Bending stress analysis of flexible touch panel

Flexible touch panel is required to undertake extensive bending operations during service; thus, bending testing of flexible touch panel for mechanical behaviors and even reliability is crucial for realizing the technology. This study aims at exploring the bending behaviors of a flexible touch panel under a four-point bending test using finite element analysis. The touch panel is a laminated structure composed of seven thin film layers, namely a polyester layer, an adhesive layer, a polyimide layer, two organic layers and two indium tin oxide conductive layers. Because the touch panel structure is symmetry, only a quarter of the flexible touch panel is established in the analysis model. The mechanical properties of the materials are first obtained using both nanoindentation and uniaxial tensile/compressive testing. Furthermore, a modeling technique based on global and local finite element analysis is applied to evaluate the bending stress at a specified radius of curvature. Special emphasis of the calculation is put on the critical region with respect to stress, which is identified as the most susceptible cracking site.