WO2012066853A1

WO2012066853A1 - Solid-state electrolytic capacitor manufacturing method and solid-state electrolytic capacitor

Info

Publication number: WO2012066853A1
Application number: PCT/JP2011/071846
Authority: WO
Inventors: 越戸　義弘; 恵美松下; 仁黒見; 太郎上野; 耕治藤本
Original assignee: 株式会社村田製作所
Priority date: 2010-11-15
Filing date: 2011-09-26
Publication date: 2012-05-24

Abstract

Provided is a method of manufacturing a solid-state electrolytic capacitor with a large static capacity per unit of area. Coat a region of a portion of the obverse face of a dielectric coated valve-action metallic sheet (1), comprising a valve-action metallic substrate (11) and a dielectric film (13) which is coated on the obverse face thereof, with a wax material (17a, 17b). Stack a plurality of the dielectric coated valve-action metallic sheets (1) such that gaps are therebetween and the positions of the regions which are coated with the respective wax material (17a, 17b) are aligned, obtaining a layered body of the dielectric coated valve-action metallic sheets (1). In the stacked plurality of dielectric coated valve-action metallic sheets (1), adjacent valve-action metallic substrates (11) are bonded using the wax material (17a, 17b), thus obtaining a bonded layered body (3). Form a solid-state electrolytic layer (5) as a contiguous layer so as to fill the gaps between the dielectric coated valve-action metallic sheets (1) in the layered body and cover the exterior obverse faces of the layered body.

Description

Solid electrolytic capacitor manufacturing method and solid electrolytic capacitor

The present invention relates to a method for producing a solid electrolytic capacitor and a solid electrolytic capacitor.

¡Solid electrolytic capacitors are required to be smaller and larger in capacity as electric and electronic devices become smaller and thinner. A multilayer solid electrolytic capacitor is known as one that meets this demand.

Conventional multilayer solid electrolytic capacitors are assembled by laminating a plurality of solid electrolytic capacitor elements. Each of the solid electrolytic capacitor elements has a surface of a valve action metal substrate, a dielectric film, a solid electrolyte layer, and a cathode lead layer (also simply referred to as a cathode layer, generally consisting of a carbon-containing layer and a silver-containing layer). Are sequentially coated. (See, for example, Patent Document 1)

Japanese Patent Laid-Open No. 2004-87893

However, the conventional multilayer solid electrolytic capacitor as described above is not necessarily sufficient to meet the demand for a small size and large capacity.

An object of the present invention is to provide a method capable of efficiently producing a solid electrolytic capacitor having a larger capacitance per unit volume.

According to the present invention, a method for producing a solid electrolytic capacitor comprising:
(A) applying a brazing material to a partial region of the surface of the dielectric-coated valve-acting metal sheet including the valve-acting metal substrate and a dielectric film covering the surface of the valve-acting metal substrate;
(B) A plurality of the dielectric-coated valve metal sheets are provided with gaps between the dielectric-coated valve metal sheets, and the positions of the regions where the brazing material of each dielectric-coated valve metal sheet is applied. Laminating to fit together to obtain a laminate of dielectric coated valve metal sheet,
(C) joining adjacent valve action metal substrates in the plurality of laminated dielectric-coated valve action metal sheets using a brazing material, thereby obtaining a laminated body, and (d) a solid There is provided a production method including a step of forming an electrolyte layer as a continuous layer so as to fill the gaps between dielectric-coated valve metal sheets in a laminate and to cover the outer surface of the laminate.

In the present invention, the “brazing material” refers to a material containing a conductive substance having a melting point lower than that of the metal material constituting the valve action metal substrate, and optionally further containing an additive.

A conventional multilayer solid electrolytic capacitor is assembled by first producing a plurality of solid electrolytic capacitor elements and then laminating these solid electrolytic capacitor elements. In such a conventional multilayer solid electrolytic capacitor manufacturing method, the plurality of solid electrolytic capacitor elements are formed with a solid electrolyte layer on each of a plurality of sheets in which the surface of the valve metal substrate is covered with a dielectric film, Further, it is produced by forming a cathode lead layer. The plurality of solid electrolytic capacitor elements thus fabricated are stacked with an anode comb terminal and a cathode comb terminal that are spaced apart from each other between them, and then the valve action metal substrate and the dielectric film are formed as described above. The anode lead portion of the sheet is resistance-welded through a through hole provided in the anode comb terminal. (See Patent Document 1)

On the other hand, in the method for producing a solid electrolytic capacitor of the present invention, a laminated body of dielectric-coated valve metal sheets, more specifically, a laminated body in which valve metal substrates are joined together using a brazing material. It has gained. Furthermore, in the method for producing a solid electrolytic capacitor of the present invention, this laminate is filled and covered with a continuous layer of solid electrolyte layers, and a cathode lead layer is provided between the dielectric-coated valve metal sheets of the laminate. not exist. In the solid electrolytic capacitor, the valve metal and the solid electrolyte layer function as an anode and a cathode, respectively, with a dielectric film interposed therebetween, and a capacitance can be formed without a cathode lead layer.

According to the method for producing a solid electrolytic capacitor of the present invention, a brazing material is applied to a partial region of the surface of the dielectric-coated valve metal sheet, and the adjacent valve action in the laminated dielectric-coated valve metal sheet. Since the metal bases are joined using the brazing material, it is possible to effectively reduce (preferably prevent) the presence of the dielectric film at the joint, and the valve action metal bases constituting the laminate can be electrically connected. Can be stably connected, and the equivalent series resistance (ESR) of the solid electrolytic capacitor can be reduced. Furthermore, according to the method for manufacturing a solid electrolytic capacitor of the present invention, the solid electrolyte layer can be filled and coated at once as a continuous layer on the laminate, which can be simplified as compared with the conventional manufacturing method. Furthermore, according to the method for producing a solid electrolytic capacitor of the present invention, it is possible to eliminate the cathode lead layer that does not contribute to the formation of the capacitance between the dielectric-coated valve metal sheets of the laminate, so that the corresponding space Can be used effectively, and a solid electrolytic capacitor having a larger capacitance per unit volume can be manufactured.

