Disclosed are methods, systems, and articles of manufactures for implementing physical design decomposition with custom conductivity by identifying custom, incomplete conductivity for an electronic design, partitioning a physical design space multiple non-overlapping cells, and iteratively moving at least some of the nodes of these multiple cells to generate a floorplan or a placement layout until one or more convergence criteria are satisfied while maintaining the custom, incomplete conductivity. The floorplan or a placement layout generated resembles the final floorplan obtained through a floorplanner or the final placement layout through a placement tool without requiring that complete conductivity information be provided to the floorplanner or placement tool.