Comportement thermo-hygro-mécanique de matériaux composites multicouches ultraminces pour écrans flexibles

Abstract

A theoretical modeling framework is proposed to follow shape and residual stress evolutions of layered flexible display structures with respect to coating deposition process, ambient temperature and relative humidity conditions. In the presented simplified version of this model, the mechanical equilibrium equations of elastic layers is coupled with transient mass transfer equations for the predictions of temperature and moisture content inside the structure. To calibrate this model, the behaviors of nanometric silicon nitride barrier layers on polyimide substrates were investigated. Then experimental measurements of the deflection dynamics of samples subjected to isothermal relative humidity jumps were compared with simulation results by considering different cases of boundary conditions. It is concluded that accurate simulations require accounting for the dependence of the water concentration-dependent diffusion coefficient.