MFDigital CD DVD Information Library
Wednesday, June 23, 2004
CD Manufacturing > Replication > Metallising
The polycarbonate discs after moulding are transparent. In order that the laser can read the pits they need to be covered by a mirror surface to reflect the laser light.
The next stage is therefore to metallise the active surface of each disc with aluminum by sputtering. Sputtering requires the transparent polycarbonate discs to be transferred to the sputtering chamber which is then quickly evacuated of air and filled with argon gas. The argon ions are attracted to the aluminum target by the use of a high voltage. As the ions strike the target, particles of aluminum are ejected and are deposited onto the CD surface.
Modern metallisers are capable of cycle times of under 2 seconds allowing them to be used in duolines where one metalliser can handle the output from two moulding machines. The fastest metallisers can achieve cycle times of about 1.5 seconds.