Low Voltage CV Loss in Tantalum Capacitors

摘要

This paper presents evidence that the low voltage CV loss in Ta capacitors is the result of the natural thermal oxide adding to thickness of the anodic oxide of Ta, thereby, increasing the dielectric thickness and decreasing capacitance. The natural thermal oxide is approximately 3.3 nm thick regardless of the powder CV. At increased formation voltage (anodic oxidernthickness) this effect is diminished due to smaller impact of the natural oxide on total oxide thickness. At the same time, at larger formation voltage the effect of high voltage CV loss is observed. It starts at lower formation voltages with finer Ta powders due to their smaller sintered necks and pores between Ta particles.2 In the highest CV/g Ta powders, these two effects become overlapped, which limits the efficiency of these powders.