Solid electrolytic capacitor and method for manufacturing same

A solid electrolytic capacitor that includes a plurality of linear conductors arranged in parallel and made of a valve action metal in which a dielectric layer is formed on a surface of the valve action metal; a conductive polymer layer covering the plurality of linear conductors and shared by linear conductors; a conductor layer covering conductive polymer layer; an anode terminal in contact with end faces of the plurality of linear conductors; and a cathode terminal electrically connected to conductor layer.

FIELD OF THE INVENTION

The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same, and more particularly to a solid electrolytic capacitor having a structure, in which a linear conductor made of a valve action metal is used as an anode-side element and a plurality of these linear conductors are arranged in parallel, and a method for manufacturing the same.

BACKGROUND OF THE INVENTION

Not only the solid electrolytic capacitor is used as a general capacitor in a decoupling circuit or a power supply circuit, but also the solid electrolytic capacitor is advantageously used as a noise filter that removes a high-frequency noise.

For example, Japanese Patent Laying-Open No. 6-196373 (PTL 1) discloses a solid electrolytic capacitor having an interest to the present invention. The solid electrolytic capacitor of PTL 1 includes a linear conductor made of a valve action metal functioning as an anode-side element.FIG. 19is a sectional view schematically illustrating a solid electrolytic capacitor1having the same basic configuration as the solid electrolytic capacitor of PTL 1.

With reference toFIG. 19, solid electrolytic capacitor1includes a linear conductor2made of the valve action metal. Linear conductor2includes a core3extending in an axial direction (a direction orthogonal to a paper surface inFIG. 19) of linear conductor2and a porous portion4covering a peripheral surface of core3and including a large number of pores. For example, etching is performed on the peripheral surface of linear conductor2formed of an aluminum wire to roughen the peripheral surface, thereby forming porous portion4.

Although not illustrated, a large number of pores including openings facing outward are formed in porous portion4. Although not illustrated, the dielectric layer is formed along the inner peripheral surface of the pores by oxidizing a surface of linear conductor2.

A conductive polymer layer5as a solid electrolyte is formed so as to cover linear conductor2with the dielectric layer interposed therebetween. A part of conductive polymer layer5is filled in the pores of porous portion4of linear conductor2.

A conductor layer6is formed so as to cover conductive polymer layer5. Although there is no specific description in PTL 1, in current products, conductor layer6often includes a carbon layer6aon conductive polymer layer5and a metal layer6bmade of, for example, silver on carbon layer6a.

An anode terminal7is electrically connected to core3of linear conductor2. On the other hand, a cathode terminal8is electrically connected to conductor layer6, more specifically, metal layer6b.

SUMMARY OF THE INVENTION

When the plurality of solid electrolytic capacitors1are used and connected in parallel, a lower equivalent series resistance (ESR) and a higher capacitance can be achieved. In this case, when downsizing and easy handling of components are pursued, as illustrated inFIG. 20, it is considered that a plurality of, for example, three linear conductors2are arranged in parallel to form a solid electrolytic capacitor1aas one component. InFIG. 20, the element corresponding to the element inFIG. 19is denoted by the same reference numeral, and the overlapping description will be omitted.

As illustrated inFIG. 20, in solid electrolytic capacitor1a, the cathode-side elements, namely, conductive polymer layer5, and carbon layer6aand metal layer6bas conductor layer7, are provided in relation to each of three linear conductors2. Three linear conductors2are arranged in parallel while the metal layers6bcovering adjacent linear conductors2are in contact with each other. InFIG. 20, a rectangle indicated by an alternate long and short dash line indicates a main body9of solid electrolytic capacitor1a, main body9being formed by covering linear conductor2, conductive polymer layer5, and conductor layer6with an insulating material. Although not illustrated, the anode terminal and the cathode terminal of solid electrolytic capacitor1aare provided so as to be exposed to an outer surface of main body9.

However, solid electrolytic capacitor1aofFIG. 20has a problem in that a ratio of a thickness of the cathode-side element to a product size is relatively large. For this reason, this obstructs the downsizing and high capacitance of solid electrolytic capacitor1a.

In order to manufacture solid electrolytic capacitor1a, it is necessary to perform a process of forming conductive polymer layer5and a conductor layer6including carbon layer6aand metal layer6bon each of the plurality of linear conductors2. Thus, an increase in the number of linear conductors2leads to an increase in the number of processes.

