PLASMA – GLOW DISCHARGE
It’s usually the first process phase that is applied and it’s commonly called “phase of substrate cleaning”.
It’s activated after the equipment has reached a vacuum value among 6×10-2 and 8×10-2 mbar. The function of glow discharge is to activate the substrate surface in order to obtain the best metal adhesion. Substrates made with different kind of material usually require different process parameters.
The glow discharge phase is a plasma that is a partially or totally ionized gas, unstable by nature.
The plasma nature changes, depending on the gas or the mixture gas injected (oxygen, Argon, etc..), the pressure located in the process chamber and the electric field that supports it.
A combination between these three elements generates a substrate with a superficial tension and then with different chemical
and electrostatic combinations.
The glow discharge cathode is located in the centre of the process chamber.
The substrates are placed around the cathode and they are made to rotate (rotation and translation) during treatment phase. After this, is generated a electric discharge that support the Plasma and that ionizes the gas and then activates the substrates surface.
PLASMA – NOS-ANTIFOG
After the polymerization process it’s possible to make some extra treatments targeted to modify the superficial tension of the substrate.
Depending on the desired goal, some kind of gas are injected in the process chamber during glow discharge phase.
NOS and ANTIFOG are two of the most used processes.
NOS process is used in order to make possible the painting of substrate surface also after the polymerization phase. This process is utilized for those substrates who require both the anticorrosion treatment (polymerization) and the final painting in some parts.
ANTIFOG process is used in order to avoid the humidity condensation over the substrate. It’s particularly widespread in the automotive industry to avoid the presence of humidity drops over the lens of the lamp, that causes a decay of his optical properties.
PLASMA – MEDIUM FREQUENCY (MF)
Glow discharge, polymerization, NOS and antifog phases require the creation of a plasma (activated gas) in the process chamber.
The gas (plasma) is activated through an electric field generated by a power supply, usually in alternating current (DC).
Instead ARZUFFI’s equipments are provided with a plasma activation system in Medium Frequency (MF) in order to reach a better quality of the process and reduce treatments time.
This technical device has the following advantages:
- Faster complete cycle time: 50% reduction of treatment time in the phases where MF is applied;
- Better quality of substrates: it’s possible to reach the desired quality level also in the presence of complicated structures and deep cavities;
- Cut in raw material costs: it’s not necessary to coil aluminium foils round the glow discharge cathode;
- Loading time reduction: it’s not necessary to replace the glow discharge cathode after every cycle because with the MF technology the cathodes must be replaced, in order to be cleaned, just once a day.
On the ARZUFFI’s equipments provided with MF technology are installed on the two sides of the fix half-shell two cathodes, that generally consists in two metallic plates that are designed depending on process chamber size.
Nuova fase di processo che permette la creazione di un plasma durante la fase di evaporazione.
Ne consegue una deposizione con maggiore aderenza al substrato, una copertura perfettamente uniforme e una maggiore riflettibilità.