Hybrid-simulation of degradation in high density power electronics packaging

High current density and high temperature gradient are major reliability concern for next generation power electronics. High current density experiments on lead free solder joints coated with NiAu and non-coated Cu pads were conducted at -20°C, -30°C, -40°C and -50°C ambient temperatures. The time to failure (TTF) shows that solder joints with NiAu coated Cu pads last longer. Results also indicates TTF plot shows that TTF rate increases exponentially when the solder joint temperature is higher than 64% of its melting temperature, and decreases exponentially reaching the maximum lifetime when the temperature is below this threshold temperature. The mass transport activation energy, E^a was determined using the test data and it was found to be 2.67 ± 0.05 eV and 3.65 ± 0.13 eV for coated and noncoated solder joints, respectively. These values are indicative of the dominant diffusion mechanism during the experiment. It was discovered that the thermomigration driving force was as high as electromigration driving force. A hybrid method of testing and simulations were used to obtain the material properties and degradation in the system.