JPS62277715A - Anode unit for electrolytic capacitor and manufacture of thesame - 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an anode body for an electrolytic capacitor and a manufacturing method thereof, and particularly relates to a sintered anode body structure and a manufacturing method thereof.

[Conventional technology]

Generally, the anode body of a decomposing capacitor is obtained by press-molding a fine powder of a so-called valve metal such as tantalum, titanium, or niobium into a certain shape under pressure, and then sintering the compact in a high-temperature vacuum. A porous body is used, and after the surface of this anode body is electrochemically oxidized to form a dielectric oxide layer i, a cathode layer is further provided on the outside to form the entire capacitor.

Conventionally, this type of anode body 10'' is generally shown in FIG. 4(a).

As shown in (b), it is manufactured by vacuum sintering a molded body 1 having, for example, a cylindrical external shape with a part of an anode lead 2 of a valve metal embedded in the center thereof.

That is, the manufacturing of this anode body 10 is as shown in FIG.
The die 21 having an inner cylinder part of a desired constant shape is completely filled with the valve metal powder 3, and the tip of the valve metal anode lead 2 is embedded in the powder 3 with the upper punch 22a1 and the lower punch 22b. A molded body 1 is formed by taking out the molded body 1 from above and below, and then the entire molded body 1 is sintered in a high temperature vacuum to obtain an anode body 10.

[Problem that the invention seeks to solve]

In the conventional method for manufacturing the anode body 10 described above, in order to introduce the anode lead 2 into the powder 3, a guide hole for the ~e electrode lead is punched in the center of the upper punch 22a, and this guide hole is It is necessary to provide a slight gap between the circular diameter and the outer diameter of the anode lead 2 in order to smooth the mechanical movement of the anode lead 2 and the upper punch 22a. Therefore, during molding, the powder 3 near the guide hole at the tip of the upper punch 22a is pressed and molded with the anode lead 2 escaping into the gap between the guide holes, so the base 2a of the anode lead shown in Fig. The density of the molded body 1 in the vicinity becomes lower than that of other parts.

Therefore, the powder 3 is near the base 2a of the anode lead.
Bonds between particles are weak, and when such a molded body 1 is manufactured using a sintered anode body, the particles of the anode body may bond together due to mechanical stress from the outside such as vibration or impact, or expansion or contraction due to temperature changes. As a result, the dielectric oxide film formed on the anode particles in the damaged area is also damaged, resulting in increased leakage current and short circuits, which reduce or eliminate capacitor function. was there.

[Means for solving problems]

An object of the present invention is to eliminate such conventional drawbacks and to provide an anode body for an electrolytic capacitor that is stable against mechanical stress and thermal stress, and a method for manufacturing the same.

According to the invention, there is provided an electrolytic capacitor characterized in that the density at the base of the anode lead of a valve metal anode body in which a part of the anode lead is buried has a higher density distribution than that at other anode body parts. An anode body is obtained, and further a step of forming a molded body of valve metal powder having a protruding portion of valve metal powder protruding from the planting surface of the anode lead on the outer periphery in contact with the root portion of the anode lead; A method for manufacturing an anode body for an electrolytic capacitor is obtained, which comprises the steps of pressing the protrusion into a molded body, press-forming it, and then sintering it in a vacuum.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings and compared with conventional examples.

First, as a conventional example, a molding device having a die 21, an upper punch 22a, and a lower punch 22bft having the structure shown in FIG. The tantalum powder of i is shown in Figure 4 (al
Mold into a cylindrical shape as shown. At this time, as the anode lead 2, a tantalum wire of 0.5φ was embedded in the tantalum powder 3 using the lead guide of the upper punch 22a having a hole diameter of 0.52φ, and the wire had a diameter of 4 tm and a length of 6.5 mm. The density is 811/cd, and the embedded length of 3 anode leads is 5 m.
A molded body 1 having an exposed length of six lengths of the anode lead 2 to the outside of the molded body 1 was formed.

Next, this molded body 1 was placed in a vacuum sintering furnace at a temperature of 1800° C. and vacuum sintered for 30 minutes to obtain an anode body 10.

Next, a dielectric oxide film and a cathode layer are provided on the surface of this anode body 10't by a known method for manufacturing electrolytic capacitors to form a capacitor element, and a resin exterior is further applied by a known method to produce a product. It became.

