Next Generation of High Voltage, Low ESR SMD Tantalum Conductive Polymer Capacitors Exceeds 100V Milestone

Next Generation of High Voltage, Low ESR SMD Tantalum Conductive Polymer Capacitors Exceeds 100V Milestone
Written By: T. Zedníček | M.Bárta | J.Petržílek | M.Uher | I.Horáček | J. Tomáško | L. Djebara

Abstract:
Tantalum capacitors designed for high voltage applications (above 25V) have been used for many years in telecommunication, industrial, automotive or other high reliability applications. The conventional high voltage tantalum capacitor design is using a manganese dioxide cathode that provides good reliability, stability and robustness. Nevertheless there are certain limitations. First of all it is the operating voltage – even with optimized processes of dielectric formation, rated voltages of such parts are mostly limited to 50 or 63V. The other limitation is ESR. Very low ESR values have been achieved by using special anode shape designs such as multianodes or fluted anodes, but further ESR decrease is limited by low conductivity of manganese dioxide. Also a thermal runaway failure mode of the conventional MnO2 tantalum capacitors is a concern for some surge current intensive circuits. Thus higher voltage derating 50% minimum is recommended in surge current intensive circuits that further limit the maximum operating voltage of conventional tantalum capacitors.
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