What is Plasma Surface Activation?Plasma surface activation is the process by which surface polymer functional groups are replaced with different atoms from ions in a plasma to increase surface energy. Plasma activation is often used to prepare a surface for bonding or printing.
Surface exposure to energetic species breaks down the polymer at the surface, creating free radicals. Plasma contains UV radiation at high levels, creating additional free radicals on the plastic or Teflon surface.
Free radicals quickly react with the material itself because they are unstable. This allows the surface to form stable covalent bonds, which are able to be printed on or bonded to.
Plasma technology is useful whenever one layer needs to be bonded to another layer. It simplifies manufacturing processes and improves the reliability and consistency of results.
Activation also improves the wettability of most surfaces, including aluminum and copper coatings. Most metal surfaces can improve their wettability with this process. Improved wettability is important for painting or printing with ink on plastic surfaces.
The most effective way to prepare a plastic or Teflon surface for printing, painting, or bonding is with plasma treatment.
Non-reactive or non-wettable surfaces may also be modified to obtain better bondability and adhesion properties. Materials coated or decorated without any form of surface activation will not adhere to the bond or the ink and thus be unreliable and messy.
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Production timing is very important; the effects of the plasma are temporary, ranging from just a few hours to a few days. This allows plenty of time to complete the manufacturing process on the materials being treated if the manufacturing process is well planned.
Several mechanisms contribute to successful treatment depending on the materials treated and the gas used.
Gases Used for Plasma ActivationTreating with oxygen gas has a significant etching effect by removing atoms from the surface one by one. This leaves a clean, bondable surface that will also accept ink or paint and create a permanent bond. If a metal surface is being treated, Argon gas is introduced with the Oxygen, to prevent oxidation of the treated surface.
Treating with oxygen will reverse the polarity of plastic materials and allow the polymers to receive new surface functionalities by increasing the surface tension and creating very small contact angles on the treated materials' surface.
There are numerous advantages to plasma processing as opposed to traditional wet-chemical activation methods. Most importantly, a second plasma treatment can be performed at any time with no degradation in the product being treated. This is not true of many treatment methods using harsh chemicals that could damage the material being treated.
Additionally, vacuum plasma is the greenest form of deep cleaning technologies in existence today. With no chemical waste, no danger to employees or facilities, and no chemicals to buy or store, being green has never been easier.
Plasma activation is most often used in the manufacturing of electronics, specifically in electronic sensors and connectors. It is useful prior to encapsulation because it strengthens the physical bond, and it ensures a reliable hermetic seal and reduces current leakage.
Plasma technology promotes increased flow of resins into plastic and polymer materials by raising the surface energy and enhancing the wettability of the treated products.
New chemical functional groups are formed with strong chemical bonds. Plasma surface activation allows more of the plastic to get into every crevice of the bonded surface. This results in improved bondability - up to 50 times the strength of a bond that is not treated with plasma activation.
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