Reliability of BGA solder joints after re-balling process

Due to the obsolescence of SnPb BGA components, electronics manufacturers that use SnPb solder paste either have to use lead-free BGAs and adjust the reflow process or re-ball these components with SnPb balls. The reliability of Lead-Free and Lead-Containing solder joints for BGA's has been investigated after re-balling using optimal microscopy. The goal was to compare the quality of the connections for both options. For the lead-free BGA, voids produced by the release of volatile species in flux during soldering were present. Large voids have been observed at the interface component/solder. Using components that were re-balled did not show the amount of voiding observed for the lead-free BGA. Kirkendall voiding has been observed for the lead-free component at the component/solder interface. It has been therefore concluded that the use of the reballed components is to be preferred to adjusting the reflow profile and using lead-free components