An object of the present invention is to provide a structure and a manufacturing method in which the number of manufacturing processes can be decreased while downsizing is achieved in a solid electrolytic capacitor including a plurality of linear conductors made of a valve action metal for proposal of achievement of a lower ESR and a higher capacitance.

In order to solve the above technical problem, according to one aspect of the present invention, a solid electrolytic capacitor includes a plurality of linear conductors arranged in parallel and made of a valve action metal in which a dielectric layer is formed on a surface of the valve action metal; a conductive polymer layer covering the plurality of linear conductors and shared by the plurality of linear conductors; a conductor layer covering the conductive polymer layer; an anode terminal in contact with end faces of the plurality of linear conductors; and a cathode terminal electrically connected to the conductor layer.

In this configuration, it is particularly noticed that the conductive polymer layer is formed so as to cover the plurality of linear conductors with the dielectric layer interposed therebetween while being shared by the linear conductors. With this configuration, volume efficiency is high, and the plurality of linear conductors can be arranged closer to each other than that of the capacitor ofFIG. 20.

In the solid electrolytic capacitor of the present invention, the conductive polymer layer is preferably formed so as to cover each linear conductor with the dielectric layer interposed therebetween. Alternatively, according to another aspect of the present invention, the conductor layer is formed so as to cover the plurality of linear conductors with the dielectric layer and the conductive polymer layer interposed therebetween while being shared by the linear conductors. With this configuration, the plurality of linear conductors can be arranged close to each other although the conductive polymer layer is interposed therebetween.

Preferably, the solid electrolytic capacitor of the present invention includes a rectangular parallelepiped-shaped main body formed by covering the plurality of linear conductors, the conductive polymer layer, and the conductor layer with an insulating material, the rectangular parallelopiped-shaped main body including a pair of end faces facing each other and a bottom surface adjacent to the end face. With this configuration, the solid electrolytic capacitor can be handled as a chip-shaped electronic component.

In the preferred embodiment, the solid electrolytic capacitor of the present invention is a three-terminal type solid electrolytic capacitor in which the pair of anode terminals is disposed on the pair of end faces of the main body, and the cathode terminal is disposed on the bottom surface of the main body, and which further includes an anode-side electric insulating member electrically insulating the anode terminal from the conductive polymer layer and the conductor layer.

On the other hand, in another preferred embodiment, the solid electrolytic capacitor of the present invention is a two-terminal type solid electrolytic capacitor in which the anode terminal is disposed on one of the end faces of the main body, and the cathode terminal is disposed on the other end face of the main body, and which further includes: an anode-side electric insulating member electrically insulating the anode terminal from the conductive polymer layer and the conductor layer; and a cathode-side electric insulating member electrically insulating the cathode terminal from the linear conductor, the conductive polymer layer and the conductor layer.

In the solid electrolytic capacitor of the present invention, preferably, the conductor layer has a laminated structure including a carbon layer in contact with the conductive polymer layer and a metal layer formed on the carbon layer. The metal layer can contribute to a decrease in ESR.

In the solid electrolytic capacitor of the present invention, preferably, each of the linear conductors includes a core extending in an axial direction of each of the linear conductors and a porous portion covering a peripheral surface of the core and including a large number of pores, and the dielectric layer extends along an inner peripheral surface of the pores of the porous portion. With this configuration, an area where the conductive polymer layer and the linear conductor are opposite to each other with the dielectric layer interposed therebetween can be enlarged, and a large static capacitance can be obtained.

In the solid electrolytic capacitor of the present invention, preferably, the anode terminal is in contact with the cores of the linear conductors. With this configuration, a conductive path length on an anode terminal side can be shortened, which can contribute to the decrease in ESR.

According to still another aspect of the present invention, a method for manufacturing a solid electrolytic capacitor includes: preparing a plurality of linear conductors arranged in parallel and made of a valve action metal in which a dielectric layer is formed on a surface of the valve action metal; covering the linear conductor with a conductive polymer layer; covering the conductive polymer layer with a conductor layer; providing an anode terminal to be in contact with an end face of the linear conductor; and providing a cathode terminal to be electrically connected to the conductor layer. With this configuration, the number of manufacturing processes can be decreased.

In the method for manufacturing a solid electrolytic capacitor according to the present invention, the step of forming the conductor layer with the plurality of linear conductors arranged in parallel does not exclude the step of forming the conductive polymer layer before the formation of the conductor layer.

