The Evolution of Cleanrooms

For a great many businesses today, managing contaminants is an ongoing problem—and it’s one that is absolutely vital for mission-critical tasks. This is especially true for businesses that manufacture delicate, highly precise electronics or process biomedical materials, as products of this nature can easily become ruined and rendered unusable due to adverse elements in the immediate environment.

To cope with this problem, businesses in these industries typically use what are known as cleanrooms. In essence, these are controlled environments that have been specially engineered to minimize the concentration of pollutants in the air, which keeps delicate materials from being damaged by microbes and/or particulate matter commonly found in buildings.

The cleanroom, in its present state, is the result of a long process of development, guided by a number of independent actors over a period of several generations. Below we’ll take a tour of the history of cleanrooms—but, first, let’s look at cleanrooms in more detail. What will you find in an average cleanroom? How do they work? How do they stay “clean”? Keep reading for answers to these and other questions.

Cleanrooms: The Basics

A cleanroom is designed to minimize airborne pollutants such as dust, vapors, and microbes. The degree to which pollutants are reduced depends on the specific cleanroom and the materials handled within it; a room where microprocessors are manufactured will require a maintenance standard different from a room that handles sensitive vaccines, for example. These maintenance standards have been determined and disseminated by the International Standardization Organization (ISO), which assigns grades to cleanrooms depending on their acceptable concentration of pollutants.

To keep the area free from unacceptable concentrations of pollutants, cleanrooms carefully regulate air flow via a variety of mechanisms. Among these are High Efficiency Particulate Air (HEPA) filters, which are constructed to remove at least 99.97% of particulate matter that passes through them.

With these measures in place, it would seem that cleanroom maintenance would be a fairly simple matter, but, in fact, it is astonishingly easy to introduce contaminants into these areas, and, as a result, it is vital for persons in these environments to be vigilant at all times to guard against this possibility.

People who are unfamiliar with cleanrooms tend to be surprised at a wide variety of pollutants that can alter the composition of the air flow. Cosmetics and perfumes can wreak havoc inside cleanrooms. Jewelry is capable of carrying pollutants into the area. Mold is sometimes accidentally introduced into the room on boxes and markers. Even an employee with foot fungus may pollute the air in the room.

The ease by which cleanrooms become compromised means that employees must take unusual measures to keep contaminants from entering the environment. Typically, employees must wear special clothing designed for use in cleanrooms, and they’re often expected to pass through an air shower to remove all pollutants that they may be carrying.

How did we arrive at the modern cleanroom? As previously noted, it’s the result of a very long process, so let’s explore this evolution below.

The Discovery of Contaminants

The latter half of the 19th century brought a number of momentous discoveries, not the least of which was the development of the germ theory of disease due to the efforts of Louis Pasteur, Robert Koch, and a number of other eminent scientists. This confirmed what many had long suspected: that diseases were caused by microorganisms invisible to the human eye.

Once this discovery was properly understood, it followed that the handling of biomedical materials had to be undertaken with great care in order to prevent contamination. Even materials that “looked clean” might still carry dangerous pollutants. This was one of the discoveries that inspired the later invention of the cleanroom.

The Problem of Miniaturization

It wasn’t until World War II that the drive to create “clean” environments really became an urgent matter. The unique pressures of wartime have resulted in a number of technological innovations that found later use in times of peace, and the cleanroom can count itself as yet another of these.

The cleanroom we would recognize today did not come along during WWII, but this period saw significant advances in miniaturization, as it became possible to fit smaller devices inside ever more complex systems and equipment. This markedly increased our technological capabilities as a whole. It also introduced a new type of manufacturing hazard.

The advent of micro-technology meant that these increasingly delicate parts could be ruined by even very tiny amounts of foreign matter, such as specks of dirt and even smaller particles. Therefore, it became necessary to figure out how to manufacture these kinds of products without exposing them to fine particulate matter.

Willis Whitfield’s Invention

In response to these various pressures and problems, the cleanroom as we know it finally came into being in 1962. It was the brainchild of physicist Willis Whitfield (1919-2012), who worked at New Mexico’s Sandia National Laboratories. His idea basically involved setting up a room that blew in a continuous, steady stream of fresh air through filters to prevent impurities from entering the environment.

The initial tests on Whitfield’s cleanroom returned data beyond anyone’s expectations—there were virtually no contaminants detectable. In fact, the cleanroom proved to be literally about one thousand times cleaner than any other solution, and some observers at the time were convinced that the numbers had to be inaccurate. Subsequent testing, however, only verified the astonishing effectiveness of the cleanroom.

On November 24, 1964, U.S. Patent No. 3158457 for the “Ultra-Clean Room” was issued to Whitfield. This invention, originally intended for nuclear facilities, soon led to a revolution of sorts in various industries; within a few years, no less than $50 billion was spent to construct cleanrooms across the globe. Whitfield was even nicknamed “Mr. Clean” in the pages of TIME Magazine.

Although Whitfield’s basic design remains in use today, the cleanroom has gone through modifications over the years. For example, U.S. Patent No. 3638404 (“Vertical laminar-flow clean room of flexible design”), assigned to the Westinghouse Electric Corporation in 1972, introduced a number of important alterations to cleanroom construction. In addition, U.S. Patent No. 6679672 (“Transfer port for movement of materials between clean rooms”) was granted in 2004; this innovation allows products to be safely transported from one cleanroom module to another.

Cleanrooms Today

The use of cleanrooms is expected to increase in the coming years. To a large degree, this growth will be driven by continuing advances in miniaturization, which makes it more vital than ever to maintain properly engineered cleanrooms to prevent tiny particles from damaging delicate parts and materials.

As noted earlier, the cleanroom was initially developed for nuclear facilities, but today it has found a home in a number of very different industries.

Sources

1. https://www.iest.org/Standards-RPs/Recommended-Practices/IEST-RP-CC001

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