The re-balling of BGA components from lead-free to tin-lead solder is a critical requirement by some high-reliability customer applications due to tin-whisker mitigation concerns. This technical paper by Circuit Technology Center discusses the key process steps of this highly specialized process.
See the full paper at: https://www.circuitrework.com/features/1040.html
Circuit Technology Center, founded in 1979, continues to be recognized as the most innovative and reliable specialist in circuit board damage repair, rework, BGA re-balling, and component-level modification services in the world.