JP2891506B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor in which a semiconductor layer made of lead dioxide and lead sulfate is provided on the surface of a metal having a valve action.

[Conventional technology]

In general, a solid electrolytic capacitor element has a dielectric oxide film layer formed on the surface of an anode substrate made of a valve metal, and a semiconductor layer such as manganese dioxide formed as a counter electrode on the outer surface of the dielectric oxide film layer. To reduce the contact resistance, a conductor layer is formed by providing a silver paste layer or the like.

As a semiconductor other than the above-mentioned manganese dioxide, lead dioxide has a relatively high conductivity, and therefore, it was expected to produce a high-performance solid electrolytic capacitor, but none was realized. Under these circumstances, the present inventors have disclosed in
No. 51621 and the like have proposed a solid electrolytic capacitor having a semiconductor layer composed of lead dioxide and lead sulfate, having good performance and industrially realizable, and a method for manufacturing the same.

[Problems to be solved by the invention]

On the other hand, as electronic devices become lighter and thinner, it is desired to increase the capacitance value of a solid electrolytic capacitor as long as it has the same volume as possible. Generally, the anode substrate of a solid electrolytic capacitor has a complicated surface shape in order to gain capacity, but the semiconductor layer cannot draw out the entire capacitance unless it covers the entire surface of the anode substrate. However, in the conventional manufacturing method in which the anode substrate is immersed in a reaction mother liquor for forming a semiconductor layer composed of lead dioxide and lead sulfate and the semiconductor layer is deposited simultaneously with the reaction, the solid electrolytic capacitor obtained per unit volume is also used. Need to be further increased.

[Means for solving the problem]

The present invention has been made in order to solve the above-mentioned problems, and the gist of the present invention is to provide a dielectric oxide film layer and a semiconductor layer made of lead dioxide and lead sulfate on the surface of an anode substrate made of a metal having a valve action. And a conductor layer are sequentially formed to manufacture a solid electrolytic capacitor. After the anode substrate having the dielectric oxide film layer is immersed in a solution containing nitrate ions and / or manganese ions and pulled up, lead dioxide and lead sulfate are formed. In a solid electrolytic capacitor in which a semiconductor layer is formed by immersion in a reaction mother liquor for precipitating the semiconductor layer to cause a reaction.

As the valve action metal used as the anode of the solid electrolytic capacitor element manufactured by the method of the present invention, any metal having a valve action such as aluminum, tantalum, niobium, titanium and an alloy using the same as a substrate can be used.

The dielectric oxide film layer formed on the surface of the anode substrate may be an oxide layer of the anode substrate itself provided on the surface layer of the anode substrate, or another dielectric layer provided on the surface of the anode substrate. It may be an oxide layer, but is preferably a layer made of an oxide of the anode valve metal itself. In any case, as a method of providing the oxide layer, a conventionally known method can be used.

Next, the semiconductor layer formed on the dielectric oxide film layer of the solid electrolytic capacitor element is a layer mainly composed of lead dioxide and lead sulfate. Examples of reagents for forming such a semiconductor layer include lead acetate trihydrate which gives a lead ion species, ammonium persulfate which gives a persulfate ion species, and the like. And the like.

In the present invention, when the semiconductor layer is formed, the semiconductor layer is immersed in a solution containing nitrate ions and / or manganese ions, then pulled up, and then immersed in a reaction mother liquor for precipitating lead dioxide and lead sulfate to react. It is important. The time until the anode substrate is immersed in a solution containing nitrate ions and / or manganese ions and pulled up varies depending on the shape of the anode substrate, and cannot be determined unconditionally, but is generally several seconds or more. After the anode substrate is pulled out of the solution, the surface may be washed with water to remove the solution remaining on the outer surface of the anode substrate.

Compounds that give nitrate ions and / or manganese ions include, for example, monovalent or divalent nitrates such as potassium nitrate, manganese nitrate, sodium nitrate, lead nitrate, nitric acid, ammonium nitrate, potassium permanganate, sodium permanganate, perchlorine Manganese phosphate, manganese chlorate, manganese tetrafluoroborate, manganese hexafluorophosphate,
Manganese carbonate, manganese phosphate, manganese borate, manganese oxalate, manganese salicylate, manganese tartrate, manganese phosphite, manganese sulfate, MnX ₂ [where X is a halogen], manganese hydroxide, Mn (OCOR) ₂ [where R represents hydrogen, an alkyl group, or an aryl group], and a conventionally known compound that provides a nitrate ion and / or a manganese ion, such as a manganese complex of manganese with ammonium, oxime, tetraethylenediamine, phthalocyanine, acetylacetone, or the like. These compounds are used alone or as a mixture of two or more.

