Cleanroom Terminology
Cleanroom Terminology
A quick reference for terms that come up constantly in cleanroom and ESD specifications.
Particle Count
The number of airborne particles of a given size per cubic meter or cubic foot u2014 the basis for ISO and Federal Standard cleanroom classification.
Protected Area (EPA)
The zone where ESD-sensitive items are handled, requiring grounded worksurfaces, grounded personnel, and controlled material entry.
Outgassing
The release of volatile compounds from a material over time u2014 a real concern for cleanroom-grade plastics, adhesives, and packaging materials near sensitive processes.
HEPA / ULPA Filter
High- and ultra-low penetration air filters that remove the large majority of airborne particles down to a specified size, forming the core of most cleanroom air handling systems.
Air Changes Per Hour (ACH)
How many times the entire volume of air in a room is replaced with filtered air each hour u2014 a major factor, alongside filter efficiency, in maintaining a room's particle classification.
Laminar Flow
Air moving in parallel, unidirectional layers rather than turbulent mixing u2014 used in the cleanest classified areas because it sweeps particles away from the work zone instead of recirculating them.