Manufacture of compact discs is the process by which a commercial compact disc (CD) is replicated in bulk using a master version created from the source record. This may be in the form of audio (CD-Audio) or data form (CD-ROM). This process is used in the compact disc read-only; CD-Rs, CD-RWs, and DVDs are made somewhat differently, although the methods are very similar.
CDs can be used to store audio, video and data in various standard formats specified in Rainbow Books. CDs are usually produced in grade 100 (ISO 5) or better clean rooms; they can usually be manufactured for fairly strict manufacturing tolerances for just a few US cents per disk.
CD mastery is different from burning, because the holes and ground of the mastered CD are printed into blank CDs, not burn marks in dyes (in CD-R) or areas with changing physical characteristics (in CD-RW). Additionally, CD burners write data sequentially, while CD presses the factory to 'write' entire disks in a single physical stamping operation.
Video Compact Disc manufacturing
Prematering
All CDs are pressed from digital data sources, with the most common sources being low-level CD-R errors or files from attached computer hard drives containing end data (eg music or computer data). Some CD pressing systems can use digital master cassettes, either in Digital Audio Tape, Exabyte or Umatic format. However the source is only suitable for audio CD production due to error detection and correction problems. If the source is not a CD, the contents list for the CD to be pressed should also be set up and stored on a tape or hard drive. In all cases except the CD-R source, the tape should be uploaded to the media control system to create a TOC (Table of Contents) for the CD. Creative processing of mixed audio recordings is common in conventional CD premastering sessions. The term often used for this is "mastered," but the official name, as described in Bob Katz's book, Audio Mastering, edition 1, page 18, is 'premastering' because there must still be other disks which carries premastered audio that supplies the work surface where the metal master (stamper) will be electroformed.
Maps Compact Disc manufacturing
Mastering
Mastery glass
The mastery of glass is done in class 100 (ISO 5) or better clean room or closed net environment itself in mastering system. Contaminants introduced during important stages of manufacture (eg, dust, pollen, hair, or smoke) can cause errors sufficient to render the master unusable. Once successfully completed, the master CD will be less susceptible to the effects of this contaminant.
During glass mastery, glass is used as a substrate for holding the CD master image when it is created and processed; then the name. The glass substrate, visible larger than the CD, is a glass plate round about 240 mm and 6 mm thick. They often also have a small steel center on one side to facilitate handling. The substrate is specially crafted to master the CD and one side is polished until very smooth. Even microscopic scratches on the glass will affect the quality of suppressed CDs from the parent image. The extra area on the substrate allows for easy handling of the glass master and reduces the risk of damage to the pits and ground structures when the "father" stamper is removed from the glass substrate.
After the glass substrate is cleaned using a detergent and ultrasonic bath, the glass is placed in a rotary twist. Spin coater rinse the blank glass with solvent and then apply the photoresist or dye-polymer depending on the mastering process. Rotation spreads the photoresist or dye-polymer coating evenly across the glass surface. The substrate is released and baked to dry the coating and the glass substrate is ready to be mastered.
After the glass is ready to master, it is placed in a laser light recorder (LBR). Most LBRs are capable of mastering more than 1x speed, but because of the weight of the glass substrate and requirements of the master CD they are usually mastered without a playback speed of more than 8x. LBR uses a laser to write information, with the wavelength and end lens NA (numerical aperture) selected to produce the required hole size on the empty master. For example, DVD holes are smaller than CD holes, so shorter wavelengths or higher NAs (or both) are required for DVD mastery. LBR uses one of two recording techniques; photo hold and mastery of non-photoresist. Photoresist also comes in two variations; positive photoresist and negative photoresist.
Mastery of photoresis
The mastery of photoresis uses a light sensitive material (photoresist) to create a hole and land on an empty master CD. Laser beam recorders use blue or ultraviolet lasers to write master. When exposed to a laser beam, the photoresist undergoes a well hardened chemical reaction (in the case of a negative photoresist) or otherwise makes it more soluble (in the case of a positive photoresist). The exposed area is then immersed in a developer solution that removes open positive photoreses or unexpected negative photoreses.
After mastering is complete, the glass master is removed from LBR and is chemically 'developed'. After the development is complete, the glass master will be dimetalized to provide a surface for the stamper to form. Then polished with lubricant and wiped.
