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equivalent beam can be obtained by optimization iteration and reduce the time-to-market in the electronic packaging industry. Fatigue life prediction of the solder joint and the overall electronic packaging requires detailed thermal-mechanics and electronic packaging geometry information. A three-dimensional finite ele-ment model is favored in this study since it can more realistically represent physical behavior of BGA packaging @6#. In low cycle fatigue analysis of BGA packaging, full-scaled model with high mesh density in solder joint region could obtain accurate elastic/ plastic stress/strain distribution. However, this model could lead to a finite element mesh up to millions of DOF ~degree of free-dom! and analyzing this model is quite difficult to complete for the substantial computational resource. An alternative approach is the micro-macro numerical tech-nique. The substructure typed micro-macro ~local-global! numeri-cal analysis technique has been developed for years @7#, as a solv-ing procedure for large domain problems of the BGA type packaging applicatio