JPS587634Y2 - Anode body for solid electrolytic capacitors - Google Patents

Description

[Detailed description of the invention] The present invention relates to an anode body for a solid electrolytic capacitor, and in particular, to reduce the phenomenon of a semiconductor layer forming member creeping up onto an anode lead protruding from the anode body made of a molded body of metal powder having valve action. The purpose is to

Generally, as shown in Figure 1, this type of capacitor is made by press-molding metal powder such as tantalum, aluminum, niobium, etc., into a cylindrical shape and sintering the anode body A, which has a valve action in advance. A metal wire having the following characteristics is installed as the anode lead B, a first external lead wire C bent in an L shape is welded to the protruding portion of the anode lead B, and a second external lead wire is attached to the anode body A. A cathode layer formed on the surface of the anode body A is soldered through an oxide layer and a semiconductor layer, and the peripheral surface of the anode body A including the protrusion of the anode lead B is covered with a resin material E.

By the way, before the first external lead wire C is welded to the protruding portion of the anode lead B, the anode body A is electrolytically oxidized together with the anode lead B, and only the anode body A is immersed in a semiconductor mother solution such as manganese nitrate solution. A semiconductor layer such as manganese dioxide is formed on the oxidized layer of the anode body A by soaking it for a time to impregnate it into the anode body A, and then causing a thermal decomposition reaction in a high temperature atmosphere of 200° C. or higher.

However, in this thermal decomposition process, the temperature of the anode body A inserted into the high-temperature atmosphere rises rapidly.
The semiconductor mother liquor impregnated inside causes a thermal decomposition reaction, and decomposed gases such as water vapor and nitrogen oxides blow out from the inside to the surface layer, so bubbles are generated in the semiconductor mother liquor layer in the middle of thermal decomposition in the surface layer. This adheres to the protruding portion of the anode lead B, causing so-called creeping of the semiconductor layer forming member.

Normally, the impregnation-pyrolysis process of the semiconductor mother liquor is repeated several times or more in view of the porous nature of the anode body A, but as the number of times of thermal decomposition increases, the semiconductor layer-forming member tends to creep up further.

Therefore, when welding the first external lead wire C to the protruding portion of the anode lead B, the first external lead wire 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, as shown in Figures 2 and 3, a configuration was adopted in which a Teflon washer F was attached to the top surface of the anode body A, and an anode lead B was inserted through the center hole of the Teflon washer F. has been done.

According to this method, although it is possible to effectively suppress the creep-up phenomenon of the semiconductor layer at the protruding portion of the anode lead B, the workability is poor and it requires an extremely large number of man-hours, making it difficult to mass-produce. There are drawbacks.

The present invention was proposed in view of the above points, and includes an anode lead made of a metal wire having a valve action protruding from the top surface of a molded body of metal powder having a valve action.
The present invention is characterized in that a recess is formed on the top surface of the molded image at the base of the anode lead, and the recess is filled with a heat-resistant insulating member.

An embodiment of the present invention will be explained with reference to FIGS. 4 and 5.
The anode body is formed by molding metal powder having a valve action into a cylindrical shape and sintering the anode body, and a recess 2 is formed in the top surface of the anode body.

Reference numeral 3 designates an anode lead made of a metal wire having a valve function and installed in advance in the anode body 1 so as to pass through the four parts 2 thereof.

Reference numeral 4 denotes a heat-resistant insulating member filled and supplied into the four parts 2 of the anode body 1, and is a member that can withstand the decomposition temperature in the thermal decomposition process of semiconductor mother liquor, such as frit glass, fine alumina powder, etc.
A heat-resistant resin material is suitable.

Reference numeral 5 denotes a first external lead wire bent into an L shape, for example, and a bent portion 5a thereof is welded so as to intersect with the protruding portion 3a of the anode lead 3.

Reference numeral 6 denotes a second external lead wire, one end of which is connected by a solder member 7 to a cathode layer (not shown) formed on the circumferential surface of the anode body 1 via an oxide layer and a semiconductor layer. ing.

