JPS5923463B2 - Manufacturing method of solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid electrolytic capacitor, and in particular to the process of attaching a semiconductor layer forming member to an anode lead extending from a capacitor element made of a metal member having a valve action. The purpose is to lessen the deterioration of characteristics.

In general, this type of capacitor is made of a capacitor element A which is made by press-molding metal powder having a valve action, such as tantalum or niohex-aluminum, into a cylindrical shape and sintering it, as shown in Figure 1. The metal wire with the metal wire is planted as an anode lead B, and the protruding part of this anode lead B is
The bent first external lead member C is welded, and the second external lead member C is connected to the electrode lead layer formed on the surface of the capacitor element A via an oxide layer and a semiconductor layer. After that, the entire circumferential surface of the capacitor element A including the protrusion of the anode lead B is covered with a resin material E.

By the way, before welding the first external lead member C to the protruding portion of the anode lead B extending therefrom, the capacitor element A is chemically treated together with the anode lead B so that an oxidized layer is formed on its surface. Further, only the capacitor element A is immersed in the semiconductor mother liquor for a certain period of time to fully impregnate it, and then a thermal decomposition reaction is caused in a high temperature atmosphere to form a semiconductor layer on the oxide layer.

However, during the thermal decomposition process of the semiconductor mother liquor, the temperature of the capacitor element A that is inserted into the high-temperature atmosphere rises rapidly, and the semiconductor mother liquor impregnated inside undergoes a thermal decomposition reaction, causing water vapor to flow from inside. , the decomposed gas such as nitrogen acclimated products blows out from the surface layer, so the surface layer p
Bubbles are generated in the semiconductor mother liquid layer during thermal decomposition, and these bubbles adhere to the protruding portion of the anode lead B, causing so-called creeping of the semiconductor layer forming member.

Normally, the impregnation-pyrolysis operation of the semiconductor mother liquor is repeated several times or more due to the porous nature of the capacitor niremen l-A, and as the number of times of thermal decomposition increases, the creeping up of the semiconductor layer forming member also progresses. There are some towns that tend to do this.

Therefore, when the first external lead member C is brought into contact with the protruding portion of the anode lead B, the first external lead member C and the semiconductor layer that has climbed up come into contact and the cathode and the anode are short-circuited. There is a problem that the capacitor cannot function as a capacitor.

Therefore, in the past, a Teflon busher F was attached to the top surface of the capacitor element A, with the anode lead B inserted through its center hole, as shown in Figures 2 to 3. configuration has been adopted.

Although this method can effectively suppress the creeping-up phenomenon of the semiconductor layer at the protruding portion of the anode lead B, it has poor workability and requires an extremely large number of man-hours, making it difficult to mass-produce. It has the disadvantage of being scarce.

In view of these points, the present invention has been developed so that even if a semiconductor layer is formed on an anode lead extending from a capacitor element made of a metal member having a valve function, the outer i4[11
This invention provides a method of manufacturing a solid electrolytic capacitor that significantly reduces the occurrence of characteristic troubles caused by connection of J-board members.One manufacturing method will be described below with reference to FIG. 4.

First, as shown in FIG. An anode lead 2 made of wire is planted.

Then, this capacitor element 1 and anode lead 2
An oxide layer 3 as a dielectric layer is formed on the surfaces of the capacitor element 1 and positive leads 2 by immersing them in a chemical solution and anodizing them.

Then, this capacitor element 1 is used as a semiconductor mother liquid,
Anode lead 2o) Immerse so that the protruding portion 2a is immersed so that the inside is sufficiently impregnated.

After lifting the capacitor element 1 from the semiconductor mother liquor,
It is inserted into a heating furnace controlled at about 200° C., and the semiconductor layer 4 is deposited on the oxide layer 3 by a thermal decomposition reaction.

At this time, the semiconductor mother liquor is attached to the protruding portion 2a of the anode lead 2 by the action of decomposition gas etc. ejected from the capacitor element 1, and the semiconductor layer 4 is formed.

The circumferential surface of the capacitor element 1 is covered with an electrode lead layer 5 made of, for example, a graphite layer or a silver paste layer.
form.

For example, the first outer HB 1J is bent in an L shape.
- The electrode member 6 is welded to the protruding portion 2a of the anode lead 2 on which the semiconductor layer 4 is formed.

In this state, the first external ') l as anode
' The HIJ material 6 is short-circuited to the semiconductor layer 4 (which serves as a cathode).

Thereafter, the 20th) external lead member 7 is soldered to the electrode lead layer 5 of the capacitor element 1 at the same time as the solder layer 8 is formed.

Next, as shown in FIG. The entire peripheral surface of the capacitor element 1 is coated with the first resin material 9 (with a trowel).

In addition to the dipping method for covering the capacitor element 1 with the first resin material 9, a fluid dipping method using powdered resin, a molding method, etc. can also be adopted.

