A Numerical Study of Fatigue Life of J-Leaded Solder Joints Using the Energy Partitioning Approach

Abstract

A surface-mount J-leaded device is modeled in this study, to investigate the effects of selected design, loading and manufacturing variables on solder joint fatigue life. The solder is modeled as a viscoplastic material, while the remaining materials are assumed to be linear elastic, as a first order approximation. Finite element analysis is used to determine the stress and strain history in the solder, due to temperature cycling. A “typical” temperature cycle with uniform dwell periods is applied to the solder joint. The computed stress and strain histories are utilized to construct hysteresis plots at each location in the solder joint. The hysteresis plots are then partitioned into elastic strain energy, plastic work and creep work dissipation. The fatigue life of the solder joint is then estimated through the energy partitioning technique. Parametric studies are conducted to investigate qualitatively the dependence of solder joint fatigue life on selected material properties, geometric variables, life cycle as well as accelerated loads, and manufacturing variabilities.