The reliability of microelectronic devices containing multilayer structures is profoundly influenced by the interfacial strength (adhesion) and resistance to fracture (debonding) of the many resulting bimaterial interfaces. Adhesion and consequent structural integrity are closely related to composition and processing conditions which determine key interfacial parameters, such as interfacial impurities, morphology and adjoining microstructures. Residual stresses, thermo-mechanical cycling and mechanical loading may drive time dependent fracture in these multilayer interconnect structures. Moisture present in the atmosphere and perhaps moisture present in the layers themselves can lead to premature failure and reduced lifetimes of these devices. We present unique data showing the effects of interface non-planarity on the interface fracture energy and the time-dependent delamination processes. Data is presented showing the effects of the phase angle of loading on the interface fracture energy and subcritical debonding processes. Behavior is rationalized in terms of the salient chemical reaction rate occurring at the debond tip. Implications for life prediction of devices are discussed.