Mechanics of Indium-Tin-Oxide Films on Polymer Substrates with Organic Buffer Layer

Abstract

ABSTRACTThis study was undertaken to derive the understandings of the electro- mechanical properties of ITO films on highly elongated polymer substrates which were subjected to thermally and mechanically stresses. The substrates are polycarbonate foils with 100, 180 and 200-mm thicknesses with gas barrier layer on their bottom surface. The metallic films used in the experiments are indium- tin-oxide (ITO) and tantalum (Ta) films. Strain- gauge measurements and numerical analyses using modified Stoney formula were carried out to determine the electro-mechanics in ITO films. The numerical analyses and empirical results show the thermally and externally induced mechanical stresses in ITO films on polymer substrates are responsible for the difference in thermal expansion between the ITO films and the substrate and for substrate material and thickness, respectively. Therefore, a ramped heating processing and a buffer layer were employed to improve the electro- mechanics, and then, the effects of the buffer layer were also quantified in terms of conductivity-strain variations.