How does the Plasma Cleaning of Metals work?

Some treatment goods are with fats, oils, waxes, silicones (not LABS-free)  and other organic and inorganic contaminants (also oxide layers) covered.

Some treatment goods are with fats, oils, waxes, silicones (not LABS-free)  and other organic and inorganic contaminants (also oxide layers) covered .

For certain applications it may be necessary to achieve absolutely clean and oxide-free surfaces e.g. B.

• before  sputtering
• before  painting
• before  gluing
• before  printing
• before PVD and CVD coating
• for  special medical applications
• with analytical sensors
• before bonding
• before soldering circuit boards
• for switches etc.

The plasma cleaning works in two different ways:

1. It removes organic layers

• These are e.g. B. chemically  attacked by  oxygen  and air  .
• Due to the negative pressure and the superficial heating of the low-pressure plasma  ,  some of the contaminants evaporate . In the case of atmospheric pressure plasma, these are blown away from the surface by the excess pressure.
• Due to the high-energy particles in the plasma, the impurities are converted into  smaller, stable molecules  and can be sucked away / transported away.
• Also,  UV radiation  can destroy the contamination and cause its detachment from the surface.

The impurities may only be  a few micrometers  thick, since the plasma is only able to remove a few nm / s.

Fats contain e.g. B. lithium compounds. Only the  organic components can be  removed from them. The same is true for  fingerprints , so that is  wearing  of  gloves  is recommended.

2. Reduction of oxides

• The metal oxide reacts  chemically  with the process gas. Pure hydrogen or a mixture with argon or nitrogen is used as the process gas.

With low-pressure plasma, it is also possible to run the processes in  two  stages. For example, the items to be treated are only oxidized with oxygen for 5 minutes  ; then they  are  reduced for 5 minutes with argon-hydrogen (e.g. mixture of 90% argon and 10% hydrogen) .