In the method for producing a solid electrolytic capacitor of the present invention, in the step (d), it is not necessary that the entire laminate is filled and covered with the solid electrolyte layer, and a part of the laminate is filled and covered with the solid electrolyte layer. It does not have to be done. Although this invention is not limited, this part of a laminated body can be used as an anode lead part.

In one embodiment of the present invention, the dielectric film is an oxide film, and the brazing material includes an additive having an action of removing the oxide.

The dielectric film is generally an oxide film made of an oxide of a valve action metal substrate. According to the above aspect of the present invention, the brazing material containing the additive having the function of removing oxides is used to join the valve action metal bases to each other. Therefore, it is possible to more effectively reduce (preferably prevent) the presence of an oxide film at the joint, and to join the valve metal bases more electrically and stably.

Moreover, according to the present invention,
A plurality of dielectric-coated valve metal sheets, and a laminate formed by bonding these dielectric-coated valve metal sheets;
Each of the dielectric-coated valve-acting metal sheets includes a continuous layer of a solid electrolyte layer that fills a gap between the dielectric-coated valve-acting metal sheets constituting the laminate and covers the outer surface of the laminate. The working metal substrate and a dielectric film that covers the surface of the valve metal substrate are bonded to each other in the plurality of laminated dielectric coated valve metal sheets that are adjacent to each other using a brazing material. A solid electrolytic capacitor is provided in which a brazing material or a conductive material derived from the brazing material is electrically insulated from the solid electrolyte layer.

In a preferred aspect of the present invention, a dielectric is interposed between the valve metal substrate and the brazing material or the conductive material derived from the brazing material at the joint portion of the adjacent valve metal substrates with the brazing material. Absent.

Such a solid electrolytic capacitor of the present invention can be manufactured by the above-described method for manufacturing a solid electrolytic capacitor of the present invention, and exhibits the same effect.

According to the present invention, a solid electrolytic capacitor having a larger capacitance per unit volume can be efficiently produced.

It is a schematic sectional drawing which shows one example of the solid electrolytic capacitor which can be manufactured with the manufacturing method of the solid electrolytic capacitor of this invention. It is a schematic sectional drawing explaining the manufacturing method of the solid electrolytic capacitor in one embodiment of this invention. It is a schematic sectional drawing explaining the process of etching a valve action metal base | substrate. It is a schematic sectional drawing which shows two other examples of the solid electrolytic capacitor which can be manufactured with the manufacturing method of the solid electrolytic capacitor of this invention. It is a schematic sectional drawing which shows another example of the solid electrolytic capacitor which can be manufactured with the manufacturing method of the solid electrolytic capacitor of this invention.

(Embodiment 1)
One embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing one example of a solid electrolytic capacitor that can be manufactured by the method for manufacturing a solid electrolytic capacitor in the present embodiment. As shown in FIG. 1, the solid electrolytic capacitor 10 includes a plurality of dielectric-coated valve metal sheets 1 (in the example shown, six dielectric-coated valve metal sheets 1 are shown. (Not limited), the gap between the laminated body 3 in which the dielectric-coated valve metal sheet 1 is joined at the joints X and Y and the dielectric-coated valve metal sheet 1 constituting the laminated body 3 is filled. And a solid electrolyte layer 5 covering the outer surface of the laminate 3. The solid electrolyte layer 5 is formed as a continuous layer so as to fill a gap between the dielectric-coated valve metal sheets 1 and to cover the outer surface of the laminate 3. However, when viewed microscopically, a portion where the gap between the dielectric covered valve metal sheets 1 is not filled or a portion where the outer surface of the laminate 3 is not covered can be inevitably formed, As long as the capacitance of the electrolytic capacitor is at an acceptable level, there is no problem even if such a portion exists in the solid electrolyte layer 5. In addition, the solid electrolytic capacitor 10 of this embodiment further includes a cathode lead layer 7 (carbon-containing layer 7a and silver-containing layer 7b) that covers the outer surface of the solid electrolyte layer 5, but this is not essential to the present invention. .

Each of the dielectric-coated valve metal sheets 1 includes a valve metal base and a dielectric film that covers the surface of the valve metal base. And the laminated body 3 is formed by joining adjacent valve action metal bases in a plurality of laminated dielectric-coated valve action metal sheets using a brazing material. In this laminated body 3, these dielectric-coated valve metal sheets 1 are joined by at least a conductive material derived from the brazing material when the

brazing materials

17 a, 17 b, or the brazing material can be altered during the joining. Thus, the valve metal bases are electrically joined to each other through the joint. The

brazing materials

17a and 17b (or the conductive material derived from the brazing material) are electrically insulated from the solid electrolyte layer 5 (in this embodiment, by an insulator described later).

In the present embodiment, a part of the laminate 3 is not filled and covered with the solid electrolyte layer 5. Specifically, the laminate 3 is divided into two parts by the insulating portion 9. More specifically, a part (hereinafter referred to as a first part) 1a of the dielectric-coated valve metal sheet 1 constituting the laminate 3 is not covered with the solid electrolyte layer 5 as an anode lead part. The insulating part 9 is exposed in a state of being electrically insulated from the solid electrolyte layer 5 and the cathode lead layer 7. On the other hand, a portion (hereinafter referred to as a second portion) 1b of the dielectric coated valve metal sheet 1 separated from the first portion 1a by the insulating portion 9 is covered with the solid electrolyte layer 5 as a solid electrolyte layer covering portion. Has been.

The position and number of joints are not particularly limited, and can be set as appropriate according to the requirements for the solid electrolytic capacitor to be manufactured. In the present embodiment, one joint X exists in the first part (anode lead part) of the dielectric-coated valve metal sheet 1 and another single joint Y is the dielectric-coated valve metal sheet 1. However, the present invention is not limited to this.

