KR20060095995A - Production method of a capacitor - Google Patents

Abstract

The present invention relates to a method for producing a capacitor comprising, as one electrode, an electric conductor having formed on the surface thereof a dielectric layer and, as the other electrode, a semiconductor layer formed on the electric conductor by energization using the electric conductor as the anode, wherein fine protrusions are formed on the dielectric layer before energization; a capacitor produced by the method thereof having a good capacitance appearance factor and a low ESR; and an electronic circuit and an electronic device using the capacitor.

Description

Production Method of Capacitor {PRODUCTION METHOD OF A CAPACITOR}

The present invention relates to a capacitor having a good capacity emergence rate and low ESR.

Condensers used in circuits related to central processing units (CPUs), such as personal computers, have high capacity and low ESR (equivalent series resistance) to suppress voltage fluctuations and reduce the generation of heat during the passage of high ripple currents. Is required. Generally, aluminum or tantalum solid electrolytic capacitors are used.

The solid electrolytic capacitor provides an aluminum foil having micropores in the surface layer or a tantalum powder sintered body having micropores therein as one electrode (conductor), and the dielectric layer formed on the surface layer of the electrode and the other formed on the dielectric layer. It consists of an electrode (usually a semiconductor layer) of the side.

The ratio of the semiconductor layer formed on the dielectric layer is represented by the impregnation rate defined by the ratio (percentage) of the capacity when the semiconductor layer is formed, assuming that the capacity that appears when the electrolyte solution is impregnated instead of the semiconductor is 100%.

One method of forming a semiconductor layer on a dielectric layer is a method of forming a semiconductor layer by energization. For example, a method of forming a metal oxide by direct current energization (Japanese Patent No. 1,985,056), a method of obtaining a semiconductor layer containing a conductive compound by alternating current energization (Japanese Patent No. 2,826,341), and a transfer by direct current energization (Method of Japanese Patent No. 3,284,993) or a semiconductor containing a conductive polymer by direct current contacting an external electrode prepared separately on a previously formed chemical polymerization layer. The method of obtaining a layer (Japanese Patent No. 1,988,457) is mentioned.

According to the methods of Japanese Patent Nos. 1,985,056 and 2,826,341, ESR is good, but a long time is required to form a semiconductor layer and the impregnation rate cannot be increased within a normal time.

The method of Japanese Patent No. 2,826,341 requires a counter electrode to form a semiconductor layer simultaneously on several conductors on an industrial scale, but has a drawback that the semiconductor layer also adheres to the counter electrode.

In addition, in the methods of Japanese Patent Nos. 3,284,993 and 1,988,457, when these methods are applied to simultaneously form a semiconductor layer on several conductors, the semiconductor layer is formed on some conductors by energization caused by interference of the chemically polymerized layer. Although the impregnation rate is large even when the layer is not well formed and the semiconductor layer is well formed, there is a disadvantage that a good ESR value cannot be obtained because the chemical polymerization layer is formed.

Therefore, there is a need for a method of manufacturing a capacitor with improved ESR and increased capacity.

The present inventors have diligently studied to solve these problems, and have found that such a problem can be solved by forming a unique microprojection on the dielectric without forming a chemical polymerization layer. The present invention has been completed based on this finding.

That is, this invention relates to the manufacturing method of the following capacitor, and the capacitor manufactured by the manufacturing method.

1. A manufacturing method comprising a semiconductor layer formed on a conductor by an electric current using a conductor having a dielectric layer formed on its surface as an electrode, and an electrode formed on the conductor by an electric current. Method of manufacturing a capacitor to form a.

2. The method for producing a capacitor according to 1, wherein the minute protrusions are island shape and / or feather shape.

3. The manufacturing method of the capacitor | condenser of 1 or 2 whose width | variety of a microprotrusion is 0.1-60 nm.

4. The method for producing a capacitor according to any one of items 1 to 3, wherein most of the micro projections are present on the inner pore surface within 10 µm from the outer surface and the outer surface of the conductor.

5. The method for producing a capacitor according to any one of 1 to 4, wherein the minute protrusions are at least one selected from metal oxides, metal salts, transition element-containing inorganic compounds, transition element-containing organic compounds, and polymer compounds.

6. The method for producing a capacitor according to 1, wherein the conductor is at least one selected from metals, inorganic semiconductors, organic semiconductors and carbon, or mixtures thereof.

7. The method for producing a capacitor according to any one of 1 to 6, wherein the conductor is a laminate having at least one selected from a metal, an inorganic semiconductor, an organic semiconductor and carbon, or a mixture thereof as a surface layer.

8. The method of manufacturing a capacitor according to 1, wherein the dielectric layer is one kind selected from metal oxides.

9. The method of manufacturing a capacitor according to 9. 8, wherein the dielectric layer has at least one selected from metal oxides such as Ta ₂ O ₅ , Al ₂ O ₃ , TiO _2, and Nb ₂ O ₅ .

