ESD glossary

ESD glossary

Our comprehensive glossary provides definitions of the most common ESD terms.

0-9

25,000 ohms

An electrical resistance measurement represented by the scientific notation 2.5 x 10E4, or 2.5 x 10,000 ohms. This is the lowest end of the acceptable conductivity range.

For safety reasons, FAA and telecom industry standards prohibit the use of flooring materials measuring below 1 x 10E6 in environments where people work around energized equipment.

See: FAA 019f, Motorola R56, and ATIS 0600321-2015.

A

AATCC 134 Test Method 134

This test method assesses the static-generating propensity of carpets when a person walks across the carpeted area. This test method uses controlled laboratory simulation of conditions that may be encountered in use, focusing on conditions known to be strong contributors to excessive accumulation of static charges. This test is valid for specifications requiring compliance to static-control standards like ANSI/ESD S20.20, FAA 019f, Motorola R56 and EN 61340-5-1

Actual Current

Voltage applied to a material generates an electrical current across the surface of the material. The electrical resistance of the material determines how well or poorly the material will resist the flow of current (how much current can flow across the material).

Current can be predicted using a formula known as Ohm’s Law. Actual current, which may differ from currents predicted by Ohm’s Law calculations, refers to the actual current measured in laboratory tests.

Ohm’s Law + i=V/r
Current (i) in amps equals voltage (V) divided by resistance (r) in ohms (Ω)

ANSI/ESD S20.20-2014

ANSI/ESD S20.20 covers static-control requirements to protect electronic parts, assemblies, and equipment susceptible to ESD damage from human body model (HBM) discharges ≥ 100 V. Unlike previous versions, the 2014 standard also covers parts with withstand limits of 200 V Charged Device Model (CDM), and 35 volts on isolated conductors.

The 2014 standard requires both resistance and walking body voltage tests.

ANSI/ESD STM97.1-2015

ESD Association Standard Test Method for the Protection of Electrostatic Discharge Susceptible Items – Floor Materials and Footwear – Resistance Measurement in Combination with a Person. This document provides test methods for measuring the electrical system resistance of floor materials in combination with persons wearing static-control footwear.

ANSI/ESD STM97.2-2016

ESD Association Standard Test Methods for the measurement of the voltage on a person in combination with floor materials and static-control footwear, shoes or other devices.

Anti Static Flooring

The term antistatic refers to a condition where static generation is inhibited during contact and separation with another material. Anti static flooring can either be static dissipative or conductive. However, not all static-dissipative or conductive flooring is antistatic. ESD floors can be conductive and still generate enough static to cause a harmful ESD event.

Note: the term antistatic has been replaced by the more accurate term: low charge generating. Low charge-generating materials prevent static from accumulating on people or objects.

Antistatic Bi-component

A type of yarn commonly found in most commercial and household carpets. The term bi-component refers to the co-extrusion of two materials within the same yarn strand. The internal cross-section of the yarn contains carbon while the surrounding fibers are composed of standard insulative nylon. The bi-component yarn provides an overall reduction in static generation—not a path to ground. Because the outer nylon insulates the internal conductive element, bi-component yarns do not discharge or conduct static electricity. Bi-component yarns help prevent static shocks due to static generation from walking on carpet. These yarns cannot be grounded and are not suitable for static control in areas where computers are used.

Antistatic Carpet

The term antistatic refers to a condition where static generation is inhibited when the antistatic material comes into frictional contact with another material—in flooring terms, inhibits static when people walk across the antistatic floor.

When referring specifically to carpet, the term “antistatic” has a slightly different meaning. Antistatic carpet is a generic term referring to any carpet product that generates less static electricity than standard carpet. Antistatic carpet is not conductive and cannot be grounded.

Antistatic carpet usually contains bi-component yarns. The reason for specifying antistatic carpet is to establish a space that will be free of static shocks, or zaps. Most new antistatic carpet will prevent shocks as long as the relative humidity (RH) is above 25%.

Anti static carpets do not offer permanent static protection and should NOT be confused with conductive or ESD carpet.

ATIS 0600321-2015

ATIS 0600321-2015 is a standard set by the Alliance for Telecommunications Industry Solutions: Protection for Network Operator-Type Equipment Positions

ATIS publishes standards for the information, entertainment and communications industries. Here’s the excerpt, from Section 4.2, pertaining to ESD flooring:

“Any carpeting or floor tiles should have a resistance to ground between 10E6 and 10E10 ohms when measured using the method of ESD-S7.1.”

Note: Staticworx does not recommend flooring with electrical resistance above 1.0 x 10E8. Time and environmental changes can affect the performance of ESD flooring materials. If a material measuring ≥ 1.0 x 10E8 were to lose conductivity—the floor dries out over time or relative humidity drops—the floor could become too resistant to discharge static to ground. Floors measuring above 1.0 x 10E9 do not meet resistance parameters outlined in ANSI/ESD S20.20.

Auxiliary Ground

A separate supplemental grounding conductor for uses other than general equipment grounding.

B

Barrier Strip

A device or apparatus that consists of a metal strip and connectors or screws that allow termination and connection of wires or conductors from various components of an ESD-protected workstation.

Body Contacting Mechanism (BCM)

The part of the foot grounder that makes electrical contact with the body.

Building Related Illness (BRI)

Term used by the Environmental Protection Agency (EPA) when symptoms of a diagnosable illness are identified and attributed directly to air quality inside a building. Symptoms may be caused by an allergic reaction to airborne contaminants, and may include cough, chest tightness, fever, chills, and muscle aches, and do not clear up when people leave the building.

Often this condition is temporary, but some buildings have long-term problems. Frequently, problems result when a building is operated or maintained in a manner that is inconsistent with its original design or prescribed operating procedures. Sometimes indoor air problems are a result of poor building design or occupant activities. In contrast to SICK Building Syndrome.

C

Calculated Current

Voltage applied to a material generates an electrical current across the surface of the material. The electrical resistance of the material determines how well or poorly the material will resist the flow of current (how much current can flow across the material).

Current can be predicted using a formula known as Ohm’s Law.