In particular, when the linear conductor includes a core extending in an axial direction of the linear conductor and a porous portion covering a peripheral surface of the core and including a large number of pores, and when the dielectric layer to extend along an inner peripheral surface of the pores of the porous portion, the step of forming the conductive polymer layer is preferably performed on each linear conductor and with the plurality of linear conductors arranged in parallel. The step of filling a part of the conductive polymer layer with the pores of the porous portion is more efficiently performed on the individual linear conductor.

In the present invention, in the solid electrolytic capacitor including the plurality of linear conductors, the size can further be reduced, the number of manufacturing processes can be decreased, and cost can be reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference toFIGS. 1 to 4, a solid electrolytic capacitor11according to a first embodiment of the present invention will be described below.

Solid electrolytic capacitor11includes a rectangular parallelepiped-shaped main body15including a pair of end faces12and13opposite to each other and a bottom face14adjacent to end faces12and13. In solid electrolytic capacitor11that is a three-terminal type, a pair of anode terminals16and17are disposed on the pair of end faces12and13of main body15, and a cathode terminal18is disposed on bottom face14of main body15.

Solid electrolytic capacitor11includes a plurality of linear conductors19, for example, three linear conductors19made of a valve action metal. For example, aluminum, tantalum, niobium, titanium, or an alloy containing at least one of these is used as the valve action metal constituting linear conductor19. In the first embodiment, linear conductor19is a columnar shape. Preferably, an aluminum wire is used as linear conductor19because the aluminum wire is inexpensive and easily available.

Linear conductor19includes a core20extending in an axial direction of linear conductor19and a porous portion21covering a peripheral surface of core20and including a large number of pores. For example, etching is performed on the peripheral surface of linear conductor19formed of the aluminum wire to roughen the peripheral surface, thereby forming porous portion21. As schematically illustrated inFIGS. 3 and 4, a large number of pores22including openings facing outward are formed in porous portion21. InFIG. 2(A), a boundary between core20and porous portion21is indicated by a dotted line.

As illustrated inFIGS. 3 and 4, a dielectric layer23is formed on a surface of linear conductor19. For example, dielectric layer23is formed by oxidizing the surface of linear conductor19in which porous portion21is formed. InFIGS. 3 and 4, dielectric layer23is indicated by a bold line. Dielectric layer23is formed so as to extend along an inner peripheral surface of pore22of porous portion21.

Solid electrolytic capacitor11further includes a conductive polymer layer24as a solid electrolyte that covers linear conductor19with dielectric layer23interposed therebetween, and the conductive polymer layer is shared by three linear conductors19. Because dielectric layer23is formed along the inner peripheral surface of pores22of porous portion21, conductive polymer layer24is in contact with dielectric layer23over a wide area. Conductive polymer layer24is divided into a first conductive polymer layer24afilling pores22of porous portion21and a second conductive polymer layer24blocated on the outer peripheral surface of linear conductor19due to a manufacturing method (to be described later). Polythiophene, polyacetylene, polypyrrole, polyaniline, and the like that contain an anion as a dopant are used as a material for conductive polymer layer24.

In the state ofFIG. 2(A), three linear conductors19are arranged so as to be in contact with each other, but may slightly be separated from each other.

As described above, linear conductor19has a form in which the peripheral surface of core20is covered with porous portion21. Linear conductor19preferably has a columnar shape or a shape similar to the columnar shape, for example, an elliptic columnar shape, a flat columnar shape, or a shape in which a ridge portion of a prism is rounded. When linear conductor19has the columnar shape or a shape similar to the columnar shape, a corner does not exist on the peripheral surface of linear conductor19. For this reason, a formation property of conductive polymer layer24can be improved.

When the corner exists on the peripheral surface of linear conductor19, for example, a part of the corner cannot be covered with conductive polymer layer24, and linear conductor19is exposed, so that a capacitor failure is easily generated. Even when the corner is covered with conductive polymer layer24, a formed thickness becomes thinner at the corner and the flat portion becomes thicker, so that uniformity tends to be poor. For this reason, a height of solid electrolytic capacitor11is hardly reduced. In other words, the excellent formation property of conductive polymer layer24means that the thickness of conductive polymer layer24is excellent in uniformity. Thus, preferably, linear conductor19does not have the corner on the peripheral surface of linear conductor19. As used herein, the corner means a portion that is not rounded like an acute angle or an obtuse angle.

