We discovered and mathematically proved that a partitioning problem under timing and capacity constraints can be formulated exactly as a Quadratic Boolean Programming Problem. This new formulation allows arbitrary component sizes arbitrary capacities of partitions, arbitrary interconnection costs and delay models between partitions. We then found a generalization/enhancement of Burkard's heuristic to efficiently solve the problem. Seven industrial circuits were used to compare our method against two other heuristics based on the traditional approach of component interchanges. Tests results showed the superiority of our new method in terms of both solution quality and CPU usage, for problems under very tight Timing and Capacity Constraints.