Ohm’s Law + i=V/r
Current (i) in amps equals voltage (V) divided by resistance (r) in ohms (Ω)

Note: Calculated current may differ from the actual current measured in laboratory tests.

Charged Device Model (CDM)

Simulates situations in electronics manufacturing or handling environments when a static-sensitive device becomes charged and discharges to a conductor – e.g., when a device slides down a shipping tube, acquiring a charge, and subsequently discharges to a person or conductive object. CDM tests predict the susceptibility of a device to damage from electrostatic discharge.

Note: CDM should not be confused with Human Body Model (HBM).

Class 0

Class 0 for Manufacturing: Please note – The term Class 0 has not been defined for manufacturing applications by any industry standard.

Surveys have shown that manufacturing failure rates escalate exponentially for devices with ESD-withstand voltages below 200 volts for either Human Body Model (HDM) or Charged Device Model (CDM). MM is intentionally omitted from this definition since it is largely redundant to HBM.

It is vitally important for the manufacturing process to have a well-defined trigger for risk assessments of ultra-sensitive components. These risk assessments involve verification of manufacturing process capability as well as accounting for any risks that may be passed on to customers.

A working definition for a Class 0 device is any component that fails below 200 volts for either Human Body Model (HBM) or Charged Device Model (CDM).

Common Point Ground

(1) A grounded device where two or more conductors are bonded.
(2) A system or method for connecting two or more grounding conductors to the same electrical potential.

Compliance Verification (Periodic Testing) Equipment

An instrument or collection of instruments that provide a periodic indication or measurement to verify the performance of ESD test equipment and materials. Compliance verification equipment is typically used to indicate pass or fail.

Note: As measurements may or may not be repeatable or accurate, these instruments do not meet the criteria for use in the qualification phase of material selection.

Computer Grade Carpet

Computer grade carpet is the predecessor to conductive and static-dissipative carpet. Designed during the infancy of the information age, computer grade carpet contains a high density of bi-component antistatic yarns. Like all antistatic carpet, it cannot be grounded.

The antistatic properties of computer grade carpet are usually described by obsolete commercial standards, such as the IBM/Burroughs standard which grades carpet by its kV rating (see low kV). A carpet specified for use around computers and other electronic equipment should be evaluated by kV rating (walking body voltage) and resistance to ground (measured in OHMS).

Computer-grade Flooring

The predecessor to permanent static-dissipative and conductive flooring, computer-grade carpet contains a high density of bi-component yarns. Sometimes called low kV or antistatic carpeting, computer-grade floors will generate no more than 3500 volts of static electricity. These floors are not ground-able and have no ability to ground a static charge: because they have no conductive or dissipative properties, computer-grade floors cannot be tested with an ohm meter.

Designed to prevent nuisance static and nothing more, they are good ONLY for preventing shocks when people touch metal objects like a doorknob. A 3.5 kV-computer-grade floor is not intended or warranted for reducing charges to the minute thresholds necessary to protect static-sensitive electronic parts and systems.

Conductive

The term “conductive” refers to the ability of a material to conduct a charge to ground. Any floor with an electrical resistance measuring < 1.0 x 10E9 is capable of conducting static charges away from people and objects to ground.

When differentiating between “conductive” and “static-dissipative” flooring materials, materials with an electrical resistance < 1.0 x 10E6 (1 million ohms) are usually considered conductive. Flooring materials measuring between 1.0 x 10E6 and 1.0 x 10E9 are considered static dissipative.

While ANSI/ESD standards do not specify a minimum electrical resistance, for best practices the industry has historically set a minimum of 2.5 x 10E4.

Electrical resistance below 2.5 x 10E4 is considered a potential shock hazard. Floors reading below 1 x 10E6 are prohibited for use around energized equipment by telecom and Federal Aviation Administration standards: Motorola R56 and FAA 019f.

Conductive Adhesive

Conductive adhesive is an electrically conductive glue used to create a mechanical bond between a subfloor and a static-control floor. Installed over the subfloor, the adhesive forms a tacky plane with conductive properties. Copper strips connect the adhesive and flooring tiles to ground, unifying the electrical potential of the adhesive, all floor tiles, and the people and machinery on the flooring surface.

Note: the conductive adhesive should always be more conductive than the flooring material.

Conductive Fibers

Fibers capable of conducting electricity to ground.

Most conductive fibers contain carbon, graphite or stainless steel. Static-dissipative and conductive carpets used in static-sensitive commercial environments are carbon-coated on the exterior of the fiber. External conductivity allows static charges to make contact with the conductive element in the fibers, then safely discharge through the carpet layers to a ground source, such as electrical conduit.

Because conductive elements are incorporated into the material in the manufacturing process, conductivity is a permanent property.

Conductive Flooring

When referring to flooring materials, the term “conductive” is often confused with the term “static dissipative.” Floors are correctly classified as conductive or static-dissipative based upon their electrical resistance to ground. Electrical resistance is measured in ohms (Ω).

The resistance to ground of a conductive floor is usually defined as < 1.0 X 10E6 ohms, measured per ANSI/ESD STM7.1. Conductive flooring meets the required resistive properties (< 10E9 ohms) for a floor complying with the resistance to ground parameter in ANSI/ESD S20.20-2014.

  • Conductive flooring should not be considered as superior to a floor in the static dissipative range.
  • Static-control floors should be selected based on two parameters: Electrical resistance and walking body voltage. While all conductive floors meet the resistance requirements of ANSI/ESD S20.20-2014, some fail to meet the walking body voltage requirement (< 100 volts).

2) A type of flooring intended to prevent, mitigate, dissipate, conduct, remove or ground excessive static electricity charges on people, furniture, mobile carts and equipment.

Note: This generic description is not useful in evaluating static-control flooring materials. Materials should be evaluated based upon their electrical resistance, suitability for the application, and compliance with industry standards.

Safety Considerations

  • Static conductive flooring should not be used near or under energized equipment.
  • Always consult industry standards as well as local building and safety codes before installing conductive flooring.
  • Depending on the application, ground fault interrupters may be required in spaces equipped with conductive flooring.
  • Conductive flooring should never be installed in dispatch areas, call centers or flight control rooms. These spaces require the electrical resistance of flooring materials to measure at least 1.0 x 10E6 or above.

