| Pressing:
A stamper, which is actually a master coated with
nickel layer and is a negative of the Optical
Disc, is required for Optical Disc replication.
At the center of the injection moulding machine
is a two part mould. One half holds the stamper
and the other half contains a flawless, mirror
like surface. In order to produce a disc, one
half of the mould closes against the other and
molten polycarbonate is injected into the cavity
between the stamper and the mirror surface. Only
after a few seconds of pressing, a compact disc
containing all the data is quickly created. The
disc is then cooled to solidify the plastic, the
mould then opens and the disc is removed.
Incase of a DVD, two such substrates, but half
in thickness are created and then bonded together
at a later stage with a transparent adhesive.
Metallization:
In order for the Disc to be readable, it must
be covered with a micro thin layer of aluminum
which is vacuum laid. The aluminum surface acts
as mirror to reflect the laser light back of the
player so that information can be read. Incase
of DVD Silicon Alloy is also used for metallization
instead of Aluminium.
Lacquering / Bonding:
To protect the CD and its information from harm—scratching,
bending, or just plain dropping it on the floor—the
disc is covered with a layer of varnish. The lacquer
envelops the aluminum and seals it from the elements.
The disc is then ready for printing.
Incase of a DVD, the two thin
substrates are bonded together with the help of
a transparent bonding adhesive. The disc is then
ready for printing
Label Printing:
The final touch comes with the printing of the
label right onto the disc, by a silk screen-printing
machine. The result is a clean, polished appearance
with an artwork of the Disc printed on the surface.
It also helps in distinguishing different Discs
and provides information about the contents of
the Discs.
Quality Check:
The Discs are then checked for quality. The data
accuracy and the playability of the Discs are
tested on various testing equipments, scanners
and also by playing them on computers and CD/DVD
Players. The printing on the Disc is visually
inspected and compared with the color proof provided
by the customer.
Packing:
The Discs are then packed manually either in bulk
spindles or in Plastic cases, as desired by the
customer. Finally the goods are packed in a carton
for shipment. |