Multi-domain analysis of PBGA solder joints for structural design optimization

This paper describes the use of stress and strain analysis to accurately predict solder joint fatigue life of plastic ball grid array (PBGA) components under cyclic thermal loading conditions. The finite element analysis (FEA) involved the complete physical make-up of the assembly, including the die adhesive of a typical "off-the-shelf'' PBGA component. By choosing the appropriate size of the assembly in the multi-domain analysis approach, a considerable saving in computational time was achieved for comparable accuracy to the finite element model (FEM). Three solder ball geometries were selected for the multi-domain models based on different assembly techniques. The strain range of the PBGA solder balls with different geometry under thermomechanical loading were computed and then converted into cycle life through the Coffin-Manson fatigue-life relationship. Experimental assessment of PBGA life cycle using thermochambers is planned to validate the analytical predictions prior to simulating newly designed PBGA solder joint configurations.