When linear conductor19has the columnar shape, the entire circumferential surface of linear conductor19can be used as a capacitance appearance portion, so that an area of the capacitance appearance portion can be expanded about 1.5 times a metal foil such as an aluminum foil.

Solid electrolytic capacitor11further includes a conductor layer25that covers conductive polymer layer24. In the first embodiment, conductor layer25has a laminated structure including a carbon layer25acontacting with conductive polymer layer24and a metal layer25bformed on carbon layer25a. For example, metal layer25bis made of a conductive resin in which powder of silver, nickel, copper, tin, gold, palladium, or the like are dispersed in resin. Alternatively, metal layer25bmay be formed of a plating film made of, for example, silver, nickel, copper, or tin. As in an embodiment described below with reference toFIGS. 8 and 9, conductor layer25may have a single-layer structure.

Main body15of solid electrolytic capacitor11is formed by covering, with an insulating material, three linear conductors19, and conductive polymer layer24and conductor layer25that are provided in association with each of linear conductors19. The insulating material includes a substrate26holding cathode terminal18and a sealing material27including an insulating resin covering conductor layer25.

Cathode terminal18is provided so as to penetrate substrate26in a thickness direction, contacts with metal layer25bof conductor layer25on an upper main surface side of substrate26, and exposed to the bottom of main body15on a lower main surface side of substrate26. Although not illustrated, cathode terminal18and metal layer25bare bonded together with a conductive adhesive. For example, an adhesive containing a filler of silver, nickel, copper, tin, gold, or palladium and resin such as epoxy and phenol is used as the conductive adhesive. Welding may be applied instead of the conductive adhesive.

For example, a printed board is used as substrate26. Sealing material27may include a filler of alumina or silica or a magnetic material in addition to the resin. When sealing material27contains the filler, mechanical strength and workability of sealing material27can be adjusted. Heat shrinkability can be adjusted by selecting the filler having a desired coefficient of linear expansion. When sealing material27contains the magnetic material, an impedance of the capacitor can intentionally be increased. For example, there is a possibility of generating anti-resonance when a plurality of low-impedance capacitors are mounted in parallel. At this point, when sealing material27contains the magnetic material, the generation of the anti-resonance can be prevented. For example, magnetic powder such as iron powder, powder of an alloy containing iron, and powder of ferrite is used as the magnetic material. The magnetic material may be a mixture of powders having different particle sizes or at least two kinds of powders having different compositions. In this way, the desired filler or magnetic material can be selected and used according to a required function.

As illustrated inFIG. 2(B), both end faces of linear conductor19are exposed from sealing material27, and contact with the pair of anode terminals16and17on the pair of end faces12and13of main body15, respectively, thereby achieving electric connection. For example, anode terminals16and17are formed of a conductive resin film containing at least one of silver, copper, nickel, tin, gold and palladium as a conductive component and an epoxy resin or a phenol resin as a resin component.

As a modification, anode terminals16and17may be formed of a plating film containing metal such as nickel, zinc, copper, tin, gold, silver or palladium or an alloy containing at least one kind of these metals, and formed on the end face of core20of linear conductor19. Alternatively, anode terminals16and17may have a multilayer structure including a conductive resin film and a plating film. Anode terminals16and17may include two plating layers and a conductive resin layer between the plating layers.

An anode-side electric insulating member28made of an electric insulating resin is disposed between conductive polymer layer24and anode terminals16and17. For example, an epoxy resin, a phenol resin, a polyimide resin, and the like are used to form anode-side electric insulating member28. Anode-side electric insulating member28can reliably achieve an electric insulation state between conductive polymer layer24and conductor layer25and anode terminals16and17. In the first embodiment, as illustrated inFIG. 4, in a portion in which anode-side electric insulating member28is in contact with core20, anode-side electric insulating member28is provided so as to fill pores22of porous portion21.

As a modification, at both the ends of linear conductor19, anode-side electric insulating member28may be provided so as to contact with core20with porous portion21removed to expose core20.

In both of these cases described above, anode-side electric insulating member28is in contact with core20. With this configuration, for example, when wet plating is applied to form anode terminals16and17, inconvenience that a plating solution permeates through and remains in porous portion21can hardly be generated. Conductive polymer layer24and conductor layer25may extend toward anode terminals16and17as long as conductive polymer layer24and conductor layer25do not come into contact with anode terminals16and17, and may overlap anode-side electric insulating member28.