10. The method of manufacturing a capacitor according to 1 1, wherein the semiconductor layer is at least one selected from an organic semiconductor layer and an inorganic semiconductor layer.

11. The organic semiconductor according to 11. 10 is an organic semiconductor consisting of benzopyrroline tetramer and chloranyl, an organic semiconductor having tetrathiotetracene as a main component, an organic semiconductor having tetracyanoquinomimethane as a main component, and the following formula (1) Or a method for producing a capacitor of at least one type selected from organic semiconductors containing a conductive polymer as a main component obtained by doping a polymer containing a repeating unit represented by formula (2):

Wherein R ¹ to R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, X represents an oxygen atom, a sulfur atom or a nitrogen atom, and R ⁵ represents only when X is a nitrogen atom It exists and represents a hydrogen atom or a C1-C6 alkyl group, and each of R <^1> and R <^2> , R <^3> and R <^4> may combine with each other, and may form ring structure.

The manufacturing method of the capacitor | condenser of 12.11 whose conductive polymer containing the repeating unit represented by Formula (1) is a conductive polymer containing the structural unit represented by following formula (3) as a repeating unit:

Wherein each of R ⁶ and R ⁷ independently contains a hydrogen atom, a linear or branched phase, a saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or two oxygen atoms when the alkyl group is bonded to each other at any position; Substituents for forming one 5-, 6- or 7-membered ring saturated hydrocarbon ring structure are shown, and the ring structure may include a structure having a vinylene bond which may be substituted and a phenylene structure which may be substituted.

13. The method of claim 11 wherein the conductive polymer is selected from polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives and copolymers thereof.

14. The method for producing a capacitor according to 12 or 13, wherein the conductive polymer is poly (3,4-ethylenedioxythiophene).

15. The method for producing a capacitor according to 10, wherein the inorganic semiconductor is at least one selected from molybdenum dioxide, tungsten dioxide, lead dioxide and manganese dioxide.

16. The method of manufacturing a capacitor according to 10, wherein the conductivity of the semiconductor is 10 ⁻² to 10 ³ S / cm.

17. The capacitor manufactured by the manufacturing method in any one of 1-16.

18. The capacitor of 17, wherein the impregnation rate of the semiconductor is at least 85%.

19. An electronic circuit using the capacitor described in 17 or 18.

20. Electronic equipment using the capacitor of 17 or 18.

The manufacturing method of the capacitor | condenser of this invention, and embodiment of a capacitor | condenser are mentioned later.

Examples of the conductor used in the present invention include at least one selected from a laminate obtained by laminating such a conductor with a metal, an inorganic semiconductor, an organic semiconductor and carbon, a mixture thereof, or a surface layer.

Examples of the inorganic semiconductors include metal oxides such as lead dioxide, molybdenum dioxide, tungsten dioxide, niobium monoxide, tin dioxide and zirconium monoxide. Examples of organic semiconductors include conductive polymers such as polypyrrole, polythiophene, polyaniline and substituents or copolymers having such a polymer backbone, complexes of tetracyanoquinomethane and tetrathiotetracene, and tetracyanoquinomethane (TCNQ). And low molecular weight complexes such as salts. As a laminated body obtained by laminating | stacking a conductor in surface layer, the laminated body which laminated | stacked the conductor described above on paper, an insulating polymer, glass, etc. is mentioned.

In the case where a metal is used as the conductor, at least one treatment selected from carbonization, ignition, boronization, nitriding, and sulfidation is performed after a part thereof in order to improve the capacitor characteristics, for example, to reduce the LC value. Can be used.

The shape of the conductor is not particularly limited, and may be in the form of foil, plate or bar, or may be used after shaping or molding the powder conductor and then sintering. Further, the conductor may be subjected to surface treatment such as etching to have fine pores. In particular, since the capacity per unit volume of the capacitor is increased, a conductor having a surface area increased by surface treatment to have a powder conductor and micropores in the form of a sintered body is preferable. When the powder conductor is sintered after molding or molding, the pressure at the time of molding can be appropriately selected to form micropores inside the molded or sintered conductor.

According to the method of the present invention in which the micro projections are formed on the dielectric layer before the energization for forming the semiconductor layer, the impregnation rate of the semiconductor can be increased.

It is particularly effective to apply the method of the present invention to a conductor which is difficult to obtain a semiconductor having a high impregnation rate. For example, as a conductor having a sintered body shape, in the case of a sintered body of tantalum metal powder material, the CV value (the product of capacity and chemical conversion voltage as measured by electrolyte) is 100,000 Pa · V / g or more, and niobium metal In the case of the sintered compact of a powder material, it is effective to apply it to the conductor which has a CV value of 170,000 Pa.V / g or more and the magnitude | size of 5 mm <^3> or more. As an etched thin conductor, it is effective to apply it to the conductor whose CV value is 1,000 Pa.V / cm <^2> or more, and the pore depth by etching is 200 micrometers or more.