Conductive Flooring Material

A floor material that has a resistance to ground of less than or equal to 1.0 x 10E6 ohms.

Note: Conductivity does not guarantee low charge generation. A conductive or even highly conductive floor can generate enough static to damage or destroy sensitive components. To prevent static, flooring materials must measure in the required resistance range and either be low charge generating or used in conjunction with special ESD footwear.

Conductive Material

A material with a surface resistivity less than 1 x 10E5 ohms/square or a volume resistivity less than 1 x 10E4 ohm-cm.

Note: “conductive flooring material” is not the same as “conductive material.” Standards for ESD flooring are different from standards for other conductive materials.

Conductive Tile

A floor tile material used for the mitigation of electrostatic discharge (ESD) composed of carpet, rubber, epoxy, paint or vinyl composition tile. Conductive tile meets the same electrical parameters as “conductive flooring.” Conductive tiles are used with conductive adhesive or a conductive underlayment and grounded to either earth ground or electrical ground.

Note: Static-dissipative floor tiles are also conductive and ground static charges. Whether static-dissipative or conductive materials are preferred for a specific application depends on a combination of factors, including: electrical standards for the particular industry (standards vary across industries); the material composition; charge generation; and what type/s of footwear will be worn in the space.

For safety and optimal performance, Staticworx recommends flooring materials that measure in the electrical resistance range we call the “Sweet Spot.”

Conductivity

(1) The ratio of the current per unit area (current density) to the electric field in a material. Conductivity is expressed in units of siemens/meter.

(2) In non-technical usage, the ability to conduct current.

Conductor

A material with low electrical resistance (a conductor) that will effectively attract and transport an electrical charge to ground.

Examples of conductors are water, copper, aluminum and carbon. Practical examples of conductors are a lightning rod and a copper wire.

Current Limiting Resistance (in a wrist strap)

A resistance value incorporated in series with the wrist strap’s electrical path to ground. This built-in resistance limits electrical current passing through the ground cord in the event of inadvertent user contact with electrical potential.

D

Decay Time

The time required for an electrostatic potential to be reduced to a given percentage (usually 10%) of its initial value. (See Federal Test Standard 101C, Method 4046).

Dielectric

An insulating material that can sustain an electric field with little current flow.

Dielectric Strength

The maximum electric field that a dielectric can sustain.

Discharge Time

The time necessary for a voltage (due to an electrostatic charge) to decay from an initial value to some arbitrarily chosen final value.

Dissipative Floor Material

Floor material with a resistance to ground above 1.0 x 10E6 and less than or equal to 1.0 x 10E9 ohms.

Note: For safety reasons, industry standards for telecommunication spaces, 9-1-1 mission-critical operations, and flight control towers require dissipative (as opposed to conductive) flooring materials, with electrical resistance measurements above 1.0 x 10E6.

See Motorola R56, ATIS-0600321.2015, and FAA 019f.

Dissipative Tile

A floor tile material used for the mitigation of electrostatic discharge (ESD). Usually composed of carpet, synthetic rubber or vinyl composition.

It is important to differentiate between the terms “SDT” and “static dissipative.” A static dissipative floor tile inherently meets the electrical properties of “static dissipative flooring” – without the use of antistatic waxes, finishes and glazes.

Floors are classified as static dissipative based on their electrical resistance. Dissipative materials measure > 1.0 x 10E6 and ≤ 1.0 x 10E9 ohms. Dissipative tile meets the required resistive properties (< 10E9 ohms) for a floor complying with the resistance to ground parameter in ANSI/ESD S20.20-2014.

Note: All static-control floors should be selected based on two parameters: Electrical resistance and walking body voltage. A dissipative floor tile can meet the resistance requirements of ANSI/ESD S20.20-2014 but fail to meet the walking body voltage requirement (< 100 volts.)

DOP or DEHP (Di(2-ethylhexyl)phthalate [bis(2-ethylhexyl)phthalate)

The Chronic Hazard Advisory Panel on Phthalates and Phthalate Alternatives (CHAP) found that exposure to Di(2-ethylhexyl)phthalate [bis(2-ethylhexyl)phthalate (DEHP) may negatively impact human reproduction and fetal development. DEHP has been permanently banned in children’s toys and child care articles at levels greater than 0.1%.

“CHAP recommends that U.S. agencies responsible for dealing with DEHP exposures from all sources conduct the necessary risk assessments with a view to supporting risk management steps.” (CPSC.gov)

E

Electrical Resistance

Electrical resistance describes the capacity of a material to stop, or resist, the flow of electricity. We use resistance tests, measured in ohms (Ω), to predict how quickly or slowly an ESD flooring material will transport static charges to ground.

For safety and optimal performance, Staticworx recommends flooring materials that measure in the electrical resistance range we call the “Sweet Spot.”

Electrification Time

The time for the resistance measuring instrument to stabilize at the value of the upper resistance range verification fixture.

Electrostatic Discharge (ESD)

The rapid, spontaneous transfer of electrostatic charge induced by a high electrostatic field.

Note: Usually, the charge flows through a spark between two bodies at different electrostatic potentials as they approach one another. Details of such processes, such as the rate of the charge transfer, are described in specific electrostatic discharge models.

Electrostatic Discharge Ground

The point, electrodes, bus bar, metal strips, or other system of conductors that form a path from a statically charged person or object to ground.

Electrostatic Discharge Sensitivity (ESDS)

The ESD level that causes component failure. (Note: See also electrostatic discharge susceptibility.)

EMI

(Electromagnetic Interference) – the transmission of a rogue electrical signal, caused by ESD, and received by a computer or electrical device. EMI has the potential to cause disruption and downtime. An example of EMI is the static interference you may hear over an automobile radio (caused by lightning) when you drive in the vicinity of an electrical storm.

EOS/ESD Association

(Based in Rome, NY) – Four thousand members representing the largest trade association for the ESD issues. The association assists in writing and setting industry standards and test methodologies and publishing the latest research and technology on ESD.

ESD

The abbreviation for electrostatic discharge.

