Plasma Technology Overview
| Article Index |
|---|
| Plasma Technology Overview |
| What is a Plasma? |
| Plasma Effects |
| Plasma Cleaning |
| Plasma Surface Activation |
| Plasma Coatings |
| Plasma Etching |
| All Pages |
Plasma Surface Activation
Plastics, i.e. polypropylene or PTFE (polytetrafluoroethylene) are homopolar and do not bond easily. Plasmas afford an effective surface activation pre-treatement prior to printing, lacquering or gluing. Glass and ceramics can be plasma activated similarly. Technical oxygen is usually used as the process gas, however, many plasma activations can also be carried out with just ambient air. Parts remain active for a few minutes up to several months, depending on the particular material that has been plasma treated. Polypropylene for example can still be reprocessed several weeks after treatment.
Tests of Plasma surface activation
The effects upon a surface of plasma surface activation are readily seen during subsequent product processing steps but there are a number of formal test methods that demonstrate the results too:
Contact angle measurements
Water beads on an untreated surface but spreads out (has lower contact angle) on a plasma activated surface
Dyne test inks
Dyne test inks indicate a specific level of surface energy, on the left <28mN/m, in the palsma activated case on the right 72mN/m
Grid cut test
Grid test cut methods (DIN EN ISO 2409) clearly demonstrate the enhanced bonding (right image) to plasma activated surfaces
how plasma surface activation works
UV radiation and active oxygen species from the plasma break up separating agents, silicones and oils from the surface. These are pumped away by the vacuum system. Active oxygen species (radicals) from the plasma bind to active surface sites all over the material, creating a surface that is highly 'active' to bonding agents.
Plasma activation is suitable for e.g.:
- general plastics and rubber
- medical plastics
- consumer electronics plastics
- automotive components
- aerospace components