CardinalFang wrote: > Not quite, the plastic part is pressed, but the pits are coated by > metallising using a plasma. The pits are then covered in plastic, but > you are right in that it is a copying process, not a mastering one like > making a CDR.
I stand corrected. http://en.wikipedia.org/wiki/CD_manufacturing says: The discs then pass, one at a time into the metaliser, a small chamber operating at approximately 10E-3 Torr vacuum. This process is called 'sputtering'. The metaliser contains a metal "target" made of an alloy of mostly aluminium and some small amounts of other metals. There is a system of a load-lock (like an airlock so that the process chamber can maintain high vacuum as the discs are exchanged. When the disc is rotated into the processing position by the swivel arm in the vacuum chamber, a small dose of argon gas is injected into the process chamber and a 700 Volt DC electrical current at up to 20 kW is applied to the target. This results in a plasma igniting and the aluminium target evaporates onto the disc (anode - cathode reaction). The metal coats the information side of the disc (upper surface) and covers the pits. This metal layer is the reflective surface that can be seen on the reverse of a CD. This thin layer of metal is unstable and will oxidise if it is not protected by a lacquer. -- Pat http://www.pfarrell.com/music/slimserver/slimsoftware.html _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
