Routability driven modification method of monotonic via assignment for 2-layer Ball Grid Array packages

Abstract

Ball grid array packages in which I/O pins are arranged in a grid array pattern realize a number of connections between chips and a printed circuit board, but it takes much time in manual routing. We propose a fast routing method for 2-layer ball grid array packages to support designers. Our method distributes wires evenly on top layer and increases completion ratio of nets by improving via assignment iteratively.