SBIR Phase I: A New Production Method for Ta Fibers for Use in Electrolytic Capacitors with Improved Performance and Packaging Options

This Small Business Innovation Research (SBIR) Phase I project is intended to demonstrate a new process for manufacturing valve metal fibers for use in producing capacitors. The technology is applicable to all valve metals used for making solid electrolytic capacitors. If successful, this technology could lead to capacitor products having higher performance and greater volumetric efficiency than are currently available. The use of fibers in place of the standard powder compacts allows the production of thin anode bodies leading to improved packaging options and component performance. The innovation underlying the technology is bundle drawing of valve metal filaments contained in copper matrix. A composite consisting of valve metal filaments in a copper matrix is drawn in series of reduction steps until the filaments are less than 10 microns. The drawn wire is rolled to produce submicron thick ribbon type filaments. The copper composite matrix is chemically dissolved to produce metallic thin fibers. The fibers are formed into thin mats, which are sintered to produce porous metal strips from which high surface area capacitor anodes can be made. A significant aspect of this approach is that fiber morphology can be varied within a wide range of thickness and widths unlike powders. This allows the morphology of the fibers to be optimized in order to maximize the properties of the capacitor. Commercially, nearly all medical, automotive and consumer electronic devices all utilize solid electrolytic capacitors due to their performance, volumetric efficiency, and high reliability. Several million pounds per year of powder are consumed in the manufacture of capacitors for these applications. The trend towards higher power components, and miniaturization, combined with the need to lower materials and manufacturing costs have created an opportunity for new methods of producing solid electrolytic capacitors. Fiber metal technology has the potential to both lower manufacturing costs, improve capacitor performance, and improve packaging options which could lead to new products that are either very difficult or very expensive to make using current methods.