The conductor can be directly connected to the lead wire. In the case of sintering the powder conductor after molding or molding, a part of the separately produced lead lead (lead wire or lead foil) is molded together with the conductor, and the outside of the lead lead is used as the lead lead of one electrode of the capacitor. Can be.

Examples of the dielectric layer formed on the surface of the conductor of the present invention include a dielectric layer mainly composed of one or more selected from metal oxides such as Ta ₂ O ₅ , Al ₂ O ₃ , TiO ₂ and Nb ₂ O ₅ , or a ceramic capacitor or Conventionally known dielectric layers are mentioned in the field of membrane capacitors. In the case of the former dielectric layer having at least one selected from the metal oxide as a main component, when a conductor having a metal element of a metal oxide is formed in an electrolyte containing a mineral acid or an organic acid to form a dielectric layer, the obtained capacitor has polarity electrolysis. It becomes a capacitor. Examples of dielectric layers conventionally known in the field of ceramics or membrane capacitors include the dielectric layers described in Japanese Patent Laid-Open No. 63-29919 and Japanese Patent Laid-Open No. 63-34917. A dielectric layer mainly composed of one or more selected from metal oxides, dielectric layers conventionally known in the field of ceramics or film capacitors may be laminated and used in multiple layers. Moreover, you may mix the dielectric layer which has at least 1 sort (s) selected from a metal oxide, and the dielectric layer conventionally known in the field of a ceramic or a film capacitor.

In the present invention, it is important to form micro projections on the dielectric layer as a pretreatment for increasing the formation ratio of the semiconductor layer.

The material for forming the micro projections on the dielectric layer may be at least one material selected from inorganic or organic materials. Examples of the inorganic material include conventionally known metal oxides, metal salts and transition element-containing inorganic compounds. Examples of the organic material include salts of organic acids or organic bases, transition element-containing organic compounds, and polymer compounds. The inorganic or organic material may be an insulator, a semiconductor, or a conductor, but a semiconductor or conductor having a conductivity of 10 ^-2 to 10 ³ S / cm is preferable in order to produce a capacitor having a small ESR value. When the material for forming the microprojections covers the entire surface of the dielectric layer to form a layer, the ESR value of the manufactured capacitor becomes large, which is not preferable. Inorganic or organic materials may be contacted with a conductor having a dielectric layer on its surface to form various microprojections on the dielectric material. In the case where the inorganic or organic material is a solid, the solution obtained by dissolving the material in a suitable solvent can be contacted with a conductor, and then the solvent is evaporated to dryness to form a microprojection. Instead of the solution, a sol in which the microprotrusion material is dispersed may be used. In addition, a fine protrusion may be produced by reacting a precursor of an organic or inorganic material on a conductor.

Although the shape of the micro-projections formed on the dielectric layer varies, the grain shape, the island shape, the feather shape, and a mixture of these shapes are preferable because a capacitor having a low ESR value and a good impregnation rate can be produced. Although the size of the microprojections varies depending on the shape thereof, in the case of a grain- or island-like microprojection, the width and height are about 0.1 to 120 nm, preferably about 0.5 to 60 nm, more preferably about 1 to 30 nm, In the case of a feather-like microprotrusion, the width is almost the same as that of the granular or island-like microprotrusion and the height (length) is about 0.1 to 600 nm, preferably 1 to 120 nm.

In the case of a shape in which the conductor has a molded or sintered body or etched pores, the part where most of the fine protrusions (50% or more, preferably 80% or more) exists can be visually confirmed by the outer surface (scanning electron microscope (SEM)). The outer surface does not contain internal pores) and the inside (this part can be confirmed by SEM observation of a broken conductor within 10 μm from the outer surface; FIG. 4 shows the original surface of the fracture surface of the sintered body formed in Example 2 described later). Is a SEM photograph of 50,000 magnification showing a portion within 3 µm.

As the formation rate of the micro-projections, when the SEM photograph of 100,000 magnification is observed, it is an average of 10 observation points at about 300 nm ² , and 1 to 1,000 micro projections having a short width of 1 to 10 nm per 300 nm ² plane are more preferable. Is 3 to 100.

Each of Fig. 1 (Example 3) and Fig. 2 (Example 2) is an SEM photograph (100,000 magnification) showing one example of the microprotrusions (microprotrusions prepared in the examples and comparative examples described later) of the present invention. . 3 (Comparative Example 2) is an SEM photograph (100,000 magnification) showing a surface on which projections are not formed. 1 and 2, the dielectric layer is formed on the surface of the conductor in the shape of a sintered body, and in FIG. 1, microscopic projections of island shape and projections of feather or island shape in FIG. 2 can be observed.

