JP2000133553A - Method for forming solid electrolytic layer in capacitor element for solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce an occurrence rate of failed products by a method, wherein in a state just before all chip pieces are apart from a liquid face of a solid electrolytic layer forming liquid body among steps of swishing liquid off, each chip piece once relatively approaches the solid electrolytic layer forming liquid body. SOLUTION: A lateral bar 10 is lifted up by the lifting move of both-receiving frame bodies E1, E2, each chip piece 2 is pulled up from a manganic nitrate aqueous solution D and is liquid is swished off. In a state in which all the chip pieces 2 are apart from a liquid face of the manganic nitrate aqueous solution D among the steps, the both-receiving frame bodies E1, E2 are once moved down by an appropriate height, whereby each chip piece 2 relatively approaches the manganic nitrate aqueous solution D and thereafter, it is again lifted. The increase in an amount of the manganic nitrate aqueous solution D adhered to each chip piece 2 is surely avoided in a specified chip piece among the respective chip pieces 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 the metal horizontal bar 10, each chip piece 2 is attached from the lower surface of the metal horizontal bar 10.
It is extremely difficult to make the under-neck dimension L up to the lower end surface 2b the same for each of the chip pieces 2, and the under-neck dimension L from the horizontal bar 10 in each of the chip pieces 2 has a long and short rose. Is present, in the step of forming the solid electrolyte layer 6a for each chip piece 2 fixed to the horizontal bar 10, the manganese nitrate aqueous solution D in the treatment tank C is discharged from the discharge valve C2. The liquid was sequentially discharged, and the liquid level was changed to each chip 2 as shown in FIG.
When each chip piece 2 is drained from the aqueous manganese nitrate solution D by descending from the lower end surface 2b of the chip piece, the descending liquid level is different from the dimension L under the neck from the horizontal bar 10 in each chip piece 2. Due to the presence of the sticking, the chip 2 does not separate from the lower end surface 2b of each chip 2 at substantially the same time. Will be away.

At this time, between the chip piece 2 having the largest neck length L 'and the liquid surface of the manganese nitrate aqueous solution D, the manganese nitrate aqueous solution adhering to the side surface of the chip piece 2 As shown in FIG. 8, due to the surface tension between
A considerably thick liquid column is formed, and the thick liquid column is finally cut off as the liquid level lowers, so that it adheres to one chip piece 2 having the largest under-neck dimension L '. The amount of the manganese nitrate aqueous solution D 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, one chip piece 2 having the largest dimension under the neck is An excessive amount of the manganese nitrate aqueous solution adheres, and the excessively adhered manganese nitrate aqueous solution hangs down toward the lower end surface 2b of the chip piece 2 so as to accumulate in the form of water droplets at the lower end.・ Baking will be repeated.

As a result, the solid electrolyte layer 6 in one chip piece 2 having the largest dimension under the neck from the horizontal bar 10 is formed.
As shown in FIG. 9, the thickness of the chip piece a gradually increases from the upper end face 2a toward the lower end face 2b.
The maximum outer dimension d0max at the lower end of the chip piece 2
And the shape after the solid electrolyte layer 6a is formed on the chip piece 2 becomes larger from the upper end to the lower end as shown in FIG. Because it will be a big swollen shape,
When simultaneously manufacturing a plurality of capacitor elements using the horizontal bar, the shape and size of the chip piece 2 having the largest protrusion from the horizontal bar and leaving the liquid surface last are within a predetermined range of the capacitor element. The problem is that the product is liable to be defective, and the incidence of defective products is high.

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 In the step of draining away from the body, in a state immediately before all of the chip pieces are separated from the liquid surface of the solid electrolyte layer forming liquid, each chip piece and the solid electrolyte layer forming liquid are once relatively It is characterized by approaching. "

[0014]

As described above, in the step of draining each chip piece on the horizontal bar so as to be separated from the solid electrolyte layer forming liquid, all of the chip pieces are at the liquid level of the solid electrolyte layer forming liquid. In the state immediately before leaving, the chip pieces and the solid electrolyte layer forming liquid relatively once approach each other, so that each of the chip pieces 2 on the horizontal bar finally separates from the liquid surface of the solid electrolyte layer forming liquid. The liquid for forming a solid electrolyte layer that adheres to the side surface of the chip piece drips down while the chip pieces and the liquid for forming a solid electrolyte layer relatively approach once, and this chip piece and the liquid for forming a solid electrolyte layer form. Since the liquid column formed by the surface tension between the liquid and the liquid surface becomes thin and cuts in a thin state, there is a variation in the dimension below the neck from the horizontal bar in each of the chip pieces. Due to Te, the amount of the electrolyte layer forming liquid that adheres to the chip piece is able reliably avoid many made possible in certain chip component of each chip component.

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

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 10, 11 and 12 show the first embodiment.
In this figure, reference numeral C 'indicates a processing tank, and an aqueous manganese nitrate solution D is contained in the processing tank C'. In addition, the horizontal bar made of metal indicated by reference numeral 10 in the figure is the same as the horizontal bar 10 shown in FIG. 5, and a plurality of porous chip pieces 2 are provided on the horizontal bar 10. The anode rods 3 protruding from the pieces 2 are fixed in a line at appropriate intervals in the longitudinal direction by being fixed. 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 connected to the processing tank C '.
Placed on the upper surfaces of the receiving frames E1, E2 arranged on both sides of
In this state, by lowering the two receiving frames E1 and E2, the chip pieces 2 of the respective capacitor elements 1 fixed to the receiving frames E1 and E2 are removed as shown in FIG. D, the respective chip pieces 2
Is immersed until the upper end surface 2a becomes substantially flush with the liquid surface of the manganese nitrate aqueous solution D, and the manganese nitrate aqueous solution D penetrates into the inside of each chip piece 2.

