JP2000049051A - Method of forming solid electrolytic layer in capacitor element for solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility that a specific chip piece from among chip pieces becomes defective, because it is out of a specified size/shape due to an excessive liquid for solid electrolytic layer sticking to it when impregnation in the liquid for a solid electrolytic layer, swishing off of the liquid, and baking thereafter are repeated with each of a plurality of chip pieces fitted to a lateral bar for forming a solid electrolytic layer. SOLUTION: When a chip piece 2 at a lateral bar 10 is swished off so as to part from the liquid for a solid electrolytic layer, the lateral bar 10 is so tilted as its one end part is lowered by an appropriate angle, thus much liquid for solid electrolytic layer sticks to at least one chip piece 2 from among chip pieces 2 at the lateral bar 10, which is positioned at one end part of lateral bar 10, while excess liquid for a solid electrolytic layer sticking much to the one chip piece 2 is absorbed with a swishing member contacting or cross to the one chip piece 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a solid electrolyte layer on a cathode side of a chip in a capacitor element of a solid electrolytic capacitor such as tantalum or aluminum.

[0002]

2. Description of the Related Art Generally, a solid electrolytic capacitor of this type is generally described, for example, in Japanese Patent Application Laid-Open No. 60-2209.
1 and FIG. 2 and a solid electrolytic capacitor 100 described in, for example, Japanese Patent Application Laid-Open No. 2-105513 and FIG.
There is a solid electrolytic capacitor 200 with a safety fuse configured as shown in FIG.

The former solid electrolytic capacitor 100 has a chip 2 made of a sintered body of metal powder and one end face 2 of the chip 2.
a capacitor element 1 comprising an anode rod 3 projecting from
Is disposed between a pair of left and right lead terminals 4 and 5 so that the anode rod 3 of the capacitor element 1 is fixed to one of the lead terminals 4 by welding or the like. The other lead terminal 5 is connected to the cathode-side electrode film 6 formed on at least the outer peripheral surface 2c of the device, and the whole of these is packaged in a synthetic resin mold part 7.

A solid electrolytic capacitor 200 with a safety fuse is a capacitor element 1 comprising a chip 2 made of a sintered body of a metal powder and an anode rod 3 protruding from the chip 2, and a pair of left and right leads. The anode rod 3 of the capacitor element 1 is disposed between the terminals 4 and 5 so as to be fixed to one of the lead terminals 4 by welding or the like. The formed cathode-side electrode film 6 and the other lead terminal 5 are connected via a safety fuse wire 8 which is blown by an overcurrent or a rise in temperature, and these are entirely made of synthetic resin. This is a structure formed by packaging in the mold part 7.

[0005] These solid electrolytic capacitors 10
At 0 and 200, the two lead terminals 4 and 5 are bent to the back surface side of the molded part 7 after the molded part 7 is formed, as shown by a two-dot chain line.
The safety fuse wire 8 is coated with an elastic resin 8a such as a silicone resin. In manufacturing the capacitor element 1 used for these solid electrolytic capacitors 100 and 200, the following method is adopted.

That is, first, as shown in FIG. 4, a metal powder such as tantalum is applied to a porous chip piece 2 having an outer shape d0 of square cross section or the like, as shown in FIG. A part of the anode bar 3 is buried so as to be compacted and sintered, and a plurality of the chip pieces 2 are placed on a metal horizontal bar 10 as shown in FIG. The anode bars 3 protruding from the horizontal bar 10 are fixedly arranged in a line at appropriate intervals in the longitudinal direction of the horizontal bar 10.

Next, as shown in FIG. 6, a direct current is applied to each of the chip pieces 2 fixed to the horizontal bar 10 in a state of being immersed in a chemical conversion solution B such as a phosphoric acid aqueous solution placed in a processing tank A. By performing anodic oxidation, a dielectric film such as tantalum pentoxide is formed on the surface of each metal powder in the chip piece 2 and a part of the surface of the anode bar 3. Next, as shown in FIG. 7, each chip piece 2 fixed to the horizontal bar 10 is loaded into a processing tank C, and an aqueous solution of manganese nitrate D is supplied into the processing tank C through a supply valve C1. The manganese aqueous solution D is supplied to a level at which the liquid level of the manganese aqueous solution D becomes substantially the same as the upper end surface 2a of the chip piece 2, and each chip piece 2 is immersed in the manganese nitrate aqueous solution D. The manganese aqueous solution D was sequentially discharged from the discharge valve C2, and the liquid level was changed to each chip piece 2 as shown in FIG.
Of the manganese nitrate aqueous solution D, and drying and firing are repeated a plurality of times by descending from the lower end face 2b of the dielectric material. A solid electrolyte layer 6a made of a metal oxide such as manganese dioxide is formed on the surface of the film.

