Clean Room Particle Counters

by | Apr 26, 2017

The particle counter market projected to reach USD 330.6 Million by 2021 from USD 275.9 Million in 2016, at a CAGR of 3.7%. Report segments particle counters market based on type, application, end user, and region. On basis of type, market segmented into airborne and liquid particle counters. Airborne particle counters segment is expected to command largest share of global market.

Stakeholders in the Particle Counter Market:

  • Particle Counters Manufacturing Companies
  • Suppliers and Distributors of Particle Counters
  • Healthcare Companies, Automotive Companies, and Semiconductor Companies
  • Research and Consulting Firms
  • Research Institutes
  • Venture Capitalists

Cleanroom Particle counters are used to determine the cleanliness of the room which in effect contributes to the control of airflow. Some cleanroom controls are driven by real time cleanliness monitoring depending on the criticality of the process of which the cleanroom encompasses. Particle counters are used to monitor the many sizes of particles of concern for a given cleanroom’s contamination control problem. The number and placement of counters will need to be determined through interaction with process engineers and may involve some experimentation. An output signal from the particle counters can directly control recirculation fan speed.

Most of today’s high-tech processes require an absence of particulates. For example, pharmaceutical companies monitor 0.5 µm particles to determine process cleanliness, and 5 µm particles to determine product sterility. Conversely, semiconductor manufacturing tends to focus on particles from 0.3 µm down to 0.05 µm.

Controlling Particle Contamination

The three ways to control particles are:

  • Implement environmental controls to eliminate particulate
  • Minimize or prevent the entering of particulate into the controlled environment
  • Avoid particulate generation within the manufacturing process in the controlled environment
  • Eliminate already existing particulate in the controlled environment

 

Classification of Cleanrooms and Mini environments

The International Organization for Standardization (ISO) creates standards for particle concentrations in clean processes. ISO 14644-1 establishes standard classes of air cleanliness for cleanrooms and clean zones, based on specified concentrations of airborne particulates. Table 3 lists the specific allowable particle limits per ISO Class:

ISO cleanroom classifications

CLASS NUMBER OF PARTICLES PER CUBIC METER BY MICROMETER SIZE
0.1 µm 0.2 µm 0.3 µm 0.5 µm 1.0 µm 5.0 µm
ISO 1 10
ISO 2 100 24 10
ISO 3 1,000 237 102 35
ISO 4 10,000 2,370 1,020 352 83
ISO 5 100,000 23,700 10,200 3,520 832 29
ISO 6 1,000,000 237,000 102,000 35,200 8,320 293
ISO 7 352,000 83,200 2,930
ISO 8 3,520,000 832,000 29,300
ISO 9 35,200,000 8,320,000 293,000

Cleanroom Evaluation and Certification

Cleanroom certification is carried out after construction or significant physical changes. Certification verifies that the facility has fulfilled the requirements for a statistically valid optimum concentration of specified-size airborne particles. Cleanroom certifications may take place in any of three different stages: As Built, Operational, or At Rest.

Particle Detection

Particle counters continuously determine particle contamination sources, levels, and trends. Using particle data, controlled environment personnel interpret the causes of contamination, correlate contamination levels with production processes, refine each step of production, and precisely schedule cleanroom maintenance cycles. Many organizations take a Lean approach to identifying and eliminating particulate in the controlled environment. After particulate sources are identified the personnel implements process refinements and controls to sustain the desired environmental changes.

Types of Particle Counters

Remote particle counters

Small particle counters that are used to monitor a fixed location typically inside a cleanroom or mini-environment to continuously monitor particle levels. These smaller counters typically do not have a local display and are connected to a network of other particle counters and other types of sensors to monitoring the overall cleanroom performance. The computer based network is interconnected to control environmental conditions, airflow etc.

Manifold particle counters

Modified aerosol portable particle counter that has been attached to a sequencing sampling system. The sequencing sampling system allows for one particle counter to sample multiple locations, via a series of tubes drawing air from up to 32 locations inside a cleanroom. Typically less expensive then utilizing remote particle counters, each tube is monitored in sequence.

Hand-held particle counter

A hand-held particle counter is a small, self-contained device that is easily transported and used, and designed for use with Indoor Air Quality (IAQ) investigations. Though lower flow rates of 0.1 ft³/min (0.2 m³/h) than larger portables with 1 ft³/m (2 m³/h), hand-helds are useful for most of the same applications. However longer sample times may be required when performing cleanroom certification and testing. (Hand-held counters are not recommended for cleanrooms). Most hand-held particle counters have direct mount isokinetic sampling probes. One may use a barbed probe on a short piece of sample tubing, but it is recommended that the length of the tubing not exceed 6 ft (1.8 m), due to loss of larger particles in the sample tubing.

Using Particle Counters

Particle counters are different to other common testing instruments. They consist of specialized optics, lasers, carefully aligned sampling regions, and printed circuit boards (PCBs). Environmental stressors like dirt, heat/cold extremes, electromagnetic interference (EMI), and vibration affect the extremely sensitive measurement. Particle counters are high-sensitivity, high-performance electronics devices that can be employed for data interpretation, trend tracking, and statistically valid sampling.

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