Cabot Corporation

Hongju Chang

James Allen Fife

Roger W Steele

Viren M Pathare

Bhamidipaty K Rao

Lee M Ruch

A capacitor having a central electrode body having sintered metal anode with an electrode lead, the anode having a sintered product produced from a tantalum powder having deagglomerated particles such that the product of the volume mean diameter in microns multiplied by the specific surface area measured in m.sup.2 /g is a number in the range of below about 25. Capacitors having a central electrode with the anode produced from a sintered product produced from a heat treated and oxidized tantalum powder wherein the oxidized particle size is greater than about 0.7 m.sup.2 /g. Capacitors are defined in terms of anodes produced from powders having specified ratios of Scott Bulk Density to surface area or ratio of die fill rate to surface area.

Tantalum metal power with controlled size distribution and products made

A process for sizing (i.e., comminuting) a tantalum powder including agglomerates of smaller particles, which process yields a tantalum powder having an as-comminuted agglomerate size distribution with the product of the Volume Mean Diameter, MV (in microns as measured by light scattering techniques such as Microtrac analysis), times specific surface area, BET (m.sup.2 /g), being less than about 25. These powders after sizing typically have ratios of Scott Bulk Density : BET Surface Area in the range from about 20 to about 35. Also provided are powders having a substantially unimodal and narrow agglomerate size distribution in all stages of production, namely after sizing (i.e., deagglomeration by comminution), thermal agglomeration (i.e., heat treatment), and deoxidation. These resultant powders have high surface area and good flowability properties and, upon sintering, exhibit controlled shrinkage with high porosity. Further provided are sized heat treated tantalum powders having agglomerate particle sizes wherein the product of the Volume Mean Diameter, MV, times the specific surface area, BET, is in the range from about 90 to about 250. Sized and agglomerated powders which are deoxidized are also provided wherein the product of the Volume Mean Diameter, MV, times the specific surface area, BET, is in the range from about 90 to about 250.

Method of making tantalum metal powder with controlled size distribution

A process for producing capacitor grade powder, electrodes, and finished capacitors therefrom having reduced electrical leakage characteristics. The powder is prepared by reacting Group V-B base materials with quantities of between 500 to 7000 ppm of nitrogen and 700 to 3000 ppm of oxygen. Electrical leakage is reduced by at least 28% for electrodes anodized at 100 volts or greater in comparison with electrodes and finished capacitors made from undoped materials. A range of specific charge of up to 25,000 uFV/g is achieved for sintering temperatures of 1400.degree. C. to 1800.degree. C.

Growing community of inventors

Wayne, PA, United States of America

Hongju Chang