What is the construction of a CD-R disc?Just like all kinds of CDs a CD-R disc is a sandwich of a number of layers. First comes a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside diameter of the disc. On top of this substrate is an organic dye recording layer (cyanine, phthalocyanine or azo) followed by a thin metal reflective layer (gold, silver alloy or silver) and finally an outer protective lacquer coating. Some discs are also topped with additional layers that improve scratch resistance, increase handling durability or provide surfaces suitable for labeling by inkjet or thermal transfer printers.
What is the construction of a CD-RW disc?
To allow information to not only be written but also re-written many times over, CD-RW disc construction is more complex than that of CD-R. A CD-RW disc uses a six-layer design beginning with a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside edge of the disc. Next comes a dielectric layer (zinc sulfide and silicon dioxide), followed by a phase change alloy recording layer (indium, silver, tellurium, and antimony), another dielectric layer, a thin metal reflective layer (aluminum) and finally a protective lacquer overcoat.