ISO 14644-14 Cleanrooms and Related Controlled Environments - Part 14: Assessment of Suitability for Use of Equipment Based on Airborne Particulate Concentration

The standard “ISO 14644-14 Cleanrooms and associated controlled environments - Part 14: Assessment of suitability of equipment for use by airborne particulates” developed by the International Organization for Standardization (ISO) describes a methodology for assessing the suitability of equipment (e.g. machinery, measuring equipment, process equipment, components and tools) for use in cleanrooms and associated controlled environments with respect to airborne particulates cleanliness specified in the ISO 14644-1 standard.

Particle sizes range from 0,1 µm to greater than or equal to 5 µm. These sizes are included in the ISO 14644-1 standard.

When regulatory bodies impose additional guidelines or restrictions, the assessment methodology may need to be adapted appropriately.

The following situations are outside the scope of this standard:

• Assessment of suitability in terms of biological contamination
• Testing the suitability of decontamination agents and techniques
• Cleanability of equipment and materials
• Requirements for equipment design and material selection
• Physical properties of materials (e.g. electrostatic, thermal properties)
• Optimizing the performance of equipment for specific process applications
• Selection and use of statistical methods for testing
• Protocols and requirements regarding local security regulations

For the purposes of this standard, the following terms and definitions apply:

• Cleanliness refers to the state in which the contamination level does not exceed a specified level.
• A cleanroom is a room designed, constructed and operated in such a way that the number concentration of airborne particles is controlled and classified and that the entry, formation and retention of particles in the room is controlled. Levels of other cleanliness attributes such as chemical, viable or nanoscale concentrations in the air and surface cleanliness in terms of particulate, nanoscale, chemical and viable concentrations may also be specified and controlled. Other relevant physical parameters such as temperature, humidity, pressure, vibration and electrostatics may also be controlled as required.
• Cleanroom suitability refers to the ability of any cleanroom to maintain critical control characteristics or conditions when used as intended. For the purposes of this standard, evaluation is based on airborne particulate concentration.
• A clean zone refers to a defined area constructed and operated in such a way as to control the number concentration of airborne particles and to classify them and to control the entry, formation and retention of contaminants within the area. Clean zones may be a defined area within a clean room or may be achieved by a separating device. Such a device may be located inside or outside the clean room. Other relevant physical parameters such as temperature, humidity, pressure, vibration and electrostatics may also be controlled as required.
• Decontamination refers to the reduction of undesirable substances to a certain level.
• Equipment refers to a system that integrates materials, components, or controls designed for specific functions, such as test and production equipment and machinery, transportation and handling equipment, storage units, tools, furniture, doors, ceilings, information technology equipment, and handling robots.
• Test environment refers to the area where testing is performed, defined by a set of parameters.

The outline of the cleanroom conformity assessment is as follows:

• Before the assessment is carried out, the customer and supplier must agree on the item to be tested, including particle size ranges and operating modes with reference to air cleanliness by particle concentration as determined by ISO Class N given in the ISO 14644-1 standard. Each selected operating mode must be assessed individually.
• A brief description of how the equipment will be used in routine operation (with operating parameters) should be given to encourage the setting of appropriate test conditions and parameters.
• Visual inspection.
• To establish a link to the ISO 14644-1 standard classification system, the procedure described in this standard should be used.
• Conducting measurements.
• The collected data is processed and the results are linked to the ISO classification system.
• The results obtained conclude the cleanroom suitability of the equipment.

Additional optional tests (not linked to ISO class N), for example total emission of particles or operational life cycle testing, are described in the annex to the standard (Annex B).

The method described in this standard can be used to determine the average total emission of equipment and provides data that can be used to determine the particle loading in the cleanroom.

Visual inspection of equipment should be performed before and after any measurement-based evaluation.

Visual inspection should ensure that all packaging has been removed and that the equipment is undamaged and correctly installed and properly connected to the required utilities.

Visual surface cleanliness should be assessed qualitatively to ensure that any subsequent measurable tests are not compromised. This portion of the visual inspection may include assessing for particles, surface films, or improperly placed lubricants.

The purposes of this examination are to:

• Identify contamination such as particles and films from manufacturing, packaging, transportation or initial assembly
• Identify contamination that has survived any previous decontamination process.

This inspection is not intended to provide a measure of surface cleanliness.

Depending on the location of contamination, the results from the visual inspection should be recorded and available for comparison with post-test visual inspection of surface cleanliness and used as a basis to guide a repeated or improved decontamination process. The efficiency of detecting visible contamination on equipment depends on the following factors:

• Accessibility and orientation of the surface to be examined
• Materials used in equipment construction, surface condition and treatment
• Imaging parameters (e.g. illumination, field of view, view magnification, viewing distance)

Among the numerous testing, measurement, analysis and evaluation studies that our organization has provided for businesses in various sectors, our organization also provides certification and testing services defined in the standard “ISO 14644-14 Clean rooms and related controlled environments - Part 14: Evaluation of suitability for use of equipment according to particle concentration in the air” with its trained and expert staff and advanced technological equipment.