In the present invention, as described above, the semiconductor layer is formed on the dielectric layer of the conductor by energization using the conductor having the microprojections as the anode. At this time, since the dielectric layer of the portion where the minute projections are formed is unstable, current easily flows, and the semiconductor layer is satisfactorily formed in a relatively short time. As a result, a capacitor having a good ESR value, a high impregnation rate, and a good capacity appearance rate can be obtained.

In addition, since the projections are minute, the increase in the electrical resistance is small due to the presence of the minute projections. In addition, because the projections are minute, impregnation of the semiconductor is not suppressed.

At least one compound selected from organic semiconductors and inorganic semiconductors is used as the semiconductor formed by energization on the dielectric layer of the conductor having the micro-projections of the present invention.

Specific examples of the organic semiconductors include organic semiconductors mainly composed of a conductive polymer obtained by doping a polymer with a repeating unit represented by the following formula (1) or (2):

Wherein each of R ¹ to R ⁴ independently represents a hydrogen atom, an alkyl group of 1 to 6 carbon atoms or an alkoxy group of 1 to 6 carbon atoms, X represents an oxygen atom, a sulfur atom or a nitrogen atom, and R ⁵ represents a nitrogen atom It exists only at and represents a hydrogen atom or a C1-C6 alkyl group, and each of R <^1> and R <^2> , R <^3> and R <^4> pair may combine with each other, and may form ring structure.

As for the conductive polymer containing the repeating unit represented by Formula (1) used by this invention, the conductive polymer containing the structural unit represented by Formula (3) as a repeating unit is preferable:

Wherein each of R ⁶ and R ⁷ independently contains a hydrogen atom, a linear or branched phase, a saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or two oxygen atoms when the alkyl group is bonded to each other at an arbitrary position; And a substituent for forming one 5-, 6-, or 7-membered saturated hydrocarbon ring structure. Examples of the ring structure include a structure having a vinylene bond which may be substituted and a phenylene structure which may be substituted.

Conductive polymers containing such chemical structures are charged and dopants are doped. The dopant is not particularly limited but known dopants may be used.

Examples of the polymer containing the repeating unit represented by formulas (1) to (3) include polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives; The copolymer is mentioned. Of these, polypyrrole, polythiophene and substituted derivatives (for example, poly (3,4-ethylenedioxythiophene) are preferable.

Specific examples of the inorganic semiconductor include at least one compound selected from molybdenum dioxide, tungsten dioxide, lead dioxide, manganese dioxide and the like.

In the case where the conductivity of the organic or inorganic semiconductor used is 10 ^-2 to 10 ³ S / cm, the manufactured capacitor is preferable because the ESR value is small.

An example of a method of forming a semiconductor layer on a conductor is described below. The semiconductor layer is formed by immersing a conductor having a minute protrusion in a separately prepared semiconductor layer forming solution and using a conductor as an anode to allow current to flow through the anode disposed in the semiconductor layer forming solution. The energization method includes a constant voltage method, a constant current method, and a combination thereof. However, the constant current method is preferable because the semiconductor layer can be stably formed when a current is flowed through various conductors simultaneously to form a semiconductor layer.

The energization time and the predetermined current value vary depending on, for example, the type, size and density of the conductors used, the type and thickness of the dielectric layer formed, or the type of semiconductor layer formed, and these are determined by performing a preliminary experiment. As a method for preliminary experiments, the appropriateness of the predetermined constant current value can be determined by adjusting the mass of the semiconductor layer. An example is a method of plotting the mass of the semiconductor with respect to the energization time in advance for each constant current value, and selecting the constant current value when the plot reaches the saturation value and becomes the maximum of the mass of the semiconductor.

In the case of using the constant current method, the initial voltage value in energization is a value determined by a predetermined constant current value. When the dielectric layer is formed by the above-mentioned chemical conversion, the initial voltage value may exceed the chemical voltage.

Known dopants such as raw materials that act as semiconductors after energization, and the above-described dopants (for example, arylsulfonic acid and salts thereof, alkylsulfonic acid or salts thereof, various polymer sulfonic acids or salts thereof and compounds having substituents described above). ) Is made to flow into the semiconductor layer formation solution in which () is melt | dissolved, and a semiconductor layer is formed on a dielectric layer. As a temperature and pH of a semiconductor layer formation solution, the conditions which facilitate formation of a semiconductor layer are determined by performing a preliminary experiment. The negative electrode plate disposed in the semiconductor layer forming solution is used as the counter electrode at the time of energization, and a conductive material, in particular metal foil or plate, is used. In the case where semiconductors are simultaneously formed on several conductors, these cathode plates are placed on several cathode plates connected to at least one feeder, and the cathode plates are arranged so as to uniformly distribute the cathodes to the various conductors immersed in the semiconductor layer forming solution. It is preferable.

