A study on the compatibility and service life of aluminium capacitors and synthetic coolants

Driven by surging power densities in data centres, immersion cooling is critical for high-heat-flux dissipation. However, despite their widespread use in data centres, there remains a lack of research into the compatibility of surface-mount aluminium electrolytic capacitors with coolants. This study evaluates the reliability of conductive polymer capacitors in synthetic oil through accelerated ageing tests at 70 °C, 80 °C, and 100 °C. Results identify butyl rubber swelling as the primary failure mode, causing structural deformation that precludes circuit assembly, rather than electrical drift. This degradation is driven by coolant molecules infiltrating the rubber matrix, inducing chain extension and reduced thermal stability. Simultaneously, poly(3,4-ethylenedioxythiophene) (PEDOT) de-doping increases the equivalent series resistance. Based on the Arrhenius model, the swelling-induced failure yields an activation energy of 43.7 kJ/mol, predicting a time to structural failure of approximately 492 days at 50 °C. These findings elucidate the physicochemical interactions between components and coolants, providing a theoretical framework for reliability design in immersion-cooled systems.