Introduction
Compact discs (CDs) are the storing medium that came along and replace the traditional LP. The technology behind compact discs began in early 1979, however the first commercially available album released on CD wasn't until Billy Joel's 52nd Street in 1982. Compact discs are optical discs that are 120 mm in diameter. A standard disc can old 80 minutes of audio or 700 MB of data. Since its conception, the CD has spawned an entire generation of adapted technology. From the basic setup of the CD came the CD-R, CD-RW, DVD, DVD-R, DVD-RW and mini-discs. Manufacturing CDs requires seven very defined steps: glass mastering, electroplating, stamping, molding, metallization, lacquering, printing and packaging.
Glass Mastering
The first process that is completed to manufacture a CD is glass mastering. The CD is molded and smashed in the premastering step. Then, in an enclosed clean environment, glass in used to keep the CD master image while it is created in a glass substrate. The glass substrates are cleaned thoroughly to remove any traces of any pollutants that can hinder the process. It is then spun on a spin coater to rinse it with a solvent and dye-polymer solution. During the entire process, the spin increases in speed for better resistance. It starts off at 1x and increases until it reaches 8x in speed.
Electroplating
The CDs master blank side needs to have pits and lands in order to be able to be read and written to. In the electroplating phrase, it is sprayed with photoresist to prepare it for forming the pits and lands. Over the photoresist, a layer of metal is melted onto the CD. There is an accuracy check that the CD must go through after the step, and then another layer of metal is evaporated over the last one.
Stamping
During the stamping step, the electroplating steps are completed three separate times. The pits and lands on the CDs are separated into three types: sons, mothers and fathers. The "fathers" are created by making three to six metal impressions. The "mothers" manipulates the "fathers" into an additional create three to six metal impressions on top of that. These two impressions together are called ""sons, or stampers.
Molding
The CD's impressions must now be molded. This is done by injecting liquid polycarbonate into the CD. It is then replicated multiple times. While the polycarbonate is being injected into the CD, it is held in place for 6 seconds to hold its shape. This is why this is called the molding phase.
Metallization
After molding, the CDs are coated with a micro-thin layer of aluminum. This is where the reflective mirroring on the CDs comes from. This aluminum surfaces helps the laser light in CD players read the information imprinted on the CD.
Laquering
The CD information must be protected from any type of harm during the following phases of manufacturing and during playback. The lacquering phase protects the CD by coating it with a thin layer of plastic having 1 to 30 microns. The printing process will destroy the CD if this step isn't completed correctly.
Printing & Packaging
Any type of artwork, text or design that the manufacturer decides to place on the CD is done in the printing phase. Using the offset or silk screen process, the printing is done and polished to leave the CD with a visually appealing and clean appearance.
The last thing to be done is the packaging. The CDs are assembled with any accompanying materials such as booklets and inlay cards. Depending on the manufacturer and the packaged item, the CDs will be packaged in jewel cases individually or in bunk on a spindle. It is then wrapped with plastic wrap.
Tags: pits lands, Compact discs, glass mastering, layer metal, metal impressions
