Failure of electronic devices due to condensation

The increasing usage of electronic devices and the progressive trend of miniaturisation in automotive applications require different installation locations. According to varying locations, different climate conditions will occur. In this article, the influence of condensation on the reliability of electronic devices is examined. For the detection of failures or the loss of functionality it is essential to determine the occurrence of condensation. A new microsensor based on the CCC-principle (condensate controlled capacitance) allows the measurement of the condensed water mass directly. Depending on the gaps of special designed stray field capacity in combination with a water drop sensitive detection system, a change of the capacity with increasing water mass is shown. It is necessary to analyse failure mechanisms like corrosion induced leakage currents and electrochemical migration. For the research of these failure mechanisms special test patterns were designed and assembled. These samples were exposed to a certain climate profile, which produces a reproducible and defined amount of condensation, this can occur in certain locations in automotives. On the bases of these test patterns, which consist of both combs with different spaces and chip capacities with variable sizes, diverse influences were examined. Beside field strength also the surface metallisation and the cleanliness of the samples were investigated and quantified.