Abstract
Among many factors which influence the reliability of plastic encapsulated semiconductor devices, the most important is the existence of impurities and water vapor in plastic encapsulants and as a consequence their influence has been the subject of several investigators. The work reported in this paper concerns the effect of impurities and water vaper on the reliability of semiconductor devices. At first, the level of impurities and water vapor in plastic encapsulants are described. Then the mechanism of metallization corrosion especially impurities induced electrochemical reaction of aluminum is discussed. Electrical degradation of devices is also described and the correlation between the time to failure of devices and environmental conditions is discussed. The method of protection against the influence of impurities on the degradation of semiconductor devices is shown. Among them, coating the chip with some specific polymers is effective for the reliability improvement of plastic encapsulated semiconductor components.
