Photoelastic and numerical investigation of thermally-induced restrained shrinkage stresses in plastics.

High stresses developed within plastic encapsulated microelectronic devices can compromise device reliability. The seriousness of this problem has intensified in recent years with the accelerating trend toward encapsulating larger chips within smaller packages. While many workers have attempted to predict the distribution of such stresses in a variety of package designs processed under a variety of molding conditions, as a rule, they have been able to predict only the relative levels of these stresses but not the absolute magnitude. In addition, very little experimental evidence exists to support current methods for predicting the level of stress developed within encapsulation materials.