Further, a graphite film 6b is formed on the surface of the solid electrolyte layer 6a in the chip piece 2, and a metal film 6c such as silver or nickel is formed on the surface of the graphite film 6b. Side 2c
As shown in FIG. 9, a method of forming a cathode-side electrode film 6 composed of the solid electrolyte layer 6a, the graphite film 6b, and the metal film 6c on the lower end surface 2b is adopted.

[0009]

However, the conventional method for manufacturing a capacitor element has the following problems. That is, as shown in FIG. 5, when a plurality of chip pieces 2 are fixed to a horizontal metal bar 10, the protrusion dimension L from the lower surface of the metal bar 10 to the lower end surface 2 b of each chip piece 2 is set. It is extremely difficult to make the same for each of the chip pieces 2, and since the protrusion dimension L of each of the chip pieces 2 has a long and short variation, it is fixed to the horizontal bar 10. In the step of forming the solid electrolyte layer 6a on each of the chip pieces 2, the manganese nitrate aqueous solution D in the treatment tank C is sequentially discharged from the discharge valve C2, and the liquid level is reduced.
As shown in FIG. 8, when each chip 2 is drained from the manganese nitrate aqueous solution D by descending from the lower end surface 2 b of each chip 2, the descending liquid surface is projected on each chip 2. Due to the variation in the dimension L, the chip pieces 2 having the largest protruding dimension L ′ out of the chip pieces 2 are not separated from the lower end surface 2b of each chip piece 2 at substantially the same time due to the variation. Will finally leave.

At this time, the surface tension is concentrated between the lower end surface 2b of the chip piece 2 having the largest protrusion L 'and the liquid surface and the liquid surface rises greatly, as shown in FIG. A considerably thick liquid column is formed, and the thick liquid column is cut last as the liquid level lowers, so that the manganese nitrate aqueous solution D adheres to the chip piece 2 having the largest protrusion size L '. Is larger than the amount attached to the other chip piece 2 that first separates from the liquid surface among the chip pieces 2. In other words, the chip piece 2 having the largest protruding dimension has an excessive amount of the manganese nitrate aqueous solution. Adheres, and
This excess manganese nitrate aqueous solution is attached to chip pieces 2
Hangs down toward the lower end surface 2b and accumulates in the form of water droplets at the lower end, and drying and firing in this state are repeated.

As a result, the thickness of the solid electrolyte layer 6a in the chip piece 2 having the largest protrusion from the horizontal bar 10 is changed from the upper end face 2a to the lower end face 2b as shown in FIG.
, The maximum outer dimension d0max at the lower end of the chip piece 2 is considerably larger than the outer dimension at the upper end of the chip piece 2, and the solid electrolyte is As shown in FIG. 9, the shape after the formation of the layer 6a is considerably greatly expanded from the upper end to the lower end, so that a plurality of capacitor elements are simultaneously manufactured using the horizontal bar. In this case, there is a problem that the shape and dimensions of the chip piece 2 having the largest protruding dimension are likely to be out of a predetermined range in the capacitor element, resulting in a defective product, and a high incidence of defective products.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for forming a solid electrolyte layer on the cathode side of a chip in a capacitor element so as to reliably reduce the incidence of defective products. Is what you do.

[0013]

In order to achieve this technical object, the method of the present invention comprises the steps of: "arranging a plurality of porous chip pieces in a row at appropriate intervals along the longitudinal direction of a horizontal bar. Then, each chip piece in the horizontal bar is raised or lowered relative to the height position of the horizontal bar and the level of the liquid for forming a solid electrolyte layer placed in the processing tank, and the solid electrolyte is removed. A step of immersing in a layer forming liquid, and raising or lowering the height position of the horizontal bar and the liquid level of the solid electrolyte layer forming liquid to each chip piece in the horizontal bar by the solid electrolyte layer In the method for forming a solid electrolyte layer, the step of draining the liquid so as to separate from the forming liquid and the step of firing each chip piece in the horizontal bar are repeated as appropriate times. For forming electrolyte layer When at least each chip piece is separated from the liquid surface of the solid electrolyte layer forming liquid in the step of draining away from the body, the horizontal bar is inclined such that one end is lower and the other end is higher. In addition, the liquid draining member contacts or approaches at least one chip piece located at one end of the horizontal bar among the chip pieces in the horizontal bar. " .