On the other hand, in the uninvented embodiment, as shown in FIG. 3, a molding having a cylindrical die 11, an outer upper punch 12a concentrically configured in a double structure, an inner upper punch 12b of small diameter, and a lower punch 12c is used. Molding is performed using a device. First, in the first step, tantalum powder with a weight of ii 0.67111 is filled into the inner cylindrical part of the die 11, and as shown in FIG. Thus, a cylindrical molded body 1 shown in FIG. 1 is formed. In this molded body, the dimensions of the cylindrical part excluding the protrusion 1a are the same as the conventional example, with a diameter of 411jlx.
It has a length of 5.5 mx, and has a structure in which a protruding part with a diameter of 2 x s and a length of 1 rug is attached to the base of the memorial reed 2 on its upper surface. At this time, as in the conventional example, a tantalum wire of 0.5φ was embedded as the anode lead 2 in the mental powder 3 through the lead guide of the internal upper punch 12b having a hole diameter of 0.52φ, and the embedded length was 6n1 and the exposed length was 5 mm. Adjusted to poultry. The apparent density of this molded body 1 is 8f/
/crd.

Next, as the second step, as shown in FIG. 3(b) K,
Pressure is applied by the internal upper punch 12b, and the protruding portion 1' a f
, the protrusion 1a is buried in the molded body 1 by pressure molding until its upper surface is at the shoulder surface position A-A' of the molded body, and a high-density part of the molded body is placed around the base 2a of the anode lead. 1b is formed.

The molded body thus formed was heated to 18°C, the same temperature as the conventional example.
The cylindrical anode body 10 shown in FIG. 2 was obtained by sintering for 30 minutes in a vacuum sintering furnace at 00'C. As a result of polishing this anode body 10 and measuring the density of each part, the high density part 10a of the anode body
The average density is 10.3. ! i'z name l.

The other parts of the anode body 10 are the same as those of the conventional anode body.
It became clear that it had a density of 7II/i.

Next, this anode body 10 was commercialized as an electrolytic capacitor using the same known means as in the conventional example.

100 products using the anode bodies obtained by the conventional method and 1 product using the anode bodies produced by the uninvented method.
00 on the low temperature side -55°C for 30 minutes, and on the high temperature side +85°C for 30 minutes.
Table 1 shows the number of defects that occurred when 50 temperature cycles were performed.

Table 1 Also, Table 2 shows the number of defects when 30 pieces of each of these torn pieces were subjected to sawtooth impact with a wave height of 100 G 20 times.

Table 2 These results show that the anode body according to the present invention is stronger and more stable against thermal stress and mechanical stress than the conventional example. It is obvious that this is due to a detailed analysis of the defective parts of conventional defective products, and it was found that all of the defective products had a dielectric oxide film on the top surface of the anode body at the base 28 of the anode body IJ-de. Since the damage is observed, it is clear that this is due to the effect of densification at the base 2a of the anode lead according to the present invention.

〔Effect of the invention〕

As described above, an electrolytic capacitor f using an anode body according to the method of the present invention
1. The density of the anode lead base, which is easily damaged by mechanical and thermal stress, is high, and the bond between the valve metals becomes strong. Very strong. (11) Therefore, it is possible to provide an extremely reliable electrolytic capacitor that does not cause deterioration in leakage current characteristics or short-circuit failure, and its industrial value is significant.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a perspective view and a sectional view of a molded body obtained by the first embodiment of the present invention. Ki 2 (
a) and (b) are a perspective view and a sectional view of an anode body obtained according to an embodiment of the invention. 3(a) and 3(b) are cross-sectional views showing the main parts of the molding apparatus according to the embodiment of the present invention.
Figure (a). (blVi A perspective view and a cross-sectional view of a conventional anode body. Fig. 5 is a cross-sectional view showing the main suction part of a conventional molding device. 1... Molded object, 1a... (Molded object of)
Projection part, lb, 10a...High density part, 2a.
...Base of anode lead, 2...Anode lead, 10...Anode body, 11.21...
・Dice, 12a...External upper punch, 12b・
...Internal upper punch, 22a...Upper bunch, 12c, 22b...Lower punch. Agent Patent Attorney Uchihara Oto 1 Figure Bud 2 Figure (L) (b) Mine 3w 3rd Figure $SmI

Claims (2)

[Claims] (1) An electrolytic capacitor characterized in that, in a valve-action metal powder anode body in which a part of the anode lead is buried, the anode body density at the base of the anode lead has a higher density distribution compared to other anode body parts. anode body. (2) forming a molded body of valve metal powder having a protrusion of valve metal powder protruding from the planting surface of the anode lead on the outer periphery in contact with the base of the anode lead; 1. A method for manufacturing an anode body for an electrolytic capacitor, comprising the steps of pressurizing, pressing into a molded body, press-forming, and vacuum sintering.