ISO 14644-17:2021 pdf download – Cleanrooms and associated controlled environments — Part 17: Particle deposition rate applications.
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 ensure that the quality of the facility remains constant. It is necessary to demonstrate control of the particle deposition 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 is in 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 being manufactured and the measuring equipment available (see Clause 6). Failure to achieve the required particle deposition rate limit may require an investigation to understand the cause of the failure. Depending on the failure cause, improvements to working, cleaning, and maintenance procedures may be required. If needed, changes in manufacturing equipment, or cleanroom design and ventilation can be implemented. Methods of reducing the risk of airborne contamination are discussed in Annex E. 6 Measurement of particle deposition rate The method for measuring the particle deposition rate is based on the collection of particles onto a test surface of a known surface area over a known time period. The particle deposition rate is then calculated by using Formula (1). The particle deposition rate shall be measured on, or in close proximity to, a vulnerable surface during the manufacturing carried out in the cleanroom. If required, the particle deposition rate can be measured at several locations. The result of the measurement can then be used to check whether the location complies with a specified maximum particle deposition rate, or maximum particle deposition rate level, for certain cumulative particle sizes.
8 Documentation By agreement between customer and supplier, the following information and data shall be recorded: a) name and address of the testing organization, and the date on which the measurement was performed; b) type of measurements and measuring conditions; c) a reference to this document (i.e. ISO 14644-17); d) clear identification of the physical location of the cleanroom or clean zone tested (including reference to adjacent areas if necessary), and coordinates of all sampling locations; e) specified designation criteria of the cleanroom or clean zone, including the ISO 14644-1 classification, and the relevant activities in the occupied state; f) details of the measurement instrument used to determine the particle deposition rate, including the identification of the measurement instrument, information on its current calibration certificate, and any special conditions relating to the measurement method; g) details of the type of test surface used with witness plate or measuring instrument; h) initial counts of surface cleanliness on test surface(s) in the case of witness plates method; i) details of time of exposure; j) a log of scheduled and unscheduled activities and incidents during exposure; k) cumulative particle size(s) that are measured; l) test results with background counts, or previous counts, subtracted; m) statement regarding compliance with the claimed particle deposition rate level designation; n) any other specific requirements that are relevant to the particle deposition rate and particle deposition rate level.