Comparative analysis of the fatigue life of the FLASH under joint error conditions

Purpose This study aims to investigate the reliability of solder joints in a NOR Flash device with joint errors under thermal cycling loads. Design/methodology/approach A numerical analysis using the finite element method was conducted in this study. Four different cases were created to examine the stress distribution and fatigue life of the solder joints. For Cases 1 and 3, the bonding size between each pin and pad on the left side is 0.65 mm, while on the right side it is 0.35 mm. Conversely, for Cases 2 and 4, the right bonding size is 0.35 mm and the left is 0.65 mm. To strengthen the device, epoxy resin was applied to both sides of FLASH in Cases 3 and 4. Findings The results show that Cases 1, 2 and 4 exhibit significant variations in high-low cyclic thermal stress, which have a more detrimental effect on fatigue life. The thermal cycling life of the left solder joints for Case-4 is 4,757 cycles, which is significantly lower than that of the other cases. In addition, the PCB mounting holes and epoxy provide indirect constraints on the solder joints, influencing thermal expansion and fatigue life. These findings can assist in failure analysis of specific Flash devices. Practical implications These findings obtained in this work can assist in the failure analysis of specific Flash devices. Originality/value Limited studies exist on the stress distribution and fatigue life of solder joints with joint errors under thermal cycling loads. This study used numerical simulations to investigate the impact of joint errors on thermal cyclic life.