JP2010165701A - Solid-state field capacitor element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state field capacitor element having a porous sintered compact for improving impregnability of the solid-state field capacitor element and improving the electric characteristics such as capacitance and induction loss: and to provide a method for manufacturing the same. <P>SOLUTION: The solid-state field capacitor element includes a porous sintered compact including first sintered bodies 2A formed to be porous by a powder of valve action metal and allowing one end of an anode wire 1 embedded, and second sintered bodies 2B formed to be porous by a powder of a valve action metal wherein the average grain diameter of the powder is smaller than the average grain size forming the first sintered compacts and formed around the first sintered bodies so that at least one part of the first sintered bodies may be exposed in the side opposing the side where the one end of the anode wire 1 is embedded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a solid electrolytic capacitor element and a method for manufacturing the same.

In general, the solid electric field capacitor element includes a porous sintered body such as tantalum. Similarly, an anode wire such as tantalum protrudes from the porous sintered body. A dielectric layer such as tantalum pentoxide is formed on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body. A solid electrolyte layer such as manganese dioxide is formed on the dielectric layer. The solid electrolyte layer is formed with a cathode layer made of a graphite layer and a silver paste layer (see, for example, Patent Document 1). The porous sintered body is sealed with a resin package. In a solid electric field capacitor, the capacity is increased by reducing the particle size of a powder of tantalum or the like, which is a material of a porous sintered body.

In order to increase the capacity without increasing the size of the solid electrolytic capacitor element, it is necessary to increase the CV value (μFV / g). The CV value is a product of the capacitance C per unit mass and the formation voltage, and is generally represented by μFV / g. This CV value greatly depends on the surface area per unit mass of fine powder such as tantalum which is a material of the porous sintered body. Since the surface area per unit mass can be increased as the finer powder is made finer, the CV value can be increased.

  However, in order to refine the fine powder such as tantalum, which is a material of the porous sintered body, the porosity is lowered when the particle diameter of the fine powder is reduced. In the manufacturing process of the solid electric field capacitor element, a porous sintered body such as tantalum is immersed in a manganese nitrate aqueous solution or the like for forming a solid electrolyte layer. When the porosity is low, this penetration is not sufficiently promoted, and a portion where the solid electrolyte layer is not formed remains on the surface of the porous sintered body. This causes problems such as a decrease in capacitance and an increase in dielectric loss.

JP 2002-231579 A

The present invention has been conceived under the circumstances described above, and is a porous firing that can improve the impregnation property of a solid electric field capacitor element and improve electrical characteristics such as capacitance and dielectric loss. It is an object of the present invention to provide a solid electric field capacitor element having a bonded body and a method for manufacturing the same.

  In order to achieve the above object, the present invention takes the following technical means.

  The solid electric field capacitor element provided by the first aspect of the present invention includes an anode wire formed of a valve action metal, a porous material made of a valve action metal powder, and one end of the anode wire embedded therein. 1 sintered body and valve action metal powder are formed porous, the average particle diameter of the powder is smaller than the average particle diameter of the powder forming the first sintered body, and one end of the anode wire is embedded A porous sintered body comprising: a second sintered body formed around the first sintered body so that at least a part of the first sintered body is exposed on a side opposite to the first sintered body; The dielectric film formed on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body, the solid electrolyte layer formed on the dielectric film, and the porous sintered body Cathode formed on at least part of the surface of the solid electrolyte layer formed on the outer surface It is characterized by having a and.

  Usually, the cathode material solution for forming the solid electrolyte layer penetrates from the outer surface of the sintered body toward the inside. According to such a configuration, the cathode material solution penetrates into the sintered body from the lower side of the sintered body (first sintered body) (the side facing the side where one end of the anode wire is embedded), and further fired. It penetrates from the inside of the bonded body toward the second sintered body formed of powder having a small particle diameter. As a result, the cathode material solution penetrates not only from the outer surface of the sintered body toward the inside, but also from the inside of the sintered body toward the outer surface. Therefore, since the impregnation property of the cathode material solution is greatly improved, problems such as a decrease in capacitance and an increase in dielectric loss can be solved.

1 is a perspective view and a longitudinal front view showing a solid electric field capacitor element according to the present invention. It is sectional drawing which shows the manufacturing method of the solid electric field capacitor element concerning this invention. It is sectional drawing which shows the manufacturing method of the solid electric field capacitor element concerning this invention. It is a perspective view which shows the modification of the solid electrolytic capacitor element which concerns on this invention.

Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic and different from actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

1 (a) and 1 (b) show an example of a solid electric field capacitor element according to the present invention. The solid electrolytic capacitor element shown in the figure includes an anode wire 1, a porous sintered body 2, a ring body 3, a dielectric film 4, a solid electrolyte layer 5, and a cathode film 6. FIG. 1A is a conceptual diagram showing the positional relationship between the first sintered body and the first sintered body of the porous sintered body, and the first sintered body 2A is sandwiched between the second sintered bodies 2B. It is formed as follows. FIG.1 (b) has shown the longitudinal cross-sectional front view of the solid electric field capacitor element based on this invention.

  The anode wire 1 is made of a valve metal such as tantalum. One end of the anode wire is embedded in the porous sintered body. The anode wire may contain a sintering inhibitor containing at least one of phosphorus, oxygen, carbon, nitrogen, hydrogen, iron, nickel, silicon and the like as an impurity.

The porous sintered body 2 is made by sintering a powder of a metal of the same type as that of the metal constituting the anode wire, for example, a valve action metal powder such as tantalum, and the like. The porous sintered body 2 includes a first sintered body 2A and a second sintered body 2B having different average particle diameters of the powder. The average particle diameter of the powder forming the first sintered body 2A is larger than the average particle diameter of the powder forming the second sintered body 2B. The larger the average particle size of the powder forming the sintered body, the higher the adhesion between the sintered body and the anode wire. Therefore, in consideration of the effect of preventing the anode wire from being removed, the first sintered body 2A includes the anode. One end of the wire is embedded. In addition, at least a part of the first sintered body is exposed on the side facing the side where one end of the anode wire is embedded, and the first firing is also performed on a surface perpendicular to the surface where the one end of the anode wire is embedded. A second sintered body is formed around the first sintered body so that at least a part of the bonded body is exposed. The first sintered body 2A is made of a powder of a valve action metal such as tantalum, and its CV value is, for example, from 100,000 μFV / g to 150,000 μFV / g. The second sintered body 2B is made of a powder of a valve action metal such as tantalum, and the average particle diameter of the powder is smaller than the average particle diameter of the powder forming the first sintered body. The CV value of the powder forming the second sintered body is larger than the CV value of the powder forming the first sintered body, and is, for example, from 150,000 μFV / g to 200,000 μFV / g. . In consideration of the adhesion between the first sintered body and the second sintered body after pressure molding, the difference between the CV values is preferably 50,000 μFV / g or less.

The ring body 3 is formed of a water-repellent resin such as a fluorinated ethylene polymer, and is formed at the base of the anode wire 1. The planar shape of the ring body has a circular shape, but is not limited to this shape, and may be, for example, a rectangular shape or a rhombus shape.

The dielectric layer 4 is made of, for example, tantalum pentoxide, and is formed on the outer surface of the sintered body and the surface of the pores of the porous sintered body. The dielectric layer 4 functions as a dielectric, and the capacity of the solid electric field capacitor is determined by the total area and thickness of the dielectric.

The solid electrolyte layer 5 is made of, for example, manganese dioxide, and is formed so as to cover the outer surface of the sintered body from above the dielectric, and to fill the pores of the porous sintered body remaining after the dielectric is formed. Has been. As the solid electrolyte layer 5, a conductive polymer such as polyethylenedioxythiophene or polypyrrole may be used instead of manganese dioxide.

The cathode film 6 is, for example, a laminate of a graphite layer and a metal layer. When the contact point resistance between the solid electrolyte layer and the metal layer is large, the graphite layer is provided for the purpose of reducing the resistance between them. The metal layer is provided, for example, by performing a plating process to form a conductor layer such as silver.

Next, a method for manufacturing a solid electric field capacitor element according to the present invention will be described with reference to the drawings.

  First, a mold M1 including a lower mold, a push mold, and an upper mold is prepared. As shown in FIG. 2 (a), a fine powder 2a made of a valve metal such as tantalum is filled in the recess formed by the lower mold 10 and the pushing mold 11. The CV value of the fine powder is, for example, from 100,000 μFV / g to 150,000 μFV / g.

  Next, as shown in FIG. 2B, the upper mold 12 holding the anode wire 1 so as to protrude from the lower end is advanced toward the fine powder 2a. A portion of the anode wire 1 protruding from the upper mold 12 is inserted into the fine powder 2a, and at the same time, the pressing mold 10 is moved inward to harden the fine powder, Harden and mold.