Reference numeral 8 denotes an exterior insulating material such as epoxy resin that covers the entire circumferential surface of the anode body 1 including the protrusion 3a of the anode lead 3.

Next, an example of a specific method for supplying and solidifying the heat-resistant insulating member 4 to the four parts 2 of the anode body 1 will be described with reference to FIG.

First, as shown in Figure a, 40 g of polyethylene oxide with a molecular weight of 400,000 to 500,000 was dispersed in 500 g of isopropyl alcohol, and then 200 meshes of frit glass (softening temperature 382°C) containing lead as the main component was prepared.
A suspension 4' prepared by adding g and 2000 g of water and stirring thoroughly is placed in case 9.

Then, a plurality of anode bodies 1 fixed to the band-shaped metal plate 10 are simultaneously immersed in the suspension 4' and pulled up.

Then, the suspension 4 is placed in the four parts 2 on the top surface of the anode body 1.
′ is filled.

Next, as shown in the figure, the anode body 1 fixed to the metal plate 10 is immersed in water 12 placed in the case 11 so that the top surface of the anode body 1 is not immersed. Remove the suspension adhering to the surface and lower surface.

Next, as shown in FIG. , the binder is scattered and the frit glass is melted and solidified in the recess 2.

Using the anode body 1 with the heat-resistant insulating member 4 filled in the recess 2 in this way, a solid electrolytic capacitor was manufactured by a normal method. (Fig. 1) The occurrence rate of 2-4% has decreased to 0.1% or less.

Furthermore, since the root portion of the anode lead 3 is hardened by the heat-resistant insulating member 4 filled in the recess 2, even if bending force is applied to the anode lead 3 during the manufacturing process, the bending force will not be applied to the anode body 1. There will be no cracks in the implanted part.

Therefore, since there is no deterioration of capacitor characteristics due to cracks, etc., the capacitor can be maintained in high quality.

Furthermore, when supplying the heat-resistant insulating member 4 to the top surface of the anode body 1, since the four parts 2 are formed on the top surface, the heat-resistant insulating member 4 can be easily held after being supplied to the top surface. And it becomes certain.

Furthermore, since the heat-resistant insulating member 4 is supplied to the anode body 1 at the same time to a plurality of anode bodies fixed to the metal plate 10, mass productivity is significantly improved.

Note that the present invention is not limited to the above embodiments in any way,
For example, heat-resistant insulating members can be deposited by dipping in a suspension, or by immersing an anode in powder.
The powder may be dropped from above the anode body to be deposited, or a paste may be supplied through a nozzle.

In addition to the shape shown in FIG. 5, the four parts can also be formed as shown in FIGS. 7 to 8.

As described above, according to the present invention, since the creeping of the semiconductor layer forming member onto the anode lead can be reduced with a simple configuration,
It is possible to prevent short circuits between the cathode and anode when welding the external lead wire to the anode lead, and because the anode lead is solidified with a heat-resistant insulating material, the anode can be prevented from shorting due to external force acting on the anode lead. This prevents cracks in the body and maintains the high quality of the container.

[Brief explanation of drawings]

Figures 1 and 2 are front sectional views showing different embodiments of conventional solid electrolytic capacitors, Figure 3 is a perspective view of the anode body of Figure 2, and Figure 4 is a solid electrolytic capacitor according to the present invention. FIG. 5 is a front sectional view showing an embodiment of the present invention, FIG. 5 is a perspective view showing an embodiment of the present invention, and FIG. 7 and 8 are front sectional views showing other different embodiments of the present invention. 1... Anode body, 2... Concavity, 3...
...Anode lead, 4...Heat-resistant insulating member.

Claims (1)

[Scope of utility model registration request] An anode lead made of a metal wire having a valve action is provided to protrude from the top surface of a molded body of a metal powder having a valve action, and a recess is formed in the top surface of the molded body at the root portion of the anode lead, An anode body for a solid electrolytic capacitor, characterized in that this recess is filled with a heat-resistant insulating material.