A Fast Four-Via Multilayer MCM Router

In this paper, we present an efficient multilayer general area router, named V4, for MCM and dense PCB designs. The unique feature of the V4 router is that it uses no more than four vias to route every net and yet produces high quality routing solutions. A number of combinatorial optimization techniques are used in the V4 router to produce high quality routing solutions in polynomial time. As a result, the V4 router is independent of net ordering, runs much faster, and has far less memory requirement compared to other multilayer general area routers. We tested our router on several examples, including two industrial MCM designs from MCC. Compared with the 3D maze router, on average the V4 router uses 2% less wirelength, 31% fewer vias, and runs 26 times faster. Compared with the SLICE router, on average the V4 router uses 4% less wirelength and runs 4.6 times faster.