JP2789074B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor (hereinafter simply referred to as "capacitor").

[0002]

2. Description of the Related Art Conventionally, this kind of capacitor is manufactured as follows.

First, as shown in FIG. 14, particles of a valve metal such as tantalum, niobium or the like are formed into a porous chip piece 2 with an anode rod 22 made of metal such as tantalum or niobium protruding.
It is molded and sintered into 1. A plurality of the chip pieces 21 are mounted by fixing the anode rods 22 in the longitudinal direction of the horizontal bar 23 at appropriate intervals. At this time, the plurality of chip pieces 21 are mounted with their upper surfaces 21a all aligned in the horizontal direction.

[0005] Next, as shown in FIG. 15, anodizing is performed by applying a direct current while the chip piece 21 is immersed in a chemical solution 24 such as a phosphoric acid aqueous solution, thereby performing chip anodization.
A dielectric layer 25 such as tantalum pentoxide is formed on the surface of each valve action metal particle in 1. At this time, the chip piece 21
With respect to the chemical liquid 24, the upper surface 21a of the chip piece 21.
Is immersed so as to sink an appropriate depth below the liquid surface of the chemical conversion liquid 24, thereby forming a dielectric layer 25 on the outer peripheral surface of the base of the anode rod 22 over an appropriate length.

[0005] Then, as shown in FIG. 16, the upper surface 21 a of the chip piece 21 is placed on the surface of the manganese nitrate aqueous solution 26. And immersed in the manganese nitrate aqueous solution 26 to the chip piece 21.
The solid electrolyte layer 2 made of manganese dioxide or the like is formed on the surface of the dielectric layer 25 by repeating the operation several times by elevating and heating to evaporate water.
7, or a solid electrolyte layer of an organic semiconductor layer is formed on the surface of the dielectric layer 25 by a chemical polymerization method such as an electrolytic oxidation polymerization method or a gas phase oxidation polymerization method. At this time, when the upper surface 21a of the chip piece 21 becomes lower than the liquid surface of the manganese nitrate aqueous solution 26, the solid electrolyte layer 27 is formed across the dielectric layer 25 formed at the base of the anode rod 22 and the anode rod 22 is formed. There is a risk that the anode side of the solid electrolyte layer 27 and the cathode side of the solid electrolyte layer 27 may be short-circuited, while the solid electrolyte layer 27 is formed at a position where the liquid level of the manganese nitrate aqueous solution 26 is too low from the upper surface 21 a of the chip piece 21. Therefore, it is not possible to obtain a sufficient electric capacity with respect to the volume of the chip 21, so that the immersion position of the chip 21 needs to be strictly adjusted.

The capacitor element thus obtained has a cathode layer made of a conductive material such as silver, copper, nickel or the like formed on the outer peripheral surface of the chip piece 21 except the upper surface 21a via a graphite layer or the like. For example, as shown in FIG. 17, a capacitor element D is formed by connecting a cathode layer 28 of a chip piece 21 to one of a pair of left and right lead terminals 29, 30 by connecting an anode rod protruding from the chip piece 21. After each of 22 was fixed to the other lead terminal 30, the whole was packaged in a resin mold portion 31 to form a capacitor.

[0007]

As described above, in the conventional capacitor manufacturing method, the individual chip pieces are mounted on the horizontal bar to form the dielectric layer and the solid electrolyte layer. The number of chip pieces to be processed at one time is limited by the length in the longitudinal direction, and the production efficiency is extremely low.

Further, when forming a dielectric layer and a solid electrolyte layer on a chip piece, a plurality of chip pieces are mounted on a horizontal bar so that the upper surfaces of the chip pieces are all aligned, and the chip pieces have an accurate depth. The work and the process management were troublesome, for example, it was necessary to adjust the temperature and the temperature of the solution and to immerse it in a chemical conversion solution and an aqueous solution of manganese nitrate.

An object of the present invention is to provide a method capable of improving the productivity of a capacitor by simply and efficiently manufacturing a capacitor element.

