Participle Deposition Rate Applications
For the manufacturing of high tech products often cleanrooms or clean zones are used. Cleanrooms are classified for particles between ≥ 0.1 µm and ≥ 5 µm according to the ISO 14644-1:2015 classification table. In many applications air cleanliness for larger particles is more important. Especially in optical systems contamination by particles ≥ 20 µm is important.
The present ISO 14644 cleanroom standards do not offer methods of controlling and monitoring of these particles. The new ISO 14644-17, of which the Draft International Standard is published in January 2020, covers the missing aspects of air cleanliness for macro-particles from ≥ 5 µm to ≥ 500 µm.
The particle deposition rate gives a direct relation between air cleanliness and contamination risk. Particle deposition rate data predicts the contamination by particles during exposure, but the data also provides information on how to reduce the particle deposition rate if required.
This paper discusses the specification and application of the particle deposition rate in clean controlled environments. As examples the production of a photo conductor and the assembly of a MEMS inkjet device is described.