Modeling Solder Joint Fatigue Life for Gullwing Leaded Packages: Part I—Elastic Plastic Stress Model

Abstract

It is a challenge to assess solder joint fatigue life in the modern electronics industry because of complex geometries, complex non-linear viscoplastic material properties, and the frequently changing environmental conditions. The first step in the fatigue life assessment process is to find the stress distribution in the solder. Traditionally, this has been done using numerical tools like finite element methods. The finite element approach requires a highly trained and experienced analyst and huge computing resources, while the accuracy is always questioned. This study aims to develop a more accurate analytical-cum-empirical model to predict critical stresses in the solder joint so as to avoid the necessity of finite element simulation. This paper presents a generic elastic-plastic stress model that is obtained based on theoretical stress analysis solutions that is tweaked by using a design of experiments technique with FEA simulations.