THERMOMECHANICAL RESPONSE OF MATERIALS AND INTERFACES IN ELECTRONIC PACKAGING - PART-II - UNIFIED CONSTITUTIVE MODELS, VALIDATION, AND DESIGN

The constitutive modeling approach based on the disturbed state concep t (DSC) described in Part I, provides a unified basis for the characte rization of thermomechanical response of materials and joints in elect ronic chip-substrate systems. Using the material constants given in Pa rt I, the DSC model predictions, obtained by integrating the increment al constitutive equations, are shown here to provide satisfactory back predictions of stress-strain, fatigue, and failure responses of typica l solder materials. The DSC also provides a simple criterion based on the critical disturbance to identify cyclic fatigue failure. Model pre dictions show good correlation with those from previous models. It is also shown how the DSC model can be used for design applications. Over all, based on Papers I and II, it can be stated that the DSC can provi de a new and powerful means to characterize the thermomechanical behav ior of materials and joints in a number of problems in electronic pack aging.