In solid electrolytic capacitor1aofFIG. 20, for example, it is assumed that a wire-shaped linear conductor2having a diameter of 0.3 mm is used. When a portion of conductive polymer layer5, the portion protruding from the outer peripheral surface of the linear conductor2has the thickness of 0.01 mm, when a carbon layer6ahas the thickness of 0.02 mm, and when the metal layer6bhas the thickness of 0.02 mm, the diameter of one linear conductor2becomes 0.3 mm+(0.01 mm+0.02 mm+0.02 mm)×2=0.4 mm. Thus, when three linear conductors2are arranged in parallel, a total dimension in the arrangement direction becomes 0.4 mm×3=1.2 mm.

On the other hand, for solid electrolytic capacitor11of the first embodiment, the total dimension of three linear conductors19in the arrangement direction becomes 0.3 mm×3+(0.01 mm+0.02 mm+0.02 mm)×2=1.0 mm, which means that downsizing can be achieved.

Further, in solid electrolytic capacitor11of the first embodiment, the pair of anode terminals16and17is disposed on the pair of end faces12and13of main body15, and both the end faces of core20in linear conductor19are in contact with the pair of anode terminals16and17, so that a conductive path length on the sides of anode terminals16and17can be shortened. Thus, a parasitic inductance generated in the conductive paths on the sides of anode terminals16and17can be decreased, and noise removal performance of solid electrolytic capacitor11can be enhanced in a high-frequency band (ωL).

Anode terminals16and17that do not contribute to capacitance formation are disposed on end faces12and13of main body15, and the end faces of core20of linear conductor19directly contact with anode terminals16and17, so that a ratio of the members that do not contribute to the capacitance formation to a total volume is relatively low and volume efficiency is high. For this reason, solid electrolytic capacitor11of the first embodiment is suitable for the downsizing and large capacitance. Thus, the high noise removal performance can be exhibited even in the frequency band (1/ωC) due to the capacitance.

As described above, in solid electrolytic capacitor11, the high noise removal performance can be exhibited in the wide frequency band including the high frequency band caused by inductance and the frequency band caused by capacitance.

Both the end faces of core20of linear conductor19are in relatively large surface contact with the pair of anode terminals16and17, so that a resistance can be kept low in the electrical connection portion between core20of linear conductor19and anode terminals16and17. For this reason, a large current can be passed through solid electrolytic capacitor11.

The conductive path length made on the side of cathode terminal18is relatively short, so that the parasitic inductance generated in the conductive path can be decreased.

FIG. 5illustrates a second embodiment of the present invention, and is a view corresponding toFIG. 2(B). InFIG. 5, the element corresponding to the element inFIG. 2(B)is denoted by the same reference numeral, and the overlapping description will be omitted.

One of the features of a solid electrolytic capacitor11ainFIG. 5is that a cathode terminal18ais made of a metal plate provided in the form of, for example, a lead frame. For this reason, the substrate such as the printed board is not used as the insulating material constituting main body15, but only sealing material27is used.

FIGS. 6 to 9illustrate third to sixth embodiments of the present invention, respectively. InFIGS. 6 to 9illustrate portions corresponding to linear conductor19, conductive polymer layer24, and conductor layer25inFIG. 2(A). InFIGS. 6 to 9, the element corresponding to the element inFIG. 2(A)is denoted by the same reference numeral, and the overlapping description will be omitted.

In the first embodiment, conductive polymer layer24and the elements outside conductive polymer layer24are shared by three linear conductors19. In the first embodiment, there is a concern that an equivalent series resistance (ESR) becomes higher than that of other embodiments, but the highest volume efficiency can be achieved.

On the other hand, carbon layer25aand the elements outside carbon layer25aare shared in the third embodiment ofFIG. 6. In the state ofFIG. 6, conductive polymer layers24located on three linear conductors19are arranged so as to be in contact with each other, but may slightly be separated from each other.

Metal layer25bis shared in the fourth embodiment ofFIG. 7. In the state ofFIG. 7, carbon layers25aeach independently covering three linear conductors19are arranged so as to be in contact with each other, but may slightly be separated from each other. In the fourth embodiment, the ESR can further be decreased although the volume efficiency is inferior to that of the first and third embodiments.

