Delamination fracture characteristics for polyimide-related interfaces under fatigue loadings

The fracture responses of interfaces under either monotonic or fatigue loading conditions were investigated by using double cantilever beam (DCB) tests. The tests were performed using a custom-developed micro-tester. The applied load vs. interfacial crack opening relationship obtained from the DCB experiment was analyzed by using a beam on elastic foundation-based closed-form expression for determining the critical strain energy release rate or the fatigue delamination growth rate for the interface of interest. From the analysis the relationship between the crack growth rate and the applied strain energy release rate range was determined. For the polyimide-SiN interface, the subcritical fatigue delamination growth rate was found to display a power-law dependence on the applied strain energy release rate range with an exponent of 3.2.