Next, a method for manufacturing the solid electrolytic capacitor in this embodiment will be described. In the solid electrolytic capacitor 10 ′ shown in FIG. 2, four dielectric-coated valve action metal sheets 1 are shown as an example. However, the solid electrolytic capacitor 10 ′ may be considered to be essentially the same as the solid electrolytic capacitor 10 in FIG. .

・ Process (a)
First, as shown in FIG. 2A, a dielectric-coated valve metal sheet 1 including a valve metal base 11 and a dielectric film 13 that covers the surface of the valve metal base 11 is prepared. Specifically, the dielectric-coated valve metal sheet 1 can be produced as follows.

弁 Prepare the valve action metal substrate 11. The valve action metal substrate 11 is substantially composed of a metal material exhibiting a so-called valve action. Such a metal material is selected from the group consisting of, for example, aluminum, tantalum, niobium, titanium, zirconium, and alloys of two or more thereof, and is preferably aluminum or an alloy containing aluminum.

The valve metal base 11 may have a sheet shape (or a flat plate shape such as a foil). The thickness of the valve action metal substrate 11 is not particularly limited, but is, for example, 50 to 200 μm, preferably 90 to 130 μm. The width and length of the valve metal base 11 can be appropriately selected according to the size of the solid electrolytic capacitor to be manufactured. In FIG. 2, the direction perpendicular to the paper surface is the width direction.

In particular, the valve-acting metal substrate 11 preferably has irregularities on the surface, and for example, the surface layer portion is more preferably porous. This is because the valve metal base 11 functions as an anode in a solid electrolytic capacitor, so that the capacitance of the capacitor increases as the surface area of the valve metal base 11, that is, the effective area increases, even with the same occupied area. . The valve metal substrate 11 having irregularities on the surface or having a porous surface layer portion can be obtained by subjecting it to a roughening treatment in advance. The roughening process is generally performed by an etching process.

-Pre-process of a process (a) Although it is not essential to this embodiment, an etching process may be implemented as follows, for example before a process (a).

As shown in FIG. 3A, an untreated valve metal base 11 'is prepared. Next, as shown in FIG. 3B, a mask 15 protects a region corresponding to the bonding portion (in other words, a region where a bonding portion is to be formed in a later step). The obtained valve action metal substrate 11 ′ with the mask 15 is immersed in an etching solution and subjected to an etching process. Thereby, as shown in FIG. 3C, in the region not protected by the mask 15 of the valve metal base 11 ', the porous portion 11a is formed only in the surface layer portion. In addition, regarding the valve action metal substrate 11 after processing, for the purpose of helping understanding, the porous portion 11a and the non-etched portion 11b that has not been made porous are schematically shown separately. It is difficult to clearly distinguish these. Thereafter, the mask 15 is removed, and the valve metal substrate 11 subjected to the etching process is obtained. As shown in FIG. 3 (d), the valve metal base 11 has a non-etched portion 11 c in a region corresponding to the joint portion, and the non-etched portion 11 c is protected by the mask 15, so that it is relatively flat. The surface state can be maintained.

Thus, it is preferable to protect the region corresponding to the joint portion with the mask 15 and leave the non-etched portion 11c because the joint property between the valve action metal substrates can be improved in a later step. The non-etched portion 11c is preferably left on at least one of the two valve metal substrates to be bonded, and more preferably left on both of the bonding surfaces. However, it is not always necessary to protect the mask 15 with the etching process.

Etching conditions, such as the etching solution, etching temperature and time, can be appropriately selected according to the metal material of the valve metal substrate to be used, desired electrical characteristics (including effective area), and the like. For example, hydrochloric acid or the like can be used as the etchant. Other conditions can be confirmed in advance and set to appropriate values according to the capacitance, withstand voltage, etc. required for the solid electrolytic capacitor to be manufactured.

Referring again to FIG. 2A, a dielectric coating 13 is formed on the surface of the valve metal base 11. Such a dielectric film 13 can be formed as an oxide film by anodic oxidation of the valve action metal substrate 11.

More specifically, the valve action metal substrate 11 is immersed in an electrolytic solution as it is and subjected to an anodic oxidation treatment (also referred to as a chemical conversion treatment, the same applies hereinafter). Then, an oxide film 13 is formed on the surface of the valve action metal substrate 11 by anodic oxidation.

Conditions for anodizing treatment, such as electrolyte solution, anodizing temperature, time, current density and voltage, etc., depend on the metal material of the valve action metal substrate used and the desired electrical characteristics (including oxide film thickness). It can be selected as appropriate. For example, the electrolytic solution may be an aqueous solution containing at least one selected from the group consisting of boric acid, phosphoric acid, adipic acid, sodium salts and ammonium salts thereof. Other conditions can be confirmed in advance and set to appropriate values according to the capacitance, withstand voltage, etc. required for the solid electrolytic capacitor to be manufactured.

In addition, regarding the dielectric-coated valve metal sheet, a metal sheet that has been roughened by etching treatment and an oxide film is formed by anodic oxidation is commercially available for solid electrolytic capacitors. You may use such a commercially available thing as a dielectric covering valve action metal sheet.

As described above, the dielectric coated valve metal sheet 1 including the valve metal base 11 and the dielectric film 13 covering the surface of the valve metal base 11 is produced. The thickness, width and length of the dielectric coated valve metal sheet 1 are approximately equal to the thickness, width and length of the valve metal base 11 used (usually the thickness of the dielectric coating is on the order of submicron). It is typically several to several tens of nanometers and is negligible compared to the size of the valve metal substrate 11), and can be appropriately selected according to the size of the solid electrolytic capacitor to be manufactured.

