Validating Reduced Order Model for Solder Reliability of Leadless Ceramic Chip Component during Temperature Cycling

Solder fatigue failure of electronics is a widespread problem, especially when the field conditions involve temperature excursions either as power cycling or diurnal cycling. The finite element method for predicting cycles to failure using damage indicators such as inelastic strain range or creep strain energy density is by far one of the most accurate methods to get detailed insights into solder reliability of electronic components. However, running detailed analysis for all the components on the board to get a realistic prediction is computationally heavy and to an extent impractical. As a first pass filter having a reliable reduced order model for predicting solder failure becomes essential. Engelmaier model is one of the most used reduced- order models for predicting solder fatigue failure of electronics due to temperature cycling. The model is based on inelastic strain as damage indicator which then gets used in Coffin-Manson power law for solder failure prediction. The prediction model is tuned based on experimental results from Wild to account for temperature and dwell time. In this paper, Blattau’s model for ceramic chip components is evaluated against experimental data. The model calculates stress on the solder joint and uses Morrow’s strain energy model for life prediction. The temperature range and dwell time effect are accounted by adjusting strain range due to global coefficient of thermal expansion (CTE) mismatch between the package and the printed circuit board (PCB) using Norris-Landzberg model. 2512 and 1206 chip resistors were subjected to thermal cycling at four temperature conditions: (1) -40oC to 125oC, (2) -15oC to 125oC, (3) 10oC to 125oC, and (4) 35oC to 125oC. Resistance was monitored during cycling and 50% increase in resistance was considered a complete failure. The model shows excellent fit with experimental data.