Observations of surface morphology and element distribution around breakdown hole of nanohybrid polyimide film by SEM

The inorganic nanoparticles hybrid polyimide films are newly emerging advanced materials with excellent corona-resistant. The breakdown mechanism of the film and the role of nanoparticles are studied by observing the microstructure of the hole region. The morphology near breakdown hole of the nanoparticles hybrid polyimide films is observed by SEM, applied by stepwise rising DC voltage. The serious damage portion of the film is located within 10-50 μm around hole. Within the edge hole, there are many uneven grains. With the hole radius increasing, the size of grains become homogeneous, accompanied with Cu content reducing and Au increasing. The electrode in other region keeps normal. Al₂O₃ nanoparticles play a role of preventing electrode damage. The breakdown mechanism of films is attributed to the thermal type.