Microscopic deformation field measurement suporting FEA based reliability analysis in electronic packaging

摘要

A strong need exists to accompany finite element simulations by strain and stress measurements on real components to ensure appropriate modeling. Because of the small scale of objects and the requried field data only a few methods are available for that purpose. One approach is image correlation on digital micrographs. It allows to determine strain fields at the surface of loaded objects. The paper reports the application of the corresponding microDAC tools developed at the IZM Berlin to electronics packaging problems. It highlights the influence of polymeric materials on the thermomechanical behavior of area array interconnects as used in flip chip and chip scale packaging technology. Comparison between simulation and measurement results makes sure that mechanical modeling for FEA has been performed adequately. Concurrently, possible weak points of finite element modeling not taking into consideration real package constitution are demonstrated. So, neglecting inner defects at interfaces or detailed components structures, e.g., the glass fabrics in laminate PWB materials, simulation results may not reflect the real package deformation.