The dielectric coated valve metal sheet 1 in this step may be in any appropriate coated state as long as the dielectric film 13 covers the surface of the valve metal base 11. For example, the dielectric coating 13 may or may not cover the side surface of the valve metal substrate 11 (a surface parallel to the cross section of the valve metal substrate 11 shown in FIG. 2). However, when the side surface of the second portion 1b of the valve action metal substrate 11 is not coated with the dielectric film 13, it is necessary to coat with a dielectric film at least before the step (d) described later.

The

brazing materials

17a and 17b are applied to a predetermined region on the surface of the dielectric-coated valve metal sheet 1 as described above. The region to which the brazing material is to be applied is a partial region on the surface of the dielectric-coated valve metal sheet 1, which is usually the same as the region corresponding to the joint, but corresponds to the joint. As long as it is located within the region, it may be smaller than the region corresponding to the joint. The area of the region where the brazing material is applied depends on the composition of the brazing material used, the coating thickness of the brazing material, and the like, but is preferably 80 to 100% of the area of the region corresponding to the joint.

As the brazing material, any appropriate material can be used as long as it contains a conductive material having a melting point lower than that of the metal material constituting the valve action metal substrate. The conductive substance contained in the brazing material can be understood as a filler material for the valve action metal substrate. The melting point of the metal material of the valve action metal substrate and the melting point of the conductive substance contained in the brazing material can be measured using, for example, a differential scanning calorimeter.

The conductive substance contained in the brazing material may be a metal material having a lower melting point than the metal material constituting the valve action metal substrate. Examples of the conductive substance contained in the brazing material include aluminum, an alloy containing aluminum, a lead-free solder material, and the like, preferably aluminum and an alloy containing aluminum.

Such a conductive material may have a form such as a granular material or a flaky material. The conductive material is preferably a granular material having an average particle diameter of 0.02 mm or less, for example, 0.002 to 0.05 mm (both volume average) because the melting point is lower than that of the lump.

The brazing material may contain an additive in addition to the conductive material as described above. Additives can be added for various purposes. The brazing material preferably contains an additive having an action of removing oxides. Examples of the additive having an action of removing oxides include flux and borax. As the flux, a commercially available brazing flux can be used. Other additives that can be used include viscosity modifiers and wettability improvers.

Although the form of the brazing material depends on its composition, it is pasty or solid, and is preferably pasty for ease of application.

ロウ The brazing material can be applied by, for example, a dispenser, screen printing, potting, or the like. The flux may be contained in the brazing material as described above, but it may be used separately from the brazing material and applied or sprayed on the region corresponding to the joint before applying the brazing material.

As described above, the

brazing materials

17 a and 17 b are applied to the predetermined region on the surface of the dielectric-coated valve metal sheet 1.

In the present embodiment, the dielectric-coated valve metal sheet 1 coated with the

brazing materials

17a and 17b in this way is formed into the first part 1a and the second part by the insulating part 9, as shown in FIG. Fractionate into 1b. The insulating part 9 is formed so as to cover another predetermined region on the surface of the dielectric-coated valve metal sheet 1.

The insulating part 9 is formed of an insulating resin, for example, a general heat resistant resin, preferably a heat resistant resin that can be dissolved or swelled in a solvent or a precursor thereof, or a composition comprising an inorganic fine powder and a cellulose resin. Things can be used. Specific examples include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, etc.), low molecular weight polyimide, and Examples thereof include derivatives and precursors thereof, and particularly low molecular weight polyimides, polyethersulfones, fluororesins, and precursors thereof.

The insulating portion 9 is a solid electrolytic capacitor 10 in a state where the first portion 1a (anode lead portion) of the dielectric-coated valve metal sheet 1 is electrically insulated from the solid electrolyte layer 5 and the cathode lead layer 7. As long as it is exposed to the outside, it may be formed at any appropriate timing, and may be formed in several stages.

・ Process (b)
A plurality of dielectric-coated valve metal sheets 1 produced as described above are laminated as shown in FIG. The lamination has a gap between the dielectric-coated valve metal sheets 1 and the positions of the regions coated with the

brazing materials

17a and 17b of the respective dielectric-coated valve metal sheets 1 are aligned (in other words, So that they are stacked and aligned in the thickness direction).

When each dielectric-coated valve metal sheet 1 is applied to a plurality of regions at different positions as in the present embodiment, the lamination is performed between the regions where the brazing material 17a is applied and the brazing material. The positions of the areas where the 17b is applied are aligned in the thickness direction in a stacked state.

In addition, in this embodiment, although the example which apply | coated the brazing material only to the upper surface side of each dielectric covering valve action metal sheet 1 is shown in Fig.2 (a), this invention is not limited to this. As shown in FIG. 2 (b), it is sufficient that a brazing material is sandwiched between adjacent dielectric-coated valve metal sheets 1, for example, only the lower surface side or upper surface of each dielectric-coated valve metal sheet 1 And you may apply | coat a brazing material to both surfaces of a lower surface.

In the gap between the laminated dielectric covered valve metal sheets 1 (more specifically, between the dielectric films 13), the raw material solution of the conductive polymer that forms the solid electrolyte layer can enter in the step (d) described later. Any size is acceptable.

When the surface of the valve metal base 11 is roughened (formed with irregularities) by the etching process described above (preferably the surface layer is porous), the dielectric-coated valve metal sheet 1 is simply overlapped. Thus, a gap is naturally formed between the dielectric-coated valve metal sheets 1.

In addition, as shown in FIG. 2B, when the insulating portion 9 is located between the plurality of dielectric-covered valve metal sheets 1, the insulating portion 9 causes a gap between the dielectric-coated valve metal sheets 1. Naturally formed. Further, in this case, a plurality of dielectric-coated valve metal sheets 1 can be fixed to each other using the insulating portion 9 (temporarily fixed before forming a joint portion in a later step). More specifically, an insulating resin is separately applied to each of the plurality of dielectric-coated valve metal sheets 1, and these are superposed, and the insulating resin is solidified or cured by heating or the like to form the insulating portion 9. The plurality of dielectric covered valve metal sheets 1 can be fixed to each other by the insulating portion 9. Note that the height of the insulating portion 9 can be adjusted by the amount applied to each of the dielectric-coated valve metal sheets 1, for example, the insulation positioned between the dielectric-coated valve metal sheets 1. The thickness may be different between the portion and the insulating portion located on the uppermost surface and / or the lowermost surface.

