JPS603769B2 - Manufacturing method of electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrolytic capacitor, and more particularly to a method for manufacturing an electrolytic capacitor, and in particular, a method for manufacturing an electrolytic capacitor, in which a semiconductor layer is applied to an anode lead led out from the top surface of a capacitor element formed by pressure-molding metal powder having a valve action into a desired shape. The purpose of this is to reduce the creeping up phenomenon of the forming member.

In general, this type of capacitor is made of a capacitor element A made by press-molding metal powder with a valve action such as tantalum, niobium, aluminum, etc. into a cylindrical shape and sintering it, as shown in Figure 1. A functional metal member is set up as an anode lead B, and a first external lead member C bent in an L shape is welded to the protruding portion 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 through an oxide layer and a semiconductor layer, and then covering the main part including condescension element A with resin material F. ing.

By the way, prior to welding the first external lead member C to the protruding portion of the anode lead B, the capacitor element A is subjected to a chemical conversion treatment together with the anode lead B, and an oxide layer is formed on its surface. 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 of 200 qo or higher to form a semiconductor layer on the oxide layer of the capacitor element A.

However, in this thermal decomposition process, the temperature of condenser element A 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. 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, which causes anode lead B.
It adheres to the protruding portion of the semiconductor layer forming member to form a so-called creeping-up portion of the semiconductor layer forming member. Normally, the process of impregnating and depositing the semiconductor mother liquor and thermally decomposing it is repeated several times or more since the capacitor element A is porous, and as the number of thermal decompositions increases, the creeping up of the semiconductor layer forming member further progresses. I'm in a bad mood. Therefore, when attaching the first external lead member C to the protruding portion of the anode lead B, the first external lead member C
There is a problem in that the cathode and the anode are short-circuited due to contact between the capacitor and the semiconductor layer that has climbed up, making it impossible to function as a capacitor.

Therefore, conventionally, as shown in Figures 2 and 3, a Teflon (trade name) washer G was inserted into the top surface of the capacitor element A, and an anode lead B was inserted into the center hole of the washer G. A configuration in which it is installed is adopted.

According to this method, although it is possible to effectively suppress the creeping-up phenomenon of the semiconductor layer at the protruding portion of the anode lead B, there are disadvantages in that it is not easy to work with and requires an extremely large number of man-hours, making it difficult to mass-produce. In view of these points, the present invention provides a method for manufacturing an electrolytic capacitor that can significantly improve workability without sacrificing the effect of preventing the semiconductor layer from creeping up onto the anode lead. An example will be described with reference to FIG.

First, as shown in Figure a, a metal part having a valve action is attached as an anode lead 2 to a capacitor element formed by press-molding metal powder having a valve action into a cylindrical shape and bonding it together. stand up

This condenser element is then immersed in a liquid 3, for example water, to impregnate the inside with water. In addition to water, the liquid 3 is
Organic solvents such as alcohol and acetone can also be used, but
From an economic point of view, water is preferred. Next, as shown in FIG. 4
Then, the capacitor element is immersed so that its top surface la is completely submerged. As the liquid of this dispersion liquid 4', an organic solvent can be used in addition to water, but water is preferable from the economic point of view. After a certain period of time has elapsed, when the capacitor element 1 is pulled up, the Teflon resin powder liquid 4' is deposited on the top surface la of the capacitor element 1, as shown in FIG.
At this time, some liquid 4' is also deposited on the circumferential surface of the condenser element except for the top surface la, but since the condenser element 1 is impregnated with water, the liquid 4' does not cover the condenser. Intrusion into the element can be prevented. Next, as shown in Figure d, the condenser element 1 is immersed in a cleaning liquid 5, such as water, so that the top surface la is not submerged, and the liquid 4' deposited on the peripheral surface is removed. Next, as shown in FIG. Next, as shown in FIG. At the same time, the first external lead member 8 is welded to the electrode lead layer 7. Then, the main part including the capacitor element 1 is covered with a resin material 10. In this way, the Teflon resin 4 is attached to the top part la of the capacitor element 1.
The coating is done with a liquid 4' made by dispersing Teflon resin powder in water.
Since this is reliably carried out by simply immersing and pulling up the capacitor element 1, the workability can be significantly improved compared to the conventional method of mounting a Teflon washer.

