Static Control Flooring Primer
by David H. Long
Application Chart for Static Dissipative and Conductive Carpet Tile
Download a pdf version of the comparison chart.
We suggest watching this video, "Antistatic Flooring: Electronics Manufacturing Is Different Than Critical Environments" before you begin researching Anti Static and ESD flooring. This video explains the difference in strategies for eliminating static in end user environments (mission critical environments) versus static control in electronics manufacturing environments. These environments are very different and you should not specify flooring based on inappropriate standards for the space you plan to outfit.
As static-sensitive electronic components grow more sophisticated, so do consumers of static-control flooring. Here are some key points to consider when helping your customers to choose such flooring for their home offices and small businesses.
As electronic components become faster and more sensitive to electrical interference, the need for static control has grown exponentially, particularly in mission-critical areas like local 911 call centers or biotech facilities, where the loss or corruption of data can pose a safety threat.
When most of us think static, we think nuisance - static cling or irritating static shocks. But for humans to feel these effects of static electricity, the discharge must be at least 3500 Volts. To put that into perspective, today's sensitive computer parts can be damaged by a static discharge as low as 20 Volts.
Since static electricity is the result of friction between two materials, walking across a floor is the major source of static buildup.
That's why the cornerstone of any static-free environment is static-protective flooring. Fortunately, almost every conceivable floor covering material, including carpet, epoxy, vinyl and rubber, can be manufactured to provide some static-protective properties.
Brooktrout Technologies' installation of ESD Rubber and ESD Carpeting
Before helping your customers select any type of static-protective flooring, it is imperative to understand how the floor will interface with its particular environment and the people working in it.
The first question a buyer or specifier should ask is this: Will the people who walk on this floor wear grounded heel straps and conductive shoes? If the answer is no - which it usually is - then the grounded floor must provide a combination of static dissipative elements and the capacity to prevent or inhibit static build-up.
To prevent static build-up, a static-control floor must meet two basic requirements. It must not contribute to static generation and it must be ground-able after it is installed.
Although these requirements seem basic, in practice they are anything but simple. For example, a 3.5 kV antistatic floor will not generate charges higher than 3500 Volts. However, the typical computer-grade antistatic floor is not ground-able and cannot come close to reducing charges to the minute thresholds necessary to protect today's ultra-sensitive electronics.
Installation of ESD Vinyl on concrete with ESD Epoxy at Acterna (provider of network solutions).
Many static-protective floors are incapable of providing both of these attributes. The fact that a vinyl tile is advertised as "conductive or static dissipative tile" does not necessarily mean that it will prevent static problems in a 911-call center or in a server room. Certain excellent conductors - conductive vinyl, for instance - are comprised primarily of ordinary static-generating materials, such as regular vinyl, with a small distribution of carbon or graphite particles. Although the embedded conductors enable the vinyl floor to be grounded, the floor fails to prevent static build-up. When that same server room is equipped with a static dissipative carpet tile, it is almost impossible to create a harmful amount of static charge - regardless of footwear.
Intuitively, we would assume that static dissipative carpet would be less capable than conductive vinyl, but the opposite is usually true. Static dissipative carpet tiles contain thousands of grounded dissipative fibers that sweep off static and safely discharge it to ground from shoes, much the same way small brushes eliminate static on high-speed copiers as paper is fed into the collator. This does not mean that conductive vinyl is an inferior product. It means that conductive vinyl works best in applications, such as electronic manufacturing and assembly, where footwear and traffic are controlled and monitored.
Static control rubber provides static inhibiting properties similar to dissipative carpet tiles. We know whenever two dissimilar surfaces are rubbed together they generate static. The corollary is also true: Similar materials generate less static when they interact. The base compound used in antistatic rubber flooring sufficiently resembles most shoe soles to the point that it will inhibit static generation. Unlike conductive vinyl, rubber is a naturally low static generator. Like dissipative carpet and vinyl, rubber can be grounded and has many of the same ergonomic properties as dissipative carpet.
Every static-control floor has its attributes and its drawbacks. Carpet, for example, despite its positive ergonomic and charge reduction properties, is inappropriate for many applications. Some areas in electronics manufacturing are constantly wet or can become contaminated with splashes of lead solder or solvents. These areas are best equipped with heavy-duty flooring materials that can be easily cleaned and mopped. Static control rubber, vinyl and quartz-filled conductive epoxies are particularly suitable for these wet, messy areas. That does not meant that adjacent areas can't be carpeted, but it does mean that extra thought should go into the layout and design of the facility. The advent of conductive release adhesive has enabled interchangeability of some flooring materials, such as rubber and carpet. Before installing, it would be wise to ensure that carpet tiles and resilient tiles are modular and compatible with the same adhesive.
Finally, in choosing static-control flooring, buyers should consider the need for permanent static protection and also maintenance procedures and costs. The static-control properties of certain floors wear off, requiring periodic buffing or waxing to maintain performance. Many vinyl tiles are not warranted unless the customer uses special antistatic floor finishes. Any carpet that requires a restoring agent, called an antistatic/stain blocker, should be carefully scrutinized.
Flooring matrix pointing out the various ESD flooring options and properties of each
Before purchasing a static-control floor, buyers must decide whether or not they're prepared to pay the additional cost, which over time can be substantial, of maintaining the floor. They must also consider whether it's prudent to install, in a mission critical area like a flight control tower, a flooring material that requires periodic rejuvenation. After all, static is invisible. How would they know exactly when the static control properties had worn off?
Today, there are static-control floors and styles to meet every flooring consideration and every budget. As with any specialty product, it's easy to be confused by the technical jargon and complicated specifications. Before helping your customers make any decisions, it's wise to identify reputable suppliers who offer a combination of flooring and static control knowledge. Finding a supplier with both skill sets will ensure that the flooring your customer purchases will yield a lifetime of utility. You also help your customers guarantee that their mission-critical operations are safe from the hazards of random static discharge.
© 2007 Compliance Engineering
Dave Long is the President of Staticworx®, based in Newton, MA. He can be reached by phone at (617) 923-2000
or to email Dave.