JPH0963904A - Pellet manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor which is provided with a wire that is located inside it and hardly bent or broken, very stable in characteristics, ands high in reliability. SOLUTION: A wire 1 is made to protrude into a cavity 8 made with a lower punch 7 and a die 6 through the lower punch 7, then power 3 is fed into the cavity 8, and an upper punch 9 is pressed down to press the powder to form a pellet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet manufacturing method used for molding a sintered capacitor element.

[0002]

2. Description of the Related Art In a method of manufacturing a sintered capacitor element, a pellet made of a powder compact in which a wire to be an anode is embedded is used. As shown in FIG. 2, the pellet 3 is molded by filling the powder 3 to be molded into the cavity 8 formed by the lower punch 7 and the die 6, and then projecting 1A of the wire 1 from the lower portion of the upper punch 9. The upper punch 9 is fitted into the cavity 8 along the die 6 to compress the powder 3.

After that, the upper punch 9 is pulled out from the cavity 8 and the wire rod 1 is cut at a predetermined position, and the powder compact embedded with the wire rod is discharged out of the die 6 to form pellets. This pellet is heated and sintered in a non-oxidizing atmosphere or vacuum to form a capacitor element.

[0004]

Conventional powder 3 has a particle size of 0.001 to 0.4 mm, and wire 1 has a diameter of 0.15 to 0.
A 6 mm one is used. Therefore, when the wire rod 1 is inserted into the powder 3 at the time of pellet molding, the contact resistance between the particles of the powder 3 and the wire rod 1 increases, and the wire rod 1 is less likely to be inserted into the powder 3. Since the powder 3 in the cavity 8 is compressed at the same time when the wire rod 1 is inserted, the resistance to insert the wire rod 1 into the powder 3 becomes large.

For the above reasons, the wire rod 1 may not be embedded in a predetermined size, may not be inserted sufficiently, or may be bent. For this reason, there are drawbacks that the wire rod 1 is pulled out during the process or when it is used as a capacitor, and the pull-out strength does not reach a predetermined strength, so that the reliability is lowered.

[0006]

In order to solve such a problem in the present invention, as shown in FIG. 3, a wire rod is inserted from an upper surface of the lower punch 7 into an empty cavity 8 formed by the lower punch 7 and the die 6. After projecting 1A of a part of the powder 1, the powder 3 is filled in the cavity 8 as shown in FIG. 4, and then, as shown in FIG. 1, the upper punch 9 is pushed downward along the die 6 to compress the powder 3.

Thereafter, as shown in FIG. 5, the wire 1 is pushed up to the outside of the pellet 2 and the cavity 8 in which the wire 1 is embedded, and the arm 1
The pellet 2 is manufactured by holding the wire rod at 0 and cutting the wire rod 1 with a cutter 11 to a predetermined size.

[0008]

The present invention, as shown in FIG. 1, does not first fill the powder 3 into the cavity 8 formed by the lower punch 7 and the die 6, but after the wire 1 is projected 1A from the upper surface of the lower punch 7. Since the powder 3 is filled, there is no contact resistance between the particles of the powder 3 and the wire 1, so that the wire 1 is not embedded in the pellet 2, is not inserted sufficiently, or is not bent, and is pulled out. It has the characteristic that pellets with stable strength and high reliability can be manufactured.

[0009]

Embodiments of the present invention will be described with reference to the drawings taking tantalum pellets as an example. As shown in Fig. 3, 0.9 x 1.0 mm
Lower punch and die 6 with a square cross section and a depth of 4.6 mm
Cavity 8 made with and is used. A tantalum wire 1 having a diameter of 0.25 mm protruding 0.8 mm from the upper surface of the lower punch 7 1A
Let it.

Next, as shown in FIG. 4, the average particle size is 3 μm, and 2
Cavity 8 is filled with tantalum powder 3 having a secondary particle size of about 100 μm. Then, as shown in FIG. 1, the lower punch 7 and the upper punch 9 are pushed down and compressed until the tantalum powder 3 becomes about 1.2 mm. After the compression, first the upper punch 9 is pulled out upward from the cavity 8, and then the lower punch 7 is pushed up until the upper surface of the lower punch 7 is aligned with the upper surface of the die 6 as shown in FIG. Discharge.

The tantalum wire 1 is fed to the roller 12 by 10 mm.
At the same time as sending out and pushing up the pellet 2, the arm 1
After supporting pellet 2 with 0, tantalum wire 1 with cutter 1
Cut at 1.

[0012]

Since the pellets of the present invention are produced as described above, they have the following characteristic effects. After the wire rod is projected through the lower punch into the cavity made by the lower punch and the die, the powder is filled in the cavity and the upper punch is pushed downward to compress the powder, so the contact resistance between the powder particles and the wire rod. The wire rod is not embedded in the pellet, is not inserted sufficiently, and is not bent, and the wire rod does not pull out after sintering.

When the pulling strength of the tantalum wire from the pellets of the present invention product and the conventional product was compared for 500 samples, the conventional product produced four withdrawals, but the invention product did not pull out.

[Brief description of drawings]

FIG. 1 shows a sectional view of the present invention.

FIG. 2 shows a cross-sectional view of a conventional product.

FIG. 3 shows a sectional view of a conventional product.

FIG. 4 shows a cross-sectional view of the present invention.

FIG. 5 shows a cross-sectional view of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wire rod, 1A ... Protrusion, 2 ... Pellet, 3 ... Powder, 6 ... Die, 7 ... Lower punch, 8 ... Cavity,
9 ... upper punch, 10 ... arm, 11 ... cutter,
12 ... Feed roller

Claims (1)

[Claims] 1. A pellet manufacturing method for making pellets in which wire rods are embedded, wherein a wire rod is projected from the upper surface of the lower punch into a cavity formed by a lower punch and a die, and powder is filled in the cavity. A method for producing pellets, which comprises pressing a punch downward to compress the powder.