Effects of die coatings, mold compounds and test conditions on temperature cycling failures

When a plastic package is subjected to repeated thermal excursions such as during thermal cycling or thermal shock, progressive damage to the silicon die occurs. Damage can be initiated in the form of interfacial delamination accompanied by passivation cracking, and subsequently, by dielectric fracture that may ultimately lead to device failure. The extent of damage depends on the interaction between the various components in the package. In this study, thermal cycling of PLCC packages indicated that the die design configuration, the nature of the coating and its thickness, the formulation of the molding compound, the preconditioning of the packages, and the thermal excursion conditions all govern the electrical failure rates observed. Thus, careful selection of the proper combination of parameters can offer improved device reliability