How Compact Discs are made?

Manufacturing compact discs is a complex combination of science and industrial techniques. Briefly, the input media submitted by you for replication is tested, glass mastered, has a stamper made, is qualified, replicated, metalised (sputtered), lacquered, scanned for quality, printed and packed. In what follows we present a briefing of each of these stages.

Input Media Testing: All CDR masters sent to SkyLine are subjected to stringent testing for errors so that we can check that the burn was good and that there are not any errors that could lead to problems during production. 

Glass Mastering: Glass mastering is the first production stage in the manufacture of any disc. A super smooth disc is prepared with a special bonding agent and photosensitive material. This is the glass master. The contents of the input media are fed to a Laser Beam recorder that cuts the glass master by exposing the photosensitive material to the laser-writing pit structure.

After exposing, the disc is developed and the exposed material is washed away. The pity structure that remains on the glass is then evaporatively coated with an ultrafine layer of silver, providing a stronger base for the stamper making process.

Stamper making: The metalised glass master is then passed to galvanics for stamper making.  

Simply, galvanics is like very advanced electro-plating. The glass is immersed in a nickel solution and a current is passed through the liquid so that the stamper grows onto the glass master. After the stamper has grown, it is cut off the glass, washed, spin-dried and coated with a special lacquer to seal the pit structure safely for the next stage.

The lacquered stamper is then back-sanded (the non-data side) then is punched to make the inner hole and outside diameter according to standards.

Qualification: The process of qualification is testing the stamper bit-by-bit against the master CDR. Through this process, we check that every bit on the stamper exactly equals every bit in the master CDR. Any failure means that the glass mastering and stamper making phases must be done again.

Replication: This is the stage where the actual discs are made. The stamper is placed into the mould of a high speed injection moulder under strict cleanroom conditions.
The discs are injection moulded with the information in the optical grade polycarbonate substance. The injection pressure is up to 1200 bar, forcing the injected material to take the pit structure of the stamper and thus a CD is created.

Metalising: A robotic arm takes the disc from the injection machine into a chamber called a metallizer or a sputter station. There aluminium is evaporated onto the data side of the disc.

Lacquering: After the disc is metallized, it needs to be lacquered. The lacquer is applied to the disc to make a protective layer to stop the aluminium layer from oxidizing and to make the print stick to the disk more easily. If the disc was not lacquered in time, the aluminium layer would change colour and be less reflective which could possibly make the disc unusable.

Quality Scanning: After lacquering, the disc is inspected to make sure it meets Skyline's stringent quality measures. The scanning system is based on Dr. Schenk's tool which rejects any discs that show scratches, dust, pinholes, blackspots,...., or any other kind of defects.

Printing: The final stage is the screen printing of art or decoration on the CD which is done via a robotic screen printer capable of printing with up to five colors. Ultra violet rays are used to achieve a very fast drying process.
The finished printed CD's are piled in spindles where they can either be bulk wrapped or sent to the packaging area to be put in sleeves, jewel cases or any other elaborated required packaging.