Abstract: In this paper, the homogenization theory and higher orderdiscrete-layer laminate model are applied to the flip-chip electronicpackage assemblies with underfills, with microstructures not completelyperiodic (singlelayer). The effective elastic properties for a laminar with BGA andunderfills are determined by an analytic method. The numerical resultsare comparedwith the previous solutions, which shows the efficiency of the presentmodel and method.