<p>The increasing electrified mobility poses a challenge on reliability prediction of automotive electronics, especially when safety systems are concerned. The use of finite element simulation for accurate end of life prediction of automotive electronic devices under harsh environmental loading condition is getting more significant. In particular, solder interconnection failure is in focus when subjected to thermomechanical loads. During cyclic loading, the initial state deformation behavior and subsequent solder degradation can be modeled within finite element simulation using material damage coupled deformation models. Such models employ the calculation of internal damage state variable at integration point level as functions of time, temperature and governing stress-strain state.<br>
In this work, a thermodynamic consistent implicit nonlocal damage formulation is presented. This modeling approach allows absolute end of life prediction of different solder joint geometries under thermomechanical cyclic loading within finite element simulation. The presented nonlocal damage model consists of damage evolution with strain and stress state dependencies, such as stress multiaxiality. Furthermore, a numerical delocalization algorithm is proposed, in order to avoid instability of damage evolution caused by finite element mesh dependency. Finally, the advantages and implications of the nonlocal damage approach are discussed based on simulation of nonlocal damage evolution in a oldered QFN48 package on PCB under combined cyclic thermal and mechanical 4-point bending loading.</p>

Nonlocal Damage Modeling of Solder Joint Failure Under Thermomechanical Cyclic Loading

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2021/volume/85505

ASME 2021 International Electronic Packaging Technical Conference and Exhibition (InterPACK2021)

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