Reliability of plastic-encapsulated integrated circuits in moisture environments

Some of the factors affecting the reliability of plastic-encapsulated integrated circuits (ICs) in moist environments are discussed. Particular attention is given to the moisture related failure mechanism EMA (electrolytic metal attack). Three types of EMA were identified in a series of experiments: galvanic cell corrosion; concentration cell corrosion; and ionic cell corrosion. In addition to EMA, the interaction of moisture with chlorides in hermetic plastic packages is found to be an important cause of IC failure in moist environments. Improved packaging materials and techniques for minimizing the effects of EMA and chloride interaction in the packaging process are described.