In the present embodiment, the plurality of laminated dielectric-coated valve metal sheets 1 have substantially the same length, and the first portion 1a and the second portion 1b also have substantially the same length. .

As described above, a plurality of dielectric-coated valve-acting metal sheets 1 are laminated such that there is a gap between them and the positions of the areas where the brazing materials are applied are aligned. A laminate of working metal sheets is obtained.

・ Process (c)
In the plurality of dielectric-coated valve metal sheets 1 laminated as described above, adjacent valve metal bases 11 are bonded together using

brazing materials

17a and 17b, as shown in FIG. 2 (c). Portions X and Y are formed, respectively, to obtain a laminated body 3 bonded thereto. Although the scales of the

brazing materials

17a and 17b are different between FIGS. 2B and 2C, FIG. 2 schematically illustrates the present embodiment, and the difference between the scales is a problem. Not.

Joining using a brazing material can be performed by heating a laminated body obtained by applying

brazing materials

17a and 17b to the dielectric-coated valve metal sheet 1 and laminating them. The heating may be for heating the entire laminate, but it is preferable to locally heat the portion including the region where the brazing material is applied. The valve metal bases 11 are joined to each other by the

brazing materials

17a and 17b once melted by the heating and then solidified. The dielectric film 13 existing between the

brazing materials

17a and 17b and the valve metal base 11 loses its form when the

brazing materials

17a and 17b are once melted and solidified. There is a tendency to disperse (for example, exist as a plurality of fragmented fragments) inside the

brazing materials

17a and 17b. As a result, it is possible to effectively reduce the presence of the dielectric film 13 in the joints X and Y (in other words, the dielectric exists in the form of a film between the adjacent valve action metals 11). Therefore, the valve action metal substrates 11 constituting the laminate can be electrically and stably joined to each other.

In particular, when a brazing material containing an additive having an action of removing oxides is used, or when flux is applied or sprayed to the region corresponding to the joint before the brazing material is applied, oxidation is performed. Since the dielectric film, which is a film, can be positively removed, it is possible to more effectively reduce, preferably prevent, the presence of an oxide film at the joint, and the valve action metal substrates can be more electrically stabilized. Can be joined together.

As described above with reference to FIG. 3, when the etching process is performed before the step (a), when the non-etched portion 11 c is left in the region corresponding to the joint portion of the valve action metal substrate 11, The region corresponding to the portion is not etched and can maintain a relatively flat original surface state. Therefore, the valve metal bases 11 can be easily joined to each other, and the region corresponding to the joint is roughened by etching. Compared with the case where it is surfaceized, the joining property of the valve action metal base | substrates 11 can be improved. However, when the wettability of the brazing material melted at the time of bonding to the valve metal base 11 is high, the region corresponding to the bonding portion may be etched. In this case, the molten brazing material enters the recesses or holes of the valve metal base 11 and high bondability can be obtained.

In the present embodiment, two joints X and Y are formed. In the case of forming two or more joint portions, the formation locations can be appropriately arranged, but the valve metal base 11 is preferably arranged so as to be joined with substantially equal force at those locations.

The joint portion X is formed in the first portion 1a (anode lead portion) of the dielectric-coated valve action metal sheet 1. In the case where the joint portion is formed in the first portion 1a of the dielectric-coated valve metal sheet 1, the entire dielectric-coated valve metal sheet may be formed on or in the vicinity of a line that bisects the width of the first portion 1a. It is preferable because a solid electrolytic capacitor can be manufactured with a reduced stress on the surface and more electrically and physically stable. Specifically, the area of the joint X depends on the area ratio between the first part 1a and the second part 1b, but is preferably 0.1% or more, more preferably 1% of the area of the first part 1a. % Or more, and preferably 10% or less, more preferably 5% or less. If the area of the joint X is 0.1% or more of the area of the first portion 1a, necessary and sufficient mechanical joint strength and electrical conductivity (conduction) can be obtained. On the other hand, if the area of the junction X is 10% or less of the area of the first portion 1a, the capacity reduction due to the formation of the junction can be suppressed to a level that does not cause a problem in practice. When two or more joint portions are formed in the first portion 1a of the dielectric-coated valve action metal sheet 1, the area of each of the joint portions is preferably 0.1% or more of the area of the first portion 1a. Preferably, it is 1% or more, and the total area of these joints is preferably 10% or less, more preferably 5% or less of the area of the first portion 1a.

