Thermo-setting polymers are widely used as underfill materials to improve the reliability of electronic packages. In the design phase, the influence of underfill applications on reliability is often judged through thermal and mechanical simulations, under assumed operating conditions. Because of lacking insight into the mechanical processes due to polymer curing, the impact of processing induced residual stress fields is often neglected. To investigate the evolution of stress and strain fields during the curing process it is important to assume a more appropriate starting point for subsequent process modeling. Furthermore, study of possible damage originating from the fabrication process then comes within reach. To facilitate future analysis of stress and strain fields during the curing process a cure dependent constitutive relation is assumed. An approximate investigation method for the process-dependent mechanical properties, based on Dynamic Mechanic Analysis (DMA), is developed. As an illustration the parameter identification is performed for a selected epoxy resin.

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Moulding compounds are used as encapsulation materials for electronic components. Their task is to protect the components from mechanical shocks and environmental effects such as moisture. Moulding compounds are epoxy resins filled with inorganic (silica) particles, carbon black and processing aids. They shows a clear viscoelastic behaviour which is not only temperature but also cure dependent. Due to both thermal and reaction shrinkage moulding compounds introduce residual stresses which may eventually result in product failure.Therefore they can be considered as key materials for the overall thermomechanical reliability. This paper deals with the characterization and modeling of the mechanical behaviour of such moulding compound. The focus will be on the effects of the degree of cure and the filler concentration.