Solder joint fatigue models : review and applicability to chip scale packages

A review of fourteen solder joint fatigue models is presented here with an emphasis on summarizing the features and applications of each fatigue model. The models are classi®ed into ®ve categories: stress-based, plastic strainbased, creep strain-based, energy-based, and damage-based. Fatigue models falling outside these categories are categorized as `other empirical models'. Each model is presented under one category with the relevant parameters and applicable packages. Following each category, common issues such as thermal cycling conditions, solder joint geometry, and coverage are addressed. Two fatigue model application scenarios are discussed. In the ®rst scenario, a set of existing fatigue test data is given to the engineer who must determine how best to interpret the data and which fatigue model(s) best apply. In the second scenario, a test scheme must be devised for a new chip scale package product. The number of cycles to failure (Nf) or fatigue life must be determined. A general procedure is presented for choosing an appropriate fatigue model(s) based on the package conditions and limited Finite Element Analysis time. This procedure is summarized in a ̄owchart. # 2000 Elsevier Science Ltd. All rights reserved.