Humidity Control of Industrial Dehumidifiers in Cleanrooms

The development of cleanrooms is closely linked to modern industry and cutting-edge technology. The development of cleanroom technology has been facilitated by the environmental requirements of the

The development of cleanrooms is closely linked to modern industry and cutting-edge technology. The development of cleanroom technology has been facilitated by the environmental requirements of the precision machinery industry (e.g., processing of gyroscopes, miniature bearings, etc.) and the semiconductor industry (e.g., production of large-scale integrated circuits).

Humidity control in cleanrooms

Humidity Control of Industrial Dehumidifiers in Cleanrooms

Cleanrooms are workplaces where contamination is controlled.

It is claimed that cleanrooms provide a conducive environment for environmental contaminants (such as dust, airborne microorganisms, aerosolized particles, and chemical vapors) (used in research, development, and manufacturing of equipment or processes).

With the increasing emphasis on quality testing and control, zero tolerance for defects and stringent manufacturing practices, the demand for cleanrooms has increased manifold. Cleanrooms are now designed as specially constructed enclosed areas with environmental controls for airborne particles, temperature, humidity, air pressure flow patterns, air movement, vibration, noise and living organisms.

The main application areas for cleanrooms are the electronics industry, pharmaceuticals, aerospace, automotive, information technology and other areas that require more stringent manufacturing conditions. Cleanroom applications range from the manufacture of small miniature components, electronic devices and instruments to the increasing need for sterility and purity of pharmaceuticals, food and sterile aseptic environments in medical and biological applications.

Contaminants can come from a variety of sources: air (whose cleanliness is defined by the type of cleanroom and the dust level), water, chemicals, the physical plant itself and personnel.

Uncontrolled humidity

Microbial growth and corrosion

Condensation on work surfaces leading to schedule delays and poor product quality

Contamination leading to product deterioration

Causes of uncontrolled humidity

Examples of high humidity in semiconductor and pharmaceutical clean rooms

Semiconductor Clean Room

Microcircuit and microchip fabrication requires hygroscopic polymers called photoresists to mask the electrical circuits used in the etching process. Due to their hygroscopic nature, they absorb moisture, so microscopic electrical circuits are cut or bridged, resulting in circuit failure. Additionally, in semiconductor manufacturing, many problems occur when humidity levels fluctuate in the wafer fabrication area. Bake times usually increase and the entire process usually becomes more difficult to control. Humidity levels above 35% RH can make components susceptible to corrosion. In addition, as the developer solvent is sprayed onto the wafer, the solvent quickly evaporates, cooling the wafer enough to condense the moisture in the air. This additional water can alter the developer properties and be absorbed into the semiconductor layer. This can lead to swelling and product quality issues that require additional process controls.

Pharmaceutical Cleanrooms

In pharmaceutical manufacturing facilities, high humidity causes fine powders to absorb moisture, blocking the powder from entering the tablet press. Powder inconsistencies caused by moisture absorption lead to crumbling tablets and clogged tablet molds. Humidity variations mean it is difficult to adjust bed temperature and spray rate, leading to heat damage and moisture ingress. In addition, humidity in the air ducts creates wet areas where bacterial colonies can grow and cause process contamination.

General Recommendations

The relative humidity in a clean room should be controlled at 35-40% RH (which is a function of process requirements) for year-round operation. At temperatures below 70°F (20°C), these RH levels are typically maintained within a narrow band of ±2% RH.

industrial dehumidifier Solutions

Industrial dehumidifiers maintain dew points at very low levels such as (-) 60°C (manifold reduction of air humidity) at all times, far beyond what can be achieved with standard HVAC refrigeration systems.

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