In the present invention, in order to repair the microdefects of the dielectric layer generated by the formation of the semiconductor layer after energization, recyclability (first chemical conversion when the dielectric layer is not formed by chemical conversion) may be performed. The energization and the recyclability may be repeated several times, and the energization conditions may be changed during the repeated energization process. When the energization is stopped, the conductor is usually taken out of the semiconductor layer forming solution to be washed and dried. However, after the energization-stopping-cleaning-drying step is repeated several times, the regeneration process may be started. Although the reason is not clear, there is a case where the mass of the semiconductor increases when the energization-stopping-cleaning-drying is repeated, as compared with the case where the energization is continuously performed at the same energization time.

Recycling can be carried out in the same manner as described above to form a dielectric layer by chemical conversion. Fire is carried out at a voltage below the Mars voltage.

In the present invention, the electrode layer is formed on the semiconductor layer formed by the method described above. The electrode layer can be formed, for example, by solidifying a conductive paste, plating, depositing a metal, or adhering a heat resistant conductive resin film. Preferable examples of the conductive paste include silver paste, copper paste, aluminum paste, carbon paste and nickel paste, and these may be used alone or in combination of two or more kinds. When using 2 or more types of pastes, you may mix or you may laminate | stack one layer on another layer as a separation layer. After applying the conductive paste, it is solidified by standing in air or heating.

The electrically conductive paste has electroconductive powders, such as resin and a metal, as a main component. In some cases, a solvent for dissolving the resin, a curing agent of the resin, and the like are added. The solvent is scattered during solidification.

Examples of the resin used for the conductive paste include various known resins such as alkyd resins, acrylic resins, epoxy resins, phenol resins, imide resins, fluororesins, ester resins, imideamide resins, amide resins, styrene resins, and urethane resins. Resin can be mentioned.

As the conductive powder, one or more selected from silver, copper, aluminum, gold, carbon, nickel or nickel or alloy mainly composed of such metals, coated powders having a surface layer composed of such metals, and mixed powders thereof are used. .

Conductive powder usually contains the quantity of 40-97 mass%. If the content is less than 40% by mass, the conductivity of the produced conductive paste is small, whereas if it exceeds 97%, the adhesion of the conductive paste is poor, which is not preferable. You may mix and use the above-mentioned conductive polymer and powder of metal oxide for forming a semiconductor in an electrically conductive paste.

Examples of the plating include nickel plating, copper plating, silver plating, gold plating and aluminum plating. Examples of metal deposition include aluminum, nickel, copper, gold and silver.

Specifically, for example, the conductor layer is formed by sequentially laminating carbon paste and silver paste on the anode substrate on which the semiconductor layer is formed.

In this manner, a capacitor device in which a cathode layer is formed by stacking up to an electrode layer is produced.

The condenser element of the present invention having such a configuration can be completed by, for example, a resin mold, a resin case, a metallic outer case, a resin dipping or a laminated film to be completed as a condenser product for various uses. Among them, the chip capacitor packaging by the resin mold is preferable because it can easily achieve downsizing and cost reduction.

As the type of resin used in the resin mold exterior, known resins used for molding solid electrolytic capacitors such as epoxy resins, phenol resins, and alkyd resins can be used. It is preferable because the molding stress of the resin on the capacitor element generated during molding can be reduced. As a molding machine for molding with a resin, a transfer machine is preferable.

The capacitor thus produced may be subjected to an aging treatment in order to recover heat and / or physical deterioration of the dielectric layer generated during the formation of the conductor layer or during the exterior. Aging is carried out by applying a predetermined voltage (usually within twice the rated voltage) to the capacitor. Since the optimum values of aging time and temperature vary depending on the type of capacitor, capacity and rated voltage, these values are determined by experiments in advance, but the aging time is usually several minutes to several days and the aging temperature is voltage. Usually below 300 ℃. Aging may be carried out usually in air or in a gas atmosphere such as Ar, N ₂ and He, or may be carried out under reduced pressure, atmospheric pressure or pressure. However, when aging is performed while supplying or supplying water vapor, stabilization of the dielectric layer proceeds. There is a case. An example of a method of supplying steam is a method of supplying steam from a water reservoir placed in an aging furnace.

As a method of applying a voltage, a direct current, an alternating current having an arbitrary waveform, an alternating current superimposed on the direct current, and a pulse current can be designed to pass. The voltage is gradually applied from low to high pressure. During aging, voltage application can be stopped and voltage can be applied again.

In the capacitor manufactured by the method of the present invention, it is preferable to use, for example, a central processing circuit and a power supply circuit in a circuit requiring a high capacitance and a low ESR capacitor. These circuits can be used for electronic devices such as various digital devices such as personal computers, servers, cameras, game machines, DVD devices, AV devices and mobile phones, and various power supplies. Since the capacitor manufactured by the method of the present invention has high capacity and good ESR performance, it is possible to obtain electronic circuits and electronic devices having good performance by using this capacitor.

