvent. The dispersion solution preferably contains a sulfonic acid based dopant such as polystyrene sulfonic acid, and may further contain a surfactant, an organic binder and the like. The pH value of the dispersion solution of the conductive polymer is adjusted to less than 3 using a pH adjuster or the like. Therefore, the acidity of the dispersion solution is high. The concentration of the fine particles of the conductive polymer in the dispersion solution of the conductive polymer is preferably in the range of 1 to 5 wt%. The term "impregnation" as used herein refers to a treatment in which the dispersion solution is contained in the element body, and for example, the dispersion body can be contained in the element body by immersing the element body in the dispersion solution. This impregnation step can be carried out under normal pressure, but by carrying out under reduced pressure or under pressure, the conductive polymer layer can be formed to the deep part of the etching pits of the anode foil and the cathode foil. The element having the solid electrolyte layer formed thereon is dried in the drying step (S23).

  In the drying step (S23), the atmosphere temperature in the drying furnace, for example, is maintained at 150 ° C., and left for 30 minutes, for example, as a fixed time. In the drying step (S23), the solvent and the like are removed from the dispersion solution of the conductive polymer to form a conductive polymer layer between the anode foil and the cathode foil of the element body. In addition, since the concentration of the fine particles of the conductive polymer in the dispersion solution of the conductive polymer is low, the immersion step (S22) -drying step (S22) is also performed to secure the loading amount of the conductive polymer in the element body. S23) is preferably repeated several times, for example, three times. Thus, the element body is formed as the capacitor element 4.

  The shape retaining treatment step (S24, S25) includes a step of immersing the shape retaining material (S24) and a step of curing the shape retaining material (S25). A filler material is used as the shape retaining material, and liquid glass is used as the filler material.

  In the immersing step (S24), the element body is immersed in the liquid glass 12, and the air gap 10 of the element body is filled with the liquid glass 12. Thereby, the liquid glass 12 is filled in the space 10 generated in the solid electrolyte layer on the electrode foil of the element body. Then, in the curing step (S25), the liquid glass 12 in the air gap 10 of the capacitor element 4 is cured. The liquid glass 12 filled in the air gap 10 is hardened and solidified. Thereby, the capacitor element 4 is maintained in the original state of the wound element.

  In the resin molding step (S26), the capacitor element 4 subjected to shape retention processing is loaded into the cavity of the mold, and the fluidized mold resin is injected into the cavity. Thereby, the resin mold layer 6 in which the external shape is formed into the shape in the cavity is formed on the outer periphery of the capacitor element 4.

  During the resin molding process, injection pressure acts on the capacitor element 4 from the mold resin which is injection-molded in the cavity. In response to the action of the injection pressure, the shape retention strength of the capacitor element 4 is enhanced by the glass filling, and the shape retention property prevents the element deformation.

  In the aging step (S27), the resin-molded capacitor 2 is subjected to an aging treatment to manufacture the capacitor 2 as a product.

  In this manufacturing process, a dispersion solution of a conductive polymer was used to form a solid electrolyte layer, but a conductive polymer solution in which the conductive polymer is dissolved, for example, a solid electrolyte layer using a soluble conductive polymer solution May be formed. Since the former is a dispersion, the conductive polymer is not dissolved in the solution but dispersed, while the soluble conductive polymer solution of the latter is in the state where the conductive polymer is dissolved in the solution. It is different. The solid electrolyte layer may be formed on the capacitor element 4 by any treatment, and the present invention is not limited to these methods.

〔Experimental result〕

<Packing factor of capacitor element 4>

  The filling factor of capacitor element 4 before solid electrolyte layer formation (immediately after winding), capacitor element 4 after solid electrolyte layer formation, and capacitor element 4 after filling of liquid glass 12 was measured. The filling factor of the capacitor element is as follows. The filling rate of the capacitor 4 is the rate at which the solid electrolyte is filled in the voids in the element existing immediately after the formation of the capacitor element (the element before the formation of the solid electrolyte) if the solid electrolyte layer is formed. If it is after filling, it is the rate in which the solid electrolyte and liquid glass are filled in the space | gap in the element which exists immediately after capacitor element formation (element before solid electrolyte formation).

After solid electrolyte layer formation: 20 to 35 [%]
After filling with liquid glass: 70 to 80 [%]

  As described above, by filling the liquid glass 12 into the capacitor element 4, the filling rate of the capacitor element 4 is significantly improved. Therefore, it is considered that the deformation of the capacitor element 4 due to the pressure at the time of injection of the exterior resin is prevented.