On the other hand, the joint portion Y is formed in the second portion 1b (solid electrolyte layer covering portion, more specifically, the portion filled and covered with the solid electrolyte layer in a later step) of the dielectric coated valve metal sheet 1. The In the case where the joint portion is formed in the second portion 1b of the dielectric-covered valve metal sheet 1, it is formed on or near the line that bisects the width of the second portion 1b. It is preferable because a solid electrolytic capacitor can be manufactured with a reduced stress on the surface and more electrically and physically stable. In the present embodiment, the joint X extends from the central portion in the length direction of the second portion 1b to the anode lead portion so that the valve metal base 11 is joined with a substantially equal force at the plurality of joints X and Y. In contrast, they are arranged to be shifted to the distal side. In the case where the joint portion is formed in the second portion 1b of the dielectric-coated valve action metal sheet 1, the capacitance corresponding to the joint portion is lost as compared with the case where the joint portion is not formed in the portion. In particular, compared to the case where the joint is roughened by etching and the effective area is increased, the formation of the joint eliminates unevenness (the porous portion is crushed), so even if the joint area is the same More capacitance will be lost. Therefore, it is more preferable to reduce the area of the joint portion as much as possible while ensuring electrical connection. Specifically, the area of the joint Y is preferably 1% or more, more preferably 5% or more, and preferably 30% or less, more preferably 20% or less of the area of the second portion 1b. . When the area of the joint portion Y is 1% or more of the area of the second portion 1b, the adjacent valve action metal bases 11 can be joined electrically and physically stably, and thus the electrical connection It is possible to prevent the joint portion from being separated when forming the solid electrolyte layer in the subsequent process while securing the above. On the other hand, if the area of the joint portion Y is 30% or less of the area of the second portion 1b, the capacitance of the solid electrolytic capacitor is not excessively lost, and therefore the loss of capacitance is compensated. In addition, it is not necessary to increase the number of laminated dielectric coated valve metal sheets 1. When two or more joint portions are formed in the second portion 1b of the dielectric-coated valve action metal sheet 1, the area of each of the joint portions is preferably 1% or more of the area of the second portion 1b, more preferably It is 5% or more, and the total area of these joints is preferably 30% or less, more preferably 20% or less of the area of the second portion 1b.

The above description regarding the position, number, and size of the joint portion is similarly applicable to the description regarding the region where the brazing material is applied. The shape of the region to which the brazing material is applied is determined according to the shape of the joint, and may have any appropriate shape such as a circle, an ellipse, a rectangle, and a square.

As described above, the laminated body 3 is obtained in which the adjacent valve action metal substrates 11 in the plurality of laminated dielectric-coated valve action metal sheets 1 are bonded together using the brazing material.

In such a laminated body 3, depending on the joining method and the brazing material used, brazing

materials

17 a and 17 b electrically connected to the valve action metal substrate 11 (more specifically, conductive materials derived from the brazing material). However, it may be exposed in the gap between the valve action metal sheets 1. Therefore, when the joint portion Y is formed in the second portion 1b of the dielectric covered valve metal sheet 1, and the brazing material 17b exposed to the second portion 1b can exist, the brazing material 17b is insulated. It is covered with a body (the insulator 19 is shown in FIG. 2 (d)). Such an insulator may be the same as or different from the material of the dielectric film 13 that covers the surface of the valve metal substrate 11 in the dielectric-coated valve metal sheet 1.

When the insulator is the same as the material of the dielectric film 13, the insulator is an oxide film or the like. In the present embodiment, it is preferable that at least the second portion 1b is subjected to an anodic oxidation treatment so that the entire surface of the second portion 1b of the dielectric-coated valve metal sheet 1 is covered with the dielectric film. Thereby, the valve action metal substrate and the brazing material (more specifically, at least a conductive substance derived from the brazing material) can be reliably coated together with the dielectric film. When the side surface of the second portion 1b of the valve metal base 11 is exposed, the side surface can be covered with a dielectric film at the same time in this anodizing process. The conditions for the additional anodizing treatment may be the same as the conditions for the anodizing treatment described above in the step (a).

When the insulator is different from the material of the dielectric film 13, the insulator may be any appropriate material that does not have conductivity, such as a polymer compound that does not have conductivity. The polymer compound having no conductivity can be applied to the exposed portion of the brazing material 17b by any appropriate method. For example, a raw material solution of a polymer compound having no conductivity is applied to the exposed portion of the brazing material 17b. It can be formed by generating a polymer compound having no electrical conductivity.

・ Process (d)
The solid electrolyte layer 5 is formed as a continuous layer on the laminate 3 obtained as described above. The solid electrolyte layer 5 fills the gaps between the dielectric covered valve metal sheets 1 in the laminate 3 (more specifically, the gaps between the dielectric coatings 13), and covers the outer surface of the laminate 3. To form. The brazing material (or conductive material derived from the brazing material) 17 b in the second portion 1 b of the dielectric-coated valve metal sheet 1 is electrically insulated from the solid electrolyte layer 5 by the insulator 19. As long as the brazing material (or the conductive material derived from the brazing material) is electrically insulated from the solid electrolyte layer 5, it is not essential to separately provide an insulator in the present invention.

In the present embodiment, the second portion 1 b of all the dielectric-coated valve metal sheets 1 constituting the laminate 3 is filled and covered with the solid electrolyte layer 5, and the dielectric-coated valve metal sheets constituting the laminate 3. The first portion 1a is left unfilled and not covered with the solid electrolyte layer 5 (hereinafter, also referred to as the first portion 1a and the second portion 1b of the laminate 3 for the sake of simplicity). ). The solid electrolyte layer 5 forms a continuous layer. The solid electrolyte layer 5 is in a state where the first portion 1a side of the multilayer body 3 is held and suspended, and the second portion 1b of the multilayer body 3 is used as a conductive polymer raw material solution, for example, before the insulating portion 9. To form a continuous layer of a conductive polymer in the gap and outer surface of the dielectric-coated valve metal sheet 1.

Examples of the conductive polymer forming the solid electrolyte layer 5 include a compound having a thiophene skeleton, a compound having a polycyclic sulfide skeleton, a compound having a pyrrole skeleton, a compound having a furan skeleton, and a compound having an aniline skeleton. Although what contains a structure as a repeating unit is mentioned, it is not limited to these.

Any appropriate solution can be used as the raw material solution of the conductive polymer. For example, you may use 2 types, the solution containing a monomer, and the solution containing a polymerization oxidizing agent and the dopant used separately as needed, and the 2nd part 1b of the laminated body 3 is sequentially added to these solutions as needed. And soaking may be repeated. However, the present invention is not limited to this. For example, even if the second portion 1b of the laminate 3 is immersed in this using a monomer, a polymerization oxidizing agent, and a single solution containing a dopant when used. Good.

