Capacitor having textured pellet and method for making same

Details Capacitor having textured pellet and method for making same Capacitor having textured pellet and method for making same

1999-04-12

2001-02-20

Kincaid, Kristine (Department: 2831)

Electricity: electrical systems and devices

Electrolytic systems or devices

Solid electrolytic capacitor

C361S524000, C361S532000

Reexamination Certificate

active

06191936

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a capacitor having a textured pellet and a method for making same.
Solid tantalum capacitors and solid niobium capacitors use as anodes porous pellets which are compressed from fine tantalum or niobium powder. The pellets are first compressed and then they are sintered in a vacuum. The porous structure of the anode provides a high surface area and thereby high specific charge (CV) of the finished capacitor (where CV refers to capacitance and rated voltage). Generally tantalum and niobium pellets contain a lead wire made of the same metal as the compressed powder. The lead wire is attached to the pellet either by welding after the pellet has been sintered, or by embedding in the pellet before the pellet is pressed and sintered.
Prior art efforts have been made to increase the surface area of the pellet by fluting the exterior surface of a cylindrical pellet, or by forming elongated bores or channels in the interior of the pellet. In these prior art efforts the press dye forming the pellet determines the shape and configuration of the pellet, and hence of the anode. A large part of the available pellet volume is lost in these prior art efforts, and the ability to coat the outside surface of these pellets was not enhanced.
FIG. 8
illustrates one of these prior art devices which includes a cylindrical body
10
having elongated flutes
12
extending along the length thereof. This capacitor removes a great deal of the volume of the body
10
and does not significantly enhance the ability of the manganese oxide layer to adhere to the outer surface of the body
10
.
FIG. 10
shows another prior art body
14
having two or more elongated bores
16
extending therethrough. This increases the surface area of the body, but removes a significant volume, thereby reducing the overall capacitance of the body.
Therefore, a primary object of the present invention is the provision of an improved capacitor having a textured pellet and method for making same.
A further object of the present invention is the provision of a capacitor having a textured pellet which increases the adhesive characteristic for the coating which is coated on the outside surface of the pellet.
A further object of the present invention is the provision of an improved capacitor having a textured pellet which improves the consistency of the ESR distribution from capacitor to capacitor and results in reduced failures related to any penetration of conductive coatings through cracks or voids.
A further object of the present invention is the provision of an improved capacitor which lowers ESR of the capacitors at mid to high frequency and increases the adhesive strength of the MnO
2
coating on the exterior of the pellet significantly.
SUMMARY OF THE INVENTION
The foregoing objects may be achieved by a pellet for use in a capacitor comprising a rectangular body formed of compressed and sintered particles of a conductive material. The body has an exterior surface which includes a textured portion comprising a plurality of indentations therein.
The indentations have a depth of from 0.254 mm to 0.508 mm. Similarly the indentations have a width of from 0.254 to 0.508 mm.
The indentations may take various forms including the form of elongated channels having a profile in cross section which is selected from the group consisting essentially of a curved profile, a sine shaped profile, a rectangular shaped profile, a U-shaped profile, and a V-shaped profile. Other cross sectional profiles may be used without detracting from the invention.


REFERENCES:
patent: 3345545 (1967-10-01), Bourgault et al.
patent: 4090231 (1978-05-01), Millard et al.
patent: 4943892 (1990-07-01), Tsuchiya et al.
patent: 5075940 (1991-12-01), Kuriyama et al.
patent: 5586001 (1996-12-01), Amano et al.
patent: 5949639 (1999-09-01), Maeda et al.
patent: 5951840 (1999-09-01), Fukaumi et al.
patent: 5959831 (1999-09-01), Maeda et al.
patent: 5965062 (1999-10-01), Sakata et al.
patent: 6042740 (2000-03-01), Uehara et al.

Affiliated with

Also associated with

Rating

Capacitor having textured pellet and method for making same does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Capacitor having textured pellet and method for making same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Capacitor having textured pellet and method for making same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2567767