Abstract

The spin coating, sputtering and bonding are main processes of DVDR(Digital Versatile Disc Recordable). The dye layer, reflective layer and protective layer are generated respectively during processes of DVDR. The curvature of DVDR varies with above processes and affects performance of reading and writing of DVDR.
In this experiment, First, the dye layer was coated on a 0.6mm thickness polycarbonate (PC) substrate (The PC substrate of DVDR was without groove) using a spin coater (polymethine dye). Second, a layer of silver as a reflective layer was deposited on dye layer using a DC sputter. Third, a new PC substrate as a protective layer was bonded on reflective layer using UV curable glue. The curvature of each layers were measured respectively before and after spin coating, sputtering and bonding processes. The residual stresses in each layer were calculated when curvature and elastic constants of each layer are given. In single layer film, it was only coated dye layer on substrate. It is found that stress decreases with increasing thickness of dye layer. When deposited silver on dye layer to form two-layer films, the stresses of dye layer and reflective layer decrease with increasing thickness of reflective layer. However, after bonded protective layer on reflective layer to form three-layer films, the stress of protective layer increases with increasing thickness of reflective layer.
In addition, we investigated some mechanical properties of thin films in DVDR. They are hardness, Young’s modulus and adhesion. From the nanoindentation test, it is observed that the hardness and Young’s modulus varied with D/t ratio and thickness of thin film. A fitting equation that predicts the hardness and Young’s modulus when the parameter a and D/t radio are given. The hardness and Young’s modulus of polycarbonate substrate obtained from nanoindenter are 0.13GPa and 2.28GPa.
Microscratch test, can evaluate the adhesion of thin film of DVDR. The adhesion of silver film between polycarbonate substrate was measured with microscratch instrument. The critical stress to peel thin film increases with increasing film thickness. Similarly, the adhesion of thin film increases with increasing film thickness.

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