MFDigital CD DVD Information Library
Tuesday, June 15, 2004
CD Manufacturing - Mastering - Glass Master Preparation
Glass Master Preparation
Glass Master Preparation of the 240 cm diameter 6mm thick glass master starts by stripping the old photo resist from its surface (since the glass blanks can be recycled). This is followed by cleaning and final washing using de-ionised water. The blank glass master is then dried carefully ready for the next stage.
The surface of the clean glass master is coated with a primer and then a photo resist layer 140 to 150 microns thick by spin coating. The thickness should be matched to the moulding cycle time. Shorter cycle times imply a thicker resist layer to ensure good pit geometry. The uniformity of the layer is measured with an infra red laser.
The photo resist coated glass master is then baked at about 80є C for 30 minutes. This hardens the photo resist layer ready for exposing by laser light.