In the fifth embodiment ofFIG. 8, as in the first embodiment, although conductive polymer layer24and the elements outside conductive polymer layer24are shared, conductor layer25outside conductive polymer layer24has a single-layer structure. Conductor layer25is form of a conductive resin or a plating film. A resin obtained by mixing carbon and silver, or silver, nickel, copper, or tin as a filler is used as the conductive resin. A film made of silver, nickel, copper, or tin is used as the plating film. In the state ofFIG. 8, three linear conductors19are arranged so as to be in contact with each other, but may slightly be separated from each other.

Conductor layer25outside conductive polymer layer24is shared in the sixth embodiment ofFIG. 9. Shared conductor layer25is made of a conductive resin. A resin obtained by mixing carbon and silver, or silver, nickel, copper, or tin as a filler is used as the conductive resin. In the state ofFIG. 9, conductive polymer layers24each independently on three linear conductors19are arranged so as to be in contact with each other, but may slightly be separated from each other.

FIG. 10illustrates a seventh embodiment of the present invention, and is a view corresponding toFIG. 2(B). InFIG. 10, the element corresponding to the element inFIG. 2(B)is denoted by the same reference numeral, and the overlapping description will be omitted.

For example, solid electrolytic capacitor11inFIG. 2(A)is a three-terminal type, whereas a solid electrolytic capacitor11binFIG. 10is a two-terminal type. In solid electrolytic capacitor11b, anode terminal16is disposed on one end face12of main body15, and a cathode terminal18bis disposed on the other end face13of main body15. Cathode-side electric insulating member29electrically insulating cathode terminal18bfrom linear conductor19, conductive polymer layer24, and conductor layer25is provided along end face13of main body15in addition to anode-side electric insulating member28electrically insulating anode terminal16from conductive polymer layer24and conductor layer25. Cathode-side electric insulating member29is formed by applying an insulating resin to end face13of main body15. For example, an epoxy resin or a phenol resin is used as the insulating resin, and a filler may be mixed in the insulating resin. Dipping, printing, spraying, transfer, and the like are applied as an application method.

In solid electrolytic capacitor11b, cathode terminal18bis electrically connected to conductor layer25with connection conductor30interposed therebetween, connection conductor30penetrating substrate26in the thickness direction. A dummy conductor31is formed on the lower surface of substrate26on the side of end face12. The thickness increase due to dummy conductor31is equivalent to the thickness increase brought to the lower surface side of substrate26by connection conductor30.

With reference toFIGS. 11(A) through 18(B), a method for manufacturing a solid electrolytic capacitor will be described below. At this point, in particular, the method for manufacturing solid electrolytic capacitor11described with reference toFIGS. 1 to 4will be taken up.

As illustrated inFIGS. 11(A) and 11(B), linear conductor19is prepared. The length of linear conductor19inFIG. 11(A)is longer than the length of one linear conductor19inFIG. 2(B), and it is expected that linear conductor19will be cut in a later process. In linear conductor19, etching is performed to form porous portion21as illustrated inFIG. 11(B), and dielectric layer23(seeFIGS. 3 and 4) formed by anodic oxidation is formed.

Subsequently, as illustrated inFIG. 12(A), anode-side electric insulating members28are formed on linear conductors19at predetermined intervals. As illustrated inFIG. 12(B), anode-side electric insulating member28becomes the state in which pores22(seeFIGS. 3 and 4) of porous portion21are filled. Anode-side electric insulating member28is formed by masking a position other than a desired formation position, applying the insulating resin by a method such as dispensing, dipping, printing, transferring, spraying, and the like, and drying the insulating resin.

Subsequently, as illustrated inFIG. 13(A), in conductive polymer layers24, first conductive polymer layer24ais formed in a region other than the region where anode-side electric insulating member28is formed on linear conductor19. As illustrated inFIG. 13(B), first conductive polymer layer24abecomes the state in which pores22(seeFIGS. 3 and 4) of porous portion21is filled.

First conductive polymer layer24ais formed by masking a position other than a desired formation position, applying a material for first conductive polymer layer24aby a method such as dispensing, dipping, printing, transferring, spraying, and the like, and drying the material. At this point, a chemical oxidative polymerization in which a monomer that is a precursor of a polymer and a reaction solution containing a dopant and an oxidant are alternately applied to perform a polymerization reaction, an electrolytic polymerization in which an electrochemical polymerization reaction is performed in the reaction solution, or a method for applying a solution in which a conductive polymer previously exhibiting conductivity is dissolved or dispersed in an arbitrary solvent can be applied.