Next, as shown in FIG. 11J-Immerse for a short time so that the weld 11b with the card member 6 is immersed.

As a result, the semiconductor layer 4 that has been formed on the portion of the anode lead 2 exposed from the first resin material 9 is dissolved.

Note that the semiconductor layer 4 formed on the anode lead 2 can be removed not only by the chemical method described above but also by mechanical or electrical methods.

After that, the capacitor element 1 is pulled up from the liquid 10,
Wash thoroughly and dry.

Next, as shown in FIG. Cover as shown.

Note that the coating method and material of the second resin material 11 can be selected as appropriate.

In this way, the protruding portion 2a of the anode lead 2 (the semiconductor layer 4 formed by climbing up) covers the entire circumferential surface of the capacitor element 1 except for the M contact portion between the anode lead 2 and the first external lead member 6. After being coated with the resin material 9, the anode lead 2 is removed by chemical gravity.
Even if the welded portion between the first outer piece tl IJ-do member 6 and the semiconductor layer 4 remains, it is electrically insulated from the semiconductor layer 4 in the capacitor element 1.
The first external lead member 6 as an anode and the semiconductor layer 4 of the capacitor element 1 as a negative electrode are electrically insulated.

Therefore, short circuits between the anode and the cathode can be completely eliminated, and leakage current between the two electrodes can be significantly reduced.

Further, the semiconductor layer 4 at the protruding portion 2ad of the anode lead 2
Prior to removing the capacitor element 1, the entire circumferential surface of the capacitor element 1 is covered with the first resin material 9? Since it is coated with a trowel, if the removal method is a chemical method, the influence of chemicals on the semiconductor layer 4 in the capacitor element 1 can be completely eliminated.

However, since the first and second external lead members 6, 7 and the first resin material 9 do not come into complete contact with each other, the immersion time in the chemical agent is limited to the extent that the semiconductor layer 4 of the anode lead 2 is removed. The shortest possible time is desirable.

Furthermore, if the surfaces of the first and second external lead members 6 and 7 are plated with solder, when removing the semiconductor layer 4 on the anode lead 2 by the above-mentioned chemical method,
, the second external IJ-1 material 6°7 tends to be immersed, but since the first resin material 9 is further covered with the second resin material 11, its strength is not impaired. There isn't.

Next, a specific example will be explained.

First, the anode lead 2 of a capacitor element using manganese dioxide as the semiconductor layer 4 is made of first and second external lead members 6 and 7 made of soldered CPS wires.
and electrode lead layer 5; after these are connected, all 1. of the capacitor element 1 except the connection portion between the protruding portion 2a of the anode lead 2 and the first external lead member 6. The Id surface is coated with a first resin material 9 made of epoxy resin by a dipping method.

Next, this capacitor element 1 is mixed with a solution 10 of concentrated hydrochloric acid, hydrogen peroxide, and water in a volume ratio of 1:1:1.
Then, the anode lead portion exposed from the first resin material 9 is immersed for 2 to 3 seconds.

After that, the hair is washed with water and dried.

H7) The resin material 9 is covered with J so that the connecting portion between the anode lead 2 and the first outer TfD IJ-de member 6 is hidden.
We fabricated 100 solid electrolytic capacitors by covering them with the second resin material 11 made of epoxy resin, and compared them with conventional products for the presence or absence of anode-cathode short circuits and leakage current.
In the product of the present invention, there were no short circuits, and the level of leakage current was improved.

However, in the conventional product, there were 5 short-circuit failures and 5 leakage current failures.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the capacitor element may be formed by pressure-forming and sintering metal powder, or may be formed by using metal wire or plate material as is, or by pressure-forming. It can also be configured as

Further, the anode lead can be welded to the circumferential surface of the capacitor element, and the external MIJ-dead member can be connected thereto by crossing the ends or by abutting the end faces.

As described above, according to the present invention, even if a semiconductor layer creeps up and is formed on the anode lead, it is possible to significantly reduce characteristic troubles after connecting the outer WVa) vgβ material, and also to greatly improve workability. .

[Brief explanation of the drawing]

Figures 1 and 2 are front sectional views showing different embodiments of conventional solid electrolytic capacitors, Figure 3 is an exploded perspective view of the main part of Figure 2, and Figure 4 is for explaining the method of the present invention. FIG.

Claims (1)

[Claims] 1. A step of forming an electrode lead layer on the circumferential surface of a capacitor element made of a metal member having a valve action via an oxide layer and a semiconductor layer, and a step of connecting the outer Ht31J-upper member to an anode lead extending from the capacitor element. A process of coating the entire circumferential surface of the capacitor element with a first resin material except for the connecting portion between the anode lead and the outer H151J-upper member, and a semiconductor formed on the anode lead portion exposed from the first resin material. The step of removing at least a part of the layer includes the step of covering the first resin material with a second resin material so that the connection part with the anode lead and the external lead member is covered. A method of manufacturing a solid electrolytic capacitor, comprising: