FEA of electronic encapsulation with moldflow

The knowledge of stress transfer on microsystems during polymer packaging is fundamental for the prediction of the overall part quality during field service. Small changes of machine parameters during procuction can have a significant effect on pre-stress of the part. Therefore the gap between simulation of the encapsulation process and of the thermo-mechanical reliability has to be closed. A new approach is the simulation of physical parameters arising from polymer encapsulation processes in moldflow and their handing over to ANSYS and its thermo-mechanical FEA capabilities. By this it is possible to supply important geometrical and material information during encapsulation like pre-stress and warpage of the part. Especially the spacial variation of orthotropic material parameters like Youngs modulus, Poissons ratio and CTE can be predicted. The knowledge of the variation of orthotropic material parameters within the plastic part and of the initial load could improve the thermo-mechanical reliability estimation significantly. The pre-condition is a link between molding and thermo-mechanical simulation as it is offered by Moldflow and ANSYS recently. The closed simulation circle from production to reliability will consist of the following steps: 1. Numerical analysis of filling process with Moldflow: Localisation and movement of air traps and weld lines, core shift of part inserts 2. Warpage, pressure and stress distribution inside the part during encapsulation, pressure phase and during cooling down from mold to ambient temperature 3. Spacial anisotropy of material parameters: Fiber orientation, local changes of Youngs modulus and coefficient of thermal expansion 4 Thermo-mechanical simulation of reliability within ANSYS.