[0014]

As described above, in the step of draining each chip piece on the horizontal bar so as to separate the chip piece from the solid electrolyte layer forming liquid, at least each chip piece is a liquid of the solid electrolyte layer forming liquid. When separating from the surface, the horizontal bar is inclined so that one end thereof is lower and the other end thereof is higher, so that there is variation in the protrusion dimension from the horizontal bar in each chip piece fixed to the horizontal bar. Also, since at least one chip piece located at one end of the horizontal bar of each chip piece is located at the lowest height, the liquid level in the solid electrolyte layer forming liquid is finally at the horizontal bar. It will be away from at least one chip piece located at one end.

Therefore, by contacting or approaching the liquid draining member to at least one chip piece located at one end of the horizontal bar among the respective chip pieces in the horizontal bar,
The liquid for forming an electrolyte layer that is attached to or attached to the at least one chip piece is sucked so as to be transferred to a liquid draining member that is in contact with or close to the at least one chip piece, so that the at least one chip piece is removed. The amount of the liquid for forming an electrolyte layer adhering to the chip pieces can be reduced so as to approach the amount of the liquid for forming an electrolyte layer adhering to other chip pieces.

Therefore, according to the present invention, when a plurality of the condensed elements are manufactured by using the horizontal bars, the number of defective products deviating from predetermined dimensions and shapes is reliably reduced, and defective products are generated. This has the effect of greatly reducing the rate.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. These FIG.
12 and FIG. 12, the processing tank shown in FIG.
The metal horizontal bar indicated by reference numeral 10 is also the same as the horizontal bar 10 shown in FIG. 5, and the horizontal bar 10 has a porous chip piece 2. Are attached in a line at appropriate intervals in the hand direction by fixing anode rods 3 protruding from the respective chip pieces 2. Further, each chip piece 2 in the horizontal bar 10 is anodized as shown in FIG.
A dielectric film such as tantalum pentoxide is formed.

First, the horizontal bar 10 is placed on the upper surfaces of the receiving frames E1 and E2 arranged on both sides of the processing tank C, so that the chip pieces 2 of the respective capacitor elements 1 fixed thereto are removed. As shown in FIG. 10, after being inserted into the processing tank C, a manganese nitrate aqueous solution D is supplied into the processing tank C, and the liquid level of the manganese nitrate aqueous solution D is changed from the supply valve C1 to the upper end surface 2a of the chip piece 2. And each of the chip pieces 2 is immersed in an aqueous solution of manganese nitrate D, and
The manganese nitrate aqueous solution D is permeated.

Next, the aqueous solution of manganese nitrate D in the processing tank C is sequentially discharged from the discharge valve C2, and the liquid level is lowered from the lower end surface 2b of each chip piece 2 as shown in FIG. Thereby, each chip piece 2 is drained from the manganese nitrate aqueous solution D. Next, the drying and firing of each chip piece 2 is repeated a plurality of times, whereby the surface of the dielectric film such as the tantalum pentoxide,
Solid electrolyte layer 6a made of metal oxide such as manganese dioxide
To form

In the present invention, as shown in FIG.
In the step of draining each chip piece 2 from the manganese nitrate aqueous solution D by lowering the liquid level of the manganese nitrate aqueous solution D, when at least each chip piece 2 separates from the liquid surface of the manganese nitrate aqueous solution D, the horizontal bar is moved. By moving only one of the receiving frames E1 and E2 supporting both ends only by an appropriate height, or by moving only the other receiving frame E2 by an appropriate height, The horizontal bar 10 is configured to be appropriately inclined at an angle θ with respect to a horizontal plane so that one end 10a is low and the other end 10b is high.

Further, in the processing tank C, a liquid draining member F such as a brush or the like is placed.
Of each chip piece 2 at one end 10a of the horizontal bar 10
Is provided so as to be in contact with or close to at least one chip piece 2 located at the position (1). As described above, in the step of lowering the liquid level of the aqueous solution of manganese nitrate D in the processing tank C to drain each chip piece 2 on the horizontal bar 10 so as to be separated from the aqueous solution of manganese nitrate D, at least each of the chip pieces 2 is separated from the liquid surface of the aqueous solution of manganese nitrate D, the chip is fixed to the horizontal bar 10 by inclining the horizontal bar 10 so that one end 10a is low and the other end 10b is high. 2
, Even if there is a variation in the projection dimension L from the horizontal bar 10, at least one of the chip pieces 2 located at one end 10 a of the horizontal bar 10 is at the lowest height position. Finally, the liquid surface of the manganese nitrate aqueous solution D is finally separated from at least one chip piece 2 located at one end 10 a of the horizontal bar 10.

