The pre-treatment of  sensitive materials is a challenge for many converters. Plasma treatment is recommended in these cases.

 Improved adhesion attained through corona pre-treatment depends largely on choosing the correct corona dosage – the quotient of power and web speed at a given working width. In practice, the process or the material usually determine the web/line speed.

However, every converter who has dealt with the surface treatment of sensitive materials or very low web speeds has been confronted with problem that power can only be reduced to about a third of its maximum performance before the corona discharge can become non-homogenous.

Lowering the power level below this level while maintaining an even corona discharge can be achieved by pulsing the corona. However, the energy of a single pulse can be relatively high which may lead to surface damage or excessive ‘pre-treatment’. The occurrence of streamers, which cannot be avoided in normal corona processes, can be especially damaging to sensitive materials, such as sensitive foams and optical films.

With these challenges in mind, Hamburg-based SOFTAL Corona & Plasma has developed its patented LinearPlasma system. The term LinearPlasma describes an indirect plasma pre-treatment method based on corona treatment. This technology enables the processing of delicate substrates because plasma treatment contains no voltage potential and therefore no steamers or high levels of electric fields. The LinearPlasma process does not cause damage typical of corona treatment on film surfaces due to producing a very low energy inputs onto substrates.

Thanks to this indirect plasma technique, surfaces of very thick materials such as foams, plates and glass can be successfully treated as well.  A welcome side benefit is that no ozone will emerge from porous materials later down the production line, possibly harming equipment or causing health concerns because plasma treatment does not produce ozone.

Additionally, SOFTAL’s LinearPlasma capabilities include the surface treatment of printed electronics.  These sensitive materials, which are increasingly embedded in state-of-the-art packaging and technical film composites, require nonconductive surface treatment. Even if electric circuits are inside the film, electrical currents produced by corona treatment may destroy the fine conducting paths.

However, SOFTAL’s LinearPlasma process has been engineered for printed electronics and potential-free pre-treatment. This means that these sensitive materials are not subjected to an electrical field and therefore conducting structures remain undamaged – no matter if the electronics are applied on the surface or embedded into the material.

In conclusion, converters can look to SOFTAL’s LinearPlasma system for improved adhesion of ink, glue, laminates, and coatings on delicate materials such as sensitive foams, optical films and printed electronics. Learn more on 3DT’s SOFTAL page or contact us at for more information about the LinearPlasma system.SOFTAL’s LinearPlasma system

Best regards,

Florian Brehmer