Many practical routing problems such as BGA, PGA, pin redistribution and test xture routing involve routing with interchangeable pins. These routing problems, especially package layout, are becoming more dicult to do manually due to increasing speed and I/O. Currently, no commercial or university router is available for this task. In this paper, we unify these dierent problems as instances of the Interchangeable Pin Routing (IPR) problem, which is NP-complete. By representing the solution space

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... with ows in a triangulated r outing network instead of grids, we developed a min-cost max-ow heuristic considering only the most important cuts in the design. The heuristic handles multiple layers, prerouted nets, and all-angle, octilinear or rectilinear wiring styles. Experiments show that the heuristic is very eective on most practical examples. It had been used t o r oute industry designs with thousands of interchangeable pins.