Non-photoresist mastery or polymer-dye
When lasers are used to record on the dye-polymers used in non-fotores mastery (NPR), the polymer-dye absorbs focused laser energy in the right place; this evaporates and forms a hole in the surface of the dye polymer. These holes can be scanned by red laser beams that follow the cutting beam, and the recording quality can be instantly and immediately assessed; for example, the recorded audio signal can also be played directly from the glass master in real time. The hole geometry and playback quality are all adjustable when the CD is being mastered, such as blue writing lasers and red read lasers typically connected via a feedback system to optimize recording. This allows the LBR-polymer color to produce highly consistent holes even if there are variations in the color-polymer layer. Another advantage of this method is that variations of hole depth can be programmed during recording to compensate for downstream characteristics of local production processes (eg, marginal print performance). This can not be done with the mastery of photoreses because the hole depth is governed by the thickness of the PR coating, while the dye-polymer holes are cut into a thicker layer than the intended hole.
This type of mastering is called Direct Read After Write (DRAW) and is a major advantage of some non-photoresist recording systems. Problems with the quality of an empty glass master, such as scratches, or uneven polymeric dye layers, can be detected immediately. If required, mastering can be stopped, save time and increase throughput.
Post-Mastering
After mastering, the glass master is baked to harden the developed surface material to prepare it for metallization. Metalization is an important step prior to the manufacture of electrogalvanic (electroplating).
The developed glass master is placed in a steam-deposition metaliser using a combination of mechanical vacuum pumps and cryopumps to lower the total vapor pressure inside the chamber to a loud vacuum. A piece of nickel wire is then heated in a tungsten boat to a hot white temperature and the nickel vapor is deposited onto a rotating glass master. The glass master is coated with nickel vapor to a typical thickness of about 400 nm.
The glass master finish is checked for stains, small holes or incomplete nickel layer coverage and forwarded to the next step in the mastering process.
Electroforming
Electroforming occurs in "Matrix", the name used for the electroforming process area in many plants; it's also class 100 (ISO 5) or better clean room. Data (music, computer data, etc.) In the glass master metalization is very easily damaged and must be moved to a harder form for use in the actual injection molding equipment resulting in an optical disc of the final product.
The metallised master is clamped in a conductive electrodeposition frame with the data side facing outward and lowered to the electroforming tank. The specially prepared and controlled tank water contains a nickel salt solution (usually nickel sulfamic) at a certain concentration that can be adjusted slightly at different plants depending on the characteristics of the previous step. The solution is carefully supported to maintain the pH, and organic contaminants should be kept under one part in five million for good results. The tub is heated to about 50 ° C.
The glass master is rotated in an electroforming tank while the pump circulates the electroforming solution above the master surface. When electroforming takes place, nickel is not plated onto the surface of the glass master, as it will obstruct the separation. Plating is somewhat avoided through passivation and, initially, because the glass is not electroconductive. In contrast, the metal layer on the glass disc actually reverses to the nickel (not the mandrel) that is being electrodeposed by electron attraction at the cathode, which presents itself as a glass-coated metal, or premlass mandrel. Electroplating, on the other hand, will require electrodepostion directly to the mandrel along with the intention it remains attached. That, and the more stringent requirements of temperature control and the purity of bath water, are the main differences between the two electrodeposition disciplines (invented by Luigi Brugnatelli and often credited to another Luigi - Sr. Galvani). The metal stamper first struck from the metal coated glass is a metal master (and we do not have to make the master from another master because it will not follow the nomenclature of the siring sequence closely with electroforming) This is clearly the opposite method with normal electroplating. Another difference for electroplating is that the internal pressure of the nickel must be carefully controlled, or the nickel stamper will not be flat. Hygiene solutions are important but are achieved by continuous filtering and regular bagging anode systems. Another major difference is that the thickness of the stamp must be controlled up to ± 2% of the final thickness so that it will fit on the injection molding machine with very high tolerance to the gas flange ring and the central clamp. This thickness control requires electronic current control and baffle in the solution to control the distribution
The current should start low enough because the metallization layer is too thin to pick up large currents, and increase steadily. Since the nickel thickness in the "nyonya" glass increases, the current can be increased. The full electric current density is very high with a full thickness typically 0.3 mm takes about an hour. This section is removed from the tank and the metallic layer is carefully separated from the glass substrate. If the coating occurs, the process must begin again, from the glass mastery phase. Metal parts, now called "dads", have desirable data as a series of bumps rather than holes. The injection molding process works better by flowing around the high points than to the hole in the metal surface. The father was washed with deionized water and other chemicals such as hydrogen peroxide amine, sodium hydroxide or acetone to remove all traces of resistance or other contaminants. Master glass can be sent for reclamation, cleaning and inspection before reuse. If a defect is detected, it will be discarded or destroyed recycled.
After cleansing of any loose and resistant nickel, the surface of the father is washed and passive, both electrically and chemically, allowing the subsequent layers to separate from the father. This layer is a layer of absorbed oxygen atoms that do not alter the physical surface. The father is clamped back into the frame and returns to the coating tank. This time the growing metal part is the mirror image of the father and is called the "mother"; because this is a hole, can not be used for printing.
