Today, many companies from the high-tech industry to the explosive arena require Electrostatic Discharge (ESD) flooring. This specifically designed floor has the ability to take unwanted static charges off the human body and safely ground to earth before damaging sensitive equipment or creating an unwanted spark in a highly flammable area. In either case, controlling ESD is essential. Fifty years or more ago, conductive flooring was developed for hospital operating rooms where explosive anesthesia was used. Today, the electronic industry has tremendous need for controlling ESD.
When a person walks across a floor, depending on what type of floorcovering is installed, he/she can generate several thousand volts of static charge. Many of today’s electronic components can be damaged with less than 20 volts and some as low as five volts. The human body cannot detect or feel a static discharge unless it reaches levels of 2,500 volts or higher. ESD flooring offers the path to ground to eliminate those charges and to keep body voltage potentials at very low levels.
In most electronic manufacturing environments, human body ESD control is facilitated by using wrist grounding straps and/or ESD floors. The wrist strap offers excellent body-to-earth ground connection, but limits movement to the length of the wire in conjunction with the wrist strap. Floors, on the other hand, provide the freedom of mobility, allowing an individual to walk from one point to another within the facility. However, it is recommended that when seated at a workstation, always use a wrist strap as your feet may lose contact with the floor.
Many ESD floors are made of a homogenous PVC tile using a carbon matrix as the conductor from the top of the tile to the bottom. When installed with specially formulated conductive adhesive, the passive floor system can take charges through the tile and follow along the floor to a specified ground point.
The main question to consider for ESD flooring is, “Are you in touch with your floor?” Putting in an ESD floor only offers the path to ground. If you are not connected to the floor, you will not use the total benefit of the floor. Today, you can purchase conductive or ESD shoes that are specially designed to make your body have the direct connection to floor, allowing your body charge buildup to decay directly into the floor. Also, you can purchase heel ground straps or toe grounders that go over your shoe and have a lead that tucks in your shoe or sock to connect you to the grounding device. Both offer good connections to the ESD floor.
Another issue is maintenance of the ESD floor. Dirt is an insulator, and if enough exists between the floor and the foot grounder, your path to earth ground may build up too much resistance and prevent the decay of unwanted body static charges. Therefore, it is very important to keep ESD floors clean and free from any elements on the surface that would act as an insulator. Use neutral cleaners and dry polish as instructed by the floor manufacturer.
Dale Gross is the ESD/International sales manager at Fostoria, OH-based Roppe Corp. (www.roppe.com).