Guide To ESD Flooring Materials
Vinyl is the oldest effective ESD flooring material. The best ESD vinyl floors are called solid vinyl tile or SVT. Properly maintained SVT vinyl is attractive and can give a facility that hospital look of cleanliness and shine. And because the material is relatively inexpensive, vinyl can be a cost-effective ESD flooring choice.
Facilities managers often favor vinyl floors because vinyl has a reputation for being inexpensive, simple to repair and easy to clean. The high quality vinyl manufacturers, aware of the need to contain cleaning costs, have developed true no-wax ESD vinyl floors. This doesn't mean they can't be waxed with static control floor finishes; but unlike cheaper SDT tiles, a good conductive SVT doesn't need waxes in order to eliminate static. They usually recommend cleaning methods that steer clear of finishes, polishes or waxes. High speed buffing, or what maintenance professionals call "burnishing," is the method most often recommended for cleaning. Using heat from the buffing equipment, burnishing melts and then reseals the floor. A lower cost alternative to burnishing is low speed buffing using a static control spray buff formula. This maintenance method gives the facility manager the best of both worlds; a reflective high shine floor and an ESD walking surface that meets the most stringent ESD specs. Handled properly, the maintenance of a high quality SVT conductive tile should cost less than carpet and only marginally more than rubber.
A recent break-through in technology has made it possible to install conductive SVT over old floors like VCT and epoxy. The use of low VOC conductive pressure sensitive adhesives now allows some ESD tile to be installed on top of most types of old floors. Before moving forward it is important to make sure that the new floor will not shrink. Before buying any vinyl tile, ask the supplier where it was manufactured. Typically, any tile made in North America, will be free of heavy metals, will not shrink and will also meet all standards for squareness and electrical properties.
Epoxy has matured to become a viable, high quality ESD flooring option. Today's epoxies are easy to install and maintain, durable, and also attractive. Along with the solid-colored coatings typically used in parking garages and aircraft hangars, the new breeds of epoxies are available in patterns as well as in multiple colors and textures. The use of multiple layers of conductive materials as part of the overall thickness of a coating provides redundant paths to ground so that, installed properly, epoxies are highly effective in meeting all necessary ESD standards.
In facilities where constant heavy loads and high traffic are the norm, epoxies are almost the only practical flooring material. Take the case of EMC Corporation in Franklin, MA. In order to identify the best looking, most durable product for their facility, EMC performed a robotic durability test, called "Project Einstein," on the various flooring materials and products. As part of the test, EMC rolled their 5000 pound computers throughout the manufacturing area, destroying then repairing the different vinyl and rubber materials. The only flooring material the computers didn't destroy was a quartz loaded epoxy. However, the upside of epoxy is also its downside: the floor is ruggedly hard and allows sound to echo throughout the facility.
In addition to ergonomic considerations, facilities managers should understand that the color of an epoxy floor is not one hundred percent stable. Over time, exposed to ultraviolet rays, epoxy has been known to yellow or haze. Repairs are always conspicuous because the newly coated areas never match the adjacent aged surface. Also, because of the rigidity and shiny sleekness of its surface, epoxy can present noise and slipperiness issues. Another, perhaps larger problem with epoxy is that you don't know for sure what you have or what it will look like until after the floor is installed and fully cured. To avoid field errors, some epoxy suppliers install several test patches at the factory immediately after blending the material.
Static Dissipative Carpet Tile
At one time, carpet manufacturers believed that, to solve ESD problems, they had only to find a way to prevent people from getting shocks when they walked across the carpeted floor. Incorrectly, they thought that, by preventing static buildup on the people who touched the components, the possibility of wiping out computer equipment would be reduced. To a certain extent, they succeeded in meeting their goal. By using anti static additives or tufting the carpet with carbon bi-components, housed inside the core of the yarn fibers, they were able to prevent static shocks. However, because the carbon bi-components were insulated from the exterior surface of the carpet and lacked contact points, the static dissipative properties of the carbon were rendered ineffective. The resulting products, while ideal for residential and generic commercial applications, did not meet the standards of the ESD industry for the manufacturing and handling of electronic components.
Static control carpet has come a long way since the days of the so-called "computer grade" carpet. Today, in the tufting process, heavier denier carbon fibers can be woven into the yarn bundle, creating an almost indefinite number of contact points, thus providing a fast and reliable path to ground. Because of the heavier denier fiber, the new generation of "ESD carpet tiles "can also withstand the punishment of high traffic areas. Because they are easy to install and remove, carpet tiles are a popular choice among facilities managers, installers and maintenance people. Carpet tiles are installed with clean, fast-drying release adhesive. And the tiles can be installed directly over old VCT or uneven concrete, which lowers the cost of installation. 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 a tremendous amount of flexibility.
At one time carpet tiles had to be installed monolithically. In layman's terms, a monolithic installation means that the tiles are all oriented in the same direction. When new, a monolithic installation looks absolutely seamless - almost like the entire area is comprised of one large piece of carpet. This type of installation looked great until a tile required replacement. The new tile stood out, appearing like a different color than the existing installation - even if the new tile was taken from a carton of leftover tiles from the original batch. This deficiency became more apparent as an installation aged. Usually by the 4 to 5 year mark, a monolithic installation would appear like a checkerboard due to the patchwork from mingling new and old tiles. All that has changed. Carpet tiles like Shadow FX SDC Patterns are produced with random non-directional (RND) design. From day one, the tiles are installed with no concern for orienting the grain, direction or pattern. The result is an the overall visual appearance that looks like a field of grain - a collection of subtle textures with no evidence of delineation from one spot to the next. When RND tile are replaced it's nearly impossible to distinguish the new tile from the old ones. This technological enhancement makes static dissipative RND tiles an ideal value for a manufacturing or assembly environment. The obvious increased lifecycle advantage to RND designs is the reason high traffic public spaces like airports have embraced RND designs around the world. RND technology adds close to 40% to the lifecycle of carpet tile.
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 an SDT dissipative 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 EC rubber tiles in combination with the carpet. As with any of the options, carpet has its disadvantages. Carpet is not well suited to accommodate heavy loads, such as forklifts and pallet jacks. Carpet has a low resistance to chemicals and solvents.
*This article originally appeared in the November '03 issue of Conformity Magazine.