JPH0786097A - Manufacture of solid-state electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve productivity, by forming dielectric layers at one time on a plurality of sintered bodies molded as bar type segments, and forming solid-state electrolytic layers. CONSTITUTION:Tantalum particles are formed on a porous bar type segment 1 of a square pole, in the state that a metal bar 2 made of tantalum protrudes as a unified body. The bar type segment 1 is sintered to form a sintered body. A plurality of the bar type segments are fixed to a horizontal bar 3 along the length direction, at suitable intervals, by welding. The bar type segments 1 are dipped in aqueous solution of phosphoric acid 4, and anodic oxidation is performed by applying a DC voltage. Thus a tantalum pentaoxide layer 5 is formed on the surface of each tantalum particle of the bar type segments 1. The bar type segments 1 are dipped in aqueous solution of manganese nitrate 6, and the insides of the bar type segments 1 are impregnated with the aqueous solution of manganese nitrate. The bar type segments 1 are pulled up from the solution and water content is vaporized by heating. By repeating the above process several times, a manganese dioxide layer 7 is formed on the surface of the tantalum pentaoxide 5. By cutting and dividing the bar type segments 1, chip type capacitor elements are obtained.

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 type of capacitor is manufactured as follows.

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

Next, as shown in FIG. 15, the tip piece 21 is immersed in a chemical conversion solution 24 such as a phosphoric acid aqueous solution to apply a direct current to anodize the tip piece 2.
A dielectric layer 25 of tantalum pentoxide or the like 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 conversion liquid 24, the upper surface 21a of the chip piece 21
The dielectric layer 25 is also formed on the outer peripheral surface of the root portion of the anode rod 22 over a portion having an appropriate length by immersing the chemical conversion liquid 24 so as to be submerged to an appropriate depth from the liquid surface.

Then, as shown in FIG. 16, the chip piece 21 having the dielectric layer 25 formed thereon is treated with, for example, a manganese nitrate aqueous solution 26, and the upper surface 21a of the chip piece 21 is the liquid surface of the manganese nitrate aqueous solution 26. The manganese nitrate aqueous solution 26 is dipped in the chip piece 21 so that
The solid electrolyte layer 2 of manganese dioxide or the like is formed on the surface of the dielectric layer 25 by impregnating the inside of the dielectric layer 25 and then pulling it up and heating it to evaporate the moisture.
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 oxidative polymerization method or a gas phase oxidative 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 to form the anode rod 22. 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 21a of the chip piece 21. Since it is not possible to obtain a sufficient electric capacity with respect to the volume of the chip piece 21, the immersion position of the chip piece 21 needs to be strictly adjusted.

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

[0007]

As described above, in the conventional manufacturing of capacitors, since individual chip pieces were mounted on the horizontal bar to form the dielectric layer and the solid electrolyte layer, the horizontal bar was not formed. Due to the length in the longitudinal direction, the number of chip pieces to be processed at one time is limited, and the production efficiency was very poor.

Further, when the dielectric layer and the solid electrolyte layer are formed on the chip piece, the plurality of chip pieces are mounted on the horizontal bar with the upper surfaces of the chip pieces all aligned, and the chip pieces are set to the correct depth. However, the work and process control were troublesome, for example, it was necessary to immerse it in the chemical conversion solution and the manganese nitrate aqueous solution.

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

[0010]

As a result of intensive studies to achieve the above object, the present inventor formed a sintered body composed of valve action metal particles into a rod-shaped piece, and sintered the rod-shaped piece. On the other hand, if the dielectric layer and the solid electrolyte layer are formed and then divided into appropriate sizes to obtain chip-shaped capacitor elements, it is possible to obtain several times as many capacitor elements in a simpler operation than before. Found.

That is, according to the present invention, a step of integrally molding valve-acting metal particles so that a metal rod protrudes and sintering them to obtain a sintered body of a rod-shaped piece, the sintered body of the rod-shaped piece is made of a dielectric material. A step of forming a body layer, a step of forming a solid electrolyte layer on the surface of the dielectric layer, and a plurality of rod-shaped piece sintered body on which the dielectric layer and the solid electrolytic layer are formed are divided 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.

