If you take a conventional plasma generator for surface treatment that operates under atmospheric pressure and compare it with the plasmabrush®, you will notice they differ considerably with regard to the low temperature, low gas flow rate, groove penetration properties of the plasma and the purity of the gases with the plasmabrush®. We call these advantages of the plasmabrush® “one step ahead” properties.
Low temperature
The more often the electrons as energy carriers collide with the heavy gas particles, the more energy the particles absorb. The more continuously this collision process occurs, the more “thermalised” the plasma becomes: The energies of electrons and heavy gas particles become more balanced, the plasma heats up. This property of a heated plasma gas is common to many atmospheric-pressure plasma generators. However, plasmabrush® in contrast has a gas temperature of maximum 70 °C at atmospheric pressure: a great advantage when the treatment of substrates that are sensitive to temperature is required. This means that materials such as thin films or contact lenses can easily be treated with the plasmabrush® – without any reverse-side heat dissipation.
Low gas flow rate
Due to the low gas temperature of the plasma gas, the plasmabrush® can be operated with low gas flow rates (normally: 10-20 standard litres per minute (slm)). In conventional systems the plasma gas functions simultaneously as a cool gas, in order to lower the temperature of the plasma generator. This type of operation requires a much higher gas flow rate with a turbulent stream and its suitability for smaller components has proved limited.
On the one hand plasmabrush® technology enables a laminar gas flow. This laminar gas flow prevents non-activated ambient gas being whirled in, an effect that results in a plasma stream that is geometrically longer than that of conventional plasma generators. On the other hand backpressure in front of a surface against which gas flows is so low that even light components (e.g. lenses) can be treated.
Groove penetration property of the plasma
Inert gas plasma generated by the plasmabrush® can be used to treat fine grooves, capillaries or templates. With our new and inventive process it is possible to ignite the gas streaming through thin grooves or capillaries to form a plasma, thus making it possible to treat the insides of contours.
Purity of the gases
The high stream density and the high gas temperature in conventional atmospheric pressure plasma generators often lead to local fusings on the excitation electrodes. More often than not the metal removed by the plasma is deposited as an impurity on the surface of the substrate being treated. In contrast there is no such electrode burn-off with the plasmabrush® due to the patented design of the plasma generator. This means that the plasmabrush® is also suitable for cleanroom applications.