Glossary of ESD and Static Control Terms:

Air Ion - A molecular cluster of about 10 molecules (water, impurities, etc.) bound by polarization forces to a singly charged oxygen or nitrogen molecule. Air Ionizer - A source of charged air molecules (ions).Ankle Strap - See Ground Strap.Antistat, Agent - A substance that is part of or topically applied to a material to render the material surface static dissipative or less susceptible to triboelectric charging.Anti-static - Usually refers to the property of a material that inhibits triboelectric charging. Note: A material's antistatic characteristic is not necessarily correlatable with its resistivity or resistance.

Auxiliary Ground - A Separate supplemental grounding conductor for use other than general equipment grounding, that is bonded to the equipment grounding conductor.

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 electrostatic discharge protected workstation. (See Bus Bar)

Bond or Bonding - The permanent joining of metallic parts to form an electrically conductive path that will assure electrical continuity and the capacity to safely conduct any current likely to be imposed.

Bonding conductor - the connection between two isolated conductors

Bus Bar - A metal strip or bar to which several conductors may be bonded.

C

Capacitance - In a capacitor or a system of conductors and dielectrics, that property which permits the storage of electrically separated charges when potential differences exist between conductors. The capacitance of a capacitor is defined as the ratio between the electric charge that has been transferred from one electrode to the other and the resultant difference in potential between the electrodes.

Catastrophic failure - a device that completely ceases to function. It is usually the result of some type of electrical, thermal or mechanical overstress.

Charge - A fundamental unit (Coulomb) to quantify an electrical phenomena. A material's (e.g., metal, plastic, air, etc.) net charge, relative to an external reference point, can be neutral, positive or negative depending on the distribution of its charged particles (free electrons, atomic ions, molecular ions, etc.) The ability for a material to store a charge refers to it's capacitance. When charging a capacitor or battery, some of the charges from one plate move to the other and the total number of charges within the device as a whole does not change. Note: A charged capacitor has a lot more energy than an uncharged one, but exactly the same net-charge and quantity of + and - particles.

Charge Decay - The decrease and/or neutralization of a net electrostatic charge.

Charge Density - The charge per unit area on a surface, or charge per unit volume in space

Charge Induction - The displacement of charge in an isolated conductor when placed in an electric field (for example, from a charged body). Note: Momentary grounding of such a conductor would result in its gaining a net charge.

Charged Device Model - A specified circuit characterizing an electrostatic discharge which results when a device isolated from ground is first charged and then subsequently grounded.

Cold Healing - The spontaneous recovery, at room temperature, of an item from a parametric change caused by electrostatic discharge.

Cold Workstation - A work area that has items, assemblies, black boxes, or systems to which no power is applied.

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.

Component - An Item such as a resistor, diode, transistor, integrated circuit and hybrid.

Component Failure - A condition in which a tested component does not meet one or more specified static or dynamic data sheet parameters.

Compressed Gas Ionizer - ionization devices used to simultaneously neutralize charged surfaces and remove surface particles with high pressure gas. This type of ionizer may be used to ionize the gas within production equipment.

Conductive Material - A material that has a surface resistivity less than 1 x 105 ohms/square or a volume resistivity less than 1 x 104 ohm-cm.

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.
Corona - The production of positive and negative ions by a very localized high electric field. The field is normally established by applying a high voltage to a conductor in the shape of a sharp point or wire.

Conductor - A material which contains movable electric charges.

Constant Monitor - Method for carrying out the wristband test in real time at the workbench.

D

Decay Rate - The decrease of charge or voltage per unit time.

Decay Time - The time required for an electrostatic potential to be reduced to a given percentage (usually 10%) of its initial value. (See Static Decay Test.)

Degradation - a type of static electricity damage that weaken an electronic device but still allows it to continue to operate within normal parameters. However, a degraded device may later fail catastrophically.

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

Dielectric Breakdown Voltage - The electric potential across an insulating material that causes a sudden increase in current through the material of the insulator.

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 - Materials that have a surface resistivity of 1 X 106 to 1 X 1012 Ohm/Sq Eg Floor and bench matting.

Dynamic Parameters - Those measured with the component in a functioning condition, and may include, but are not limited to: full functionality, output rise and fall times under a specified load condition, and dynamic current draw.

E

EED - Electrically Explosive Device

Electric Charge - An absence or excess of electrons.

Electrical Ionizer - A device that creates ions in gases by use of high voltage electrodes.

Electrical Overstress (EOS) - The exposure of an item to a current or voltage beyond its maximum ratings. This exposure may or may not result in a catastrophic failure.

Electrification Period - The average of five electrification times, plus five (5) seconds.

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

electrostatic Charge - Electric Charge at rest.

electrostatic Damage- Change to an item caused by an electrostatic discharge that makes it fail to meet one or more specified parameters.

