Category Archive: Florian Brehmer

Gentle Plasma – Surface Treatment for Sensitive Materials

Pre-treating sensitive materials presents a significant challenge for many converters. In these applications, plasma treatment is often the preferred solution.

Achieving improved adhesion through corona pre-treatment depends largely on selecting the correct corona dosage — the relationship between power, web speed, and working width. In most production environments, however, the process or material requirements dictate the web or line speed, limiting flexibility in treatment settings.

Converters working with delicate substrates or very low web speeds often encounter another challenge: corona power can typically only be reduced to about one-third of its maximum output before the discharge becomes unstable and non-uniform.

One method of lowering the treatment level while maintaining a more even discharge is pulsed corona treatment. However, the energy contained in each individual pulse can still be relatively high, potentially causing surface damage or excessive pre-treatment. In addition, streamers — localized high-energy discharges that are common in conventional corona processes — can be especially harmful to sensitive materials such as foams and optical films.

To address these challenges, Hamburg-based SOFTAL Corona & Plasma developed its patented LinearPlasma system. LinearPlasma is an indirect plasma pre-treatment technology derived from corona treatment principles but designed specifically for delicate substrates.

Unlike conventional corona systems, plasma treatment with LinearPlasma contains no voltage potential at the substrate surface. As a result, there are no streamers and no strong electrical fields that could damage sensitive materials. The process delivers an extremely low-energy discharge to the substrate surface, minimizing the risk of film damage commonly associated with standard corona treatment.

This indirect plasma technology also enables the effective treatment of thick materials such as foams, rigid plates, and glass. An additional advantage is that the process does not generate ozone within porous materials, eliminating the possibility of ozone release later in the production line that could potentially affect equipment or raise health concerns.

Beyond traditional converting applications, SOFTAL’s LinearPlasma technology is also well suited for the surface treatment of printed electronics. These increasingly common materials are used in advanced packaging structures and technical film laminates. Conventional corona treatment can damage conductive circuits embedded within these materials due to exposure to electrical fields. Because LinearPlasma provides a potential-free, non-conductive treatment process, these sensitive electronic structures remain protected.

SOFTAL specifically engineered the LinearPlasma process for printed electronics and other sensitive applications requiring potential-free pre-treatment. Whether conductive elements are located on the surface or embedded within the substrate, the material is not exposed to damaging electrical fields, ensuring that delicate conductive structures remain intact.

In conclusion, converters seeking improved adhesion of inks, adhesives, laminates, and coatings on delicate materials — including sensitive foams, optical films, and printed electronics — can benefit from SOFTAL’s LinearPlasma technology.

3DT represents SOFTAL Corona & Plasma in the USA and Canada. Learn more on 3DT’s SOFTAL page or contact a sales engineer at sales@3DTLLC.com

Best regards,
Florian Brehmer
CTO SOFTAL Corona & Plasma

Corona Laboratory Table from SOFTAL

Designing a printing or coating process is a tricky thing. Not only during specification of new lines, but even in existing production lines, the coatings and inks always need to be matched to the surface tension of the substrate. Typically, a substrate is treated with corona, increasing the surface tension of the substrate and, thereby, matching the substrate to the ink or coating. Not only in development, but also in production the question arises, how intense should the corona treatment should be? This is especially the case when using older, pre-treated materials that have lost surface tension due long storage periods and requiring refreshment treatment.

Corona treatment is always characterized by the amount of corona dosage or discharge. The dosage (D) describes the energy put into one m2 of the substrate, measured in [Wmin/m2]. It can be calculated by dividing the applied corona power (P) through the web speed (v) and the electrode width (CB) of the corona system:

The applied Corona dosage couples the corona power to the web speed and can be set in direct relation to the achievable dyne level on the substrate surface. The critical task in designing or optimizing a printing or coating process is to determine the right corona dosage that is high enough to enable the process but not overtreat and thus damage the substrate.

Deciding on the right corona dosage is ideally done on test samples in a lab environment. Here, only small amounts of material are used to determine the dosage parameters, resulting in reduced cost and waste. Importantly, production lines remain open for production instead of time consuming testing and development tasks.

SOFTAL solves these issues in the form of a fully integrated Laboratory Table Corona system, the LTC. The motorized substrate holder moves at speeds up to 50 m/min under the 230mm wide corona electrode. This electrode can provide 10 W up to 400 W of power, enabling dosages from to 1 to over 1500 Wmin/m2. The motor itself guarantees a constant speed under the electrode, hence fully reproducible treatment results. Moreover, generator, transformer, drive and ozone destruction are completely integrated in the system, eliminating any requirement for peripheral equipment. Therefore, all the flexibility that is needed in a process engineered laboratory is given to treat conductive as well as non-conductive samples, specifying the exactly right corona dosage needed for the new product.

Furthermore, by using the LTC, surface treatment know-how can be substantially increased at the production facility while minimizing uncertainties caused by transport and storage from external laboratories. Old, pre-treated and long stored material can be easily tested on site with minimal waste and assigned the correct dosage for refreshment treatment.

For more information about the LTC, SOFTAL’s lab system, click here.

Kind Regards,

Florian Brehmer
CTO SOFTAL Corona & Plasma