  Next, as shown in FIG. 2 (c), the lower mold 10 is moved while the pressing mold 11 is moved outward and at the same time the upper mold 12 is held with the compact of the fine powder 2a. Then, it is pulled out from the recess formed by the pushing mold 11. Then, the 1st sintered compact is obtained by heating the 1st molded object of the said fine powder to appropriate temperature, and sintering.

  Next, as shown in FIG. 3A, the valve action of tantalum or the like having an average particle size smaller than the average particle size of the fine powder 2a in the recess formed by the lower mold 10 and the pushing mold 11 A fine powder 2b made of metal is filled. The CV value of the fine powder 2b is, for example, from 150,000 μFV / g to 200,000 μFV / g. The difference in CV value between the fine powder 2b and the fine powder 2a is preferably 50,000 μFV / g or less.

  Next, as shown in FIG. 3B, the upper mold 12 holding the first sintered body is advanced toward the fine powder 2b. At the same time when the first sintered body is inserted into the fine powder 2b, the pressing mold 11 is moved inward to harden the fine powder 2b. At this time, the bottom surface of the first sintered body, that is, the side facing the side where one end of the anode wire is embedded is brought into contact with the lower mold 10 so that the bottom surface of the first sintered body is not covered with the fine powder 2b. To. Thus, by compacting and molding the fine powder 2b, the side opposite to the side where one end of the anode wire is embedded is placed around the first sintered body so that at least a part of the first sintered body is exposed. A molded body of the fine powder 2b can be formed.

Next, as shown in FIG. 3C, the pressing mold 11 is moved outward, and at the same time, the upper mold 12 holds the compact of the fine powder 2b around the first sintered body. In this state, it is pulled out from the recess formed by the lower mold 10 and the pushing mold 11. Thereafter, the second molded body of the fine powder 2b is heated to an appropriate temperature and sintered to obtain a porous sintered body having the first sintered body and the second sintered body. In this embodiment, the sintering was performed in two steps, but after forming the fine powder molding around the fine powder molding, by heating to a suitable temperature and sintering, The number of times of sintering may be one.

Next, a dielectric film is formed on the porous sintered body. The dielectric film is formed by anodizing a porous sintered body. A chemical conversion solution such as a phosphoric acid aqueous solution is held in a metal container functioning as a cathode, and the porous sintered body and the metal container are energized in a state where the porous sintered body is immersed in the solution as an anode. As a result, a dielectric film made of tantalum pentoxide is formed on the portion of the porous sintered body in contact with the phosphoric acid solution, that is, on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body. A dielectric film made of tantalum pentoxide is also formed on the surface of the base portion of the anode wire protruding from one end face of the porous sintered body.

Next, a ring body made of a water-repellent resin such as a fluorinated ethylene polymer is attached to the base of the anode wire. The mounting of the ring body is to prevent a solid electrolyte aqueous solution, which will be described later, from seeping into a portion of the anode wire where the dielectric film is not formed and coming into electrical contact with the anode wire.

Next, a solid electrolyte layer is formed on the porous sintered body on which the dielectric film is formed. The porous sintered body on which the dielectric film is formed is immersed in a solid electrolyte aqueous solution such as a manganese nitrate aqueous solution and then pulled up, and then a series of processes such as a heat treatment are performed a plurality of times (for example, Repeat about 10 times). Thereby, a solid electrolyte layer made of manganese dioxide is formed so as to cover the outer surface of the sintered body from above the dielectric, and to fill the pores of the porous sintered body remaining after the dielectric is formed. Here, when the porous sintered body is immersed in the solid electrolyte aqueous solution, the portion above the portion where the ring body at the base of the anode wire is attached should not be immersed in the solid electrolyte solution. preferable.

Next, a cathode film having a graphite layer as a base and a metal layer such as silver as an upper layer is formed on the surface of the solid electrolyte layer, thereby forming the solid electrolytic capacitor element.

According to the present embodiment, in addition to the normal infiltration, the cathode material solution such as the solid electrolyte aqueous solution is placed inside the sintered body from the lower side of the first sintered body (the side opposite to the side where one end of the anode wire is embedded). And penetrates from the inside of the sintered body toward the second sintered body formed of powder having a small particle diameter. As a result, the cathode material solution penetrates not only from the outer surface of the sintered body toward the inside, but also from the inside of the sintered body toward the outer surface. Therefore, since the impregnation property of the cathode material solution is greatly improved, problems such as a decrease in capacitance and an increase in dielectric loss can be solved.