The process of forming first conductive polymer layer24ainFIG. 13may be performed while three linear conductors19are arranged in parallel as illustrated inFIG. 14.

Subsequently, as illustrated inFIGS. 15(A) and 15(B), in order that the thickness of conductive polymer layer24is increased and first conductive polymer layer24aseparately formed on separate linear conductor19are connected in parallel, second conductive polymer layer24bis formed so as to commonly overlap the region where first conductive polymer layer24ais formed on three linear conductors19arranged in parallel.

Second conductive polymer layer24bis formed by masking a position other than a desired formation position, applying a material for second conductive polymer layer24bby a method such as dispensing, dipping, printing, transferring, spraying, and the like, and drying the material. For second conductive polymer layer24b, similarly to the case of first conductive polymer layer24a, a chemical oxidative polymerization in which a monomer that is a precursor of a polymer and a reaction solution containing a dopant and an oxidant are alternately applied to perform a polymerization reaction, an electrolytic polymerization in which an electrochemical polymerization reaction is performed in the reaction solution, or a method for applying a solution in which a conductive polymer previously exhibiting conductivity is dissolved or dispersed in an arbitrary solvent can be applied.

As described above, a configuration in which conductive polymer layer24is shared by three linear conductors19is obtained.

Subsequently, as illustrated inFIGS. 16(A) and 16(B), carbon layer25aand metal layer25bare sequentially formed on the region where conductive polymer layer24is formed, thereby forming conductor layer25. Each of carbon layer25aand metal layer25bis formed by applying the process of masking a position other than a desired formation position, applying the conductive resin and a plating solution by a method such as dispensing, dipping, printing, transferring, spraying, and the like, and drying them.

Subsequently, a structure32inFIG. 16is placed on substrate26, and cathode terminal18and conductor layer25are bonded together by, for example, a conductive adhesive. Structure32inFIG. 16is indicated by an alternate long and short dash line inFIG. 17.

Subsequently, as illustrated inFIG. 18, resin sealing is performed so as to cover substrate26, and thereby forming sealing material27. Transfer molding, compression molding, thermocompression bonding, or the like is applied to form sealing material27.

As described above, in molding sealing material27, an external stress applied to linear conductor19is advantageously dispersed because linear conductor19has a cylindrical shape. Thus, during the molding of sealing material27, a situation in which linear conductor19is damaged can advantageously be avoided.

When linear conductor19has a columnar shape, sealing material27has an excellent filling property. Thus, because sealing material27has a high packaging effect, a barrier property against moisture and air is high, and obtained solid electrolytic capacitor11has excellent moisture resistance and heat resistance.

Subsequently a cutting process along cutting lines33and34illustrated by an alternate long and short dash line inFIG. 18is performed using, for example, a dicer or a laser. Main body15for a plurality of solid electrolytic capacitors11is obtained through the cutting process. At this point, a cut surface that appears by cutting along a cutting line33constitutes end faces12and13of main body15. As can be seen fromFIG. 18(B), cathode terminal18is exposed on bottom surface14of main body15.

Subsequently, anode terminals16and17are formed so as to be connected to both the end faces of linear conductor19exposed to end faces12and13of main body15. In order to form anode terminals16and17, for example, a conductive resin is prepared, and dipping, spraying, transfer, or the like is applied. A plating film may further be formed on the conductive resin film formed in this way.

As described above, the method for manufacturing solid electrolytic capacitor11of the first embodiment is described as the method for manufacturing a solid electrolytic capacitor. However, a basic configuration of the manufacturing method can also be applied to a method for manufacturing the solid electrolytic capacitor of other embodiments.

For example, in the method for manufacturing the solid electrolytic capacitor of the second embodiment inFIG. 5, a lead frame functioning as cathode terminal18ais used instead of substrate26holding cathode terminal18in processes at and after the process inFIG. 17.

In the method for manufacturing the solid electrolytic capacitor of the third to sixth embodiments inFIGS. 6 to 9, similarly to the same method as the method for manufacturing solid electrolytic capacitor11of the first embodiment, three linear conductors19are arranged in parallel in performing the process of forming the shared element.

As described above, the present invention is described above in reference to the illustrated embodiments. However, these embodiments are merely examples, and it is understood that partial replacement or combination of the configurations between different embodiments can be made.

REFERENCE SIGNS LIST