Did you know that the concept of contamination control originated as early as the medieval period and on a slow boat from China?
However, it was during the 20th century — and the subsequent race to space — that brought about the need for precision manufacturing in clean environments, and the idea for the modern cleanroom was born. Here, Michael Rodd, Chief Sales Officer at M+W Products explores the journey of development and also discusses pointers to the future for cleanrooms.
Where did it all start?
Securing the environment has been the driving force in the pioneering development of the concept of the cleanroom. It may be hard to imagine, but man’s attempt to create as near a perfect and pure working environment can be traced back to Chinese lacquer work painters of centuries ago. They crafted the forerunner of what we now refer to as laminar air flow benches in order to produce lacquer work designs. Their version required sailing out to sea in what are commonly known as junks (or djonks) — traditional sailing ships that are still used today — in order to work under the cleanest environment, far away from the contamination in workshops in the busy and polluted life experienced on land.
However, the first conscious effort to control an environment harks back to the less than ideal conditions of nineteenth century operating theatres and hospitals. British surgeon Joseph Lister was the first person to pioneer the idea of antiseptic surgery after reading Louis Pasteur’s work on wine being soured through microorganisms in the air. By using carbolic acid to wash his hands, Lister experimented it on wounds and equipment and noticed that it began to reduce infection and eliminate bacteria. By 1867, in a time where there were no gloves on the surgeon’s hands, Lister began to offer sterile techniques to his patients.
From those formative days of what we regard as surgery, the accepted format of cleanrooms goes back to the dawn of the 20th century and the commercial imperatives driving manufacturing processes. The industrial revolution in Europe was a catalyst and innovative processes were rapidly deployed to develop controlled facilities in factories to reduce contamination on the manufacturing belt. One such example includes dust filters employed on bearings and gears on the first aircraft instruments. As a result, controlled assembly areas were built.
It is the development of clean air environments that produced the demand for a cleanroom.
In his book Cleanroom Design, William Whyte states that it was during World War II that industrial manufacturers in the U.S. and U.K. developed the first cleanrooms to improve the quality and reliability of instrumentation used in weaponry, tanks, and aircraft. With this in mind, the high-efficiency particulate air (HEPA) filter was introduced, which Whyte states was the start of what would become the cleanroom. The original HEPA filter was used during America’s development of nuclear capabilities in the Manhattan Project, to prevent the spread of airborne radioactive contaminants. The government realized that exposure to radiation could be lethal for scientists and so the filter was able to vacuum tiny radioactive contaminants. HEPA filters were introduced commercially in the following decade to eliminate contamination from the air in buildings.
All of these periods point to innovations that have had an effect on how the modern day cleanroom came about.
The first actual cleanroom
In 1962, the modern cleanroom was adopted by American physicist Willis Whitfield, who wanted to remodel the Manhattan Project to remove dust particles that caused reliability and quality issues within nuclear weapon components.
Whitfield’s brainwave was to create a room that would continuously circulate air in through the ceiling, down and out the floor, and then back up to the ceiling again, using gravity to extract particles where they would be filtered out and sent into an exhaust system. By installing HEPA filters, Whitfield’s system was able to keep the levels of dust and other particles incredibly low within an enclosed room.
Whitfield’s invention worked so well, in fact, that many found it difficult to believe his results. To put it into perspective, Whitfield’s cleanroom technology was about a thousand times more effective at removing particulates from the air within closed spaces than anything previously created. Controlling the environment had advanced from applying filters on components to creating an environment that could be self-sustained. This design allowed over 600 air changes per hour compared to 20 air changes per hour of previous clean, air conditioned rooms. To Whitfield himself however, the idea was not revolutionary. “The idea was so simple, that some place, some time, somebody must have had this idea before,” Whitfield said in a media interview. Although this initial enclosure couldn’t hold much more than an adult human body, the stage had been built for the cleanroom to come of age. He called this the “laminar flow cleanroom.”
In 1964, Whitfield patented his technology under U.S. Patent No. 3158457 entitled “Ultra-Clean Room,” which stated that the invention provided air that is 100 times cleaner than that found within other enclosures or cleanrooms at that time. The system completely circulated air within a certain capacity at a rate of about ten air changes per minute.
Within just a few years, Whitfield’s invention was shared by the government and became used for a variety of industrial applications, from medical facilities to research laboratories to electronics manufacturers. The National Inventors Hall of Fame profile on Whitfield reports that nearly $50 billion in cleanroom technology investment occurred within a few years of the innovation. Additionally, amazing improvements were achieved in the quality of medical procedures through a significant reduction in the rates of infection. In the manufacturing sector, organizations could now produce complex machinery like engine transmissions with a much greater service life.