The solid electrolytic capacitor element and the manufacturing method thereof according to the present invention are not limited to the above embodiment. The specific configuration of the solid electrolytic capacitor element and the method for manufacturing the same according to the present invention can be varied in design in various ways.

For example, as shown in FIG. 4A, a plurality of first sintered bodies 2A and second sintered bodies 2B may be laminated on the side parallel to the anode wire 1. In this case, it penetrates from the lower side of the first sintered body toward the inside of the sintered body, and further penetrates from the inside of the sintered body to the second sintered body formed of powder having a small particle diameter. As a result, the cathode material solution penetrates not only from the outer surface to the inside of the sintered body but also from the inside to the outer surface of the sintered body. Since it becomes thinner, it becomes easier to penetrate into the sintered body.

Further, as shown in FIG. 4B, the second sintered body 2B may be formed so as to cover the entire circumference of the first sintered body 2A on the side parallel to the anode wire 1. In this case, at least a part of the first sintered body 2A is exposed on the side facing the side where one end of the anode wire 1 is buried. As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 Anode wire 2 Porous sintered body 3 Ring body 4 Dielectric layer 5 Solid electrolyte layer 6 Cathode film 10 Lower die 11 Pushing die 12 Upper die

Claims (9)

An anode wire formed of valve metal,
A first sintered body formed porous with valve action metal powder and having one end of the anode wire embedded therein, and formed porous with valve action metal powder, the average particle size of the powder being the first The first sintered body is smaller than the average particle size of the powder forming the sintered body and at least a part of the first sintered body is exposed on the side facing the side where one end of the anode wire is embedded. A second sintered body formed around the porous sintered body,
A dielectric film formed on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body;
A solid electrolyte layer formed on the dielectric film;
A cathode film formed on at least a part of the surface of the solid electrolyte layer formed on the outer surface of the porous sintered body;
A solid-state electric field capacitor element comprising: The CV value of the first sintered body is 100,000 μFV / g to 150,000 μFV / g and the CV value of the second sintered body is 150,000 μFV / g to 200,000 μFV / g. The solid-state electric field capacitor element according to claim 1 characterized by things. The solid electrolytic capacitor element according to claim 2, wherein the difference between the CV value of the first sintered body and the CV value of the second sintered body is 50,000 µFV / g. The solid electrolytic capacitor element according to claim 3, wherein a plurality of the first sintered body and the second sintered body are laminated on a side parallel to the anode wire. The solid electrolytic capacitor element according to claim 3, wherein the second sintered body is formed so as to cover the entire circumference of the first sintered body on a side parallel to the anode wire. Inserting the anode wire formed of the valve metal into the fine powder of the valve metal, and simultaneously forming the first molded body by compacting and molding the fine powder;
Forming the porous first sintered body by heating the first molded body to an appropriate temperature and sintering;
A step of forming a second molded body by compacting and molding a fine powder having an average particle diameter smaller than that of the fine powder so as to expose a side of the first sintered body facing a side where one end of the anode wire is embedded; ,
Forming the porous sintered body by appropriately heating and sintering the first sintered body and the second molded body; and
Forming a dielectric film on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body;
Forming a solid electrolyte layer on the dielectric film;
Forming a cathode film on at least part of the surface of the solid electrolyte layer formed on the outer surface of the porous sintered body;
A method for producing a solid electric field capacitor element, comprising: Inserting the anode wire formed of the valve metal into the fine powder of the valve metal, and simultaneously forming the first molded body by compacting and molding the fine powder;
A step of forming a second molded body by compacting and molding a fine powder having an average particle size smaller than that of the fine powder so that a side of the first molded body facing a side where one end of the anode wire is embedded is exposed;
Forming a porous sintered body composed of the first sintered body and the second molded body by appropriately heating and sintering the first molded body and the second molded body; and
Forming a dielectric film on the outer surface of the porous sintered body and the surface of the pores of the porous sintered body;
Forming a solid electrolyte layer on the dielectric film;
Forming a cathode film on at least part of the surface of the solid electrolyte layer formed on the outer surface of the porous sintered body;
A method for producing a solid electric field capacitor element, comprising: The CV value of the first sintered body is 100,000 μFV / g to 150,000 μFV / g and the CV value of the second sintered body is 150,000 μFV / g to 200,000 μFV / g. The method for producing a solid electric field capacitor element according to claim 5 or 6. The method for manufacturing a solid electrolytic capacitor element according to claim 7, wherein the difference between the CV value of the first sintered body and the CV value of the second sintered body is 50,000 µFV / g.

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