The influence of the operating mode of IC-devices on their lifetime: a reliability test of plastic encapsulated CMOS-circuits in a humid environment

An investigation of the way in which voltage applied to components during an accelerated humidity test influence the test lifetime of these components is discussed. A humidity test in which plastic-encapsulated CMOS circuits were aged in an environment of 130°C and 85% RH was performed. The components were divided into groups with different voltage conditions. The applied voltage was either pure supply voltage, which does not give rise to any significant power dissipation, or a voltage condition that causes a power dissipation of 30 mW. The first of these voltage conditions is the most common way to bias CMOS components being tested in a pressure cooker, whereas the second one is similar to real operating conditions. The voltage condition of the components in the different groups were altered in time between the two conditions in a pattern specific for each group, so that an intermittent operating mode was obtained. The humidity test indicated that the test lifetime differed among the groups. A group that was operated intermittently showed the highest number of failed components