A Parametric Study of Thermal Stress and Analysis of Creep Strain Under Thermal Cyclic Loading in a Hybrid Quad Flat Package

Abstract

Due to the variation of temperature during service, the leads in quad flat packages (QFP) and plastic leaded chip carrier (PLCC) undergo high thermal stress, which can lead to large deformation and failure. Thus, the prediction of thermal stress and strain distributions is a prerequisite for reliability analysis of such components. Along this line, this work analyzed the performances for gull wing and J-lead with different geometries. The thermal stress and strain distributions of both leads were determined by using the finite-element method (FEM). For each type of the lead, a parametric study was conducted in order to evaluate the effect of lead geometry on stress and strain distributions. Based on the simulation results, an optimum lead design was suggested. In addition, simulation work of package under thermal cyclic loading has been done, accumulated creep strain was found in the critical location of solder in package, and lifetime was predicted.