Cleanrooms are meticulously controlled environments where the concentration of airborne particles is maintained at extremely low levels. These specialized settings are fundamental to industries where even microscopic contaminants can compromise product integrity, such as in the manufacturing of microchips, pharmaceuticals, and sensitive medical devices. To uphold these stringent atmospheric conditions, strict operational and personnel procedures must be followed. The clothing worn by technicians represents one of the most significant barriers against contamination, isolating the human body from the controlled workspace.
Naming the Garment
The specialized protective clothing worn by technicians within these controlled environments is most formally referred to as a cleanroom suit, cleanroom garment, or controlled environment apparel. These terms accurately describe the function and setting of the full-body covering. However, in industry vernacular, the garment is most often known by the informal, yet widely accepted, nickname: the “bunny suit”.
This peculiar nickname stems from the garment’s appearance, particularly when the hood is worn, as the complete coverage and full-body enclosure can give the wearer a rounded shape. The common sight of technicians in these suits across semiconductor fabrication plants and other sensitive facilities has cemented the term into the professional lexicon. Regardless of the name used, the purpose remains the same: to create a physical separation between the worker and the product.
The Primary Purpose of the Cleanroom Suit
The central function of the cleanroom suit is contamination control, specifically mitigating the particulates generated by the human body. Humans are a major source of contamination, constantly shedding skin flakes, hair, lint from street clothes, and respiratory droplets. The suit acts as a complete barrier to contain these biological and fibrous contaminants, preventing them from entering the clean workspace.
The effectiveness of this containment relates directly to the cleanroom’s classification, which is defined by ISO standards based on the maximum allowed particle count per cubic meter of air. Highly sensitive environments, such as ISO Class 5, require garments with superior filtration capabilities to block particles as small as 0.5 micrometers. The garment’s design must trap and retain shed particles, ensuring the air quality remains within the specified limits necessary for the manufacturing process. This containment is important because a single human hair, measuring approximately 50 to 100 micrometers in diameter, is large enough to damage microelectronic components.
Essential Components and Materials
A complete cleanroom suit system is composed of several integrated components designed to provide total coverage and eliminate exposed skin. The main piece is the coverall, a one-piece garment with full legs and sleeves, often featuring zippers with plackets and tightly fitting cuffs to seal the openings. Separate items include a hood, a face mask, specialized boots or booties, and gloves, all designed to overlap and create a continuous protective shell.
The materials selected for these garments are engineered to be low-linting, minimizing the shedding of their own fibers. Reusable suits are frequently made from continuous filament polyester, sometimes interwoven with conductive fibers, typically carbon, which dissipate electrostatic charges. Electrostatic discharge (ESD) control is important because static electricity can attract airborne dust particles or damage sensitive electronic components. Disposable garments often utilize non-woven materials like Tyvek polyethylene or polypropylene, chosen for their excellent particle barrier and fluid resistance properties.
The Gowning Procedure
The process of putting on the cleanroom suit, known as gowning, is a controlled procedure performed in a dedicated area called the gowning room. The sequence is designed to prevent the transfer of contaminants from the outside world onto the clean garment or into the cleanroom environment. Technicians must first remove all personal items and street clothes before sanitizing their hands.
The order of donning typically begins with items covering the head, such as a bouffant cap and face mask, followed by the main coverall, and then the boots and gloves. The cuffs of the gloves and boots must fully overlap the coverall to maintain the integrity of the barrier. The gowning process often involves the use of a step-over bench to demarcate the “dirty” changing area from the “clean” side where the finished suit is donned. Taking the suit off, or doffing, follows a reverse sequence, which must be performed carefully to avoid re-contaminating the person or the environment.