In the present invention, a semiconductor layer is formed by immersing the anode substrate in a solution containing nitrate ions and / or manganese ions, pulling it up, and then immersing it again in a reaction mother liquor for depositing lead dioxide and lead nitrate to react. .

The above-described step may be repeated a plurality of times, and after the above-mentioned step, a conventionally known method of immersing the anode substrate in a reaction mother liquor and reacting the same in order to further completely adhere the semiconductor layer is also used. You may.

Further, after the reaction with the above-described reaction mother liquor or after the reaction with the reaction mother liquor between a plurality of repeated steps, the surface of the semiconductor layer may be washed with an aqueous solution of ammonium acetate, carboxylic acid, oxyacid, or the like (Japanese Unexamined Patent Application, First Publication No. H11-163873). JP-A-62-98714).

The solid electrolytic capacitor element formed up to the semiconductor layer by the above-described method is sufficiently washed and dried, and then a conductor layer is formed on the semiconductor layer. Conventionally known conductor layers and methods can be employed as the conductor layer, but a method in which the solid electrolytic capacitor element is immersed in a carbon paste and / or silver paste, pulled up and dried is particularly simple.

As described above, the solid electrolytic capacitor manufactured by the method of the present invention is, for example, a resin mold, a resin case,
A general-purpose capacitor product for various uses can be obtained by using a metal outer case, resin dipping, and a laminate film.

[Action]

When forming a semiconductor layer composed of lead dioxide and lead sulfate on the anode substrate, the anode substrate is immersed in a solution containing nitrate ions and / or manganese ions and then pulled up to deposit lead dioxide and lead sulfate again. When the reaction is carried out by immersion in the reaction mother liquor, the reaction mother liquor penetrates all the way into the complicated shape of the anode substrate, resulting in an increase in the capacity of the solid electrolytic capacitor produced.

That is, nitrate ions and / or manganese ions are
Since it is an ionic species that can penetrate into the micropores very easily, by impregnating these ionic species at the initial stage, it is possible to exchange liquid with a reaction mother liquor that is difficult to impregnate into the inside of the anode substrate. It is considered that the reaction mother liquor is impregnated inside.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 12 A Ta sintered body having a length of 3 mm, a width of 2 mm, and a thickness of 0.5 mm in which a full capacity of 7.9 μF and a part of an anode lead wire of about 20 mm was partially buried was subjected to 22 V conversion in a phosphoric acid aqueous solution. Then, a dielectric oxide film layer was formed. This Ta sintered body was immersed in each of the aqueous solutions shown in Table 1, pulled up after one minute, and mixed with a separately prepared aqueous solution of lead acetate trihydrate 2.4 mol / and ammonium persulfate 4 mol /. Immersed in the solution,
The reaction was allowed to stand at 30 ° C. for 30 minutes. After the reaction, the device was taken out of the reaction mother liquor, washed sufficiently with water, and dried. The above reaction was repeated three more times to form a semiconductor layer composed of lead dioxide and lead sulfate on the surface of the dielectric oxide film layer.

Next, a carbon paste and a silver paste were sequentially adhered on the semiconductor layer to form a dielectric layer, and then sealed with a resin to produce a solid electrolytic capacitor.

Comparative Example A solid electrolytic capacitor was produced in the same manner as in the example, except that the capacitor was not immersed in each of the aqueous solutions shown in Table 1.

In each of Examples 1 to 12 and Comparative Example, 50 points of solid electrolytic capacitors were produced, and the performance of the average value of each 50 points is shown in Table 2.

[Effects of the Invention] An anode substrate having a dielectric oxide film layer on its surface is immersed in a solution containing nitrate ions and / or manganese ions, then pulled up, and then immersed in a reaction mother liquor for depositing lead dioxide and lead sulfate. Since the semiconductor layer is formed in this manner, a solid electrolytic capacitor capable of sufficiently drawing out the capacitance can be manufactured.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-177409 (JP, A) JP-A-63-166207 (JP, A) JP-A-63-166205 (JP, A) JP-A 54-167 12447 (JP, A) JP-A-62-124728 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01G 9/032

Claims (1)

(57) [Claims] 1. A method for manufacturing a solid electrolytic capacitor comprising a dielectric oxide film layer, a semiconductor layer composed of lead dioxide and lead sulfate, and a conductor layer sequentially formed on the surface of an anode substrate composed of a metal having a valve action. After immersing the anode substrate having the dielectric oxide film layer on the surface thereof in a solution containing nitrate ions and / or manganese ions and lifting it up, the substrate is immersed and reacted in a reaction mother liquor for precipitating lead dioxide and lead sulfate. Forming a solid electrolytic capacitor.