利用雙材料破壞力學理論探討可撓式AMOLED取下行為

Abstract

本研究以雙材料破壞力學理論為基礎，透過有限元素法模擬分析可撓式AMOLED面板於取下過程當中界面破壞行為，並分析OLED應力分佈情形，期望藉此降低OLED承受之應力，以提高取下良率。 本研究所探討的取下方式分為機械式取下與氣壓輔助取下兩種。在取下實驗中可以觀察到，若於AMOLED面板外黏貼保護膜時，OLED脫層現象較容易發生；相反地，若面板外不具保護膜時，則較少脫層發生。利用實驗數據進行有限元素分析，結果顯示當面板外黏貼保護膜，其OLED具有較高之正向應力，因而導致AMOLED結構較容易發生脫層。本研究亦針對氣壓輔助取下試片之幾何結構與邊界條件進行參數分析，以尋求應力較小之參數，作為取下開發依據。有限元素模擬結果顯示，若保護膜選用剛性較低的膠材，有助於降低OLED層之應力。此外，若提升氣壓輔助取下試片上表面壓力，亦有助於降低OLED承受之正向應力，進而減少脫層發生的可能性。

This research aims to characterize the behaviors of a flexible active-matrix organic light-emitting diode (AMOLED) display during the debonding process using finite element analysis based on bimaterial fracture mechanics theory. In order to reduce the stress states within OLED and the defective rate, the stress distribution of OLED is also be concerned. There are two common ways to debond the AMOLED from the substrate, one is mechanical loading induced debonding and the other is pressure assistance debonding. Experimental observation indicated that when the AMOLED contains protection film, the possibility for the occurrence of delamination is relatively high. Simulation results show that the protection film would increase the normal stress within AMOLED and lead to the delamination, which is in a good agreement with the experimental observation. Pressure assistance debonding technology is developed in order to reduce the delamination rate and the normal stress of AMOLED. As a results of pressure assistance debonding technology is in development, this research using finite element analysis and bimaterial fracture mechanics concepts to calculate total energy release rate of the interface at the crack tip, then estimating the critical state of the interfacial crack and simulate the stress distributions of OLED. In addition, the possible parameters which may influence the stress distributions such as, the applied pressure and the adhesive material properties, were examined and discussed. Results for pressure assistance debonding process indicated that increasing the applied pressure to the sucker of AMOLED, the normal stress of OLED is decrease. On the other hand, the employment of the softer adhesive can also reduce the stress state of OLED.