[0010]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has formed a sintered body composed of valve action metal particles into a rod-shaped piece, and obtained a sintered body of this rod-shaped piece. In contrast, if the dielectric layer and the solid electrolyte layer are formed and then divided into appropriate sizes to obtain chip-shaped capacitor elements, several times more capacitor elements can be obtained by a simpler operation than before. Was found.

That is, the present invention provides a step of integrally molding and sintering valve action metal particles so that a metal rod protrudes into a sintered body of a rod-shaped piece. Forming a body layer, forming a solid electrolyte layer on the surface of the dielectric layer, and dividing the sintered body of the rod-shaped piece on which the dielectric layer and the solid electrolyte layer are formed into a plurality of pieces at appropriate intervals. The present invention relates to a method for manufacturing a solid electrolytic capacitor including a step of forming a chip-shaped capacitor element.

[0012] Further, the present invention provides the above-mentioned sintered body of the rod-shaped piece,
The present invention also includes a method for manufacturing a solid electrolytic capacitor having grooves at appropriate intervals in the longitudinal direction.

[0013]

[Action] For a plurality of sintered bodies formed into rod-shaped pieces,
Since the dielectric layer is formed at a time and the solid electrolyte layer is formed, a large number of capacitor elements can be manufactured at once in a series of steps only by dividing the sintered body of the rod-shaped piece into appropriate dimensions.

Also, since the rod-shaped sintered body on which the dielectric layer and the solid electrolyte layer are formed is divided into appropriate dimensions to manufacture a capacitor element, in the step of forming the solid electrolyte layer, the anode projecting from the rod-shaped piece is formed. Even if a solid electrolyte layer is formed so as to cover the dielectric layer formed at the base of the rod, there is no problem when positioning the rod-shaped piece on the horizontal bar, and align the rod-shaped piece with a chemical solution and manganese nitrate. It is not necessary to strictly adjust the immersion depth when immersing in the aqueous solution.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to the drawings.

First, as shown in FIGS. 1 and 2, a tantalum particle is formed into a rectangular rod-shaped porous rod-shaped piece 1 with a tantalum-made metal rod 2 integrally projecting therefrom. At this time,
The opposite end of the metal rod 2 protruding from the upper end surface 1a in the longitudinal direction of the rod-shaped piece 1 may reach the lower end surface 1b in the longitudinal direction of the rod-shaped piece 1 or may be inserted into the vicinity of the lower end surface 1b. This rod-shaped piece 1 is sintered into a sintered body, and a plurality of the rod-shaped pieces 1 are fixed to a horizontal bar 3 by welding a metal rod 2 protruding from the rod-shaped piece 1 by welding. The bars 3 are mounted at appropriate intervals along the longitudinal direction.

Next, as shown in FIG. 3, each of the tantalum particles in the rod-shaped piece 1 is anodized by applying a direct current while the rod-shaped piece 1 is immersed in a phosphoric acid aqueous solution 4 (chemical conversion solution). Tantalum pentoxide layer 5 (dielectric layer)
To form At this time, the rod-shaped piece 1 is immersed in the phosphoric acid aqueous solution 4 so that the upper end surface 1a of the rod-shaped piece 1 is sunk to a proper depth from the liquid surface of the phosphoric acid aqueous solution 4,
It is preferable that the tantalum pentoxide 5 is also formed on the outer peripheral surface of the base portion of the metal rod 2 over an appropriately long portion.

Then, the rod-shaped piece 1 on which the tantalum pentoxide 5 was formed was immersed in an aqueous manganese nitrate solution 6 as shown in FIG. 4 to impregnate the rod-shaped piece 1 with the aqueous manganese nitrate solution 6. The manganese dioxide layer 7 (solid electrolyte layer) is formed on the surface of the tantalum pentoxide 5 by repeating the process of pulling up and heating to evaporate the water a plurality of times.
To form