In layman’s terms: an electrical event that takes place when two objects with different electrical potential make contact or are positioned closely enough for a spark to discharge from one surface to another. ESD events occur when people walk across various forms of flooring, then touch or approach computers and other static-sensitive electronic devices.

ESD should not be identified solely by shocks or zaps. Although shocks and zaps are ESD events, they are the result of at least thirty-five hundred (3500) volt discharges. An ESD event as low as 20 volts can disrupt electronic components. Because of this extremely low voltage, an event can go completely undetected.

ESD Carpet Tile

A modular floor tile comprised of conductive/dissipative carpet and a conductive/dissipative backing, used to control the accumulation of static electricity on people, chairs and tables.

To meet the requirements of industry standard ANSI/ESD S20.20, ESD carpet tiles must have an electrical resistance ≤ 1.0 X 10E9 ohms and generate ≤ 100 V static charges on people walking on the floor.

Designed to prevent static generation and provide an electrical path to ground, ESD carpet dissipates unwanted static charges in applications where electronics are stored, manufactured, handled or used.

ESD carpet tile is usually manufactured using conductive fibers woven into the carpet face. ESD-grade flooring materials remain conductive/dissipative at any relative humidity level.

Not to be confused with computer grade or low kV carpet materials.

ESD Event

(A static discharge or spark) ESD events range across a broad spectrum—from microscopic discharges far below the threshold of human sensitivity to violent static shocks like the ones you may feel when you touch a metal door handle on a dry day.

ESD events far below the human threshold for perception—static charges humans cannot see, hear, or feel—can damage sensitive devices and cause disruption or loss of operational data.

In work environments, most ESD events are caused by the static generated when people walk, called walking body voltage.

ESD Floors

This is a catch-all term for any type of floorcovering with antistatic or conductive properties.

This descriptor is usually used during the investigative phase of static-control flooring materials. Referring to a conductive or dissipative flooring material as an ESD floor is not a sufficient reference for defining certifiable and quantifiable electrical properties.

The proper way to specify a flooring material intended for use in sensitive electronic environments requires stating resistance to ground (ohms) and charge generation characteristics (walking body voltage).

Electrical resistance is tested using ANSI/ESD Standard Test Methods 7.1 and 97.1 (system resistance). Charge generation is tested using ANSI/ESD Standard Test Method 97.2.

ESD Protected Area (EPA)

Areas where sensitive electronic parts are handled, requiring special ESD protection.

Electronics manufacturing and handling facilities have designated EPAs, where static-control measures are in place and stringently enforced – including the use of special ESD footwear – following protocols outlined in ANSI/ESD S20.20.

ESD Protective

A property of materials capable of one or more of the following: preventing the generation of static electricity, dissipating electrostatic charges over its surface or volume, or providing shielding from ESD or electrostatic fields.

ESD S7.1

The ESD Association Standard 7.1 – “Resistance Characteristics of Materials.” A generally accepted test method used to determine conductivity of flooring and other material surfaces.

ESD Withstand Voltage

The maximum voltage (static discharge) that does not cause component failure.

Evaluation Testing

Stringent testing of a wrist strap (a personal grounding device used in a static control program) to determine its electrical and mechanical performance abilities. Data are in the form of values from laboratory testing.

Excessively Porous Subfloor

Any subfloor surface that has an extremely rough surface, such as concrete that has recently been shot-blasted, scarified or mechanically etched. Also, any subflooring that has leftover residue of old latex adhesive, recent skimcoat or cementitious underlayment application, rough wood subflooring, etc.

Such subfloor conditions can over-absorb adhesives and create bonding issues and lead to the necessity of using sealers or a greater amount of adhesive to properly adhere floorcoverings.

F

Failure Threshold

The supply current value that, when exceeded, causes device failure is called the Failure Threshold Current.

Floor Contacting Surface (FCS)

That part of the foot grounder that makes electrical contact to the grounding surface.

Flooring/Foot Grounder System Resistance

The total resistance of the ESD flooring system, including the foot grounder, person and floor, when measured according to ESD STM97.1, with a person standing on a static control floor.

To meet ANSI/ESD S20.20, system resistance must measure > 1.0 x 10E9.

Foot Grounder

Personnel grounding device, including toe, heel and sole straps or ESD shoes, worn to provide electrical continuity from a person’s body to a grounded floor.

Foot Grounder System Resistance

The measure of the total resistance of the foot grounder when worn by the person standing on a stainless steel plate.

G

Ground

In electrical terms, ground is the safe point of discharge of unwanted static electricity. Ground represents “zero electrical potential.”

When something is grounded, it’s neutral; it has no charge. Attaching a conductive floor to ground ensures that static charges will be diverted to earth through the conductive flooring system. Typical grounds include: electrical conduit, building steel, copper bus bars and steel rods buried in the earth.

Ground Lead

The portion of the wrist strap, which provides flexibility of movement while completing the electrical circuit between the cuff at one end and a ground system at the other.

Ground Strap

(1) A conductor intended to provide an electrical path to ground.

(2) An item used by personnel with a specified resistance, intended to provide a path to ground.

Groundable Point

A designated connection location or assembly used on an electrostatic discharge protective material or device that is intended to accommodate electrical connection from the device to an appropriate electrical ground.

Groundable Point ESD Protective Floor Material

The electrical connection—e.g. grounding bolt, snap, wire or conductive adhesive or underlayment, used to attach the flooring material to an appropriate electrical ground.

Grounded Floor

Any floor with dissipative/conductive properties that is attached to either electrical or earth ground.

Grounding of conductive or static-dissipative floors is usually achieved by physically attaching the ESD flooring material— conductive or dissipative epoxy coating, conductive or dissipative carpeting or carpet tiles, conductive or dissipative vinyl tiles or sheet goods, conductive or dissipative rubber tiles or sheet goods—to a certified ground connection using copper strips or grounding wires.

The most common methods of grounding involve the combination of conductive adhesive, for securing the floor and electrically unifying all tiles in the installation, and copper strips attaching the adhesive to the electrical ground connection in a building.

Grounding Resistance

The total resistance from any given point in an electrically conductive path to the grounding electrode.

