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Simulation based analysis of secondary effects on solder fatigue

: Dudek, R.; Doering, R.; Bombach, C.; Michel, B.


Wymyslowski, A.:
Thermal, mechanical and multi-physics simulation and experiments in micro-electronics and micro-systems, EuroSimE 2008 : Selected papers presented at the 9th international conference, was held in Freiburg-im-Breisgau (Germany) on April 2008
Amsterdam: Elsevier, 2009 (Microelectronics reliability 49.2009, Nr.8)
ISSN: 0026-2714
International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Micro-Electronics and Micro-Systems (EuroSimE) <9, 2008, Freiburg/Brsg.>
Conference Paper, Journal Article
Fraunhofer IZM ()
Fraunhofer ENAS ()

Secondary effects on thermal fatigue of solderjoints, which frequently have been neglected, were studied by means of the finite element method (FEM). Based on a semi-empirical approach to predict fatigue life by evaluating the cyclic accumulated equivalent creep strain or energy density, effects of organic boards intrinsic properties on solder joint fatigue were investigated. Aspects of more realistic FR-4 board modelling were studied, in particular concerning its in-plane anisotropy and intrinsic warpage behaviour. Intrinsic board warpage was measured on test board level as well as for boards from series production. High intrinsic warpage was in particular found for several test boards. The effects for the worst case scenario observed so far were analysed for both first level and second level interconnects. The change in predicted fatigue life varied between 30% and 500%, the latter most critical effects were found at large QFN components. Another secondary effect studied was to include the frequently neglected interfacial intermetallics into FEM. It turned out that for components with relatively large standoff like LFBGAs the effects were actually negligible, but for the highly miniaturized components like chip resistors CR0201 they are the decisive factor.