Thermal Stress Analysis of Pin Grid Array Structures: Pin and Solder Joint Problems

Abstract

The role of the solder joint as an elastic foundation is investigated first for structural analysis of the pin. Failure mechanisms are discussed. For various pin cross sections, guidelines for computing the foundation constant by analytical and finite element methods are established. Exact expression are derived for the pin stress. The solder stress (radial pressure or tension) is found by an approximate contact analysis. Elasto-plastic pin analysis, for excessive thermal mismatch, is effected by an iterative method. The variation of the plastic domain is examined for various size and material parameters. Axial forces in the presence and absence of pin plasticity are investigated, and the overall effect on the PGA is discussed.