H

Hard Ground

A connection to ground through a wire or other conductor that has very little or nearly no resistance (impedance) to ground.

Heel Straps

Made of conductive material, heel grounding straps cup the heels of the shoes. An attached ribbon tucks into the sock, making contact with the skin, forming an electrical bond or bridge between the wearer’s body and the carbon veins in the static-dissipative or conductive floor, discharging static to ground.

Used in conjunction with floors—such as static-dissipative or conductive vinyl—that are not made of low-charge-generating materials, grounded heel straps prevent static from accumulating when people walk.

(Some people tuck the conductive ribbon into their shoes, as opposed to the socks, in which case the ribbon makes contact with the sweat inside the shoes.)

Human Body Model (HBM)

An electrostatic discharge circuit that meets the set model values by conforming to waveform criteria specified ESD-S5.1, characterizing the discharge from the fingertip of a typical human being.

Human Body Model Electrostatic Discharge (ESD)

An electrostatic discharge event meeting the waveform criteria specified in ESD S5.1, approximating the discharge from the fingertip of a typical human being.

Human Body Model Electrostatic Discharge Tester

Equipment that applies Human Body Model electrostatic discharges to a component.

Human Sensitivity

The threshold of human sensitivity to electrostatic discharge is approximately 3.5 kV. A discharge of only 500 volts, too minute for humans to see, hear or feel—or as low as 20 volts for ultra-sensitive high-speed electronics—can corrupt data and damage or destroy static-sensitive components.

Humidity Dependence

Environmental or relative humidity (RH) can affect the performance of conductive adhesives and many ESD flooring materials.

When humidity is high, the adhesive or flooring material absorbs moisture and becomes more conductive; when RH is low, the adhesive or flooring material loses moisture and can become less conductive. To avoid fluctuations due to relative humidity, always test the floor in question in a humidity chamber at no higher than 12% RH for at least three days.

I

IBM Burroughs Standards

An outdated ESD standard designed to minimize static electricity in data centers. According to this standard, floors must measure above 150,000 ohms (1 x 10E5) for use in data centers and server rooms.

While the test is outdated, the resistance minimum is now a universally accepted practice across the ESD industry.

Impedance

The total opposition (i.e., resistance or reactance) a circuit offers to the flow of alternating current. It is measured in ohms and the lower the ohmic value, the better the quality of the conductor.

For ESD flooring materials, high conductivity alone is not a measure of quality. In end-user environments, such as 9-1-1 dispatch operations, call centers, and flight control towers (among others), conductive floors are not permitted*, as they can be an electrical safety hazard.

* Industry standards, including Motorola R56, ATIS 0600321.2015, and FAA 019f, for the telecom industry and flight control towers, require floors to measure > 1.0 x 10E6

Indoor Air Quality (IAQ)

A term used to describe the quality of the air breathed by occupants of an indoor or enclosed environment.

Installed Cost

The actual cost for materials and labor that also includes floor preparation, shutdown or loss of use of space, removal of old flooring and any procedures such as initial required cleaning, vapor test or vapor barrier applications.

Insulative

The property of “insulation” refers to a material’s ability to store as opposed to conduct electrical current.

An insulator is the opposite of a conductor. A good example of an insulator is a stone hearth. Although the hearth stores heat from a hot fire, it can be touched without danger because the heat is retained by the hearth and not transferred to the skin (as opposed to touching the metal grille on the same fireplace).

In the case of carpet construction, all fibers are insulators unless a conductive coating is applied to the external perimeter of the fibers. Insulated fibers will both generate and store static electricity. They cannot be grounded, even if a copper wire is attached to the tile.

Insulative Material

A material having a surface or volume resistivity ≥ 1 x 10E11 ohms.

Insulator

A material with high electrical resistance, (an insulator), will not conduct a charge to ground. Examples of insulators are plastic, rubber, vinyl, and wood. A practical example of an insulator is the rubber or vinyl casings around common electrical wires.

Internal Dye Variability

The change in dye uniformity across diameter and along the length of a yarn’s individual filaments. Affects appearance of the dyed product and is a function of fiber, dye, dyeing process, and dye bath characteristics.

International Gray Scale for Color Change

The Gray Scale for Color Change is an AATCC Evaluation Procedure that uses a gray scale to visually assess color changes in textiles during color fastness tests. Degrees of color change are rated from 5 (no change) to 1 (severe change).

International Gray Scale for Staining

The AATCC EP2 Gray Scale for Staining procedure for textiles uses a gray scale to visually assess stains resulting from color-fastness tests. Assessors rate degrees of staining from 5 (no stain) to 1 (severe stain).

ISO (The International Organization for Standardization)

A non-governmental, worldwide organization whose work results in international agreements that are published as International Standards.

J

J-cut

Uneven cutting of the loops in cut-pile carpets caused by poor adjustment of the knives and hooks or excessive yarn tension.

Jet

A device used to bulk yarns by introducing curls, coils and loops that are formed by action of a high velocity stream, usually air or steam.

Jute

A natural fiber, native to India, which can be shredded and spun into yarn. Jute yarns are used for backing in woven carpets, or the fiber is woven into sheets and used as secondary backing on tufted carpet. In many applications, jute is being replaced by fiberglass, polypropylene or other synthetic fibers.

K

Knitting

A fabrication process comprised of interlacing yarns in a series of connected loops with needles, like weaving. Carpet produced by knitting is generally categorized as woven carpet. In carpet knitting, pile and backing are produced at the same time using multiple sets of needles in one operation.

Kraftcord

A tightly twisted yarn made from plant fiber, used as a backing yarn.

Kuster

A trade name of a manufacturer of continuous dyeing machines which apply dye to tufted carpet.

kV

A measurement of electrical voltage. The measurement stands for kilovolts or one thousand volts. Currently, the floor covering industry measures the static generating propensity of products by using a kV measurement.

L

Laboratory Evaluation Equipment

An instrument or collection of instruments that meet the criteria of a standard or standard test method and provide a measurement that is accurate and repeatable. This equipment is typically used to qualify materials, devices or procedures prior to acceptance and under controlled conditions.