The mother-dad sandwich is carefully separated and the mother is then washed, passivated and returned to the electroforming bath to have a mirror image produced on it called a boy. Most CD prints are produced from boys.
Mothers can grow back from fathers if they become damaged, or run very long. If handled properly, there is no limit to the number of stampers that can be grown from single mothers before the quality of the stamper is reduced unacceptably. Father can be used as a stamper, directly, if very fast turnaround is required, or if the result is 100%, in this case the father will be kept extravagantly. At the end of the journey, the mother will be saved.
A father, mother, and collection of stampers (sometimes called "sons") are known collectively as "family". Father and mother have the same size as glass substrate, usually 300 m thickness. Stampers do not require extra space outside the program area and they press to remove excess nickel from the outside and inside the information area to fit the injection molding machine mold (IMM). The physical dimensions of the mold vary depending on the injection tool used.
Replication
The CD printing machine is specially designed for high-temperature polycarbonate injection materials. They have an average throughput of 550-900 discs per hour, per line of prints. The first clear polycarbonate pellet was dried approximately 130 degrees Celsius for three hours (nominal depending on the optical grade resin used) and fed through vacuum transport to one end of the injection barrel of the barrel (ie, the feed throat) and transferred to the injection chamber via a screw big inside the barrel. The barrel, wrapped with heater bands starting temperature from ca 210 to 320 degrees Celsius melts polycarbonate. When the mold is closed, the screw moves forward to inject the molten plastic into the mold cavity. When the mold is full, the cold water flows through the mold, outside the cavity, cooling the plastic so that it is slightly compacted. The entire process of closing the mold, injection and opening again takes about 3 to 5 seconds.
The "disc" formed (referred to as 'green' disk, without final processing) is removed from the mold by vacuum handling; high speed robotic arm with a vacuum suction cap. They are transferred to the finish line infeed conveyor, or cooling station, in preparation for metallization. At this point the disc is clear and contains all the desired digital information; But they can not be played because there is no reflective layer.
The disc passes, one at a time, into the metaliser, a small space at about 10 -3 Torr (130 mPa) vacuum. This process is called 'sputtering'. The metaliser contains a "target" metal - almost always an aluminum alloy (mostly) and a small amount of other metals. There is a load-lock system (similar to airlock) so the process space can be stored at high vacuum when disk is exchanged. When the disk is rotated to a processing position by a rotary arm in a vacuum chamber, a small dose of argon gas is injected into the process chamber and a 700 volt DC electric current at up to 20 kW is applied to the target. It generates the plasma from the target, and the plasma vapor is deposited onto the disk; it is anode - cathode transfer. The metal coats the disc data side (top surface), covering holes and soil. This metal layer is the reflective surface that can be seen on the back side (not the label) of the CD. This thin layer of metal undergoes corrosion of various contaminants and is therefore protected by a thin layer of lacquers.
After metallization, the disc is passed to the spin-coater, where UV curable lacquers are ejected onto the newly metallized layer. With a fast turnaround, the lacquer coats the entire dish with a very thin layer (approximately 70 nm). Once the lacquer is applied, the disc passes through a high intensity UV lamp that heals the lacquers quickly. Lacquer also provides surfaces for labels, generally screen printed or offset printing. The printing ink (s) must be chemically compatible with the varnish used. Markers used by consumers to write on a blank surface can cause damage to the lacquer protective layer, which can cause corrosion of the reflective layer, and CD failure.
Test
For quality control, both the stamper and the molded disc are tested before running the production. Samples from the disk (stress test) were taken during long run production and tested for quality consistency. The suppressed disk is analyzed on the signal analysis engine. Metal stamps may also be tested on specially adapted signal analysis machines (larger, more brittle, diameter...). The machine will "play" the disk or stamper and measure various physical and electrical parameters. Errors can be introduced at each production step, but the printing process is the least adaptable subject. The source of the error is more easily identified and compensated during mastery. If the error is too severe then the stamper is rejected and replaced. Experienced machine operators can interpret reports from the analysis system and optimize the printing process to create disks that meet the required Rainbow Book specifications (eg Red Book for Audio from the Rainbow Books series).
If no defects are found, the CD will continue to print so that the label can be a screen or offset printed on the top surface of the disc. After that, the disc is calculated, packaged, and shipped.
Manufacturer
- Moser Baer
- Ritek
- Sony DADC
- Cinram (previous)
See also
- CD publishing
- The author of the optical disk
References
External links
- How compact discs are made - Described by layman to layman
- Introduction to CD Duplication
- Disk creation checklist.
Source of the article : Wikipedia
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