JPH01181509A - Manufacture of solid electrolytic capacitor element formed body - Google Patents

Abstract

PURPOSE:To enable the formation of element formed body wherein forming density is uniform regardless of the length of an element by providing multiple staged of metal powder and by performing multiple-stage press forming by upper and lower punches accordingly. CONSTITUTION:One third of required amount of value operation metal powder 3 such as tantalum, niobium, and titanium is supplied and an upper punch 4 and a lower punch 5 are operated to form a primary forming body 6. Then, the upper punch 4 and lower punch 5 are returned to their original positions and 1/3 of required amount of the valve operation metal powder 3 is supplied onto the primary forming body 6 to form a secondary forming body 7 which coalesced with the primary forming body 6. Then, in the similar manner as the second time, an element forming body 8 which coalesced with the secondary forming body 7 is formed. It allows forming density to be uniform, electrostatic capacity per unit weight of powder to be large, and deterioration and damage of dielectric oxide layer due to heat shock which is applied to in the later process to be reduced for improved reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a solid electrolytic capacitor element molded body by improving a press molding method.

(Prior Art) Generally, the manufacturing method of capacitor elements by press-molding valve metal powder such as tantalum, niobium, titanium, etc. is as follows.
As shown in FIG. 7, a required amount of valve metal powder 13 is filled into a mold 12 having an inner cylindrical portion 11 having a desired shape, and compressed by an upper punch 14 and a lower punch 15.

Conventionally, the compression operation by the upper punch 14 and the lower punch 15 is basically performed once, although there is a difference in time and stroke length between the upper punch 14 and the lower punch 15.

In the above manufacturing method, there is no problem if τ, the diameter or width of the element is larger than the length in the compression direction (hereinafter referred to as element length), but if the relationship is reversed, that is, the element length is longer than the diameter or width of the element , the density at the center becomes coarse, causing variations and deviations in the molding density as a whole, making it impossible to mold elements with uniform molding density.

As described above, variations and deviations in molding density lead to a decrease in capacitance per unit and a decrease in LG characteristics (resulting in τ).

(Problems to be Solved by the Invention) As described above, in the conventional element molding means, the molding density of the element cannot be made uniform, leading to a problem of deterioration of characteristics.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor element molded body using an improved press molding means that can uniformize the molded density of the element. be.

[Configuration 1 of the Invention (Means for Solving the Problems) The method for manufacturing a solid electrolytic capacitor element molded body of the present invention includes the following steps:
A method for manufacturing a solid electrolytic capacitor element forming means, in which a mold having an inner cylindrical portion is filled with valve metal powder and the metal powder is compressed by an upper punch and a lower punch, includes multi-stage powder supply and the like. It is characterized by molding by multi-stage pressing using corresponding upper and lower punches.

(Function) According to the above configuration, the amount of metal powder required for element molding is not put in at once and pressed once, but the molding is performed by supplying powder and pressing several times as necessary.
Uniform element molding without variation or bias in molding density becomes possible.

(Example) Examples of the present invention will be described below. That is, as shown in FIG. 1, 1/3 of the required amount of valve metal powder 3, such as tantalum, niobium, titanium, etc., is supplied to a mold 2 having an inner part 1 having a desired shape, and a second As shown in the figure, the upper punch 4 and lower punch 5, which have been set in advance so that compression ends at the center of the element length, are moved toward the center of the element length to form a primary formed body 6, and then As shown in FIG. 3, return the upper punch 4 and lower punch 5 to their original positions,
1/1/2 of the required amount of valve metal powder 3 is placed on the primary molded body 6.
3 is supplied, and as shown in FIG. 4, the upper punch 4 and the lower punch 5 are again moved in the direction of the center of the element length to form a secondary molded body 7 that is combined with the primary molded body 6. As shown in the figure, the upper punch 4 and the lower punch 5 are returned to their original positions, and the remaining valve metal powder 3 is supplied onto the secondary formed body 7, as shown in FIG. 6, in the same manner as the second time. The upper punch 4 and the lower punch 5 are moved in the direction toward the center of the element length to form and form an element molded body 8 that is combined with the secondary molded body 7. In the figure, 9 is an anode wire through hole, and 10 is an anode wire.

According to the method for manufacturing the solid electrolytic capacitor element molded body constructed as described above, the obtained element molded body 8 is formed by several rounds of compaction, so that the compacting density is made uniform, and the powder Large electrostatic capacity per unit weight,
Furthermore, there is little deterioration or damage to the dielectric oxide film due to thermal shock applied during the process, which greatly contributes to improved reliability.

Next, a comparison of characteristics with the conventional example will be described.

That is, 35V-1μF of the present invention molded using tantalum powder using the 3-time press method explained in FIGS. The LC characteristics of the tantalum solid electrolytic capacitor were investigated after applying a rated voltage of 35 V for 30 seconds before the solder dip and after the solder dip was heated at 260 DEG C. for 10 seconds, and the results were as shown in FIG.

As is clear from FIG. 8, in the conventional example B, the LC characteristics deteriorated significantly after soldering, whereas in the invention A, there was almost no change, and an excellent effect in heat resistance characteristics was obtained.

Furthermore, as a result of investigating the capacitance characteristics of the present invention formula and the conventional example B, the present invention A has an improvement of about 5% compared to the conventional example B, and the conventional example B has a frequency characteristic of 0.9 to 3.4 Ω. DeY
l, 1Ω, whereas the formula of the present invention had a resistance of 0.3 to 1Ω.
An improvement effect was seen with 2ΩteX017Ω.

The samples used in each test were 30 each for both A and B.

In addition, in the above example, the metal powder supply and pressing were performed three times as an example of the multi-step number of times.
It goes without saying that the number of times is not limited to this, and may be set as necessary.

[Effects of the Invention] According to the present invention, it is possible to easily form an element molded body with a uniform molding density regardless of the element length, and a solid electrolytic capacitor that contributes to providing a highly reliable solid electrolytic capacitor. A method for manufacturing an electrolytic capacitor element molded body can be obtained.

[Brief explanation of the drawing]

1 to 6 are for explaining a method of forming an element molded body according to an embodiment of the present invention. FIG. 1 is a schematic diagram showing the first metal powder supply state, and FIG. A schematic diagram showing the state of press forming for the first time, FIG. 3 is a schematic diagram showing the state of metal powder supply for the second time, FIG. 4 is a schematic diagram showing the state of press forming for the second time, and FIG. A schematic diagram showing the metal powder supply state, FIG. 6 is a schematic diagram showing the third press molding state, FIG. 7 is a schematic diagram illustrating the conventional method of forming an element molded body, and FIG. 8 is a schematic diagram showing the LC characteristics. FIG. 1...Inner cylinder part 2...Mold 3...Valve metal powder 4...Upper punch 5...Lower punch
6... Primary molded body 7... Secondary molded body
8... Element molded body patent application Hito Marukon Electronics Co., Ltd. Figure 5 Figure 6 Figure 7 Present invention A Conventional example date Figure 8

Claims (1)

[Claims] A method for manufacturing a solid electrolytic capacitor element molded body, in which a mold having an inner cylinder part is filled with valve metal powder, and the metal powder is compressed by an upper punch and a lower punch, the metal powder being supplied in multiple stages, A method for manufacturing a solid electrolytic capacitor element molded body, characterized by performing multi-step press molding using an upper punch and a lower punch corresponding to the above.