LAN

An acronym for Local Area Network.

Latent Failure

A malfunction that occurs following a period of normal operation.

Note: The failure may be attributable to an earlier electrostatic discharge event. The concept of latent failure is controversial and not totally accepted by all in the technical community.

Low Charge Generation

The term “low charge generation” replaces the older, less descriptive term “antistatic” (or anti-static). Low charge generation is a property that refers to the propensity of a material (or flooring material) to inhibit static charges.

Low charge generation should not be confused with conductivity or grounding. A low charge-generating floor may or may not be electrically groundable. Likewise, a grounded floor may generate enough static to cause a damaging ESD event.

This is why ESD floors should be evaluated for both conductivity (electrical resistance) and charge generation.

Low Charge-generating Floor

Low charge-generating floors generate little or no static electricity and inhibit or prevent static from building on people, rolling chairs, carts, and other mobile equipment.

The conductive fibers in ESD carpet brush static away from shoe soles as people walk—much the way brushes in a copier brush static from paper as it slides through the machine—and conduct those charges to ground, making ESD carpet a low charge-generating material. Because its chemical makeup is sufficiently similar to that of most shoe soles, conductive (EC) rubber is a naturally low charge-generating material.

Low charge generation should not be confused with conductivity or grounding. Some grounded floors—conductive vinyl and some ESD epoxy, for instance—can generate enough static on regular street shoes to cause a damaging ESD event.

Note: Charge-generating ESD flooring materials should only be used in areas where people are required to wear ESD-protective footwear.

Low kV

Low kV is a synonym for antistatic carpet.

Low kV carpet reduces the shock hazards associated with walking on standard carpet. The typical human threshold for feeling a static zap is 3.5 kV or three thousand five hundred (3500) volts. Most low kV carpet will inhibit static sufficiently so the people do not feel painful shocks. Low kV carpet cannot be grounded and will not reduce static electricity when the humidity is low or after extended carpet wear.

M

Minimum Resistance

The ANSI/ESD S20.20 static control standard does not offer a minimum resistance reading. Strictly in terms of grounding static charges, any floor with a resistance <1 x 10E9 meets the 2014 version of ANSI/ESD S20.20 and is considered acceptable.

While S20.20 does not specify a lowest acceptable resistance, for best practices the flooring industry has historically set the minimum resistance at no less than 2.5 x 10E4, or 25,000 ohms. This number was based on a defunct NFPA test method, requiring a resistance test with 500 volts of DC current applied to the surface of the flooring material. Current standard test methods apply much lower voltage and yield higher readings.

A floor measuring 25,000 ohms using the NFPA test method would yield a far lower resistance reading with less applied voltage.

ANSI/ESD standards do not offer a minimum resistance requirement because the built-in resistor in the ESD footwear required in manufacturing and handling spaces protects the wearer from potential electric shocks. In data centers, call centers, FAA flight towers, 9-1-1 dispatch centers, and other spaces where ESD-protective footwear is not required, materials with electrical resistance below 2.5 x 10E4 are considered a potential safety hazard.

For this reason, telecom and Federal Aviation Administration standards prohibit the use of flooring materials with resistance below 1 x 10E6 in spaces where energized equipment is used.

Mission Critical

Any operation that cannot tolerate intervention, compromise or shutdown while performing its critical function is considered a mission-critical environment. Mission critical environments usually support health, safety, security and human welfare. They also monitor, store, support and communicate data that cannot be lost or corrupted without compromising their core function.

Since all computer and communications systems are highly sensitive to static electricity, static events pose an internal threat to mission-critical operations, such as flight control towers, energy management operations, 911 centers, command centers, dispatch, control rooms, data storage centers, hospitals, stock exchanges, laboratories, university research facilities, computer rooms—any space where the loss or corruption of data cannot be tolerated.

ESD-protective flooring is a mandatory element in mission critical environments, because it inhibits charge generation and dissipates static to ground before it becomes a problem.

N

NFPA 99

(National Fire Prevention Agency section 99), NFPA 99 provides a test methodology for measuring the conductivity of flooring and other surfaces. This test was originally designed in the 1960’s for hospital operating rooms that used explosive gases for anesthesia. Operating room surfaces were required to be conductive so that static fields would be safely discharged to ground instead of dangerously discharged, as a spark could ignite an explosion.

Note: The NFPA no longer includes ESD flooring in their standard and the NFPA test method, which uses 500 volts of applied D/C current, is not used to evaluate ESD floors.

O

Ohm’s Law

Ohm’s Law is a mathematical equation showing that the current passing between two points on a conductor or conductive material is directly proportional to the applied voltage.

Ohm’s Law + i=V/r
Current (i) in amps equals voltage (V) divided by resistance (r) in ohms (Ω)

One Hundred Megohms

One Hundred Megohms, or “One Hundred Meg,” equals one hundred million ohms or 1.0 x 10E8. The exponent 8 refers to the eight zeros after the 1. Staticworx® recommends an electrical resistance measurement of 1 x 10E8 as the maximum upper level for an ESD flooring specification.

Note: Many ESD flooring manufacturers recommend electrical resistance measurements as high as 1.0 x 10E9 (1 Billion ohms or One Thousand Meg).

StaticWorx believes that resistance measurements higher than 1.0 x 10E8 gives the flooring material too narrow a margin of error, and that the 900-million-ohm gap between 100 million and 1 billion ohms is too large a jump in electrical resistance. If a material has a resistance of 1.0 x 10E8, or 100,000,000 ohms, environmental changes and other mitigating factors should have little or no effect on the floor’s electrical performance. If a material has a resistance of 1 x 10E9 when it’s installed and low RH reduces conductivity or its resistance deteriorates over time, the floor may no longer provide adequate ESD protection.

One Megohm

One Megohm, or “One Meg,” equals 1 million ohms or 1.0 x 10E6. The exponent 6 refers to the number of zeros after the 1. This measure is generally considered the maximum electrical resistance for a conductive flooring specification.

The telecom industry and Federal Aviation Administration have determined that floors with resistance levels below 1 x 10E6 (one megohm) are unacceptable for use near energized equipment. Industry standards—Motorola R56 and FAA 019f—prohibit the use of flooring with electrical resistance below 1 x 10E6 ohms.

