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Pre-mastering and media verification:
When your project arrives at The Gate the media is verified image ready or non-image ready. Image ready implies that the data is in a form ready to go into mastering. Non image ready implies that the data is in a form that needs to be converted/Mastered and pre-mastered into an image ready form. The verification is also done on DAT for vinyl projects as well. If an order is image ready it usually arrives at The Gate on a CD-R (one off, Gold/Green master) or 16/30 tape. If an order is non-image ready the data can be in a variety of forms (tape, disc, hard drive, removable media, etc.). During pre-mastering non-image ready orders are usually converted to PMCD’s. When the projects is converted, we check for equalization, song placement and complete any post-production the client has requested. These PMCD’s are then sent to the customer to be approved. Once approved the CD-ROM image is ready to go to glass mastering.
Glass Mastering:
The first part of glass mastering involves the preparation of a glass substrate. The glass substrate is a round disk of polished glass. First, a liquid layer of material called photo resist is spin coated evenly onto the glass. The glass substrate with photo resist is then baked for about 1/2 of an hour. The glass master is then placed into a laser beam recorder (LBR) that is connected to a computer. The data image source (CD-R, 16/30, etc.) is loaded into the computer. The data image is then read from the computer and recorded to the photo resist on the glass master using a laser. The data is recorded from the center of the glass master in a spiral track that goes towards the outside of the glass master. After recording, the glass master is developed by spinning a Sodium Hydroxide solution over the glass master. Where ever the laser touched during recording the photo resist washes away leaving a tiny pit of information. The developed glass master is then placed into a vacuum chamber and a small amount of silver is deposited (only molecules thick) onto the surface of the photo resist. The developed glass master coated with silver is called the metalized glass master. The metalized glass master is then sent onto Electroforming.
Electroforming:
The metalized glass master is placed into a tank of Nickel Sulphamate solution for two hours. During this time a layer of Nickel is grown onto the silver surface of the metalized glass master. When finished the metalized glass master is removed from the tank and the Nickel is separated from the Silver. This sheet of Nickel is called the father. The father is a reverse image of the data. The father is put back into the electroforming tank for two hours and another layer of Nickel is grown. The electroformed father is removed from the tank and the new layer of Nickel is removed from the father. This new layer is called the mother. The mother is then returned to the electroforming tank for two hours and another layer of Nickel is grown. This layer of Nickel is removed from the mother and is called the stamper. The stamper is a reverse image of the data like the father and therefore can be used to create discs. Several stampers can be grown from a mother. Stamper Finishing: The stamper is finished by punching out the center hole and outer edge and polishing its backside to be perfectly smooth. The stamper is now ready to be loaded into an injection-molding machine to make discs.
Injection Molding:
The stamper is placed into an injection-molding machine. The injection-molding machine is connected to a continuous supply of polycarbonate. Polycarbonate is the plastic material that is used to make compact discs. The Polycarbonate is heated to a molten state and shot into a mold that contains the stamper. The plastic is compressed against the mold under several tons of pressure. The plastic is then cooled using chilled water and the clear disc with the information stamped into it is removed. The whole process to stamp a disc takes between 5 and 10 seconds depending on the speed of the molding machine used. After being stamped a thin layer of Aluminum is sputtered onto the side of the disc that contains the pits or information. This thin layer of Aluminum is the reflective surface that the playback laser reflects off of to read the information. This process of putting Aluminum onto the discs called metalization. After metalization a thin layer of sealant or lacquer is spin coated onto the Aluminum. This sealant or lacquer is called protective coating. The protective coating is dried or cured using ultraviolet light. The discs are now sealed and ready to be printed.
Printing:
Most compact discs are screen printed with anywhere from 1 up to 5 different colors. Each separate color requires its own screen and is printed one at a time. The screen allows ink to pass through in the shape of the desired image. Ink is pressed through the screen by a squeegee and put onto the protective coated layer of the disc. The ink is then dried or cured using ultraviolet light. This process is repeated until all of the colors have been printed.
Packaging:
After printing the discs are ready to be packaged. Several different types of packaging can be used for compact discs. One of the most common is the jewel box. Jewel box packaging can be done automatically where most other types of specialized packaging is done manually. The Gate offers Standard Jewel boxes, Slim line Jewel boxes, Univenture slim packs, Jackets and die-cuts along with many other packaging alternatives.
Quality Assurance:
Throughout the above manufacturing process several different quality assurance tests are performed. The basic tests include DVS (Data Verification System) test and signal verification tests. The DVS testis a bit-for-bit comparison between the customer's original image ready data and a replicated disc. This test insures that the replicated discs are identical to the original image. Signal verification tests insure that the
Discs playback parameters are within red book specification. Several other tests are performed during manufacturing to insure that replicated discs are up to spec.
And there you have it...
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