Further, according to the present invention, the sintered body of the rod-shaped piece is
It also includes a method of manufacturing a solid electrolytic capacitor characterized by having grooves at appropriate intervals in the longitudinal direction.

[0013]

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

Further, since the rod-shaped sintered body on which the dielectric layer and the solid electrolyte layer are formed is divided into appropriate sizes to manufacture a capacitor element, the anode protruding from the rod-shaped piece is formed in the step of forming the solid electrolyte layer. There is no problem even if a solid electrolyte layer is formed so as to cover the dielectric layer formed at the base of the rod, alignment when mounting the rod-shaped piece on the horizontal bar, and the rod-shaped piece with the chemical conversion liquid and manganese nitrate. It is not necessary to strictly adjust the immersion depth when immersed in an aqueous solution.

[0015]

EXAMPLE A first example of the present invention will now be described with reference to FIGS. 1 to 6 in the case of producing a tantalum solid electrolytic capacitor.
Will be described with reference to the drawings.

First, as shown in FIGS. 1 and 2, the tantalum particles are formed into a square pole-like porous rod-shaped piece 1 with a tantalum metal rod 2 protruding integrally. 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 be inserted near the lower end surface 1b. The rod-shaped pieces 1 are sintered to form a sintered body, and a plurality of the rod-shaped pieces 1 are fixed to the horizontal bar 3 by welding the metal rods 2 protruding from the rod-shaped pieces 1 to a horizontal bar. The bars 3 are mounted along the longitudinal direction at an appropriate pitch.

Next, as shown in FIG. 3, each tantalum particle in the rod-shaped piece 1 is subjected to anodic oxidation 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) on the surface of
To form. At this time, by immersing the rod-shaped piece 1 in the phosphoric acid aqueous solution 4 so that the upper end surface 1a of the rod-shaped piece 1 is submerged by an appropriate depth from the liquid surface of the phosphoric acid aqueous solution 4,
It is preferable to form the tantalum pentoxide 5 also on the outer peripheral surface of the root portion of the metal rod 2 over a portion having an appropriate length.

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

As shown in FIG. 5, the rod-shaped piece 1 thus obtained is divided into chip-shaped capacitor elements A ₁ , A ₂ , A ₃ , A by cutting them into appropriate dimensions, for example, by cutting with a diamond cutter or the like. You get ₄ . Of the obtained capacitor elements A ₁ , A ₂ , A ₃ , and A ₄ , the capacitor element A ₂ , which is obtained from the central portion of the rod-shaped piece 1 and whose both end surfaces are split surfaces,
As shown in the cross section of FIG. 6 (a), A ₃ has the end faces 2a of the metal rod 2 exposed on both end faces (divided faces) thereof, and the tantalum pentoxide layer 5 and the dioxide on the surfaces other than the both end faces. The manganese layer 7 is formed. Further, the capacitor element A ₄ obtained from the lower end portion of the rod-shaped piece 1 has an end face 2 of the metal rod 2 on one end face thereof, as shown in the cross section of FIG.
a is exposed, and the tantalum pentoxide layer 5 and the manganese dioxide layer 7 are formed on the other surfaces. The capacitor element A ₁ obtained from the upper end portion of the rod-shaped piece 1 cuts the protruding metal rod 2, while removing the tantalum pentoxide layer 5 and / or the manganese dioxide layer 7 formed on the upper end surface 1a of the rod-shaped piece 1. For example, the structure is the same as that of the capacitor elements A ₂ and A ₃ as shown in FIG. 6A, and if only the protruding metal rod 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 when dividing. Of course, if the capacitor element is obtained as described above, when the tantalum pentoxide layer 5 and the manganese dioxide layer 7 are formed, the rod-shaped piece 1 completely reaches the upper end surface 1a of the phosphoric acid aqueous solution 4 Alternatively, there is no problem even if it is immersed in the manganese nitrate aqueous solution 6, and at this time, the manganese nitrate aqueous solution 6 is more than that when the rod-shaped piece 1 is immersed in the phosphoric acid aqueous solution 4.
There is no problem even if the manganese dioxide layer 7 is formed so as to cover the formation region of the tantalum pentoxide layer 5 by immersing it deeper in the process of immersing in, and the work and process management is 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 11a are formed on the circumferential surface of the rod-shaped piece 11 at appropriate intervals in the longitudinal direction of the rod-shaped piece 11.
Is provided over the entire circumference, and the protruding metal rod 2 is integrally provided on the end surface of the rod-shaped piece 11. The sintered body of the rod-shaped piece 11 thus formed is mounted on the horizontal bar 3 in the same manner as in the first embodiment, and the dielectric layer and the solid electrolyte layer are formed. If the groove 11a is formed in this manner, the chip-shaped capacitor element after the solid electrolyte layer is formed can be easily divided at a predetermined position by bending without using a cutting means such as a cutter. be able to. In addition, at this time, the groove 11a is formed in the rod-shaped piece 1
They may be provided discontinuously or partially at appropriate intervals in the longitudinal direction.