P

Path to Ground

The electrical link between a static-dissipative and conductive material and the earth.

Electrical conduit is an example of path to ground; the neutral or “green wire” is attached to the conduit and discharges electricity safely to the earth through the metal housing and pipes encapsulating the “hot wires.”

Functioning conductive or dissipative flooring materials must have some form of external (or exposed) conductivity in order to attach or connect to a path to ground. Static-dissipative carpet, for example, finds a path to ground from: 1) exposed conductive fibers; 2) its dissipative backing; 3) conductive adhesive; 4) copper grounding strips attached to conduit or building steel.

A breach or omission in any of these four mechanisms will result in an open circuit on the flooring surface, with no path to ground.

Personnel Grounding Device

An electrostatic discharge protective device designed to ground any electrostatic charge accumulated on a person.

Point-To-Point Resistance

The resistance in ohms measured between two electrodes placed on any surface.

R

Resilient Flooring

A type of flooring material designed to be comfortable to stand and work on, stain resistant, and durable enough to withstand heavy traffic.

There are several static-control options within the resilient flooring category, at a range of price points. The most common types of resilient flooring are made with vinyl, rubber, and recycled rubber. These materials are all known for being extremely durable while providing some level of cushioning (as compared to hard concrete). Rubber is especially good for this, providing an exceptional ergonomic walking surface.

Another common trait of resilient flooring is resistance to stains, including chemicals, dirt, and liquids. Resilient flooring also resists penetration by water, making it less likely than textile-based materials to become a breeding ground for mold and mildew.

Resilient flooring withstands heavy foot traffic. The materials used to make resilient flooring resist scuffing and damage from rolling furniture, dollies, or pallet jacks that are dragged across the floor. Rubber flooring is also slip resistant, making it an ideal solution for wet applications in manufacturing facilities.

Resistance Range

User-specified upper and lower resistance values for personnel grounding devices, such as wrist strap, heel straps or wrist strap or heel strap systems, and ESD flooring materials.

Standard industry practice is to specify a resistance range as opposed to a single reading, which would be difficult to achieve.

Staticworx recommends a resistance range we call “the Sweet Spot,” of between 1 x 10E5 and 1 x 10E8 for ESD flooring.

Resistance To Groundable Point

The resistance in ohms measured between a single electrode placed on a surface and a groundable point. Same as Resistance to Ground (Rtg).

Resulting Current

Resulting Current refers to tests conducted by an independent laboratory, measuring current resulting from applying A/C voltages to different flooring materials. The tests were conducted to determine the electrical safety of various conductive and dissipative flooring materials.

Rtt

This is the abbreviation of resistance across the surface of a material between one point and another, also called point-to-point resistance.

S

Sick Building Syndrome (SBS)

Describes situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building. In contrast, to the term “building related illness (BRI).”

Static Electricity

Literally static at rest, or stored energy. When this stored energy discharges to flammable materials or electronic equipment, the sudden burst of electricity can ignite fires, damage the circuitry inside sensitive electronics, or cause equipment to malfunction and disrupt or lose important data. This is called an ESD event.

Static electricity results from the exchange of electrons that occurs when two objects with different electrical potentials come into frictional contact. When people walk across a floor, the friction between the soles of their shoes and the surface of the floor generates static—also called walking body voltage.

The static that accumulates on the human body is the cause of most static events in spaces like call or data centers, 9-1-1 dispatch operations, laboratories, flight towers, and other spaces where operations rely on sensitive electronic equipment.

Static Generation

When people walk across a floor, the friction between the soles of their shoes and the surface of the floor generates static—also called walking body voltage.

Static-control Floor

A permanently installed floor material such as tile, carpet, polymer, epoxy, or sheet flooring that controls static charges on personnel, equipment, or other objects contacting the floor material.

Static-control Floor Finish

A non-permanent conductive or static-dissipative coating periodically applied to existing floor surfaces. Floor finishes ground personnel, equipment, or other objects touching the floor finish and dissipate charges to ground. Some finishes control the generation and accumulation of static charges associated with certain charge-generating flooring materials.

Because finishes wear off over time, without constant electrical testing there is no way to know when they’ve lost conductivity. For this reason, they do not provide reliable static protection.

Static-control Floor Mat

A movable island of material placed over an existing floor. Static-control floor mats dissipate static charges by grounding personnel, equipment, or other objects contacting the material.

Some, though not all, static-control floor mats may also inhibit the generation and accumulation of static charges.

Static-control Floor Material

A permanently installed floor material—such as ESD carpet, vinyl or rubber tiles or sheet flooring or epoxy coatings—that dissipate static charges by grounding personnel, equipment, or other objects contacting the floor.

Some static-control floor materials also control the generation and accumulation of static charges.

Static-control Flooring

A generic term used to describe any form of flooring designed to reduce static electricity on people. Static-control flooring is available in numerous forms including: carpet, carpet tile, vinyl tile, rubber tile or sheet flooring, and epoxy coatings.

A more specific description should be used when specifying static-protective flooring. A meaningful specification should always include electrical resistance in ohms and triboelectric performance (walking body voltage) measured in volts.

Static-control Footwear (shoes)

Covering for the human foot with properties to ground personnel. When used in conjunction with a static-control floor, floor finish, or floor mat, static-control footwear controls the accumulation of static charges.

Static-control Seating

ESD-protective chairs, used in conjunction with a static-control floor or static-control floor mat, ground personnel and control the generation and accumulation of charges normally associated with seating and upholstery.

Static-dissipative Flooring

Static-dissipative floors are defined by a property called electrical resistance. Electrical resistance, measured in ohms, is a material’s ability to resist, or stop, the flow of electricity.

One of the two important parameters for describing a static-control floor is resistance to ground or path to ground. In order to qualify as static dissipative, a floor must have an electrical resistance to ground that’s > 1.0 X 10E6 (one million ohms) AND ≤ 1 x 10E9 (one billion ohms).

The term “static dissipative” should not be confused with the terms “conductive,” “antistatic” or “low charge generating.”

