Anshul Shrivastava1, Michael Azarian1, and Michael Pecht1
1 CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
Aluminum electrolytic capacitors with polymer
electrolytes were developed to obtain lower equivalent
series resistance (ESR) than that is achievable with liquid
electrolytes. Replacement of the liquid electrolyte with a
solid conductive polymer also overcomes the propensity of
the liquid to evaporate over time, which leads to a reduction
in capacitance and an increase in ESR values.
However, capacitor manufacturers acknowledge that
humidity can degrade the polymer, thereby having an
adverse effect on the reliability of polymer aluminum (PA)
capacitors. In the current study, surface mount and thruhole
PA capacitors from two different manufacturers were
subjected to highly accelerated stress testing (110C, 85%
RH) and elevated temperature–humidity (85C, 85% RH)
conditions for rapid assessment. The polymer electrolyte
in the capacitors was poly(3,4-ethylenedioxythiophene).
Failure analysis was performed to determine the observed
failure modes and the underlying failure mechanisms. The
dominant failure modes observed were an increase in
leakage current and an increase in ESR.