JPS62102515A - 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 [Field of Industrial Application] The present invention relates to an electrolytic capacitor and a method for manufacturing the same, and more particularly to an anode body structure used in a sintered electrolytic capacitor and a method for manufacturing the same.

[Conventional technology]

Generally, the anode bodies of electrolytic capacitors are made by press-molding fine powder of so-called valve metals such as tantalum, titanium, and niobium into a certain shape, and then sintering the molded body in a high-temperature vacuum. After electrochemically oxidizing the surface of this anode body to form a dielectric oxide film, a cathode layer is further provided on the outside to form a capacitor.

[Problem that the invention seeks to solve]

Conventionally, this type of molded body has generally been manufactured to have a cylindrical external shape, for example, with a part of the valve metal anode lead buried in the center, as shown in FIG. 4(a), Φ). There is.

That is, as shown in FIG. 5, this molded body is manufactured by filling a die 41 having an inner cylindrical portion with a desired constant shape with valve metal powder 43, and then inserting the tip of the anode lead 44 of the valve metal into This is done by applying pressure from above and below using a punch 42 while embedded in powder 43, and then this molded body is sintered in a high-temperature vacuum to obtain an anode body.

In the method of manufacturing such a molded body, the anode lead 44
In order to guide the powder into the powder 43, a lead guide hole 45 is formed in the center of the punch 4 on one side.
It is necessary to provide a slight gap between the inner diameter of the anode lead 5 and the outer diameter of the anode lead 44 in order to smooth the mechanical movement of the anode lead 44 and the punch 42. Therefore, during molding, the powder 4 near the guide hole 45 at the tip of the punch 42 is
3 is pressure molded in a state in which it escapes into the gap between the anode lead 44 and the guide hole 45, as shown in FIG.

The density of the molded body near the anode lead root 31 is lower than that in other parts.

Therefore, the powder 43 is near the anode lead base 31.
If the bond between powder particles is weak and such an anode body is manufactured into a product, the bond between powder particles will be damaged due to external mechanical stress such as vibration or shock, or expansion and contraction due to temperature changes, resulting in damage. Since the dielectric oxide film formed on the valve metal powder at the location is also damaged, there are drawbacks such as increased leakage current and short circuits, which degrade or eliminate capacitor functions.

[Means for solving problems]

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

That is, according to the present invention, the root part of the anode lead of the anode body for an electrolytic capacitor, which is formed by pressure-molding and vacuum sintering of valve metal powder in which a part of the anode lead is buried, is 1Siik compared to other parts. An anode body for a TA electrolytic capacitor characterized by having a high density distribution in a single stage is obtained, and further,
A small, high-density pressure-molded body of valve metal is adhered to the surface of one end of the anode lead.

A step of vacuum sintering to obtain a small sintered anode body, and a step of press-molding the small sintered anode body with an anode lead protruding into a molded body of valve action metal powder of the same type, followed by vacuum sintering. A method for manufacturing an anode body characterized by the following.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail in comparison with conventional examples.

As a conventional example, tantalum powder weighing 1 g is molded into a columnar shape as shown in FIG. 4(a) using a molding apparatus having a die 41 and a punch 42 having the structure shown in FIG. At this time, a 0.5φ mental wire as the anode lead 44 was embedded in mental powder φ using a punch 42 having a lead guide hole diameter of 0.52φ, with a diameter of 4 mm x length of 5.5 mm, and an apparent density of 8 g/Crn'. A molded body was formed in which the embedded length of the anode lead wire was 5 mm, and the exposed length of the anode lead 44 to the outside of the molded body was 5 mm.

Next, this molded body is placed in a vacuum sintering furnace, and the temperature is 180°C.
A sintered body was obtained by vacuum sintering at 0°C for 30 minutes.

Next, this sintered body is used as an anode body, and a dielectric oxide film and a cathode layer are provided on the surface thereof by known means for manufacturing electrolytic capacitors to form a capacitor element, and a resin exterior is further applied by known means. Commercialized.

On the other hand, as an example of the present invention, the anode body shown in FIG. 1(a) was used as a lead. This anode body 2 for the anode lead was manufactured using a molding device similar to that shown in FIG.
．． 5rng of tankle powder 1mm in diameter x 2m in length
The anode lead has a structure in which a 0.5φ mental wire is embedded in tantalum powder as a J-do 1. Embedment length: 1.5 mm.

