Pad minimization for planar routing of multiple power nets

The problem of minimizing the number of power pads, in order to guarantee the existence of a planar routing of multiple power nets, is discussed. A general lower bound is derived, and a heuristic for the general problem is discussed. Several important special cases, including the case of three power nets, are examined, and optimal strategies for pad placement are presented. It is also shown that the general pad minimization problem is NP-complete. >