Flexible end-products like banking cards and wearable electronics are about to pervade our lives massively. Due to the fact that flexibility is a must, reliability problems are expected due to the mechanical handling loading conditions the end-product is subjected to. This paper presents our effort to predict reliability problems for packages in flexible end-products. Current field returns indicate that mechanical loadings are causing crack failures in dies and packages. Both parametric 2D and 3D Finite Element models are constructed to analyse the impact of such loadings to the stress levels in the constituents. The results gain a better understanding of reliability issues and, where possible, give suggestions for preventing such issues. With the aid of the simulation results mechanical test methodologies can be designed suitable as to insure a given lifetime statement.@en

A multiscale (global-local) numerical method for the assessment of reliability issues in substrates is presented. The method allows for the calculation of accurate local quantities, without the need for heavy calculations. A global step is performed by first subdividing the substrate into cells. Next, the structure (circuit) of each cell is analysed and quantified and, based on the result, appropriate effective properties are assigned. In this way a homogenised finite element model of the substrate is constructed which is used to determine its global response. A local step is subsequently performed, where only a small 'region of interest' of the substrate is modelled in detail. The loading is accomplished by describing boundary conditions extracted from the global simulation.@en