Reliability Tests and Stress in Plastic Integrated Circuits

Temperature cycling and pressure cooker environmental tests were performed on integrated strain gauge and metal test structures. Test bars were packaged in different plastic encapsulation materials and under different packaging procedures. For temperature cycling, dramatic differences in build-up and relief of internal stress in silicon bars were found as a function of the packaging conditions selected. Packaging conditions also affected the performance of test structures and actual circuits in pressure cooker. Conclusions for plastic IC reliability are reached, as illustrated by an innovative test structure for simultaneous measurement of stress, leakage and corrosion. In conclusion, modular reliability test bars are discussed in relation to the strategy for reliability prediction.