Development of failure assessment methodology for lead-free electronic assembly

Abstract

The function and reliability of electronic product are very important concerns for customers and product users. Hence, methods to improve and predict the service life of electronic products are significant challenges for ongoing research on design for reliability. Lead-free solders will replace tin-lead solders in electronic products due to European Union laws to restrict the use of lead (Pb) by July 1 st , 2006. Solder is the weakest link material in electronic assemblies and failures are often caused by solder joint failures. In this study, reliability test and analysis methodology for lead-free (Pb-free) soldered assemblies subjected to thermal cycling, cyclic bend, drop impact and vibration loadings are investigated. Finite element analysis (FEA) is used as a numerical modeling tool for simulating solder micro-deformation and integrated with solder fatigue failure analysis assessment. In this project, a failure assessment methodology for modeling Pb-free (and Pb-based) soldered assemblies is proposed. A global-local submodeling finite element analysis technique is developed and compared with full 3D model results. The global-local FEA technique reduces computational effort and resources significantly (i.e. hard disk space, memory, and computational time). The global-local submodeling method results in good agreement with full 3D model results. A global-local beam (GLB) method is proposed for approximate application for vibration analysis. The global-local modeling technique is applied on reliability issue when electronic assembly subjected to different loadings such as thermal cycling, cyclic bending, drop impact and vibration.