If the carpet is accidentally damaged, the damaged area is easily replaceable without the use of special tools or even the need to install new adhesive. Because carpet tile is durable and also easy to clean, repair and replace, ESD carpet usually offers the lowest cost of ownership among ESD floors.Jim McIsaac, the facilities manager at Brooktrout Technologies, has been using carpet tiles for eight years and has found them to be the most effective solution for his assembly and test areas. Tired of waxing the old vinyl ESD floor, McIsaac switched to carpet tile, which he finds much easier to maintain. To handle motorized forklift traffic, he installed two aisles of heavy-duty rubber tiles in combination with the carpet.As with any of the options, carpet has its disadvantages. Carpet is not wellsuited to accommodate heavy loads, such as forklifts or EMC's 5000 pound computers. Carpet also has a low resistance to chemicals and solvents, which make broadloom carpets a poor choice in areas where wet processes are employed. ESD Rubber
Rubber, the Rolls Royce of flooring materials, meets all of the recommended parameters of ANSI/ESD S.20-20. Like static control carpet, the walking body voltage properties of ESD rubber are low, so a rubber that measures in the dissipative range can be every bit as effective as an extremely conductive vinyl. Additionally, ESD rubber is viewed by many experts as a highly desirable walking surface because it not only performs with grounded footwear, but is highly effective at preventing static in areas where grounded footwear is not or cannot be used—places such as command centers, computer labs and flight towers.The old aesthetic issues have also been resolved. A new version of conductive rubber has the carbon contact points commonly associated with vinyl, with the attractive patterns of a more decorative floor tile. Ergonomically, rubber is a better anti-fatigue floor than either epoxy or vinyl and, like carpet, rubber dampens noise from rolling carts and automatic equipment. Rubber, which is less porous than vinyl, is also easier to clean, wash and maintain. In fact, after a two-year study, Lucent Technologies found rubber to be the easiest ESD surface to care for. Rubber can be washed with neutral cleaners mixed with water; and finishes and buffing are unnecessary. Though its installed cost is the highest among the various options, the total cost of ownership for rubber is low because it is durable and inexpensive to maintain, making it a good choice for companies concerned about the long-term implications of their investment. Nevertheless, despite its many advantages, the initial cost of rubber is substantially higher than some of the other choices. Also, it is important to be sure that the selected rubber is corrosion-free, as certain rubbers are manufactured with too much sulfur, making them a liability in clean-rooms or in places where ESD parts might contact the flooring material. High Tech Companies Turn To A Combination of Materials
To address the diverse needs of their various departments, managers of high tech facilities have begun to combine flooring solutions. For example, Acterna, a manufacturer of network solutions, located in Germantown, Maryland, installed vinyl tile over access floors and a quartz epoxy product in heavy traffic areas. Plexus Corporation, a contract manufacturer in Ayer, Massachusetts, installed conductive carpet tiles in their SMT assembly area then surrounded the carpet with a ten foot perimeter of quartz epoxy to handle the majority of their forklift traffic.Nova Bio-Medical, a manufacturer of medical electronic equipment, located in Waltham, Massachusetts, installed an island of conductive carpet tile over their painted epoxy floor. Most of the workers stand in the island, designated for test and assembly. The island provides an ESD-safe environment and eliminates the ergonomic issues associated with the hard epoxy paint used in the remainder of the building. The island also reduces sound coming from a nearby packaging machine. In the installation process, the carpet tiles
were placed directly over the paint and will be easy to move if layouts change. The installation was done by the Nova employees themselves. Future Considerations
According to the Sematech road map (Sematech is the industry website for the semiconductor industry), ESD will present a major reliability issue for semiconductor manufacturers over the next several years. Ted Dangelmayer, a widely recognized and respected ESD consultant, agrees. In the next five years, Dangelmayer predicts,component sensitivity, which at one time was over 1000 volts, will drop to as little as 25 volts, due in part to new engineering designs. The internal protection devices in the traditional design made the components more robust, but encumbered circuit speed, inhibiting the production of faster, more capable components. According to Dangelmayer, the tradeoff for higher performance devices will be designs that are likely to be more vulnerable to ESD. It stands to reason that more vulnerable sub-components will bring a concurrent need for more ESD-tolerant environments, not only in manufacturing areas, but anyplace where electronic equipment is manufactured, handled or used. That need may be especially acute in places, such as the home office or media room, where people do not wear ESDpreventative footwear. The need for reliable flooring will be particularly important in places where sophisticated electronics are used to protect life, perform secure transactions, protect our airspace or provide mission-critical services. To safely and dependably manufacture, handle or use these faster, more capable electronics, we'll need floors that not only ground out static charges, but robust, reliable ESD flooring surfaces that prevent static events from occurring in the first place. About The Author
Dave Long is a Principle Partner of Julie Industries, Inc., and can be emailed by Clicking Here. Another of his articles, Taking The Mystery Out Of Selecting ESD Floors, appeared in the December 2002 issue of Conformity, and is available at www.conformity.com.  |
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