Next, as shown by the two-dot chain line in FIG. 10, each of the chip pieces 2 of the horizontal bar 10 is moved by nitric acid by the ascending movement of the receiving frames E1 and E2 on which both ends are placed. By lifting (pulling) away from the liquid surface of the aqueous manganese solution D, each chip piece 2 is drained from the aqueous manganese nitrate solution D. Next, the drying and firing of each chip piece 2 is repeated a plurality of times, whereby a solid electrolyte layer 6a made of a metal oxide such as manganese dioxide is formed on the surface of the dielectric film such as tantalum pentoxide.

In the present invention, each chip piece 2 is lifted up from the aqueous manganese nitrate solution D by raising the horizontal bar 10 by raising and lowering the receiving frames E1 and E2. When all of the pieces 2 are in a state immediately before separating from the liquid surface of the aqueous solution of manganese nitrate D, the both receiving frames E1 and E2 are temporarily moved down by an appropriate height H once, so that After relatively approaching the manganese aqueous solution once, it rises again to the state shown by the two-dot chain line in FIG.

As described above, in the process of lifting each chip piece 2 of the horizontal bar 10 from the manganese nitrate aqueous solution D and draining the liquid by the ascending movement of both the receiving frames E1 and E2, all of the chip pieces are made of the nitric acid. In the state immediately before the manganese aqueous solution D is separated from the liquid surface, the both receiving frames E1 and E2 are temporarily moved down by the height H once, so that the horizontal bar 10 is moved.
The manganese nitrate aqueous solution adhering to the side surface of the chip piece 2 which is lastly separated from the liquid surface of the manganese nitrate aqueous solution D among the respective chip pieces 2 in FIG.
As described above, the tip piece 2 and the manganese nitrate aqueous solution D
The liquid column formed by the surface tension with the liquid surface becomes thin and cuts in a thin state, so that the dimension L under the neck from the horizontal bar 10 in each of the chip pieces 2 varies. Due to the existence, the amount of the manganese nitrate aqueous solution adhering to each chip piece 2 can be reliably prevented from increasing in a specific chip piece among the chip pieces 2.

In the first embodiment, the horizontal bar 1
0 is raised and lowered by raising and lowering both receiving frames E1 and E2, so that each chip piece 2 in the horizontal bar 10 is immersed in the manganese nitrate aqueous solution D in the processing tank C ′.
The case of rising and draining liquid was shown. Instead of the first embodiment, each chip piece 2 shown in FIGS. 13 and 14 and fixed to the horizontal bar 10 was loaded into the processing tank C in the same manner as in the conventional FIG. Thereafter, the aqueous solution of manganese nitrate D is supplied into the processing tank C from the supply valve C1 until the liquid surface of the aqueous solution of manganese nitrate D becomes substantially flush with the upper end surface 2a of the chip piece 2. 2 is immersed in an aqueous solution of manganese nitrate D, and then the aqueous solution of manganese nitrate D in the treatment tank C is sequentially discharged from a discharge valve C2, and the liquid level is reduced as shown in FIG.
Each chip piece 2 descends from the lower end surface 2b of the
When the liquid is drained from the aqueous manganese nitrate solution D, the horizontal bar 10 is also moved to a position immediately before all the chips 2 are separated from the liquid surface of the aqueous manganese nitrate solution D in the draining step. In the receiving frames E1 and E2,
Once the tip piece 2 and the manganese nitrate aqueous solution once approach each other by lowering the height H as needed,
The same effect as described above can be obtained.

In the second embodiment, the tip bar 2 and the aqueous solution of manganese nitrate are relatively moved by moving the horizontal bar 10 down by the appropriate height H of both the receiving frames E1 and E2. Instead of approaching once, the discharge valve C2
During the discharge of the aqueous manganese nitrate solution D from the tank, the discharge is temporarily stopped while the treatment tank C from the supply valve C1 is stopped.
Of course, by supplying an appropriate amount of the aqueous solution of manganese nitrate D therein, each chip piece 2 and the aqueous solution of manganese nitrate may be allowed to relatively approach once.

[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 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. 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 the horizontal bar by the method according to the first embodiment of the present invention.

FIG. 11 is a diagram showing a state in which each chip piece in the horizontal bar is being lifted from the manganese nitrate aqueous solution in the method according to the first embodiment of the present invention.

FIG. 12 is a view showing a state in which the chip pieces and the manganese nitrate aqueous solution are relatively once approached while each chip piece in the horizontal bar is being lifted from the manganese nitrate aqueous solution in the method according to the first embodiment of the present invention. .

FIG. 13 is a view showing a state in which each chip piece in a horizontal bar is being lifted from a manganese nitrate aqueous solution in the method according to the second embodiment of the present invention.

FIG. 14 is a view showing a state in which the chip pieces and the manganese nitrate aqueous solution are relatively once approached during the lifting of each chip piece in the horizontal bar from the manganese nitrate aqueous solution in the method according to the second embodiment 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 C, C 'Treatment tank D Manganese nitrate aqueous solution E1, E2 Receiving frame

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 The method of forming a solid electrolyte layer, wherein the step of baking the pieces and the step of baking the pieces are repeated an appropriate number of times. All the above In the state immediately before leaving the liquid surface of the body electrolyte layer forming liquid, each chip piece and the solid electrolyte layer forming liquid relatively once approach each other. Forming method.