Routability-driven RDL routing with pin reassignment

Due to the infeasible pre-assignment of IO connections in a flip-chip design, all the published RDL routers cannot guarantee 100% routability for the pre-assigned IO connections. In this paper, based on two swapping processes for pin reassignment, the unroutable conditions in a flip-chip design can be eliminated. Furthermore, by using the assignment of routability-driven transfer and boundary pins, a given set of pre-assigned IO connections between the wire-bonding pads and the bump balls can be completely routed to minimize the total wirelength with 100% routability in a flip-chip design.