1 is an SEM photograph (100,000 magnification) showing micro projections in an embodiment (Example 3) of the present invention.

Fig. 2 is a SEM photograph (100,000 magnification) showing micro projections in another embodiment (Example 2) of the present invention.

3 is an SEM photograph (100,000 magnification) showing a surface on which projections are not formed.

Fig. 4 is an SEM photograph (50,000 magnification) of a sintered compact portion below 3 mu m in which minute projections according to the present invention (Example 2) are formed.

Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited to these Examples.

Example 1:

A sintered compact of size 4.5 × 1.0 × 1.5 mm was formed by using a tantalum powder having a CV (product of capacity and chemical conversion voltage) of 150,000 Pa · V / g and a Ta lead wire of 0.24 mmφ (sintering temperature of 1300 ° C. and sintering time). Density of sintered compact: 6.2 g / cm <^{3> for} 20 minutes; Ta lead wire was inserted perpendicularly to the 1.0 x 1.5 mm center part of the sintered compact so that 4 mm was put inside the sintered compact, and 10 mm outside.) Polyimide resin plate of 250 mm in length, 30 mm in width and 2 mm in thickness prepared separately (circuit via printed wiring to circuit conductor connection terminals for 32 conductors, each anode of a constant current diode and a feed terminal on the left side of the plate, and The lead wires of the 32 sintered sintered bodies are equally spaced and equally dimensioned, leaving a space of 30 mm left and right on the back side of the circuit electrically connected to the connection terminals for conductors on the right side of the plate through rectifier diodes). Sort by. A metal frame in which 20 sheets of resin plates are arranged in parallel at intervals of 5 mm and electrically connected at left and right sides of 15 mm (the centers of the left and right sides of the frame are electrically insulated from each other, the former being the front of the resin board, and the latter being the back of the resin board). The feed terminal installed on the is insulated). In this way, 640 sintered bodies are arrange | positioned at equal intervals on a metal frame, and each sintered body is electrically connected to the left-right feed terminal provided on the metal frame via a lead wire. A series of sintered bodies were used as one lot in the said metal frame, and the following various operations were performed.

Immerse the sintered body except a part of the lead wire in a 1% phosphoric acid solution, and use a feed terminal on the right side of the back surface of the metal frame to apply a 10V voltage between the lead wire and the Ta cathode plate disposed in the aqueous solution to form a Ta and A dielectric oxide film layer containing ₂ O ₅ was formed. The obtained sintered body except each lead wire was immersed in a microprotrusion formation solution (prepared by dissolving 30 g of ammonium molybdate and 200 g of nickel sulfate hexahydrate in 800 g of water and adding 250 ml of 1N ammonium hydroxide), and the surface of the metal frame. A micro precipitate having molybdenum oxide as a main component on the dielectric oxide film layer by electrically reacting at a room temperature for 150 minutes while applying 2.2 V between the lead wire as a anode and a Ta plate as an anode using a feed terminal on the left side. Formed. When observed through SEM, most of the 10--30 nm-wide particulate protrusions exist in the area | region within 100 micrometers from the surface and surface layer of a sintered compact. Accordingly, the sintered body was taken out of the solution, washed with water, dried, and refired for 30 minutes at 8 V and 80 ° C. in a 0.1% phosphoric acid aqueous solution using a feed terminal on the right side of the rear surface of the metal frame. Next, the sintered compact was washed with water and dried.

The obtained sintered body except for each lead wire was immersed in an electrolyte solution (semiconductor layer forming solution) containing 20% ethylene glycol and water, ethylenedioxythiophene (used as an aqueous solution whose monomer is below a saturated concentration) and anthraquinonesulfonic acid were dissolved, and 20 mA The DC constant current was flowed on the left side surface using a feed terminal between the lead wire and the negative electrode tantalum electrode plate disposed in the electrolytic solution at room temperature for 30 minutes to conduct a current to form a semiconductor layer. The sintered body was taken out, washed with water to remove the unpolymerized material, washed with ethanol, dried, and repaired LC (leakage current) causing micro-defects in the dielectric layer in a 1% aqueous solution of phosphoric acid using a feed terminal on the right side of the metal frame. Recyclability (80 degreeC, 30 minutes, 6V) for following was implemented. These energization and recyclability were repeated 12 times (the last two energization processes were performed for 60 minutes). Next, the sintered body was washed with water, then washed with ethanol and dried to form a semiconductor layer. Next, carbon pate and silver paste were deposited in this order on the semiconductor layer except for the surface on which the lead wires were sandwiched, and dried to form a cathode layer to complete the cathode portion. In this way, a solid electrolytic condenser element was produced.

