Failure analysis of aluminum electrolytic capacitors based on electrical and physicochemical characterizations

Because of their temperature sensitivity, investigation of thermal effects on electrolytic aluminum capacitors is required using ageing tests. In general, a reliability assessment methodology for these components is carried out during ageing tests, which reports dimensions and weight characterizations, electrical parameter measurement (capacitance and equivalents series resistance (ESR)) and identification of electrolyte's chemical components. However, this chemical analysis typically focuses on the main solvent and salts, without considering the percentage of the other substructures. In this paper, physical characteristics and capacitance has slightly changed according to test's severity unlike ESR which remained constant. Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy was performed, giving information about electrolyte's composition and percentage of identified substructures based on integral calculation of corresponding peaks in the resulting spectrum. The results show that the percentage of some electrolyte's substructures has outstandingly changed for all aged capacitors compared to unaged electrolyte, but not necessarily in the same way. The interpretation of the chemical variation and its influence on physical and electrical characteristics are presented, describing the relationship between mechanisms and modes of failures.