KEMET has been manufacturing conductive polymer based surface mount tantalum capacitors (KO-CAP[registered trademark]) since 1999. Capabilities have been successfully introduced into the market, such as low equivalent series resistance (ESR) series for decoupling, high voltage series for DC-DC converters and power management, and high-energy series for enterprise solid state drives (SSD) applications.
A recent application trend of conductive polymer based tantalum capacitors requires high performance in harsh environments. One example is the application in the automotive industry which requires AEC-Q200 qualification. Amongst all of the AEC-Q200 requirements, the most challenging one for polymer tantalum capacitors with traditional technology is the highly accelerated test under 85 °C / 85% relative humidity (RH) with DC bias up to rated voltage for 1000 hours.
Other industries such as telecommunication are also starting to request 85 °C / 85% RH qualification. A possible reason is an extrapolation based on data from other components that any device passing the 85 °C / 85% RH condition for 1000 hours could have field use life for 5 to 10 years under the real-life environmental conditions.
In this paper, the basic construction and manufacturing process of polymer Ta capacitors is first described. The challenges for polymer Ta capacitors under unbiased and biased high temperature and high humidity conditions will be discussed. This will be followed by possible technical solutions and the performance of our current Polymer Electrolytic T598 series of products.