A tip of a 100-μm thick copper alloy lead frame (with a pair of 3.4 mm wide ends having a width of 3.4 mm and projected on the same plane, a 1.0 mm gap was present between both ends) on a separately prepared surface. On the pair of upper surfaces of, the cathode part surfaces (4.5 mm x 1.5 mm surface) and the anode lead wires (partially cut and removed) of the two electrolytic capacitor elements manufactured above were aligned in each direction and installed without gaps. In the former, the same silver paste was used as the solid used in the cathode, and the latter was electrically and mechanically connected by spot welding. Next, the element is transferred to an epoxy resin, leaving a part of the lead frame external, and a predetermined portion outside the resin of the lead frame is cut and bent along the exterior portion. Thereafter, the external resin was cured at 185 ° C., aged at 4 ° C. at 105 ° C. for 4 hours, and 320 chip solid electrolyte capacitors having a size of 7.3 × 4.3 × 1.8 mm were produced.

Comparative Example 1:

206 chip-shaped solid electrolytic capacitors (manufactured from 412 relatively well formed capacitor elements of a semiconductor layer) were fabricated in the same manner as in Example 1, except that a sintered body was obtained by forming a dielectric layer without forming a fine protrusion. The obtained sintered compact was immersed in the semiconductor layer formation solution, and the semiconductor layer was formed by repeating the electricity supply process and the same recyclability as Example 1 for 30 hours at 2 mA.

Example 2:

In Example 1, instead of the tantalum sintered body and the tantalum lead wire, niobium sintered body (CV 270,000 Pa · V / g, nitride amount: 10,000 ppm, oxygen content due to natural oxidation on the surface: 84,000 ppm, sintering temperature: 1,280 ° C., sintering time: 30 minutes And a dielectric oxide film layer containing Nb ₂ O ₅ through chemical conversion at _{23 V} using a density of sintered body: 3.4 g / cm ³ ) and a niobium lead wire. Next, a series of operations, that is, the sintered body is immersed in an alcohol solution of 2% ethylene dioxathiophene, taken out and left to stand, immersed in an alcohol solution of 18% iron naphthalenesulfonate, and then taken out, and left for 30 minutes at 40 ° C. The immersion in alcohol and immersion in alcohol was repeated seven times, and a micro-projection mainly composed of ethylenedioxy polymer was prepared on the dielectric layer. Observed by SEM, the microprojections had an island shape or streak with a width of 0.1 to 20 nm, and most of the microprojections existed within 3 µm from the surface and surface layer of the sinter. The sintered compact was refired at 17 V, 80 ° C. for 30 minutes in a 0.1% acetic acid solution, washed with water, and dried. Thereafter, the conduction and recyclability (14V) was repeated in the same manner as in Example 1 to form a semiconductor layer, and the formation of the cathode layer and aging (85 ° C., 6V, 4 hours) were performed. In this way, 320 solid chip electrolytic capacitors were produced.

Comparative Example 2:

The operation of immersing the alcohol solution of 18% iron naphthalenesulfonate and the sintered compact alternately in this solution without changing the concentration of the ethylenedioxythiophene alcohol solution used at the time of forming the microprotrusion to 20% and immersing the alcohol 30 times 187 chip-like solid electrolytic capacitors (from 374 capacitor elements with a relatively good semiconductor layer) were formed in the same manner as in Example 2, except that a chemical polymerization layer was formed on the conductor prepared in the dielectric layer instead of the formation of the micro projections. Produced). The chemical polymerization layer described above covers the dielectric layer in a layered manner.

Example 3:

Instead of the tantalum powder used in Example 1, a sintered compact (sintering temperature: 1,360 ° C., sintering time: 20 minutes, density of sintered compact: 6.0 g / cm ³ ) was used using tantalum powder having a CV value of 70,000 Pa · V / g. A capacitor was manufactured in the same manner as in Example 1 except that the capacitor was manufactured.

The capacity, impregnation rate, ESR value and LC value of each of the capacitors prepared above were measured by the following method. The measurement results (average values) are shown in Table 1.

Capacitor Capacity:

The capacity was measured at 120 Hz at room temperature using an LCR meter from Hewlett Packard, Ltd.

Impregnation rate:

It is a percentage of the value obtained by dividing the capacity of the capacitor by the capacity of each conductor which formed the dielectric layer measured in 30% sulfuric acid.

ESR value:

The equivalent series resistance of the capacitor was measured at 100 KHz at room temperature.

LC value:

The LC value was measured after continuously applying a predetermined rated voltage (2.5 V in Examples 1 and 3 and Comparative Example 1, 4 V in Examples 2 and 2) for 30 seconds between terminals of a conde wire produced at room temperature.

Table 1

 Capacity * (㎌)  Impregnation rate * (%)  ESR * (mΩ)  LC * (㎂)  Example  One  1071  85  8  33  2  459  85  13  29  3  509  91  13  6  Comparative example  One  945  75  9  39  2  400  74  26  40

In Examples 1-3, the average of 320 capacitors.

In Comparative Example 1, the average of 206 capacitors.

