- CO2 snow cleaning uses "snow" particles formed from CO2 gas.
- The process is effective for particle removal. Some success has been
reported in removing finger prints and flux residue.
- The exact removal mechanism is not completely understood. Some sources
believe it is a weak blasting process in which the kinetic energy of the
traveling snow flake removes particles. Other sources believe that
there is a phase transition of the snow flake as it travels over a
surface, which is actually removing the particle.
- CO2 snow cleaning is more suitable for the higher cleanliness levels.
- It may be a good option for particle removal, and possibly thin fluid
removal, on delicate surfaces such as optical components and thin-film
- The equipment required is fairly simple:
- A source of CO2 gas
- A gas purifier (optional)
- A proprietary "snow" gun.
- The "snow" gun can be mounted in a controller for automated processes.
One version has been designed to clean small (less than 0.25-inch
diameter) blind holes.
- Welding grade CO2 can be used if it is processed through a purifier.
- This process can introduce a certain amount of contaminant, depending on
the purity of the CO2 gas. This is usually not a problem except for the
highest semiconductor cleanliness levels.
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All SAGE material, Copyright© 1992,
Research Triangle Institute
18 March 1995