Thereafter, as shown in FIG. 2D, a cathode lead layer 7 covering the outer surface of the solid electrolyte layer 5 is formed. The cathode lead layer 7 is generally formed by applying and drying a carbon paste so as to cover the outer surface of the solid electrolyte layer 5 to form the carbon-containing layer 7a, and then covering the outer surface of the carbon-containing layer 7a. Thus, it can be formed by applying and drying a silver paste to form the silver-containing layer 7b.

As a result, the solid electrolyte layer 5 and the cathode lead layer 7 are electrically insulated from the solid electrolyte layer 5 and the cathode lead layer 7 by the insulating portion 9. Exposed outside. The first portion 1a can be used as an anode lead portion and connected to an anode terminal (not shown). On the other hand, the cathode lead layer 7 can be connected to a cathode terminal (not shown). As the anode terminal and the cathode terminal, for example, a lead frame can be used.

Thus, the solid electrolytic capacitor 10 'is obtained. The entire solid electrolytic capacitor 10 ′ is enclosed in an insulating resin (not shown) such as an epoxy resin with at least a part of an anode terminal and a cathode terminal (both not shown) exposed. Good.

According to the method for manufacturing a solid electrolytic capacitor of the present embodiment, the laminate can be filled and covered at once with the solid electrolyte layer as a continuous layer. Furthermore, since there is no cathode lead layer between the dielectric covered valve action metal sheets of the laminate (more specifically, between the dielectric films), the space can be used effectively, and the capacitance per unit volume can be reduced. Larger solid electrolytic capacitors can be manufactured.

Further, according to the method for manufacturing a solid electrolytic capacitor of the present embodiment, since the valve action metal bases are joined together using the brazing material, a strong joint (sufficient mechanical joint strength) can be obtained. The part and size can be freely controlled. Furthermore, according to the solid electrolytic capacitor of the present embodiment, the action of the brazing material can reduce (preferably prevent) an oxide film from intervening in the joint portion between the valve action metal substrates, and the valve action metal substrates can be electrically connected. Can be stably joined, and the equivalent series resistance (ESR) of the fixed electrolytic capacitor can be reduced.

(Embodiment 2)
The present embodiment is a modification of the first embodiment, and shows two kinds of modifications. 4 (a) and 4 (b), members similar to those described in the first embodiment are denoted by the same reference numerals, and hereinafter, differences from the first embodiment will be mainly described, and there is no particular notice. As long as the description is the same as in the first embodiment, the same applies.

In the solid electrolytic capacitor 20 shown in FIG. 4 (a), the multilayer body 3 ′ includes a plurality of dielectric-coated valve metal sheets 1 ′ (in the illustrated example, seven dielectric-coated valve metal sheets 1). ', But not limited thereto), these dielectric-coated valve metal sheets 1' are joined at the joint Y '. These dielectric-coated valve action metal sheets 1 ′ are joined by a brazing material 17b ′ (or a conductive substance derived from the brazing material), whereby the valve action metal bases are electrically connected to each other through a joint portion. It is joined. The brazing material 17b '(or a conductive material derived from the brazing material) is electrically insulated from the solid electrolyte layer 5 (for example, by an insulator). Of the plurality of dielectric-coated valve metal sheets 1 ', only one dielectric-coated valve metal sheet is relatively long and has a first portion 1a. The first portion 1a is not covered with the solid electrolyte layer 5 as an anode lead portion, and is exposed in a state of being electrically insulated from the solid electrolyte layer 5 and the cathode lead layer 7 by the insulating portion 9. The remaining dielectric coated valve metal sheet has a substantially substantially equal length, and is entirely filled and coated with a solid electrolyte layer coating, more specifically, a solid electrolyte layer in a later step. Except for the point that it is a part and away from the insulating part 9, the same description as the second part 1b in the first embodiment applies.

In the illustrated embodiment, a long dielectric coated valve metal sheet having a first portion 1a (anode lead) is sandwiched between the remaining short valve metal sheets (more specifically, the middle of these). However, the present embodiment is not limited to this.

The junction Y ′ may be the same as the junction Y in the first embodiment. However, in this embodiment, since there is only one joining portion Y ′, the joining portion Y ′ is on or near a line that bisects the width of the second portion 1b (solid electrolyte layer covering portion), And it is preferable to form in the center part of the length direction of the 2nd part 1b since joining property is electrically and physically stabilized.

Such a solid electrolytic capacitor 20 is produced by producing one long dielectric-covered valve metal sheet and the remaining short dielectric-coated valve metal sheet, and appropriately laminating them and then joining them at the joint Y ′. On the other hand, after the joined laminate is filled and coated with the solid electrolyte layer 5, the first portion 1a (anode lead portion) of one long dielectric-coated valve metal sheet is left in contact with the solid electrolyte layer 5. The insulating portion 9 is formed, and then the cathode lead layer 7 that covers the outer surface of the solid electrolyte layer 5 is formed. The first portion 1a of the dielectric-coated valve metal sheet is formed by the insulating portion 9 so that the solid electrolyte layer 5 In addition, it is formed so as to be exposed to the outside of the solid electrolytic capacitor 20 while being electrically insulated from the cathode lead layer 7, and even if the valve action metal substrate is covered with a dielectric film in the first portion 1a. , Except that may not be overturned, it can be produced in the same manner as in Embodiment 1.

In the solid electrolytic capacitor 20 ′ shown in FIG. 4B, in addition to one long dielectric-covered valve metal sheet, the remaining dielectric-coated valve metal sheet is also embedded in the insulating portion 9. Other points are the same as those of the solid electrolytic capacitor 20 shown in FIG.

Such a solid electrolytic capacitor 20 ′ can be manufactured in the same manner as the solid electrolytic capacitor 20. However, as in the first embodiment, before forming the junction Y ′, a plurality of dielectrics can be obtained using the insulating portion 9. It is preferable to fix the body-covered valve action metal sheet 1 ′ to each other (temporarily fix before forming the joint in the subsequent step). More specifically, after appropriately laminating one long dielectric coated valve metal sheet and the remaining short dielectric coated valve metal sheet, an insulating resin is applied across the dielectric coated valve metal sheet. Then, the insulating resins can be solidified or cured by heating or the like and fixed to each other.

