Variability of impact life and reliability assessment of electronic packages

The study aims to predict the life and assess the reliability of electronic packages subject to multiple drop-impacts. Engineers used to adopt mechanics analysis as well as a certain life prediction model to predict the impact life of the package, and it is usually a deterministic value. However, drop test results show that the impact life of the package is not a single deterministic value but scatters to a certain extent. To cope with the discrepancy, some parameters involved in the finite element analysis and life prediction analysis should be considered as random variables. First, the solder-ball diameter is modeled as a random variable. Its effect on the random impact life prediction and quantitative reliability assessment of the package is investigated and discussed through statistical analysis. Secondly, parameters in the life prediction model are modeled as random variables. Their effects on variability of the impact life are investigated and discussed through both analytical derivation and simulations. Our research results reveal that randomness of solder-ball diameter and parameters of the electronic package do affect the life distribution and reliability of the package to a certain degree.