<Hardness of capacitor element>

  The hardness of the capacitor element 4 not filled with the liquid glass 12 and the hardness of the capacitor element 4 filled were compared. The hardness was confirmed by the deformation rate of the capacitor element 4 when a constant load was applied in the diametrical direction to the capacitor element having a diameter of 5.66 [mm] and a height of 1.6 [mm]. That is, a load is applied to the side of the capacitor element 4 toward the center of the capacitor element 4. The deformation rate of the capacitor element 4 is as shown in Table 1.

  As described above, the filling of the liquid glass 12 makes the capacitor element 4 difficult to deform.

  Although the above experiments in which the filling rate and hardness of the capacitor element were measured all used a capacitor in which a solid electrolyte layer was formed by a dispersion solution of a conductive polymer, but a solid electrolyte layer was formed by a soluble conductive polymer solution. The same result is obtained for the capacitor in which

[Measurement of leakage current]

  For the measurement of the leakage current, each capacitor is prepared with a plurality of (for example, n = 9, but n is the number) capacitors which are shape-retained with liquid glass and a plurality of unprocessed (for example, n = 9) capacitors Of the same characteristics, the leakage current of each capacitor after assembly and aging was measured. The initial value of the leakage current of a capacitor using a dispersion solution of a conductive polymer or a soluble conductive polymer solution for forming a solid electrolyte layer is as follows.

  <Use of dispersion solution of conductive polymer for formation of solid electrolyte layer>

  a Without glass filling: Leakage current = 198. 17 [μA]

  b With glass filling: Leakage current = 0.13 [μA]

  <Use of soluble conductive polymer solution for formation of solid electrolyte layer>

  a Without glass filling: Leakage current = 20935.89 [μA]

  b With glass filling: Leakage current = 153.58 [μA]

  As is clear from this experiment, it is confirmed that the leakage current of the capacitor for which shape retention has been processed is extremely small, and a significant reduction effect of about 1/1000 can be obtained with respect to the leakage current of the unprocessed capacitor. It will be understood that the shape-retaining treatment prior to the resin molding treatment for the capacitor element 4 contributes significantly to the reduction of the leakage current and enhances the reliability of the capacitor.

Other Embodiments

  (1) Although the manufacturing process of a solid electrolytic capacitor was illustrated in the above-mentioned embodiment, capacitors, such as an electrolytic capacitor, may be used.

  (2) In the above embodiment, the winding center portion and the winding portion of the external terminal are clearly indicated for the air gap 10 generated in the capacitor element 4, but the present invention is not limited to this. And a void formed in the solid electrolyte layer of

  (3) Although liquid glass 12 was illustrated as a shape-retaining material in the above embodiment, other fillers may be used other than liquid glass 12, and the filler may be either conductive or nonconductive. Good. For example, polyurethane resin, nylon, polyester, polyester imide, polyester imide nylon, polyamide imide, polyamide, polyvinyl formal, polyvinyl butyral, polyethylene, polypropylene, polybutylene, polystyrene, phenol resin, amino resin, melamine resin, epoxy resin, acrylic, alkyd , Silicone resin, acrylic silicone resin, silicone oil, silicone gel, fluorine resin, alkoxysilane, alkoxysilane epoxy composite resin, cellulose, amylose, liquid crystal polymer, polyanion, polycation, water-soluble monomolecular compound, and two or more hydroxyls Even when a compound having a group is used, the same effect as that of the above embodiment can be obtained.

Note that the present invention is not limited to the description of the above-described embodiment and examples, but is based on the gist of the invention described in the claims or disclosed in the modes for carrying out the invention. Various modifications and changes are possible at the vendor. It goes without saying that such variations and modifications are included in the scope of the present invention.

In the method of manufacturing a capacitor according to the present invention, since the shape retaining material for retaining the element shape is filled in the air gap of the capacitor element covered with the resin mold layer, and the shape retaining property is enhanced. The increase in the leakage current due to the element deformation can be suppressed.

DESCRIPTION OF SYMBOLS 2 capacitor 4 capacitor element 6 resin mold layer 8 element center 10 air gap 12 liquid glass 14-1 anode side external terminal 14-2 cathode side external terminal 102 capacitor 104 capacitor element 106 resin mold layer 108 air gap 110 bending portion

Claims (1)

Winding an electrode foil and a separator to form an element;
Impregnating the element body with a dispersion solution of a conductive polymer or a soluble conductive polymer solution to form a solid electrolyte layer to form a capacitor element;
Filling a shape-retaining material for retaining the shape of the element in the gaps formed between the electrode foils of the capacitor element and between the electrode foil and the separator;
Forming a resin mold layer on the outer periphery of the capacitor element filled with the shape retaining material;
A method of manufacturing a capacitor comprising:

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