Boundary element analysis of the stress field at the singularity lines in three-dimensional bonded joints under thermal loading

Abstract

The stress distribution near a point on the stress singularity line of dissimilar materials in three-dimensional joints under thermal loading are investigated using BEM based on Rongved's fundamental solutions. Stress distributions for the material combinations in the singularity region, in the no singularity region, and in the boundary between them on the Dundurs composite plane are investigated. The influences of thermal expansion coefficients, loading conditions and dimensions on the stress distribution in three-dimensional joints composed of two blocks are examined. The stress intensity factors in threedimensional joints under a uniform change in temperature are proportional to the temperature variation, T , and depend on the difference in the thermal expansion coefficients. Furthermore, the level of the stress distributions around the stress singularity lines also increases significantly as the length of one side in the parallel cross section to the interface decreases.

A Study of Chip Top Delamination in Plastic Encapsulated Packages under Temperature Loading

“…Another approach for investigation of crack initiation in semiconductor packages based on the stress singularity analysis at singular points are also often simplified to the 2D space [2], [3], [4] and are suitable for analysis of stress-strain state at 3D edges. Although there exist problem solutions for 3D corners [5], the analysis procedures are much more involving in this case and are not state-of-the-art of modern commercial finite element software which restrains their application to solving practical problems of semiconductor package development. Therefore, the authors chose a fracture mechanics based approach incorporated as a standard procedure in a commercially available finite element software code ABAQUS® and allowing for treatment of the problem without reducing it to the 2D space.…”