As technology evolves into the deep sub-micron era, signal integrity problems are growing into a major challenge. An important source of signal integrity problems is the crosstalk noise generated by coupling capacitances between wires. Test vectors that activate and propagate crosstalk noise effects are becoming an essential part of design verification and manufacturing test. However, deriving such vectors is a complex task. In this paper, we propose HyAC, a fast yet accurate hybrid ATPG method targeting multiple-aggressor induced crosstalk errors. Given a victim and a set of aggressors, the proposed ATPG method searches for test vectors to activate and propagate a crosstalk error for the victim. Due to logic constraints, it may not be possible to trigger all aggressors simultaneously. Therefore, firstly we use an implication graph (IG) that consists of logic variables and structural information to check for logic conflicts. If the current set of aggressors is not feasible, our algori...