ISO 14644-17-2021 pdf free download – Cleanrooms and associated controlled environments — Particle deposition rate applications.
5.1General
Particle deposition rate data obtained in a cleanroom can be used to establish the probability ofairborne particles depositing onto a vulnerable surface during exposure and provide a methodologythat supports the required quality of a cleanroom during operation.The information in 5.2 and 5.3 givesa method that can be used to establish the correct particie deposition rate cleanliness conditions in acleanroom and associated controlled environments.This information is used to demonstrate continuedcontrol of these cleanliness conditions. ISO 14644-2 shall be considered as a guide for the developmentand application of a monitoring plan.
5.2 Establishing the particle deposition rate required for control of particle depositionon vulnerable surfaces
Establishing control of macroparticles in the controlled environment through use of the particledeposition rate is required when a new facility is designed, or when cleanliness requirements arechanged in existing facilities.An assessment shall be made of the product attributes and the processactivities performed in the cleanroom. Based on this assessment, the required degree of control ofparticle contamination shall be established using the following steps.
1) The surfaces in the cleanroom or associated controlled environments that are vulnerable to particle deposition shall be identified.This can be done by considering the manufacturingcarried out in the cleanroom, the status of the technical installations, production equipment, andoperational procedures.
2)The smallest particle size that impacts on product or production quality on each vulnerable surface (critical particle size) shall be determined.
NOTE1 Differences in particle type (metallic vs non-metallic, transparent vs opaque, microbial vs non-microbial) can lead to a particle-specific approach.
3) The maximum number of particles of the critical size that contaminates each vulnerable surface considered shall be determined.
4)Knowing the maximum number of particles of a critical size that is acceptable on each surface, the particle deposition rate or particle deposition rate level (see Table 1) at the critical particle sizeshall be determined.
5) The critical surface with the tightest requirements on particle deposition rate and particle deposition rate level will determine the particle deposition rate and particle deposition rate levelfor the critical area.
6) After the maximum particle deposition rate or particle deposition rate level requirements aredefined for the critical area, the measurement method shall be chosen and put into operation.The method can be selected based on sensitivity, required measurement frequency, and other factorssuch as ease of use.ISO 14644-3 can be consulted for information on measurement methods.
NOTE2 Examples of the method described above are given in Annex E.
5.3 Particle deposition rate for demonstrating control of particle contamination
Demonstrating control of the particle deposition rate in a cleanroom over time is important to ensurethat the quality of the facility remains constant. It is necessary to demonstrate control of the particledeposition rate by demonstrating that the required particle deposition rate limits are still achieved.Monitoring shall be carried out where the most vulnerable surfaces are located, or at a location that isin close proximity and representative of the location of the vulnerable surface.
The required frequency of monitoring shall be determined by the criticality of the product beingmanufactured and the measuring equipment available (see Clause 6).
Failure to achieve the required particle deposition rate limit may require an investigation to understandthe cause of the failure.Depending on the failure cause, improvements to working, cleaning, andmaintenance procedures may be required. If needed,changes in manufacturing equipment,orcleanroom design and ventilation can be implemented.Methods of reducing the risk of airbornecontamination are discussed in Annex E.ISO 14644-17 pdf download.