Experimental Measurements for Moisture Permeations and Thermal Resistances of Cyclo Olefin Copolymer Substrates

Abstract

Plastic substrates for organic light-emitting devices (OLED) are extremely sensitive to moisture and oxygen. On the basis of higher transparence, lower birefringence, lower dispersion and lower water absorption, a new amorphous engineering thermoplastic, nominated cyclic olefin copolymer (COC) has been used for this application. However, COC plastic substrates can’t sustain plasmabased processing temperatures at 350°C. This study is focus on two important topics regarding to measurements of the permeation rate and thermal resistance of a SiO2 layer structure deposited upon the COC substrate. Silicon dioxide layer of thickness, 0.25μm, 0.5μm, and 1μm, respectively, are fabricated by PECVD. For the permeation rate measurement, the Ca-test method is adopted. For the thermal resistance measurements, both of the thermocouple in atmosphere and the IR thermographic methods are adopted and measured results are compared. Different surface temperatures, 323.15K, 373.15K, 408.15K, and 473.15K, respectively, are applied upon the silicon dioxide film and temperature differences for varied thickness of silicon dioxide film are measured. Experimental results are presented to investigate the behaviors of moisture diffusion barrier and thermal barrier characteristics of the COC/SiO2 structure.