Further, in these examples, as shown in FIG. 9, a resin layer 12 is provided on the rod-shaped pieces 1, 11 and the rod-shaped pieces 1, 1 are formed before or after the tantalum pentoxide layer 5 is formed.
If it is formed by coating so as to straddle each of the dividing lines X of 1,
It is possible to surely perform insulation separation between the anode side and the cathode side when divided into capacitor elements A ₁ , A ₂ , A ₃ , and A ₄ , which is convenient when assembled into the capacitors described below. To work.

The capacitor element A thus obtained
(A ₁ , A ₂ , A ₃ , A ₄ ) can be made into a capacitor, for example, as follows. As shown in FIGS. 10 and 11, one division surface of the capacitor element A, the convex portion 8a, and the convex portion 8 are formed.
copper, iron, aluminium, which is composed of the collar portion 8b that supports a,
With the collar portion 8b of the anode member 8 made of metal such as tantalum, the insulator layer 9 made of resin or the like having a through hole through which the protrusion 8a of the anode member 8 penetrates, and the protrusion 8a of the anode member 8 is formed. A capacitor is formed by integrally assembling the tip surface and the end surface 2a of the metal rod 2 of the capacitor element A so as to face each other and sandwich them. 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 coating a conductive paste on the surface A ′ if necessary. The formation of the conductor layer may be performed after dividing the rod-shaped pieces 1 and 11 into the capacitor elements A, or may be performed collectively in the state of the rod-shaped pieces 1 and 11. In addition, the other split surface of the capacitor element A is
It may be protected by an insulating layer 10 made of resin or the like.

Further, as shown in FIG. 9, the rod-shaped piece 1,
If the capacitor element A obtained when the resin layer 12 is formed so as to straddle the respective dividing lines X of 11 is applied to a lead frame B having inner lead portions B ′ and B ″ as shown in FIG. 12, for example. As shown in FIG. 13, the tip of the inner lead B ′ is connected to the end surface 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. The conductor layer 14 made of, for example, a graphite layer and a silver layer
A resin-sealed capacitor can be obtained by connecting the capacitor element A and a part of the inner leads B ′, B ″ with the molding resin 15 by connecting the capacitor element A through the molding resin 15.

As described above in detail, in the present embodiment, a rod-shaped piece having a quadrangular prism shape as a sintered body has been described, but the present invention is similarly applied to other rod-shaped pieces such as a polygonal column shape and a column shape. It is possible.

[0025]

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

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

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

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

[Brief description of drawings]

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

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

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

FIG. 4 is a cross-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 where 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 cross-sectional view taken along the line II-II of FIG.

FIG. 9 is a perspective view showing a state in which a resin layer is formed in the vicinity of each dividing line of the sintered body in the first example 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.

11 is a sectional view taken along line III-III in FIG.

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

13 is a 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 in which a dielectric layer is formed in the conventional method.

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

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

[Explanation of symbols]

1, 11 Rod-shaped piece 2 Metal rod 3 Horizontal 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)

[Claims] 1. A step of integrally molding valve-acting metal particles so that a metal rod protrudes and sintering them to form a rod-shaped sintered body, and forming a dielectric layer on the rod-shaped sintered body. And a step of forming a solid electrolyte layer on the surface of the dielectric layer, and a plurality of chip-shaped capacitors by dividing the rod-shaped sintered body on which the dielectric layer and the solid electrolytic layer are formed at appropriate intervals. A method for manufacturing a solid electrolytic capacitor, comprising the step of forming an element. 2. The method for producing 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.