In Comparative Example 2, the average of 187 capacitors.

As shown by the comparison between Example 1 and Comparative Example 1, Example 2, and Comparative Example 2 and Example 3, when the minute projections were formed on the dielectric layer before the energization of the semiconductor layer was formed, the capacity emergence ratio was good and the low ESR value was obtained. The capacitor shown can be obtained.

The present invention uses a conductor formed on a surface as one electrode, and a semiconductor layer formed on a conductor by energization using the conductor as an anode. It is to provide a method for producing a capacitor comprising a formed in.

According to the present invention, since the capacity appearance rate is good, a capacitor having a high capacity and a low ESR can be obtained.

Claims (19)

A manufacturing method comprising a semiconductor layer formed on a conductor by conduction using one conductor as an electrode and a conductor having a dielectric layer formed on its surface as the other electrode. Method of manufacturing a capacitor The method of manufacturing a capacitor according to claim 1, wherein the minute protrusions are island-shaped and / or feather-shaped. The method of manufacturing a capacitor according to claim 1 or 2, wherein the width of the minute projections is 0.1 to 60 nm. The method of manufacturing a capacitor according to any one of claims 1 to 3, wherein most of the minute projections are present on the inner pore surface within 10 m of the outer surface and the outer surface of the conductor. The method for producing a capacitor according to any one of claims 1 to 4, wherein the micro-projections are at least one selected from metal oxides, metal salts, transition element-containing inorganic compounds, transition element-containing organic compounds and polymer compounds. The method of manufacturing a capacitor according to claim 1, wherein the conductor is at least one selected from a metal, an inorganic semiconductor, an organic semiconductor and carbon, or a mixture thereof. The method of manufacturing a capacitor according to any one of claims 1 to 6, wherein the conductor is a laminate having at least one selected from a metal, an inorganic semiconductor, an organic semiconductor and carbon, or a mixture thereof as a surface layer. The method of manufacturing a capacitor according to claim 1, wherein the dielectric layer contains at least one selected from metal oxides such as Ta ₂ O ₅ , Al ₂ O ₃ , TiO _2, and Nb ₂ O ₅ . The method of manufacturing a capacitor according to claim 1, wherein the semiconductor layer is at least one selected from an organic semiconductor layer and an inorganic semiconductor layer. The organic semiconductor according to claim 9, wherein the organic semiconductor is an organic semiconductor consisting of benzopyrroline tetramer and chloranyl, an organic semiconductor containing tetrathiotetracene as a main component, an organic semiconductor containing tetracyanoquinomimethane as a main component, and the following formula (1). ) Or a method for producing a capacitor, wherein the polymer containing the repeating unit represented by Formula (2) is at least one selected from organic semiconductors containing a conductive polymer as a main component:

Wherein each of R ¹ to R ⁴ independently represents a hydrogen atom, an alkyl group of 1 to 6 carbon atoms or an alkoxy group of 1 to 6 carbon atoms, X represents an oxygen atom, a sulfur atom or a nitrogen atom, and R ⁵ represents a nitrogen atom It exists only in a case, and represents a hydrogen atom or a C1-C6 alkyl group, and each of R <^1> and R <^2> , R <^3> and R <^4> may combine with each other, and may form ring structure.) The method for producing a capacitor according to claim 10, wherein the conductive polymer containing the repeating unit represented by formula (1) is a conductive polymer containing the structural unit represented by the following formula (3) as a repeating unit:

Wherein each of R ⁶ and R ⁷ independently contains a hydrogen atom, a linear or branched phase, a saturated or unsaturated alkyl group having 1 to 6 carbon atoms, or two oxygen atoms when the alkyl group is bonded to each other at an arbitrary position; Substituents for forming one 5-, 6- or 7-membered saturated hydrocarbon ring structure, and the ring structure may include a structure having a vinylene bond which may be substituted, and a phenylene structure which may be substituted.) The condenser of claim 10, wherein the conductive polymer is selected from polyaniline, polyoxyphenylene, polyphenylene sulfide, polythiophene, polyfuran, polypyrrole, polymethylpyrrole, and substituted derivatives and copolymers thereof. Manufacturing method. The method for producing a capacitor according to claim 11 or 12, wherein the conductive polymer is poly (3,4-ethylenedioxythiophene). 10. The method of manufacturing a capacitor according to claim 9, wherein the inorganic semiconductor is at least one selected from molybdenum dioxide, tungsten dioxide, lead dioxide and manganese dioxide. The method of claim 9, wherein the conductivity of the semiconductor is 10 ⁻² to 10 ³ S / cm. The capacitor manufactured by the manufacturing method in any one of Claims 1-15. 17. The capacitor of claim 16, wherein the impregnation rate of the semiconductor is at least 85%. An electronic circuit using the capacitor according to claim 16 or 17. An electronic device using the capacitor according to claim 16 or 17.

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