Durability of Lead-Free Solder Interconnections for Printed Circuit Board Applications: Comparing Energy-Based Thermo-Mechanical Fatigue Models

Abstract

Fatigue models for predicting the cycles to failure of solder interconnections under temperature cycling situations have been discussed and developed for decades. However, most models were developed for different solder materials, components, and printed circuit boards. No previous work has systematically compared these models. Therefore, the variability of their durability predictions is unknown. This study compared nine existing low-cycle energy-based fatigue models for different solder materials and components and then analyzed the differences among them. Each fatigue model had a specific combination of the factors that affect the strain energy density accumulation. Therefore, we adjusted the strain energy density (input) and the predicted cycles to failure (output) in a consistent way to compare the selected fatigue models on the same basis. The differences among the predictions on cycles to failure from the fatigue models was significantly reduced after applying the adjustments, and they exhibited excellent consistency around 1 mJ/mm 3 strain energy density. In the end, factors that can affect the prediction consistency of fatigue mode were provided, including the number of data points while building the fatigue model, the range of strain energy density while selecting the electronic components, and the application of volume-weighted averaging technique on the critical solder joint.