It is a molded body with an anode lead extending 5 mm in length. This molded body is then heated to a temperature of 1900°C in a vacuum sintering furnace.
As a result of sintering for 60 minutes, the density was 10.3 g/cr.
A small sintered anode body of n' was obtained, and this small sintered anode body was used as a lead.

Next, this small sintered anode body is mounted on a punch 12 of a molding device shown in FIG. 2, and then tantalum powder 14 is filled into a die 11 and molded under pressure from above and below by the punch 12 to form a formed body. did. At this time, the diameter of the molded body was 4 mm as in the conventional example, and the length was taken into consideration so that the density of the parts other than the anode body for the drawer lead would be 8 g/cm', the same as in the conventional example.5. l
mm.

The molded body thus obtained was sintered in a vacuum sintering furnace at a temperature of 1800°C for 30 minutes in the same way as in the conventional example, resulting in a sintered body having an external shape and a cross section as shown in FIG. This sintered body was polished, and the density of each part was measured.
It has become clear that the density of the sintered body is &7g/CIn3, which is the same as that of the conventional sintered body, and that it changes stepwise at the boundary between the two. Next, this sintered body was used as an anode body, and the product was manufactured using exactly the same means as in the conventional example.

A temperature cycle of 100 products using the conventional anode bodies obtained in this way and 500 products using the anode bodies according to the present invention for 30 minutes on the low temperature side and +85℃ on the high temperature side for 30 minutes. Table 1 shows the number of defects that occurred when 50 cycles were performed.

Table 1 Also, for 30 of these product pots, the wave height value 1oo()
Table 2 shows the number of defects that occurred when the sawtooth impact was applied 20 times.

〔Effect of the invention〕

As mentioned above, the electrolytic capacitor using the anode body according to the present invention has a high density at the base of the anode lead, which is easily damaged by mechanical and thermal stress, and the bond between the valve metals is strong, so (1)! It is extremely resistant to mechanical and thermal stress after being made into an R product. (11) Therefore, it is possible to provide an extremely reliable electrolytic capacitor that does not suffer from deterioration of leakage current characteristics or short-circuit failure, and has great industrial value.

In this example, one end of the lead wire is buried inside the molded body as the lead wire anode body, but as another example, as shown in FIG.
Of course, the effect can also be achieved by having the center part of the molded body 22 buried inside the molded body and both ends exposed to the outside of the molded body.

Table 2 From these results, it is clear that the anode body according to the present invention is stronger and 6D stable against thermal stress and mechanical stress compared to the conventional anode body. However, this is because a detailed analysis of the defective parts of conventional defective products revealed that all defective products had damage to the dielectric oxide film at the base 31 of the top drawer lead of the anode body. It is clear that this is due to the effect of increasing the density of the root portion of the drawer door according to the invention.

[Brief explanation of drawings]

FIG. 1(a) is a perspective view of an anode body for an anode lead used in an embodiment of the present invention, and FIGS. 1(b) and 1(C) are perspective views of 1@pole body obtained by an embodiment of the present invention. Diagrams and cross sections, 2nd
The figure is a sectional view showing the main parts of a molding device used in an embodiment of the present invention, FIG. 3(a) is a perspective view of an anode body for an anode lead used in another embodiment of the present invention, and FIG. 3(b) FIG. 4(a) is a sectional view of an anode body obtained according to another embodiment of the present invention;
(b) is a perspective view and a cross-sectional view of a conventional anode body, and FIG. 5 is a cross-sectional view mainly showing main parts of a conventional manufacturing apparatus. 1, 15.21.32.44...-Anode lead, 2,13゜22...Anode body for anode lead, 3.14.23.33゜43... Valve metal powder, 11.41...Dice, 12.42-...
...Punch, 31...The base of the anode lead. −≠D3 Figure 2 (I)) Figure 3

Claims (2)

[Claims] (1) In an anode body for an electrolytic capacitor, which is made by press-molding and sintering valve action metal powder with a part of the anode lead embedded, the base of the anode lead is higher than the other parts in a stepped manner. An anode body for an electrolytic capacitor characterized by having a density distribution. (2) A step of attaching and forming a small high-density press-molded body of valve metal on the peripheral surface of one end of the anode lead and sintering it to obtain a small sintered anode body; A method for manufacturing an anode body, comprising the steps of: protruding an anode lead into a molded body of the same type of valve-acting metal powder, molding under pressure, and vacuum sintering.