Impact of Crack Evolution in Solder Balls on Thermoelectric Model Under Electrical Stress

Current thermoelectric models under electrical stress often neglect the critical impact of crack formation, limiting their predictive accuracy for solder ball reliability. To study the impact of cracks under electrical stress conditions, this study designed an electrical stress-induced failure experiment, applying stepwise current loading to the devices under tests (DUTs) to obtain resistance-time curves, with computed tomography (CT) revealing cracks in the solder balls. Based on these experimental results, a thermoelectric coupling model was developed to predict the temperature-resistance relationship of heterogeneous interconnect structures, incorporating crack factors observed during the experiment. The thermoelectric coupling model demonstrated high accuracy, achieving a maximum error of less than 2.5%. By incorporating the effects of crack formation under high electrical stress, the model provides precise predictions of solder ball resistance evolution.