Modeling solder joint reliability of VFBGA packages under board level drop test based on dynamic constitutive relation with thermal effect

In this paper, according to the condition B in the drop test standard of JEDEC, create 3D finite element model of VFBGA (very-thin-profile fine-pitch BGA) packages in drop and impact, the material model of solder joints can be indicated by Cowper-Symonds model obtained from experiment data, taking into the consideration of strain rate and temperature effect. Comparing with traditional elastic for solder balls, this material model has better correlation with experimental measurement of dynamic strain, PCB center deflection. For conducting reliable analysis of VFBGA packaging in board-level drop condition, impact acceleration curve is applied to numerical simulation in input-G method.