JPS5871613A - Method of producing solid electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid electrolytic capacitor, and in particular, an object of the present invention is to reduce the tendency of a semiconductor layer forming member to creep up and adhere to an anode lead led out from a capacitor element.

In general, this type of solid electrolytic capacitor is made by press-molding metal powder with valve action into a cylindrical shape and sintering it, as shown in Figure 1. One lead B is planted, and the lead-out part of this anode lead B is welded to the HL-shaped first external lead member C, and one strut-shaped second external lead member is attached to the surface of the capacitor element (A). The capacitor element A is soldered to an electrode lead layer lc formed through an oxide layer and a semiconductor layer, and after soldering, the entire circumferential surface of the capacitor element A is covered with a resin material F.

In the capacitor element hV, an oxide layer as a dielectric layer is formed by chemical conversion treatment together with the anode lead B before welding the first external lead member 0 to the lead-out portion of the anode lead B. After only the capacitor element A is immersed in the semiconductor mother liquor for a certain period of time, a thermal decomposition reaction is caused in a high temperature atmosphere to form a semiconductor layer on the oxide layer.

However, during this thermal decomposition process, the temperature of the capacitor (A) inserted into the high-temperature atmosphere rises rapidly, and the semiconductor mother liquor impregnated inside undergoes a thermal decomposition reaction, resulting in water vapor and As decomposed gases such as nitrogen oxides blow out to the surface layer, bubbles are generated in the semiconductor mother liquid layer in the middle of thermal decomposition in the surface layer, and these bubbles adhere to the lead-out portion of the anode lead B, causing so-called creeping of the semiconductor layer forming member. It causes an upslope. Normally, the impregnation-pyrolysis operation of the semiconductor mother liquor is repeated several times or more in view of the porous nature of the capacitor element A, and the creeping up of the semiconductor layer forming member tends to progress further.

Therefore, when welding the first external lead member 0 to the lead-out portion of the anode lead B, the first external lead member O and the semiconductor layer that has climbed up may come into contact and leakage current may increase, and sometimes the cathode There is a problem in that the capacitor and the anode are short-circuited and cannot function as a capacitor.

Therefore, prior to forming a semiconductor layer on a capacitor element, the present applicant prevents the formation of a creeping semiconductor layer by forming a hydrocarbon film only on the anode lead portion led out from the surface of the capacitor element. We proposed a manufacturing method for this purpose.

According to this method, even if the semiconductor mother liquor in the middle of thermal decomposition scatters when a bubble bursts and adheres to the anode lead in the pyrolysis process of the semiconductor mother liquor, it will be repelled by the water-repellent action of the water-repellent coating. It is possible to prevent the formation of a semiconductor layer on the anode lead portion of the external lead member No. 1 to be welded, and it is possible to prevent deterioration of leakage current characteristics.

However, the formation of a water-repellent coating on an anode lead is difficult, for example, by applying a liquid water-repellent material to a capacitor element and lIi&
This is done by immersing the lead and then cleaning and removing the water-repellent material that has adhered only to the capacitor element. It cannot be removed by π. Therefore, since it has to be immersed in the cleaning liquid for a long time, the workability is significantly impaired, and there is a problem that it is difficult to apply it to a mass production process.

In view of these points, the present invention is capable of suppressing the formation of a semiconductor layer on the water-repellent member and on the anode lead portion led out from the surface of the capacitor element, and also suppresses the formation of the semiconductor layer on the water-repellent member in the deep part of the capacitor element. The purpose is to provide a method for manufacturing a solid electrolytic capacitor that can reliably prevent the penetration of A metal wire having a valve function is installed in advance as an anode lead 2 in a capacitor element 1 which is formed by press-forming metal powder having a valve function into a cylinder shape and sintering it. The ends of the anode leads 2 extending from the capacitor element surface 1a are connected to the band-shaped metal plate 3 at regular pitch intervals to form a band-shaped component. Then, the liquid water-repellent member 4 is dropped onto the lead-out portion of the anode lead 2 that is sufficiently separated from the capacitor element surface 1a, and is deposited in granular form and dried. Next, as shown in FIG. 3, the water-repellent member 4 is moved from the dotted line position to the solid line position and brought close to the capacitor element surface zaKm. Next, as shown in FIG. 4, an electrode lead layer 5 is formed on the circumferential surface of the capacitor element 1 via an oxide layer and a semiconductor layer. Then, cut the anode lead 2 to a desired length, and add L to this part.
The straight-shaped first external lead member 6 is welded, and the straight-shaped second external lead member 7 is soldered to the electrode bow 1 extension layer 5. Thereafter, the entire circumferential surface of the capacitor element 1 is covered with a resin material 8 to obtain a solid electrolytic capacitor.

