Accelerated temperature and voltage life tests on aluminium electrolytic capacitors: A DOE approach

Purpose - The purpose of this paper is to focus on conducting accelerated life tests on aluminium electrolytic capacitors under accelerated temperature and voltage stress to study the effect of applied voltage and ambient temperature on the capacitor, its degradation over time, failure data collection, analysis and then modelling the failure times. Principles of DOE are used for studying the effect of temperature and voltage. Design/methodology/approach - Life tests are conducted at three levels of temperature and applied voltage and the life of capacitor is ascertained at each treatment level. Life variation with voltage and temperature is studied to gain an insight as to how these factors affect the lifetime of the capacitor. The interaction effect of temperature and voltage on capacitor life is also established. Findings - The life of the capacitor decreases exponentially with temperature and voltage at all the three factor levels. Ambient temperature, applied voltage and their interaction effect significantly affects the life of the capacitor. Applied voltage has the greatest effect followed by ambient temperature and then their interaction effect. Life of the capacitor has been estimated as 4,206 hrs when only voltage is taken as the accelerated stress using Inverse Power Law and as 4,003 hrs when both temperature and voltage are taken as accelerating stress using combination model. Research limitations/implications - This work consider only decrease in capacitance as the failure criterion. However, as a future scope, it is proposed that test may be conducted by taking into consideration not only the decrease in capacitance as the failure criteria but by monitoring all the performance parameters of the capacitor. This would give a more realistic assessment of life as it is possible that capacitor may have failed much before it reached the lower threshold capacitance value. Practical implications - This work has lots of practical implications. It shows how DOE approach can be used for ALT data analysis and identification and effect of critical stresses acting on capacitors in real practice. Most critical types of stresses affecting the reliability can thus be controlled to ensure better performance. Product manufactures as well as users will be benefited by such findings. The paper has also illustrated how failure data can generated by degradation analysis using life test data collection at discrete intervals. Originality/value - The methodology presen