ASHRAE Journal - November 2019 - 38

CELEBRATING 125 YEARS

History of Cleanrooms
BY PHILIP NAUGHTON, MEMBER ASHRAE

Cleanrooms are areas in which particle concentration and environmental conditions
are controlled within specified limits. The limits of the particle concentrations are
normally set by the requirements of the process occurring within the space so that
contamination of people, processes and equipment can be mitigated. Today cleanroom applications have increased from its early days in hospitals and precision manufacturing to include:1
* Pharmaceuticals/Biotechnology. Preparations
of pharmaceutical, biological and medical products
require clean spaces to control viable (living) and nonviable particles that could impact product sterility.
* Microelectronics/Semiconductors. Feature sizes in
semiconductors are smaller than many molecules, and
controlling the concentration of particles pushes these
cleanrooms to limits of cleanroom technology.
* Flat Panel Display: flat panel display (FPD) factories are some of the largest cleanrooms in the world,
with some cleanroom spaces greater than 2,000,000 ft2
(200,000 m2). New FPD factories are controlling particles and chemical concentrations.
* Aerospace. Cleanrooms were first developed for
aerospace applications to manufacture and assemble
gyroscopes, precision ball bearings, satellites and aerospace electronics.
* Hospitals. Controlling infection during surgery was
the driver for many early contamination control techniques.
* Miscellaneous Applications. Cleanrooms are also
used in aseptic food processing and packaging, micro-

electronic and nanotech applications, medical device
manufacturing, automotive paint booths, crystal, laser/
optic industries, and advanced materials research.
Design of clean spaces covers much more than traditional control of particles concentrations. Controlling
other environmental parameters may also be necessary
to a process within the clean space. Additional factors
may include air temperature and humidity; electrostatic
discharge (ESD); molecular and gaseous contamination;
airflow patterns; air pressurization; sound and vibration.
The objective of good cleanroom design is to maintain
effective contamination control while ensuring required
levels of reliability, productivity, installation and operating costs. Cleanrooms are a specially constructed
enclosed space with environmental control of particulates, temperatures, humidity, air pressure, airflow
patterns, air motion, vibration, noise, viable organisms
and lighting (ASHRAE, 2018).1 Cleanrooms are used in
advanced manufacturing, controlling contamination to
the manufacturing process and in medical operations
where controlling the spread of infection is of utmost
importance.

Philip Naughton is a senior engineer and energy manager for Applied Materials Inc. He is past chair of ASHRAE TC 9.11 Clean Spaces, and is current subcommittee chair for TC 9.11
Energy Efficiency for Cleanrooms and is ASHRAE liaison to U.S. TAG for ISO 14644 Cleanrooms and Associated Controlled Environments. He also participates in other committees
and industry activities related to cleanrooms.
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ASHRAE Journal - November 2019

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