A hybrid 3D thermo-elastic infinite element modeling for area-array package solder joints

In this paper, we present a 3D thermo-elastic infinite element methodology (IEM) for modeling solder joints in area-array packaging. We also propose a new concept which involves converting the IEM into an infinite element (IE). The special element is formulated based on the conventional finite element method (FEM) using the similarity property of stiffness in isoparametric elements and matrix condensation operations. We developed an IE-FE coupling scheme and implemented it using the commercial finite element software ABAQUS so that a complete elastostatic analysis can be conducted. This study investigated out-of-plane thermal deformation (warpage) and its effect on thermal stress distribution in the solder joints of multi-chip module (MCM) BGA assemblies. The proposed model was able to simulate a large number of solder joints for efficient computations. The most susceptible solder joints were identified and replaced by 3D finite element models for thermal elastic-plastic re-analysis. Two types of MCM BGA assemblies with symmetrical and non-symmetrical area-array solder joints are studied. (C) 2004 Elsevier B.V. All rights reserved.