Uses Of Vacuum Chambers And Pumps
A vacuum chamber is a rigid enclosure from which air and other gases are removed by a vacuum pump. A vacuum is created to allow for the testing or manufacture of substances that must be conducted in an environment where the pressure is far less than that of the atmosphere. Chambers made of aluminum allow one to control the magnetic field inside from outside the vacuum. On the other hand, chambers that are constructed of mu-metal will prevent external magnetic fields from interfering with the vacuum.
To eliminate the possibility of contamination, vacuum chambers are used in a variety of industrial processes, particularly in the semi-conductor manufacturing arena, where the slightest amount of contamination can destroy the substrate. These ultra high vacuum applications are frequently utilized in semi-conductor manufacturing processes, because even the slightest degree of contamination can be disastrous in this industry. As we mentioned earlier, thermal vacuum chambers are an ideal environment for testing devices and instruments that must operate in outer space. Various vacuum chambers are constructed of aluminum because it is not magnetic, unlike other types of metals, and it absorbs small amounts of moisture and trace gases.
Most vacuum chambers are made with ports that allow for instruments to be installed in the walls of the chamber. In applications that require only low vacuum levels, rubber seals are used. In higher vacuum applications, the flanges have hardened steel knives welded onto them, which cut into a copper gasket when the flange is bolted on.
A type of vacuum chamber frequently used in the field of spacecraft engineering is a thermal vacuum chamber,, which provides a thermal environment representing what a spacecraft would experience in space. This type of application will also utilize a highly advanced vacuum pump.
When resins and silicon rubbers are produced, vacuum chambers and pumps are used. In the manufacture of resins and silicone rubber an vacuum is utilized to insure that air bubbles are removed from the mold. A smaller sized vacuum chamber is utilized to eliminate air bubbles from occurring in materials before they set. The substrate upon which the vacuum is applied is mixed according to the manufacturers specifications. When this type of material is placed in a vacuum, it will normally expand to over 4 times its initial volume, consequently the vacuum chamber must be large enough to handle this volume expansion. If not, there will insufficient volume to complete the process. The material container is then placed into the vacuum chamber; a vacuum pump is connected and turned on. Once the vacuum reaches 29-inches of mercury, the material will begin to rise. . When the material falls it will plateau and not rise any more. The vacuum is applied for an additional three minutes in order to remove all air from the substrate. After reaching this interval, there is no longer a need to apply a vacuum and valves are open that allow the pressure inside the chamber to equilibrate with the ambient air pressure. At this juncture, the vacuum is discontinued, the chamber is opened, and the material is placed in a mold.
Vacuum chambers utilized in the semi-conductor industry involve an exceedingly complex process. Due the very high levels of air purity required to avoid contamination of semi-conductor devices, these devices must be processed in ultra pure vacuums. As semi-conductor devices have packed increasingly dense circuitry into smaller and smaller silicon real estate, the need for ever increasing vacuum levels has also risen. For this reason, the most advanced ultra high vacuum chambers and pumps are used in space research and semi-conductor manufacturing. The semi-conductor industry utilizes such densely packed circuitry that even impurities that consist of one or two molecules, can disrupt their processes.
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