Abstract
In recent years, consumers’ eager demand of flexible products with great lightweight, miniaturization and flexible feature has nowadays driven the characteristic of ultra-thin glass substrate toward high thinning and flexibility. Ultra-thin glass holds many advantages over other flexible substrate materials for flexible electronics or printed electronics, including excellent chemical stability, hermeticity, moisture resistance, high optical transmission, low surface roughness and long-term stability. It has increasingly become a ideal substitute of substrate material in various microelectronics applications. With the advances in printed electronics technology, if ultra-thin glass can apply in roll-to-roll gravure offset printing process, which will useful in continuous mass production and reduce the manufacturing costs. Despite of the great flexibility capacity of ultra-thin glass, glass itself is generally a brittle and fragile material. Thus, to explore its ultimate flexural strength and flexural fatigue life is essential, they also are the main target in this thesis. Firstly, the ultra-thin glass substrate with thicknesses of 50μm and 100μm are cut by three kinds of cutting processes, namely mechanical dicing, pico-second laser dicing and wet etching. To measure and caculate the ultimate flexural strength of an ultra-thin glass substrate under different cutting processes by two-point / three-point bending test and bending strength formula. Compare the ultimate bending strength of ultra-thin glass substrate with different thickness between each cutting process to find the suitable thickness and cutting process for ultra-thin glass substrate. Then, in order to improve the bending strength of the ultra-thin glass substrate, the quality of the cutting edges and cross-sections of the glass cutting are observed and analyzed by optical microscope and field emission scanning electron microscope to investigate the reasons for impact of the ultimate bending strength. And the laser peeling proposed by Industry Technology Research Institute, Taiwan, is further applied for eliminating micro edge cracks/flaws of the ultra-thin glass substrate. Finally, this thesis cut the ultra-thin glass substrate which is printed with metal electrode and using a self-designed two-point tester for fatigue experiments, to explore the effects of different radius of curvature, temperature and frequency on fatigue life and its damage mechanism. The finite element analysis software ANSYS is used to bending stress analysis of ultra-thin glass specimens. The S-N curve is constructed by the fatigue test results of the self-designed two-point tester and the results of the finite element analysis The results of this paper will help to understand the ultimate bending strength of ultra-thin glass substrate under different cutting processes with different thicknesses and provide the reference for the flexible products design when evaluate its bending life.