Methodology for predicting solder joint reliability in semiconductor packages

A new experimental method for detecting solder joint strain in package assemblies using digital image correlation metrology has been developed. A new methodology is proposed which utilizes strain data generated by this technique for predicting solder joint fatigue life for any desired package configuration based on a reference configuration. This approach has significant practical appeal since it obviates brute-force temperature cycle testing for the qualification of every new variation of an existing package configuration. In this paper, we describe the principle, experimental set-up and sample preparation techniques for this method. We present typical strain data on solder joints for a ball grid array (BGA) package mounted to a FR4 PC board. We apply the technique to the prediction of temperature cycling reliability of a Ceramic BGA package wherein, the effect of a new substrate material is examined and the predictions are confirmed based on empirical temperature cycle testing data. Finally, we show a co-relation of measured strain data with computations by finite element modeling performed for a specific package configuration.