EFFECTS OF ATOMIC OXYGEN ON MECHANICAL PROPERTIES OF POLYIMIDE FILMS

Effects of atomic oxygen (AO) on mechanical properties of polyimide films were investigated using surface topography observations and tensile tests. The ITO‐coated polyimide films, which are expected to have a high durability against AO attacks, were also evaluated. Surfaces of polyimide films irradiated by AO were deeply eroded, exhibiting a rough texture. The roughness developed as the AO fluence increased. Tensile strength and elongation of the polyimide films degraded after AO irradiation tests. In addition, that degradation became marked concomitantly with increased AO fluence. These results indicate that development of surface roughness can degrade mechanical properties of polyimide films. In contrast, surfaces of ITO‐coated polyimide films remained flat and were hardly affected by AO irradiation. Nevertheless, the tensile strength and elongation of ITO‐coated polyimide films were decreased by AO irradiation. Such degradation resulted from undercut cavities formed by AO erosion at the defects sites of ITO coating.