JPS6043006B2 - 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, an object of the present invention is to reduce the creeping up of a semiconductor layer forming member onto the anode lead of a capacitor element made of a metal member having a valve action. It is something to do.

In general, this type of solid electrolytic capacitor is manufactured by forming a capacitor element A in advance, which is made by press-molding metal powder having a valve action such as tantalum, niobium, or aluminum into a cylindrical shape and sintering it, as shown in Fig. 1. A metal wire having a valve action is installed as an anode lead B, a first external lead member C bent in an L shape is welded to the protruding part of this anode lead B, and a second external lead member D is connected to the capacitor. It is constructed by soldering to an electrode lead-out layer E formed on the circumferential surface of element A via an oxide layer and a semiconductor layer, and then coating the entire circumferential surface of capacitor element A with resin material F. .

By the way, prior to welding the first external lead member C to the protruding portion of the anode lead B led out from the capacitor element A, an oxide layer is formed on the surface of the capacitor element A by a chemical conversion treatment together with the anode lead B, and further the capacitor After only element A is immersed in the semiconductor mother liquor for a certain period of time to ensure sufficient impregnation, a thermal decomposition reaction is caused in a high temperature atmosphere to form a semiconductor layer on the oxide layer.

However, since there are many die scratches in the axial direction on the surface of the anode lead B, the capacitor element A
The semiconductor mother liquor impregnated with the semiconductor layer passes through the die scratches and adheres to the protruding portion of the anode lead B from the capacitor element A, and is thermally decomposed to cause so-called creeping of the semiconductor layer.

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 C to the anode lead B, the first external lead member C comes into contact with the semiconductor layer that has climbed up, resulting in a disadvantage that leakage current characteristics are significantly impaired. There is.

In view of these points, the present invention provides a method for manufacturing a solid electrolytic capacitor that can suppress the creeping of the semiconductor layer onto the anode lead with a simple configuration and can significantly improve the quality of the capacitor. Specific examples will be described with reference to FIGS. 2 to 6. First, as shown in FIG. 2, a metal wire having a valve function is installed in advance as an anode lead 2 on a capacitor element 1 which is formed by press-forming metal powder having a valve function into a cylindrical shape and sintering it.

Then, the non-lead side of the anode lead 2 of the capacitor element 1 is sucked by the vacuum suction device 3, and the anode lead 2 exposed from the capacitor element 1 is attached to the die free MS-
543 (fluorine-based mold release agent), the capacitor element surface 1a on the outlet side of the anode lead 2 is 0.5 to
It is immersed so that it is separated by about 1.0 TBm. and,
By pulling it up, a die-free (water repellent material) coating 4 is formed on almost the entire circumferential surface of the anode lead 2, as shown in FIG. Incidentally, the thickness of this coating 4 is, for example, approximately several micrometers depending on one immersion operation. Next, as shown in FIG. 4, while maintaining the suction state by the vacuum suction device 3, the tip portion of the anode lead 2 extending from the capacitor element 1 is brought into contact with the plate-shaped metal member 5. Then, the anode lead 2 and the metal member 5 are held together under pressure by welding electrodes 6, 6,
Weld. Incidentally, the coating 4 is easily destroyed when pressurized, so that welding can be performed reliably. Next, as shown in FIG. 5, an electrode lead layer 7 is formed on the circumferential surface of the capacitor element 1 via an oxide layer and a semiconductor layer. Next, as shown in FIG.
For example, the first external lead member 8 bent in an L shape is overlapped and welded so that the bent portions 8a intersect. Then, for example, one end of the straight second external lead member 9 is brought into contact with the electrode lead layer 7 of the capacitor element 1, and the second external lead is immersed in a molten solder bath and pulled up. The member 9 is soldered to the electrode lead layer 7. Thereafter, the entire circumferential surface of the capacitor element 1 is covered with a resin material 10 to obtain a solid electrolytic capacitor. In this way, prior to forming a semiconductor layer on the capacitor element 1 and welding the metal member 5 to the anode lead 2 on almost the entire circumferential surface of the anode lead 2 extending from the capacitor element 1,
Since the coating 4 made of a water-repellent material is formed, the countless dice scratches formed on the circumferential surface of the coating 4 are filled in.

Therefore, when the capacitor element 1 is immersed in a semiconductor mother liquor such as a manganese nitrate solution, even if the semiconductor mother liquor creeps upward through the die scratches, the coating 4 prevents
Since further creeping up is prevented, even if the first external lead member 8 is welded to the film forming portion of the anode lead 2, contact with the semiconductor layer can be greatly reduced. For example, according to the conventional method, leakage current failure occurs at 4 to 5%, but according to the method of the present invention, it can be reduced to 1% or less. In addition, when forming the coating 4 on the anode lead 2, the anode lead 2 is die-free so that the capacitor element surface 1a does not come into contact with the anode lead 2, for example, by 0.5 to 1.0 rsn.
Since they are immersed at a certain distance, the dye-free (water-repellent member) is not impregnated into the interior of the capacitor element 1, and the capacitance does not decrease at all due to this.

Further, since the coating 4 of the anode lead 2 is formed to have a thickness of, for example, several microns, it is easily torn by mechanical impact during welding with the metal member 5 and the first external lead member 8.

For this reason, there is no need to remove the coating 4 prior to welding, so welding work can be performed efficiently. Further, since the coating 4 is formed of a material having excellent heat resistance, it can sufficiently withstand temperatures of about 200 to 400'C during the semiconductor layer forming process.

For this reason, the creeping up of the semiconductor mother liquor can be effectively suppressed without impairing the water repellency. 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 press-molding metal powder and sintering it;
It can be constructed from a wire rod or a plate material, and the anode lead extending therefrom can also be led out by welding as well as planting.

Furthermore, in addition to fluorine-based materials such as Daifree, silicone and the like can also be used as water-repellent materials. As described above, according to the present invention, the creeping of the semiconductor layer forming member onto the anode lead can be suppressed with a simple configuration, and the quality of the capacitor can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional solid electrolytic capacitor, Figures 2 to 6 are diagrams for explaining the method of the present invention, and Figure 2 shows an anode lead immersed in a water-repellent member. Fig. 3 is a side sectional view showing the state in which a coating is formed on the anode lead, Fig. 4 is a side sectional view showing the welding state of the anode lead and metal member, and Fig. 5 is a capacitor. 6th sectional side view showing a state in which an electrode extraction layer is formed on the element;
The figure is a side sectional view showing the completed state. In the figure, 1 is a capacitor element, 2 is an anode lead, 4
is a coating, and 5 and 8 are metal members.

Claims (1)

[Claims] 1 After forming a coating with a water-repellent material on almost the entire circumference of an anode lead made of a metal wire having a valve action derived from a capacitor element made of a metal member having a valve action, the metal member is attached to this anode lead. A method for manufacturing a solid electrolytic capacitor, which is characterized by pressurizing and welding through a film.