High voltage tantalum anode and method of manufacture

摘要

Tantalum powders produced using a tantalum fiber precursor are described. The tantalum fiber precursor is chopped or cut into short lengths having a uniform fiber thickness and favorable aspect ratio. The chopped fibers are formed into a primary powder having a controlled size and shape, narrow/tight particle size distribution, and low impurity level. The primary powder is then agglomerated into an agglomerated powder displaying suitable flowability and pressability such that pellets with good structural integrity and unifrom pellet porosity are manufacturable. The pellet is sintered and anodized to a desired formation voltage. The thusly created capacitor anode has a dual morphology or dual porosity provided by a primary porosity of the individual tantalum fibers making up the primary powder and a larger secondary porosity formed between the primary powders agglomerated into the agglomerated powder.

主权项

1. A method for providing an anode for a high voltage implantable electrolytic capacitor, the method comprising the steps of:
a) providing tantalum fibers having a diameter ranging from 0.5 μm to 2.5 μm and a length ranging from 5 μm to 50 μm; b) providing a primary tantalum powder as a loosely packed mass of the tantalum fibers; c) agglomerating the primary tantalum powder into a randomly oriented, substantially non-aligned, porous agglomerated tantalum powder; d) pressing the agglomerated tantalum powder into a tantalum pellet of a desired shape; e) sintering the tantalum pellet into a coalesced body of the tantalum fibers to thereby provide a sintered tantalum pellet; and f) anodizing the sintered tantalum pellet to a formation voltage of at least 300 V to form an anode having a dielectric oxide on the tantalum fibers.