Plasma activation provides perfect surface adhesion

Even a high-puridity clean surface may provide only poor adhesion. In particular in case of polymer materials (plastics) a low surface energy of the substrate material itself restricts wetting, in case of metalls it may be an oxidized surface.

Plasma Activation of plastics

Most plastics have a very low surface energy. That means that  surface molecules of the plastic only cause low attracting forces for molecules of extrinsic sucstances. The most essential reason is, that most plastic polymers are non polar. That means that no electric dipol  momentum occurs at their surface. However oxygene plasma can provide polar groups on these surfaces

Plastic activation
Non polar surface with a low surfaca energy.
Plastic activation
Active species of the oxygene plasma privide polar links.
Wettable activated surface with a high surface energy
large contact angle
The non polar surface does not allow for wetting
small contact angle
Small contact angle after activation. The surface is wetted by the liquid.

A plastic surface will automatically be activated if a plasma treatment by oxygene plasma will continue after the cleaning process is completed.

After plasma activation almost all substrates can be perfectly wetted and consequently also coated by glueing, printing or painting.

However there is a rest of substrates which are impossible candidates for glueing. Even for those plasma technology provides solutions as will be explained in clause "Etching"