According to Wikipedia (sometimes notoriously incorrect), CD's ARE layers of Polycarbonate, Metal, lacquer and ink. I suggest the reason it is not the tough stuff we are accustomed to, is probably the tension + resonance (on impact) between the welded/glued layers, and the burned grooves cause it to break????? hummmmmm interesting possibilities here!! So John, we are on the trail - Pete:?
Replicated CDs are mass-produced initially using a hydraulic press. Small granules of raw polycarbonate plastic are fed into the press while under heat. A screw forces the liquefied plastic into the mold cavity. The mold closes with a metal stamper in contact with the disc surface. The plastic is allowed to cool and harden. Once opened, the disc substrate is removed from the mold by a robotic arm, and a 15 mm diameter center hole (called a stacking ring) is removed. The cycle time, the time it takes to "stamp" one CD, is usually 2–3 seconds.
This method produces the clear plastic blank part of the disc. After a metallic reflecting layer (usually aluminum, but sometimes gold or other metals) is applied to the clear blank substrate, the disc goes under a UV light for curing and it is ready to go to press. To prepare to press a CD, a glass master is made, using a high-powered laser on a device similar to a CD writer. The glass master is a positive image of the desired CD surface (with the desired microscopic pits and lands). After testing, it is used to make a die by pressing it against a metal disc.
The die is a negative image of the glass master: several are typically made, depending on the number of pressing mills that are to be making the CD. The die then goes into a press and the physical image is imposed onto the blank CD, leaving a final positive image on the disc. A small amount of lacquer is then applied as a ring around the center of the disc, and fast spinning spreads it evenly over the surface. Edge protection lacquer is also applied before the disc is finished. The disc can then be printed and packed.
Manufactured CDs that are sold in stores are sealed via a process called "polywrapping" or shrink wrapping.
Diagram of CD layers.
A. A polycarbonate disc layer has the data encoded by using bumps.
B. A reflective layer reflects the laser back.
C. A lacquer layer is used to prevent oxidation
D. Artwork is screen printed on the top of the disc.
E. A laser beam reads the polycarbonate disc, is reflected back, and read by the player.