BonnCell: Placement of leaf cells in VLSI design The automatic layout of leaf cells in VLSI design requires significantly different algorithms than classical tools for the physical design of VLSI instances. While the number of placement objects in leaf cells is very small, at most a few dozen, the placement constraints are not covered by usual approaches. We present the placement engine of our tool BonnCell, which computes optimal placements for most real-world instances within seconds. Optimality is measured with respect to a target function that models the cell routability and proved to be very accurate in practice