The next step
Following Whitfield’s original concept, the next significant technological leap came at the end of the 1980s when Siemens needed a cleanroom that could contend with something higher than a Class 10. Instead of a large “ballroom”, the solution changed to be called ”local cleanrooms” which were designed to hold individual production stations. Siemens had to make sure that no contaminants could be transferred to their chips during transport from one local cleanroom to the next, especially when loading and unloading. This requirement led to the next major change in cleanroom design.
What does the future hold?
The latest technological innovations related to cleanrooms show us that development is still being pursued more than 50 years after the first cleanroom clothing was developed, although much of the innovation deals with improved equipment for individuals working within a cleanroom environment as well as important procedures for the operation of the cleanroom.
Further developments in contamination control were introduced through good housekeeping practices, by segregating the work area from other manufacturing operations, and by providing a filtered air supply, including protective clothing for workers and personal cleaning equipment such as air showers. The velocity of air in an air shower must be specific so that high velocity can be inputted and the same volume of air can be removed from the system in the floor. Nowadays, most air showers are built on air locks and comprise of an alarm that triggers if someone tries to leave the containment prior to its completion. Air showers involve standing in containments, with arms lifted, whilst jets of air turn slowly 360 degrees.
All personnel operating in cleanrooms are encouraged to maintain hygiene, receive periodic re-indoctrinations and wear protective garments. Most garments are made from fibers that produce little or no particle emission of itself, and be created using a minimum of seams and the absence of pockets.
Even with such advancements in contamination control, there is more work to be done.
For example, when considering clothing, anyone working in a cleanroom has to change frequently. This costs time and money. This has led many to ask the question: what if the clothing could remain uncontaminated throughout the entire process, mainly as people tend to be the biggest contaminants? A potential solution being worked on is called “photodynamic disinfection.” With no negative impacts on the human body, photodynamic disinfection is a way to develop a highly disinfectant affect that destroys microorganisms in minutes. In order to achieve this, a suitable lighting technology is required which assures that light can penetrate into difficult areas of clothing such as folds or seams.
Another development includes the construction of transportation facilities of cleanroom equipment. Wagon trolleys using filters to contain the air within capsules have been designed to improve logistics and distribution of cleanroom apparatus. These innovations have an expounded interest within the food and medical industries as well as cleanrooms.
Over the past year, there has been a clear shift in the way laboratory users want their cleanrooms to be designed, not only to meet current needs, but to future proof them for years to come. In fact, the finish has become just as important as the function. There is increasingly a focus on achieving a ‘showroom’ finish in cleanrooms. This is due to the demands for the best quality working environment. Robustness of technological systems has taken center stage.
And, finally …
At NASA, cleanrooms became important fixtures as work was conducted to build spacecraft during the 20th century space race and beyond. Cleanrooms are instrumental in the research and development programs that have produced the technology that surrounds us today and they are essential in the manufacture of many modern devices.
Cleanrooms are not your everyday purchase; they have a very specific purpose — to control and remove contamination. To this end, the main infrastructure, as developed by Willis Whitfield, has largely stayed the same over the last 50 years, although clearly innovations have happened along the way. The cost of such investments can also be treated in different ways by commissioning organizations.
A cleanroom is often a significant capital expenditure since it includes the major purchase of physical components combined with varying degrees of technology elements (monitoring, controlling etc.) Today modern technologies, material advancements as well as the impact of certain innovations provide the platform for optimal investment planning and efficient operational expenditure. The demands of the cleanroom extend beyond the contamination control requirements more than ever before whereby the influence on the owners’ balance sheet and overhead costs have to be key considerations.
Cleanroom technology today is not only about air, but also gases including outgassing from materials and ultra-pure water through to temperature tolerance and the need to identify locations minimizing the potential for vibrations and other interference to production such as seismic activity. Additionally, in today’s technologically advanced world, the key now is to secure efficient and smart technologies and processes in the cleanroom.
For example, many vendors are making products and controls that will be key to enhancing flexibility and sustainability in cleanroom facilities, and many of these systems are getting so complex and subtle in terms of how they will react to the building and its technologies. By concentrating efforts on the equipment and controls, we are able to continue innovating, and more importantly, improve efficiencies and save costs. Here’s to the future!
Michael Rodd is with M+W Products GmbH of Stuttgart, Germany. www.mwgroup.net
This article appeared in the November/December 2015 issue of Controlled Environments.