Moreover, since the capacitor element 1 is impregnated with the liquid 3 before the liquid 4' is applied to the capacitor element 1, the top surface la of the liquid 4' is well coated when the liquid 4' is applied. However, the surrounding surfaces other than the top surface portion la are not coated very much.

Therefore, it is possible to easily wash away the undesired liquid 4' adhering to the surrounding area. If the capacitor element 1 is not impregnated with the liquid 3, the liquid 4' will infiltrate into the pores of the capacitor element 1 and adhere thereto when the capacitor element 1 is immersed in the Teflon resin powder liquid 4'.
Once the Teflon resin powder in the liquid 4' has entered the hole, it takes a lot of man-hours and time to remove it, and if it is not removed sufficiently, it will not be possible to obtain the desired capacitance. In addition, since the Teflon resin powder in the liquid 4' on the top surface la of the capacitor element is melted and densified by the heating operation, it is transferred to the anode lead 2 of the semiconductor layer forming member in the semiconductor mother liquor impregnation and thermal decomposition process. It is possible to reliably prevent the creeping up of

Therefore, when the first external lead member 8 is welded to the anode IJ-de 2, there is no short circuit between the anode and the cathode, and the quality can be improved. Furthermore, the semiconductor layer and oxide layer on the top surface la tend to be damaged by welding sparks when welding the first external lead member 8 to the anode lead 2. However, according to this embodiment, the Teflon resin 4 Such troubles can be completely prevented since they are tightly adhered.

The formation of the Teflon resin layer 4 on the top surface la of the capacitor element 1 can be carried out before the formation of the oxide layer as described above, or alternatively, for example, after the formation of the oxide layer.

That is, after forming an oxide layer on the capacitor element 1 by chemical conversion treatment, the capacitor element 1 is washed with a cleaning liquid and dried. Then, the capacitor element 1 is immersed in the liquid to impregnate the inside with the liquid. Note that when water is used as the cleaning liquid, drying and the next step of impregnation can be omitted. Then, a liquid 4' mainly composed of Teflon resin powder is applied to both top portions la of the capacitor element 1 in the same manner as in the above embodiment. Then, this condesosure element 1 is placed in a heating furnace to densify the Teflon resin powder. At this time, an annealing effect can be obtained by setting the heating temperature to a temperature higher than the thermal decomposition temperature of the semiconductor mother liquor, for example, 250 qo or higher, and heating for about 40 minutes. Then, it undergoes reconversion treatment. According to this embodiment, since the Teflon resin 4 is deposited after the oxidized layer is formed, the area where the oxidized layer is formed can be increased.

In particular, if the Teflon resin powder is melted and annealed at the same time, a single heat treatment can produce an annealing effect.
It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the anode lead may be installed on the capacitor element or may be welded to the surface of the capacitor element, and the material thereof may be limited to metal members having valve action. Not restricted by. In addition to Teflon, epoxy resin or the like may also be used as the insulating powder.
Furthermore, in addition to water, organic solvents can also be used as the impregnating liquid. As described above, according to the present invention, it is possible to reliably prevent the semiconductor layer from creeping up onto the anode lead, and it is also possible to significantly improve workability.

[Brief explanation of the drawing]

1 to 2 are front sectional views showing different embodiments of the conventional example, FIG. 3 is an exploded perspective view of the main part of FIG. 2, and FIG. 4 is a front sectional view for explaining the method of the present invention. It is a diagram. Yakuna zuzai 2 zuai 3 zuai 4 zu

Claims (1)

[Claims] 1. A capacitor element made of a metal powder having a valve action and having an anode lead made of a metal member led out from the top surface thereof is impregnated with a liquid prior to the impregnation deposition-pyrolysis process of semiconductor mother liquor. a step of immersing the capacitor element in an insulating powder liquid in which insulating powder is dispersed and pulling it up; a step of removing the insulating powder liquid adhered to the peripheral surface of the capacitor element except for the top surface;
A method for manufacturing an electrolytic capacitor, comprising the step of densifying the insulating powder by heating the insulating powder liquid on the top surface of the capacitor element.