Thermo-mechanical FE analysis and micro deformation measurements-basis for reliability assessment of microelectronic components

The design process of advanced electronic components and assemblies includes not only electrical aspects but also thermal and mechanical influences due to loadings which may occur throughout the whole lifetime. It is the aim of this paper to indicate the advantages of a combined numerical and experimental approach in order to determine the deformation behaviour and stress distributions as a base for reliability assessment in plastic packaging. The paper discusses how stress and deformation concentrations depend on special geometry and on material properties. Using the finite element method, it is often possible to investigate the thermal and thermo-mechanical behaviour of electronic assemblies using the same discretization. Computational series can be carried out by varying selected parameters, loading or boundary conditions. It is possible to determine sensitivities due to special inputs and to decide whether a modeled detail is essential or negligible. In addition, a special methodology also allows modification of the geometry without any topology changes. Wherever possible, computations should be combined with corresponding measurements. The authors prefer laser optical methods combined with careful metallographic preparation of objects in the micro region. The method is less time consuming as it takes advantage of current image processing techniques combined with numerical simulation tools which provide advanced reliability assessment.