As shown in FIG. 5, the rod-like piece 1 thus obtained is divided into appropriate dimensions by cutting it with, for example, a diamond cutter or the like, and chip-shaped capacitor elements A ₁ , A ₂ , A ₃ , A ₄ is obtained. Of the obtained capacitor elements A ₁ , A ₂ , A ₃ , A ₄ , the capacitor elements A ₂ , obtained from the center of the bar-shaped piece 1, whose both end faces are divided surfaces,
A ₃ is, as shown in the cross section in FIG. 6 (a), both end faces the end face 2a of the metal rod 2 (dividing surface) is exposed, tantalum pentoxide layer 5 and dioxide on the surface other than the both end surfaces The manganese layer 7 is formed. The capacitor element A ₄ obtained from the lower end of the rod-shaped piece 1 has an end face 2 of the metal rod 2 on one end face as shown in a cross section in FIG.
a is exposed, and a tantalum pentoxide layer 5 and a manganese dioxide layer 7 are formed on other surfaces. The capacitor element A ₁ obtained from the upper end of the bar 1 cuts the protruding metal bar 2 while removing the tantalum pentoxide layer 5 and / or the manganese dioxide layer 7 formed on the upper surface 1 a of the bar 1. For example, the structure becomes the same as that of the capacitor elements A ₂ and A ₃ as shown in FIG. 6A. If only the protruding metal bar 2 is cut, the structure as shown in FIG. 6C is obtained.
Since these differ depending on the region where the manganese dioxide layer 7 is formed with respect to the region where the tantalum pentoxide layer 5 is formed, the cutting position is appropriately determined at the time of division. Needless to say, if the capacitor element is to be obtained as described above, when the tantalum pentoxide layer 5 and the manganese dioxide layer 7 are formed, the rod-shaped piece 1 is completely covered with the phosphoric acid aqueous solution 4 up to its upper end surface 1a. Alternatively, there is no problem even if the rod 1 is immersed in the aqueous manganese nitrate solution 6.
If the manganese dioxide layer 7 is formed so as to cover the region where the tantalum pentoxide layer 5 is formed, there is no problem, and work and process management are easy.

Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 7 and 8, in the second embodiment, a plurality of continuous groove portions 11 a are formed on the peripheral surface of the bar-shaped piece 11 at appropriate intervals in the longitudinal direction of the bar-shaped piece 11.
Are provided over the entire circumference, and a protruding metal bar 2 is integrally provided on an end surface of the bar-shaped piece 11. The sintered body of the bar-shaped piece 11 thus formed is mounted on the horizontal bar 3 in the same manner as in the first embodiment, and a dielectric layer and a solid electrolyte layer are formed. As described above, if the groove 11a is formed, in the dividing step into chip-shaped capacitor elements after the formation of the solid electrolyte layer, it is easily divided at a predetermined position by bending without using a cutting means such as a cutter. be able to. At this time, the groove 11a is
It may be provided discontinuously or partially at appropriate intervals in the longitudinal direction.

In these embodiments, as shown in FIG. 9, a resin layer 12 is provided on the bar-shaped pieces 1, 11 before or after the tantalum pentoxide layer 5 is formed.
If it is formed by coating or the like so as to straddle each division line X of 1,
When the capacitor elements A ₁ , A ₂ , A ₃ , and A ₄ are divided so as to make insulation separation between the anode side and the cathode side, it can be reliably performed. Works.

The capacitor element A thus obtained
(A ₁ , A ₂ , A ₃ , A ₄ ) can be a capacitor, for example, as follows. As shown in FIGS. 10 and 11, one of the divided surfaces of the capacitor element A and the convex portion 8 a and the convex portion 8
a, copper, iron, aluminum,
With the flange 8b of the anode member 8 made of metal such as tantalum, the insulating layer 9 made of a resin or the like having a through hole through which the projection 8a of the anode member 8 penetrates is formed. A capacitor is formed by integrally assembling the front end face and the end face 2a of the metal rod 2 of the capacitor element A so as to be opposed and sandwiched therebetween. At this time, the exposed surface A ′ of the capacitor element A can be used as a cathode as it is or after forming a conductive layer by applying a conductive paste to the surface A ′ as necessary. The formation of the conductor layer may be performed after the rod-shaped pieces 1 and 11 are divided into the capacitor elements A, or may be performed collectively in the state of the rod-shaped pieces 1 and 11. Also, the other divided surface of the capacitor element A is
It may be protected by an insulating layer 10 such as a resin.

