Improved dimensional stability of asymmetric structures for media applications

A simple dimensional stability model is used to identify the relevant material, geometric and environmental parameters critical for warpage of high-density optical media structures. Asymmetry in the system disk geometry gives rise to a transient dimensional stability, i.e. curvature in the cover layer is induced by changes in the surrounding environment. Humidity and temperature changes will induce curvature into the total asymmetric structure, and hence the cover layer, every time the assembled asymmetric disk is moved from one environment to another. The goal of this work is to examine the material properties, the assembled disk geometry, and environmental parameters on the resulting environmentally induced tilt. Using the validated model, the material property/geometry parameter space was defined to minimize the dynamic tilt and equilibrium tilt of the assembled disk.