Therefore, the liquid draining member F provided in the processing tank C contacts or contacts at least one chip piece 2 located at one end 10a of the horizontal bar 10 among the chip pieces 2 of the horizontal bar 10. By approaching, a large amount of the manganese nitrate aqueous solution that adheres to the at least one chip piece 2 or is about to adhere is sucked so as to move to the liquid draining member F that comes into contact with or comes close to the manganese nitrate aqueous solution. The amount of the aqueous manganese nitrate solution adhering to at least one chip piece 2 can be reliably reduced so as to approach the amount of the aqueous manganese nitrate solution adhering to the other chip pieces 2.

In the above-described embodiment, each chip piece 2 of the horizontal bar 10 is immersed in the aqueous manganese nitrate solution D by supplying the aqueous manganese nitrate solution D into the treatment tank C and raising the liquid level. The manganese nitrate aqueous solution D in the treatment tank C was discharged and the liquid level was lowered, so that each chip piece 2 in the horizontal bar 10 was drained away from the manganese nitrate aqueous solution D. However, the present invention is not limited to this, and the two receiving frames E1, E
2 is immersed in the aqueous manganese nitrate solution D by lowering the horizontal bar 10 by the downward movement of the horizontal bar 10, while the horizontal bar 10 is moved by the upward movement of both the receiving frames E1 and E2.
, The liquid may be drained so as to separate each chip piece 2 from the aqueous solution of manganese nitrate D, and the horizontal bar 10 may be configured to be inclined in the middle of this. Needless to say, F may be provided on the horizontal bar 10 or provided on another bracket instead of being provided in the processing tank C as in the above-described embodiment.

In particular, according to an experiment conducted by the present inventors, when a sponge was used as the liquid draining member F, bubbling occurred in the manganese nitrate aqueous solution D. However, when a brush was used instead of the sponge. Was able to reduce the occurrence of bubbling in the manganese nitrate aqueous solution D.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a solid electrolytic capacitor.

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

FIG. 3 is a vertical sectional front view of a solid electrolytic capacitor with a safety fuse.

FIG. 4 is a perspective view showing a capacitor element.

FIG. 5 is a perspective view showing a state in which a plurality of the capacitor elements are fixed to a horizontal bar.

FIG. 6 is a diagram showing a state where an anodizing process is performed on each capacitor element in the horizontal bar.

FIG. 7 is a view showing a state in which a solid electrolyte layer is formed on each capacitor element in the horizontal bar by a conventional method.

FIG. 8 is a diagram showing a state in which a solid electrolyte layer is formed on each capacitor element in the horizontal bar by a conventional method.

FIG. 9 is a vertical sectional front view of a capacitor element according to a conventional method.

FIG. 10 is a diagram showing a state in which a solid electrolyte layer is formed on each capacitor element in a horizontal bar by the method of the present invention.

FIG. 11 is a diagram showing a state in which a solid electrolyte layer is formed on each capacitor element in a horizontal bar by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Chip piece 2a Upper end face of chip piece 2b Lower end face of chip piece 3 Anode rod 6 Cathode side electrode film 6a Solid electrolyte layer 6b Graphite film 6b 6c Metal film 10 Horizontal bar 10a One end of horizontal bar 10b Horizontal bar Other end C Treatment tank C1 Supply valve C2 Discharge valve D Manganese nitrate aqueous solution E1, E2 Receiving frame F Fluid draining member

Claims (1)

[Claims] 1. A plurality of porous chip pieces are fixedly arranged in a row on a horizontal bar at appropriate intervals along the longitudinal direction thereof, and then placed in a processing tank at a height position of the horizontal bar. Immersing each chip piece in the horizontal bar in the solid electrolyte layer forming liquid at a relative rise or fall with respect to the liquid level of the solid electrolyte layer forming liquid, and the height position of the horizontal bar; A step of draining each chip piece in the horizontal bar so as to be separated from the solid electrolyte layer forming liquid by relative ascent or descent with respect to the liquid surface of the solid electrolyte layer forming liquid, and each chip in the horizontal bar And a step of baking the piece is repeated as appropriate times. In the method for forming a solid electrolyte layer, at least each chip piece in the step of draining each chip piece in the horizontal bar so as to be separated from the solid electrolyte layer forming liquid Before When the horizontal bar is separated from the liquid surface of the liquid for forming a solid electrolyte layer, the horizontal bar is inclined so that one end thereof is low and the other end is high, and one end of the horizontal bar among the chip pieces in the horizontal bar. Wherein the liquid drain member is brought into contact with or close to at least one chip piece located at the position (1) above.