Spin Coating of Blu-Ray disks: modeling, experiments, limitations, and manipulation

Authors: Tammisola, O., Lundell, F., Hellström, G., Lagerstedt, T.
Document Type: Article
Pubstate: Published
Journal: Journal of Coatings Technology and Research
Volume: 7   315-323
Year: 2010


A major challenge in the production of Blu- Ray Disks (BDs) is making the cover layer over the information area. The layer has to be both thick enough to protect the information and even enough for the information to be read through it optically. Furthermore, it is preferred not to cover the hole in the center of the disk. Spin coating is a candidate method for the production of these layers in a rapid reproduction process. When dispensing is performed off-center (in order not to cover the hole), a new complication appears, namely the formation of a slope toward the inner rim of the liquid ?lm. Here, funda- mental limitations for achieving even ?lms in this system and ways to overcome the dif?culties by manipulation of the process are studied. A mathemat- ical model for this particular case of spin coating is obtained and validated by comparison with experi- ments made in industrial equipment aiming at produc- ing BDs. The model agrees well with the experimental data. The model is then used to show that cover layers that ful?l the Blu-Ray speci?cation are very dif?cult to produce with the spin-coating technique. Manipulation by inline curing and surface shear is added to the model and the results show that it is considerably easier to meet the BD speci?cation when utilizing the manipulation.