Abstract
In order to investigate the delamination behavior along the interface between a submicron thick polymer (epoxy) film and substrate (silicon) due to the time-dependence deformation (creep), we develop in-situ observation techniques of the interface crack using a cantilever specimen (Stainless steal/Si/epoxy/glass). Under the unidirectional loading, an interface crack is initiated from the free edge of Si/epoxy and propagates stably along the interface, which leads to the delamination fracture of the specimen. The result of unidirectional loading test with the different loading speed shows the different Si/epoxy delamination behavior. This indicates that the Si/epoxy interface crack propagation depends on the loading speed due to the creep of epoxy thin film. To evaluate the effect of creep on the delamination, the constant loading test is conducted. It is revealed that Si/epoxy interface crack propagates with the passage of time although the load is constant. These results conclude that the interface crack between Si and epoxy propagates due to the creep. We also conduct the unidirectional loading test for the specimen with different thick epoxy thin film. The average interface crack propagation rate is increased with decreasing the thickness of epoxy thin film. Considering that the deformation of epoxy thin film is constrained by hard material of glass and Si, this result indicates that the creep zone, where the creep strain dominates, is localized near the Si/epoxy interface crack tip (Small Scale Creep (SSC) condition). It is concluded the delamination behavior between Si and submicron thick epoxy film is dominated by SSC condition.
