Mechanical reliability estimation for μBGA solder joints based on heating factor Qη

A novel method of mechanical reliability analysis on vibration fatigue failure of muBGA solder joints, based on the heating factor Q_eta, is introduced. Firstly, a two-parameter weibull distribution is used to model the collected data of vibration fatigue lifetime for different Q_eta. After that, two explicit functions are deduced in a unified mathematic expression form, which give an intuitionistic description of the MTTF and reliability of solder joints against induced variable Q_eta, thus revealing definitely the effect of Q_eta on the mechanical fatigue lifetime of solder joints suffering from cyclic vibration loading. Numerical analysis and calculation are performed. The results show that the solder joints reflowed at Q_eta near 500 have higher reliable, and those reflowed farther away this optimal process parameter have less reliability.