Abstract
Fatigue behavior of multiple-stacked film-type flexible displays under flexural load has received considerable research attention, whereas the requirement of a considerably thin and flexible packaging structure with single/multiple neutral axis has not been systemically explored. Consequently, this study evaluated the flexural load induced strain and corresponding resistance change in flexible display architecture by both experimental and simulation works. The relationship between mechanical strains and the relevant resistance change in a touch panel module is estimated by both nonlinear finite element analysis and actual experiments. The aforementioned results revealed that the simulated strain and the resistance change of indium tin oxide (ITO) film were increased as the bending radius becomes narrow. Moreover, the influences of several mechanical parameters within an entire organic light-emitting diode device package with multiple coatings were estimated by a simulation-based parametric study. It should be noted that the structure design would lead the single/multiple neutral axis (N.A.) occurred in the concerned flexible displays. Among all the designed structural and material properties, the Young’s modulus of the adhesive is the most dominant factor to determine the bending strain of ITO film and the phenomenon occurrence of multiple N.A. The analytic results indicated that the multiple N.A. design is contributed to decrease the flexural strain and corresponding resistance change of ITO film. Therefore, the design rules of single/multiple N.A. and its influences on stress-induced electric variation in flexible display are revealed.