A static-control floor can be dissipative (or conductive) and still generate charges significant enough to cause an ESD event.

Note: the secondary definition below does NOT apply to ESD flooring or flooring materials.

2) Another definition of static dissipative is: a material that can conduct an electrical charge and has an inherent resistivity range between 1 x 10E4 ohms and 1 x 10E11 ohms. Sometimes referred to as electrically dissipative.

Static-resistance Resilient Flooring

A durable, stain-resistant floor-covering with ergonomic features and low charge-generating (formerly antistatic/anti-static) properties. Describing a flooring material as static resistant does not mean the material can also ground or dissipate static electricity.

A static-resistant flooring material could inhibit static generation but lack the conductive properties necessary for grounding static charges. Likewise, a resilient ESD floor material—vinyl, for example—may be conductive enough to ground charges, and still generate enough static to cause an ESD event.

The ideal static-control floor covering material should be both groundable and low charge generating.

2) A term found in Division 9 – Finishes 09650.6 Static-resistant resilient flooring.

Surface Resistance

The ratio of applied voltage to the current flowing between two electrodes in contact with the surface of a material.

Surface resistance tests measure the capacity of a material to resist the flow of electricity. To test surface resistance, an ohmmeter applies a current through a material, measures the voltage, and displays the resistance in ohms.

Resistance measurements depend on a number of factors, including ambient temperature and humidity; the most important factor is the resistivity of the material. Results can also vary according to the size of the material under test, as well as the shape of the electrodes and where the electrodes are placed.

Note: Not to be confused with Surface Resistivity.

Surface Resistivity

Surface resistivity is a measurement of a material’s inherent electrical resistance. Surface resistivity measurements are expressed in ohms/square.

Surface resistivity is a physical property of the material, and is not affected by size of the material or the shape/distance of the electrodes.

Note: Not to be confused with surface resistance.

The “Sweet Spot”

Buyers and specifiers often question whether an ESD floor should be static dissipative or conductive. Which category – and resistance range – is best for a specific application depends on a combination of factors, including: electrical resistance standards for the particular industry (standards vary across industries); the composition of the flooring material and its potential for charge generation; and which type/s of footwear will be worn in the space.

For safety and optimal performance, Staticworx recommends that flooring materials measure in the resistance range we call the “Sweet Spot.”

T

Topical Antistat

An antistat that is applied to the surface of a material for the purpose of making the surface static dissipative or reducing triboelectric charging. Topical antistats are temporary.

Without constant monitoring, there’s no way to tell when the static-control properties have worn off. For this reason, applying topical antistats is not a reliable form of static control.

Total Cost of Ownership

The real cost of a product, encompassing the cost of the material, along with installation, maintenance, anticipated repairs and necessary monitoring. These hidden costs are often overlooked or ignored in the initial cost analysis, but they add up and over time can outpace the expense of owning a floor with a higher material cost.

For instance, a floor with static-protective properties reliant on periodic buffing with conductive wax must be tested and monitored after each maintenance interval to ensure electrical compliance. If routine maintenance requires shutting down an operational space for some period of time, loss of use should also be factored into the flooring decision.

Triboelectric Charging

Whenever two objects with different electrical characteristics make contact and separate, the molecules in the two materials interact, forming an electrical bond. Separating the materials creates friction. This frictional force draws electrons away from one material and deposits an excess of electrons on the other, leaving a positive or negative electrical charge on both materials. This charge is called a triboelectric charge—or a tribocharge. Also known as tribocharging.

(See also Triboelectric series)

Triboelectric Series

A list of common materials, such as leather, nylon, wool, and paper, showing whether a material tends to give up or take on electrons when in frictional contact with other materials on the list. Those that give up electrons become positively charged, and materials that accept electrons become negatively charged.

In the ESD industry, the triboelectric series is used primarily to predict resultant charge polarities after triboelectric generation.

Note: This series is only a guide. The list is derived from tests on specially prepared and cleaned materials tested in ultra-controlled conditions. In everyday circumstances, materials reasonably close to one another in the series can produce charge polarities opposite to expectations based on the series.

V

Volatile Organic Compounds (VOCs)

Gases emitted from certain solids or liquids, including a variety of chemicals, which may have short- and long-term adverse health effects. Concentrations are consistently higher indoors than outdoors: often up to ten times higher. Flooring should always be tested for VOC content by independent certification organizations like FloorScore and GreenGuard.

Voltage Suppression

Voltage suppression occurs when an ESD-protective material, such as a static-dissipative table covering, suppresses static charges rather than dissipating charges to ground. For instance, an ESD laminate with a buried conductive layer will suppress the electrostatic field from a charged object, but is incapable of discharging static even when the charged object touches its surface.

The voltage suppression test determines whether a work surface actually bleeds off the static from a charged object placed on its surface or only suppresses the electrostatic field. If the surface bleeds off the charge, when the object is lifted its voltage will measure zero. If the surface only suppresses the charge, the voltage will remain on the object when it is lifted from the surface, making it a potential ESD threat.

Note: voltage suppression is a serious deficiency of many static-dissipative table covering materials.

W

Walking Body Voltage

The static charge, in volts, generated by a person walking across the floor. Static charges that accumulate on the body discharge to the first object the person touches, potentially damaging or disrupting sensitive electronics.

Share on twitter
Twitter
Share on linkedin
LinkedIn
Share on facebook
Facebook
Share on reddit
Reddit
Share on pinterest
Pinterest
Share on email
Email
Play Video

StaticWorx high-performance static-control floors protect electronic components, explosives, and high-speed computers from damage caused by static electricity. ESD flooring is part of a system. Choices should always be based on objective, researched evidence. When you partner with us, we look at all possible items that may need to integrate with the floor, and, focusing on your goals and objectives, help you find the right floor for your application.

Play Video

StaticWorx high-performance static-control floors protect electronic components, explosives, and high-speed computers from damage caused by static electricity. ESD flooring is part of a system. Choices should always be based on objective, researched evidence. When you partner with us, we look at all possible items that may need to integrate with the floor, and, focusing on your goals and objectives, help you find the right floor for your application.