JPH04167512A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To decreace the internal resistance value of a solid electrolytic capacitor element itself by a method wherein, when value-action metal powder is pressure-molded in an anode member element manufacturing process, the value- action metal powder is introduced plural times, and the powder is molded by changing compression ratio. CONSTITUTION:A high density molded part 1 is formed by conducting a high density press-molding operation of the value-action metal powder of tantalum and the like, and then a low density molded part 2 is formed by introducing tantalum powder and press-molded it at low density. By introducing the metal powder material divided in a plurality of times and also by molding the metal powder by changing the ratio of compression, an anode member element having a lead-planted part of high green density and high molded body strength, and also having a part where a low green density semiconductor layer is easily formed, are manufactured. As a result, the internal resistance value, possessed by a capacitor element itself as the electric characteristics of a solid electrolyte capacitor, can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a solid electrolytic capacitor, and particularly to a pressure molding method in the manufacturing process of an anode body element.

[Conventional technology]

Conventionally, in the manufacturing process of the anode body element of a solid electrolytic capacitor, the anode body element was manufactured by one-time pressure molding under constant pressure conditions while an anode lead wire was planted in the valve metal powder.

[Problem to be solved by the invention]

In the conventional anode body element manufacturing method described above, molding is carried out by one pressurization, so in order to maintain the strength of the molded product, it is necessary to increase the compression ratio to some extent and increase the molding density. However, if the molding density is high, a sufficient semiconductor layer cannot be formed inside the molded body in the subsequent step of forming the cathode semiconductor layer. In addition, if the compression ratio is lowered and the molding density is lowered, the strength of the molded product will be weakened, and the mechanical stress caused by welding the anode lead wire to the external anode terminal, etc. during the assembly process, and the mechanical stress caused by curing and heat shrinkage of the exterior resin, etc. This increases the leakage current value. In particular, the area around the anode lead wire planting part directly receives the stress applied to the anode lead wire, which has the disadvantage that it becomes a point where the leakage current value deteriorates.

The purpose of the present invention is to improve the permeability into the inside of the molded body during the formation of a semiconductor layer while maintaining the strength of the molded body high, to reduce the internal resistance value of the solid electrolytic capacitor element itself, and to further improve the manufacturing of the solid electrolytic capacitor element. It is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor that is resistant to external stress during the process and external heat stress after commercialization, and that does not easily deteriorate the leakage current value.

[Means to solve the problem]

In the manufacturing method of a solid electrolytic capacitor of the present invention, in the anode body element manufacturing process, when the valve metal powder is pressure-molded, the valve metal powder is introduced in multiple steps and the compression ratio is changed. The method is characterized by having a step of:

As mentioned above, the present invention has a lead planting part that maintains the strength of the molded product with high molding density by charging the metal powder material in multiple times and molding by changing the compression ratio, and a semiconductor with low molding density. It is possible to manufacture an anode element having a portion where layers can be easily formed.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

Valve metal powder such as tantalum, aluminum, niobium, etc., in the case of tantalum, about 6.0 to 10.0 g/cc.

High-density press molding is performed to form a high-density molded part 1, and then tantalum powder is added to form approximately 20 to 6.0 g/cc.
A low density molded part 2 was formed by press molding at a low density of .

Next, the molding method will be explained with reference to FIG. First, as shown in FIG. 2(a), the anode lead wire 3 is introduced through the anode lead wire introduction hole 7, and the lower molding punch 5 is placed in the die 6, and a valve metal powder such as tantalum is inserted into the die. 6 and put the upper bunch 4 for molding into approximately 8Of) kg.
/at! The first stage pressure molding is carried out at a pressure of 1 to form a high-density molded part l. Next, insert the upper punch 4 into the die 6.
Then, the valve metal powder was put on the high-density molding part 1, and the upper molding punch 4 was used again to give about 600 kg/cni.
A second-stage pressure molding was performed at a pressure of 100 mL to obtain a low-density molded part 2.

After cutting the anode lead wire 3, the molded body is removed from the die 6 and has a diameter of approximately 4.5 m/m and a height of approximately 6 m/m (high density part approximately 2 m/m).
A cylindrical molded body with a low density part of about 4 ω/m) was obtained.

Thereafter, using known techniques, a self-supporting resin-clad solid electrolytic capacitor with a rated voltage of 10V%' [capacity of 100μF] is manufactured by performing high-temperature vacuum sintering, forming an anodic acid electrode layer 1, assembling, and resin-cladding. Obtained.

