Ablation

• Plasma ablation involves the mechanical removal of surface contaminants by energetic electron and ion bombardment
• Surface contamination layers (e.g. cutting oils, skin oils, mold releases) are typically comprised of weak C-H bonds
• Ablation breaks down weak covalent bonds in polymeric contaminants through mechanical bombardment
• Surface contaminants undergo repetitive chain scission until their molecular weight is sufficiently low for them to boil away in the vacuum
• Ablation affects only the contaminant layers and the outermost molecular layers of the substrate material
• Argon is often used for its high ablation efficiency and chemical inertness with the surface material

Activation

• Plasma surface activation involves the creation of surface chemical functional groups through the use of plasma gases - such as oxygen, hydrogen, nitrogen and ammonia - which dissociate and react with the surface
• In the case of polymers, surface activation involves the replacement of surface polymer groups with chemical groups from the plasma gas
• The plasma breaks down weak surface bonds in the polymer and replaces them with highly reactive carbonyl, carboxyl, and hydroxyl groups
• Such activation alters the chemical activity and characteristics of the surface, such as wetting and adhesion, yielding greatly enhanced adhesive strength and permanency

Crosslinking

• Cross-linking is the setting up of chemical links between the molecular chains of polymers
• Plasma processing with inert gases can be used to cross-link polymers and produce a stronger and harder substrate microsurface
• Under certain circumstances, crosslinking through plasma treatment can also lend additional wear or chemical resistance to a material

Deposition

• Plasma deposition involves the formation of a thin polymer coating at the substrate surface through polymerization of the process gas
• The deposited thin coatings can possess various properties or physical characteristics, depending on the specific gas and process parameters selected
• Such coatings exhibit a higher degree of crosslinking and much stronger adherence to the substrate in comparison to films derived from conventional polymerization