Further, as shown in FIG.
If the capacitor element A obtained when the resin layer 12 is formed so as to straddle the respective division lines X of 11 is applied to a lead frame B having inner lead portions B ′ and B ″ as shown in FIG. As shown in FIG. 13, the tip of the inner lead B 'is connected to the end face 2a of the metal rod 2 of the capacitor element A via a conductor such as a metal bump 13 and the inner lead B "is connected to the capacitor element A. A conductor layer 14 composed of, for example, a graphite layer and a silver layer.
By connecting the capacitor element A and a part of the inner leads B ′ and B ″ with the mold resin 15, a resin-sealed capacitor can be obtained.

As described in detail above, in the present embodiment, a rod-shaped piece having a square pillar shape in the shape of the sintered body has been described. However, the present invention is similarly applied to rod-shaped pieces having a polygonal pillar shape, a cylindrical shape, and the like. You can do it.

[0025]

According to the present invention, several times as many capacitor elements can be manufactured at once in the same operation process as compared with the conventional method of manufacturing a capacitor, so that the production efficiency can be greatly improved.

Further, according to the present invention, the management of the manufacturing process of the capacitor can be made very easy.

Further, according to the present invention, it is possible to manufacture capacitors having various electric capacitance values only by changing the division size of the same bar-shaped piece.

As described above, the present invention realizes simplification and efficiency in the production of capacitors, and is extremely practical for mass production of capacitors.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a rod-shaped sintered body according to a first embodiment of the present invention is mounted on a horizontal bar.

FIG. 2 is a sectional view taken along line II of FIG.

FIG. 3 is a sectional view showing a state where a dielectric layer is formed in the first embodiment of the present invention.

FIG. 4 is a sectional view showing a state in which a solid electrolyte layer is formed in the first embodiment of the present invention.

FIG. 5 is a perspective view showing a state in which a rod-shaped sintered body on which a dielectric layer and a solid electrolyte layer are formed is divided into individual chip-shaped capacitor elements in the first embodiment of the present invention.

FIG. 6 is a sectional view of a capacitor element obtained in the first embodiment of the present invention.

FIG. 7 is a perspective view showing a second embodiment of the present invention.

8 is a sectional view taken along line II-II of FIG.

FIG. 9 is a perspective view showing a state in which a resin layer is formed near each dividing line of the sintered body in the first embodiment of the present invention.

FIG. 10 is a perspective view showing an example of a capacitor using the capacitor element obtained in the first embodiment of the present invention.

FIG. 11 is a sectional view taken along line III-III of FIG. 10;

FIG. 12 is a plan view of a lead frame applied to another example of the capacitor using the capacitor element obtained by the present invention.

FIG. 13 is a cross-sectional view of a capacitor assembled using the lead frame of FIG.

FIG. 14 is a perspective view showing a state in which a chip-shaped sintered body is mounted on a horizontal bar in a conventional method.

FIG. 15 is a cross-sectional view showing a state where a dielectric layer is formed in a conventional method.

FIG. 16 is a cross-sectional view showing a state where a solid electrolyte layer is formed in a conventional method.

FIG. 17 is a cross-sectional view showing a general capacitor obtained by a conventional method.

[Explanation of symbols]

1,11 bar-like piece 2 metal rod 3 lateral bar 5 tantalum pentoxide layer 7 manganese dioxide layer _{A 1, A 2, A 3} , A 4, A capacitor element 11a groove 12 resin layer X dividing line

Claims (2)

(57) [Claims] 1. A process in which valve metal particles are integrally formed so that a metal bar protrudes and sintered to form a rod-shaped sintered body, and a dielectric layer is formed on the rod-shaped sintered body. Performing a step of forming a solid electrolyte layer on the surface of the dielectric layer, and dividing the sintered body of the rod-shaped piece on which the dielectric layer and the solid electrolyte layer are formed at appropriate intervals into a plurality of chip-shaped capacitors. A method for manufacturing a solid electrolytic capacitor, comprising a step of forming an element. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the sintered body of the rod-shaped piece has grooves at appropriate intervals in the longitudinal direction.