In this way, the granular water-repellent part numbers are formed on the anode lead portion led out from the capacitor element surface 1a before the semiconductor layer forming process, so that the thermal decomposition of the semiconductor mother liquor impregnated with the capacitor element 1v], After a while,
Even if the semiconductor mother liquor undergoing thermal decomposition on the capacitor element surface 1a tries to scatter when a bubble bursts, the presence of the water-repellent member 4 prevents it from adhering to the anode lead 2; , adhesion is prevented by the water-repellent action of the water-repellent member 4. Therefore, even if the first external lead member 6 is welded to the anode 1''-de 2, the leakage current will increase.
Short circuits between the cathode and anode can be prevented, and the quality of the capacitor can be improved.

In addition, the water-repellent member 4 is applied to the anode lead portion sufficiently separated from the capacitor element surface, and after drying, the water-repellent member 4 is moved so as to come into contact with or come close to the capacitor element surface 1a. element 1
It is possible to reliably prevent ff from seeping into. For this reason, there is no need to clean or remove the water-repellent material that has soaked into the capacitor element 1, so that work efficiency can be significantly increased, and the present invention can be applied to mass production processes.

Next, a mounting example will be described.

Example 1 A capacitor element made by press-molding tantalum powder into a 35ψ x 4 column shape and sintering it was preliminarily 05φ x 5011 mm.
The tantalum wire is planted with S polarity.

Then, Daifree (a fluorine-based resin) manufactured by Daikin Corporation is dropped onto the anode lead portion located 15 mm apart from the capacitor element surface on the output side of the anode lead, and is deposited in the form of particles. 1- After drying, move it so that it forms a dense layer on the surface of the capacitor element. A tantalum solid electrolytic capacitor is manufactured using the following conventional method.

In this capacitor, there was no creeping up of the semiconductor layer onto the anode IJ-board, and even when the first external IJ-board member was welded, no increase in leakage current or electrode short circuit occurred. . Further, no penetration of the water-repellent member into the capacitor element occurred.

Example 2 An anode lead made of tantalum wire is welded to the surface of a capacitor element. Example 1: A tantalum solid electrolytic capacitor was manufactured using the method described in Example 1 below.
A similar effect was obtained.

Example 3 The same effect as in Example 1 was obtained by using a water-repellent member made of silicone resin mixed with fluororesin powder instead of the dye-free material in Example 1. Further, the viscosity of the water-repellent member can be easily adjusted, and the size of the granules can be changed arbitrarily.

In addition, in the present invention, the capacitor element and anode lead are made of niobium, aluminum, titanium, in addition to tantalum.
It can also be composed of a single substance or an alloy of hafnium or the like. Further, the water-repellent member can be moved not only in a dry state but also in a heat-cured state or a solidified state.

As described above, according to the present invention, the water-repellent member can suppress the formation of the semiconductor layer that is drawn out from the surface of the capacitor element and climb up to the very top part, and also prevent the water-repellent member from seeping into the capacitor element. Desired capacitor characteristics can be obtained in a relationship that prevents interference.

[Brief Description of the Drawings] Fig. 1 is a side sectional view of a conventional solid electrolytic capacitor, Figs. FIG. 3 is a side sectional view showing the water-repellent material in contact with the surface of the capacitor element; FIG. 4 is a side sectional view showing the state in which the water-repellent material is in contact with the surface of the capacitor element. . In 1m, l is the capacitor element, 1a is the capacitor element surface, 2 is the anode lead, 4 is the water repellent member, 6,
This is a 7 piece external lead member. Figure 1 H Figure 2 Figure 3 Figure 4 62

Claims (1)

[Claims] 1. Prior to forming a semiconductor layer on a capacitor element made of metal powder having a valve action, and from which a metal wire having a valve action is led out as an anode lead, 1. A lead-out portion of the anode lead separated from the surface of the capacitor element. A method for producing a solid electrolytic capacitor, which comprises applying a water-repellent material in granular form to a surface of the capacitor element, and moving the water-repellent material into contact with a surface of a capacitor element or to a nearby lead-out portion.