For comparison, the diameter was approximately 4.5 mm using the conventional method of one-time molding.
One with a slightly lower molding density and a height of about 5.5 m/m, and the other with a slightly higher molding density with a diameter of about 4.5 m/m and a height of about 5.2 m/m. A comparison of the leakage current value defective rate between the product according to the embodiment of the present invention and the product manufactured using the conventional method revealed the following improvements.

The electrical characteristic value tan δ, which is an index of the formation status up to the inside of the molded body in the semiconductor formation process, is shown in Figure 3 (a).
As shown in the histograms of , (b) and (c), no improvement was observed.

As described above, the method of the present invention takes advantage of the advantages of the conventional method and compensates for its disadvantages. By supplying the anode lead wire from the lower molding punch 5 on the lower side, it is possible to mold the area around the anode lead wire planting part with high density.

Next, a second embodiment of the present invention will be explained using a tantalum solid electrolytic capacitor.

Tantalum metal powder is made into different grain shapes and surface areas depending on the manufacturing method. In the present invention,
Pressure molding can be divided into multiple stages, and the type of powder supplied can be changed for each stage.

For example, during the first stage pressure molding mentioned in the first example, the particle shape is approximately 10 to 40 μm, and the surface area is approximately 3,000 μm.
A material with a CV level is used and molded at a high density of approximately 100 g/cc, and during the second stage pressure molding, the grain size is approximately 2 to 8 g/cc.
A material with a surface area of about 23.0000 V in μm2 is used, and is molded at a low density of about 3.0 g/cc, with a diameter of about 4.5 φ and a height of 6.5 mm (high density part about 2 g, low density part about 4.0 g/cc). A cylindrical molded body with a diameter of 5 mm) was obtained. Thereafter, high-temperature vacuum sintering is performed using known techniques, and processes such as anodization, cathode layer formation 2 assembly, and resin exterior are performed to obtain a rated voltage of 10V and a capacitance of 1.
A self-supporting resin-clad solid electrolytic capacitor of 00 μF was obtained.

When the leakage current value defect rate was compared with that of the prototype according to the first example, the following improvements were observed.

In addition, as shown in FIG. 3(d), the histogram of the electrical characteristic value tan δ, which is one indicator of the state of formation up to the inside of the molded body in the semiconductor forming process, decreased, indicating an improvement effect.

As described above, according to the molded body manufacturing method of the present invention that takes advantage of the characteristics of tantalum powder, the first
During stage pressure molding, a powder with high compaction strength is used that is easy to mold into high density, and during second stage pressure molding, molding is performed at low density to ensure internal permeability in the cathode layer forming process. Thereby, the effects of the first embodiment can be further improved.

〔Effect of the invention〕

As explained above, the present invention is capable of maintaining the strength of the compact by dividing the valve action metal powder into multiple batches and changing the compression ratio during pressure molding. It is possible to improve the permeability into the inside of the molded body in the formation of a semiconductor layer, and it has the effect of reducing the internal resistance value of the capacitor element itself as an electrical characteristic of the solid electrolytic capacitor.

In addition, the strength of the molded product around the anode lead planting part is high, so external stress during the manufacturing process of solid electrolytic capacitors, such as the welding process with external terminals, internal stress of the exterior resin, etc., and after commercialization. It is resistant to external heat stress (soldering, etc.) and has the effect of preventing the leakage current value from deteriorating.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an anode body element manufactured according to an embodiment of the present invention, and FIGS. 2(a) and 2(b) are schematic diagrams for explaining a molding method according to an embodiment of the present invention. Figure 3(a)~
(d) is a histogram of the distribution of tan δ values between the prototype according to the embodiment of the present invention and the product according to the conventional example;
Figure (a) is the conventional product (1) (low density), Figure 3 (b) is the conventional product (■) (high density), and Figure 3 (c) is the example 1 of the present invention.
, FIG. 3(d) is a histogram of Example 2 of the present invention. DESCRIPTION OF SYMBOLS 1... High-density molded part, 2... Low-density molded part, 3... Anode lead wire, 4... Upper punch for molding, 5... ...lower punch for forming, 6...
...Dice, 7...Anode lead wire introduction hole. Agent Patent Attorney Uchihara Otosen 1 tt-J [1 (i 1kHz) (%) taJfMr
d tkJ4zX'l) (α)
(b) - (oilHz) (%)
Value (atmh) (%) ('C) -1←
(d) -111111 Figure 3

Claims (1)

[Claims] In the manufacturing process of the anode body element of solid electrolytic capacitors, in which the valve metal powder is pressure-formed to form the anode body, the injection and molding of the valve metal powder are divided into multiple steps and compressed. A method for manufacturing a solid electrolytic capacitor, which is characterized by molding with varying ratios.