Abstract
Microorganisms and their products may be responsible for deterioration in electrochemical properties of polymeric materials. We investigated the microbial degradation of polyimides used as insulators in electronic packaging. Growth of common microorganisms on these polymers was found to result in loss of their dielectric properties. Failure of polyimide films caused by microbial degradation was evaluated with a fungal consortium tentatively identified as Aspergillus versicolor and a Chaetomium spp. We obtained distinctive electrochemical impedance spectroscopic (EIS) spectra showing failure of the insulating properties of the polyimides in the presence of the fungal consortium. A decrease of film resistance by more than two orders of magnitude relative to the uninoculated controls was observed within one week of incubation. The relationship between changes of impedance spectra and microbial degradation of the coatings was further established by scanning electron microscopic (SEM) observations of fungi on the surface of the polyimides from the failed EIS cells. Our data suggest that polyimides used in electronic packaging are susceptible to degradation by environmentally ubiquitous fungi.
