Stress-strain analysis of double-bump solder joints under temperature cycling loading using finite element modeling

The way of stacking solder joint can increase the standoff height of the solder joint, thus improving the fatigue lifetime of solder joints under thermal cycling conditions. Double layer solder joint PBGA package finite element model was established by general-purpose finite element software ANSYS to simulate the stress-strain of solder joints under the thermal cycling loading condition. Base on the results of FE analysis, the thermal fatigue lifetime of solder joint is calculated by the modified M-C equation. The results of study show that larger stress and strain concentration at the PCB under the package; at the starting time of low temperature the stress reaches to the largest, the value is 69.5Mpa; and at the ending time of low temperature the plastic strain reaches to the largest, the value is 0.022151; the stress-strain response changes with the temperature loading curve; the outmost solder joint is the critical one. Base on the stress-strain curve, the thermal fatigue lifetime of double-bump solder joint is 2161.02 cycles.