In the solid

electrolytic capacitors

20 and 20 ′ of the present embodiment, the first portion 1a (anode lead portion) is used only for one dielectric-coated valve metal sheet among the plurality of dielectric-coated valve metal sheets 1 ′. Provided. The first portion 1a (anode lead portion) does not contribute to capacitance formation. That is, according to the present embodiment, the area occupied by the first portion 1a (anode lead portion) that does not contribute to capacitance formation can be made smaller than that of the solid electrolytic capacitor of the first embodiment. A solid electrolytic capacitor having a larger capacitance can be manufactured.

(Embodiment 3)
This embodiment is another modification of the first embodiment. In FIG. 5, the same members as those described in the first embodiment are denoted by the same reference numerals, and hereinafter, differences from the first embodiment will be mainly described. Unless otherwise noted, the same as in the first embodiment. The explanation is true.

In the solid electrolytic capacitor 30 shown in FIG. 5, the multilayer body 3 ″ includes a plurality of dielectric-coated valve metal sheets 1 ″ (in the illustrated example, six dielectric-coated valve metal sheets ″. The dielectric-coated valve metal sheet 1 ″ is joined only at the joint X. These dielectric-coated valve action metal sheets 1 '' are joined by a brazing material 17a (or a conductive material derived from the brazing material), whereby the valve action metal bases are electrically connected to each other via a joint portion. It is joined. For the plurality of dielectric-coated valve metal sheets 1 ″, the same description as that of the plurality of dielectric-coated valve metal sheets 1 in the first embodiment applies.

Such a solid electrolytic capacitor 30 can be manufactured in the same manner as in Embodiment 1 except that the joining at the joining portion Y is not performed.

In the solid electrolytic capacitor 30 of the present embodiment, no joint is provided in the second portion 1b (solid electrolyte layer covering portion). The second portion 1b (solid electrolyte layer covering portion) contributes to the formation of capacitance. That is, according to the present embodiment, the entire second portion 1b (solid electrolyte layer covering portion) that contributes to capacitance formation can be used for capacitance formation. Large solid electrolytic capacitors can be manufactured.

As mentioned above, although this invention was demonstrated by some embodiment, these embodiment can be variously changed. For example, the number, position, arrangement, and the like of the region (and thus the joint) to which the brazing material is applied may be appropriately set according to the requirements required for the solid electrolytic capacitor to be manufactured.

In addition, the present invention can be variously modified without departing from the basic concept. For example, the order in which steps (c) and (d) are performed can vary depending on the location of the joint. When at least one joining part exists in the 2nd part (solid electrolyte layer coating | coated part) of a dielectric coating valve action metal sheet, a process (d) is implemented after implementing a process (c). However, when all the joints are present in the first part (anode lead part) of the dielectric-coated valve metal sheet, the process (d) is performed after the process (c) is performed. Step (c) may be performed after (d) is performed.

The present invention can be widely used to manufacture a solid electrolytic capacitor that is required to have a small size and a large capacity. The solid electrolytic capacitor produced according to the present invention is not particularly limited in its use.

1, 1 ′, 1 ″ Dielectric coated valve metal sheet 1a First part (anode lead part)
1b Second part (solid electrolyte layer covering part)
3, 3 ', 3 "laminate (joined laminate)
DESCRIPTION OF SYMBOLS 5 Solid electrolyte layer 7 Cathode extraction layer 7a Carbon containing layer 7b Silver containing layer 9 Insulating

part

10, 10 ', 20, 20', 30 Solid electrolytic capacitor 11 Valve action metal base | substrate 13 Dielectric film 15

Mask

17a, 17b, 17b ' Brazing material X, Y, Y 'joint

Claims

A method for producing a solid electrolytic capacitor, comprising:
(A) applying a brazing material to a partial region of the surface of the dielectric-coated valve-acting metal sheet including the valve-acting metal substrate and a dielectric film covering the surface of the valve-acting metal substrate;
(B) A plurality of the dielectric-coated valve metal sheets are provided with gaps between the dielectric-coated valve metal sheets, and the positions of the regions where the brazing material of each dielectric-coated valve metal sheet is applied. Laminating to fit together to obtain a laminate of dielectric coated valve metal sheet,
(C) joining adjacent valve action metal substrates in the plurality of laminated dielectric-coated valve action metal sheets using a brazing material, thereby obtaining a laminated body, and (d) a solid A manufacturing method comprising a step of forming an electrolyte layer as a continuous layer so as to fill the gaps between dielectric-coated valve metal sheets in a laminate and to cover the outer surface of the laminate.
The manufacturing method according to claim 1, wherein the dielectric film is an oxide film, and the brazing material includes an additive having an action of removing the oxide.
A plurality of dielectric-coated valve metal sheets, and a laminate formed by bonding these dielectric-coated valve metal sheets;
Each of the dielectric-coated valve-acting metal sheets includes a continuous layer of a solid electrolyte layer that fills a gap between the dielectric-coated valve-acting metal sheets constituting the laminate and covers the outer surface of the laminate. The working metal substrate and a dielectric film that covers the surface of the valve metal substrate are bonded to each other in the plurality of laminated dielectric coated valve metal sheets that are adjacent to each other using a brazing material. A solid electrolytic capacitor in which a brazing material or a conductive material derived from the brazing material is electrically insulated from the solid electrolyte layer.
4. The dielectric material according to claim 3, wherein a dielectric is not interposed between the valve action metal substrate and the brazing material or the conductive material derived from the brazing material at a joint portion of the adjacent valve action metal substrates with the brazing material. Solid electrolytic capacitor.