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The three states of matter – solid, liquid, and gas – are well known. These represent the changing physical states of a material as energy is introduced. When we heat a solid material, for example, it melts to a liquid; if we continue to heat the liquid, it is vaporized to a gas. But if we continue to heat this gas, it will typically become a plasma. While solids, liquids, and gases are familiar, it is actually plasma – the fourth state of matter – that constitutes the majority of known matter in the universe – the stars.
Plasmas are “clouds” of highly energetic gas atoms and molecules moving at high speed. As these atoms or molecules collide, they fragment or are ionized to produce a rich source of ions, electrons, activated molecules or atoms, and ultraviolet and visible light. This is a very reactive mixture that is capable of both breaking and making chemical bonds, and it can be used to change the properties, such as surface energy or hydrophobicity, of any surface with which it comes into contact.
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Hot Plasmas
Plasmas can be hot or cold. Industry uses hot plasmas in the form of arcs, torches, and sprays. These operate at temperatures greater than 1,000ºC and are used for cutting, welding, or coating metallic components. For example, plasma-deposited abrasion-resistant coatings are commonly used for engineering parts.
Cold Plasmas
Cold plasmas deliver a unique combination of ultra-high reactivity and very powerful processing capability at room temperature. This combination is ideal for processing a wide range of temperature-sensitive materials, such as:
• Semiconductors
• Plastics
• Textiles
• Food packaging film
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Cold-plasma processes typically change only the top few nanometers of any surface. This fact allows the surface properties of any material to be changed, without altering or degrading bulk properties.
A plasma may be used to surface clean, to remove material or etch, or to deposit a thin coating. Traditionally, cold-plasma technologies have required low-pressure (vacuum) operation. This has been very successful in the microelectronics business, where highly specific vacuum processes have been used to produce high-value components for integrated circuits.
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Plasma in Action
Since the late 1980s, Dow Corning has used plasmas as special ingredients to form polymeric thin films. These films are less than one-tenth the thickness of a human hair. By forming polymer films from gas-phase chemistry, unique electrical and mechanical properties can be achieved.
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Dow Corning uses plasma-enhanced chemical vapor deposition (PECVD) technology to develop new materials so you can make faster microprocessors, better solar-energy devices, and integrated circuits with enhanced reliability. |
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Dow Corning has launched a new range of atmospheric cold-plasma processes. These provide the ability to make specific surface modifications on a range of substrates while operating at atmospheric pressure. With these processes, customers are able to coat wide-area substrates – such as textiles, films, paper, and foil – in continuous operation.
Read more about our plasma solutions.
Learn more about some of Dow Corning’s other new technology ventures, including:
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