Constrained filament electrolytic anode and process of fabrication

Abstract

Porous metal compacts suitable for use as electrodes are formed through the reduction of a metal billet consisting of multiple filaments of an appropriate valve metal, preferably tantalum, contained within, and spaced apart by, a ductile metal, preferably copper. The filaments are elongated and substantially parallel within the billet. The array of valve metal filaments within the billet is surrounded by a continuous layer of valve metal. This metal is preferably, but not necessarily, the same as that which forms the filaments. The valve metal layer preferably completely surrounds the filament array circumferentially and runs the full length of the filaments. The layer is separated from the array by the same ductile metal that serves to separate the filaments from each other. This same ductile metal forms the surface of the billet, preventing exposure of the valve metal layer. The billet is reduced by conventional means, such as extrusion and wire drawing, the composite product is cut into short lengths, and the ductile metal separating the valve metal components of the composite is removed, preferably by leaching in mineral acids. The filaments are constrained within the valve metal tube, making handling during subsequent capacitor manufacture much less difficult than if the filaments were allowed to move freely.

Dependencies are inferred from the claim text.