Failure of Polymer Aluminum Electrolytic Capacitors Under Elevated Temperature Humidity Environments

Polymer aluminum (PA) electrolytic capacitors have solid conductive polymers as electrolyte. Reliability of polymer capacitors at elevated temperature humidity is not well understood. Elevated temperature-humidity testing was performed on PEDOT PA electrolytic capacitors by two manufacturers, Nichicon and Nippon Chemi-Con. Both the companies are among the top suppliers of aluminum electrolytic capacitors worldwide. Two different dominant failure modes of increase in equivalent series resistance and increase in leakage current (LC) were found in the PA capacitors from the two different capacitor manufacturers. The capacitance value of the polymer capacitors remained stable during the test. In the subsequent analysis, a new failure mechanism that has not been previously reported in the literature was found that leads to the high LC failure of PA electrolytic capacitors. The criteria for evaluation for this new failure mechanism should be included during the part and manufacturer selection process.