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 Control - see Static Control

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 Protected Area - A designated environment provided with materials and equipment to limit electrostatic potentials.

electrostatic Discharge Protective - A property of materials capable of one or more of the following: reducing the generation of static electricity, dissipating an electrostatic charge, or providing shielding from electrostatic discharge or electrostatic fields.

electrostatic Discharge Protective Workstation - An area that is constructed and equipped with the necessary protective materials and equipment to limit damage to electrostatic discharge susceptible items handled therein.

electrostatic Discharge Protective Worksurface - A worksurface that dissipates electrostatic charge from materials placed on the surface or from the surface itself.

electrostatic Discharge Sensitivity (ESDS) - The electrostatic discharge level that causes component failure.

electrostatic Discharge Shield - A barrier or enclosure that limits the passage of current and attenuates an electromagnetic field resulting from an electrostatic discharge.

electrostatic Discharge Spark Testing - Testing performed with operating equipment or parts to determine their susceptibility to the transient electromagnetic fields produced by an air discharge event.

electrostatic Discharge Susceptibility (sensitivity) (ESDS) - The propensity to be damaged by electrostatic discharge.
electrostatic Discharge Susceptibility Classification - The classification of items according to electrostatic discharge susceptibility voltage ranges. Note: There are various classification methods.

electrostatic Discharge Susceptibility Symbol - The graphics placed on hardware, assemblies, and documentation for identification of electrostatic discharge susceptible items.

electrostatic Discharge Susceptible Item - Electrical or electronic piece part, device, component, assembly, or equipment item that has some level of electrostatic discharge susceptibility.

electrostatic Discharge Withstand Voltage - The maximum electrostatic discharge level that does not cause component failure.

electrostatic Field -An attractive or repulsive force in space due to the presence of electric charge.

electrostatic Potential - The voltage difference between a point and an agreed-upon reference.

electrostatic Shield - A barrier or enclosure that limits the penetration of an electrostatic field.

Electrostatics - The study of electrostatic charge and its effects.

Emitter - A conducting sharp object, usually a needle or wire, which will cause a corona discharge when kept at a high potential.

EOS - See Electrical Overstress.

Equipment Ground - 1. The ground point at which the equipment grounding conductor is bonded to any piece of equipment, at the equipment end of the conductor. 2. The 3rd wire (green) terminal of a receptacle. 3. The entire low impedance path from a piece of electrical equipment to a hard ground electrode.

E.P.A - electrostatic Protected Area. A clearly defined area in which preventative mechanisms are in place to prevent or control any electro static discharges.

Equipotential -   Having a uniform  electrical potential throughout.

ESD - See electrostatic discharge.

ESD Co-ordinator - Person responsible for ensuring ESD program is defined, implemented and monitored

ESD Sensitivity - See electrostatic discharge susceptibility.

ESD technical element - All of the devices, equipment, materials and tools that make up an EPA for ESD control

ESDS - See electrostatic discharge susceptibility.

F Failure model - several different models have been developed to identify the way an ESD event can damage or destroy a device. The three most common failure models are the charge device model (CDM), the human body model (HBM) and the machine model (MM).

Farad - The capacitance of a capacitor in which a charge of 1 coulomb produces a change of 1 volt in the potential difference between its terminals. The Farad is the unit of capacitance in the mksa system.

Faraday Cage - A conductive enclosure that attenuates a stationary electrostatic field.

Field Induced Charging - A charging method using electrostatic induction.

G

1 GigOhm - 1E09 or 1 thousand Meg ohms

Ground - 1.A conducting connection, whether intentional or accidental between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of earth. 2. The position or portion of an electrical circuit at zero potential with respect to the earth. 3. A conducting body, such as the earth or the hull of a steel ship, used as a return path for electric currents and as an arbitrary zero reference point.

Ground-Fault Circuit Interrupter - A device intended for the protection of personnel that functions to de- energize a circuit or portion thereof within an established period of time. It is activated when a current difference between the neutral and hot conductors exceeds some predetermined value that is less than that required to operate the over current protective device of the supply circuit. The current difference is usually caused by a current to ground.

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.

Grounded Conductor - A system or circuit conductor that is intentionally grounded.

Grounded - Connected to earth or some other conducting body that serves in place of the earth.

Grounding Conductor - A conductor used to connect equipment or the ground circuit of a wiring system to a ground electrode or electrodes.

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.

Horizontal Laminar Flow - Non-turbulent air flow in a horizontal direction.

Hot Workstation - A work area that has items, assemblies, black boxes, or systems, which have power applied for testing or repair.

Human Body Model - An electrostatic discharge circuit that meets the set model values by conforming to the waveform criteria specified in ANSI/EOS/ESD-S5.1-1993, characterizing the electrostatic discharge from a human being.

Human Body Model electrostatic Discharge - An electrostatic discharge event meeting the waveform criteria specified in ANSI/EOS/ESD-S5.1-1993, 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.

Humidity - Humidity has a direct effect on the amount of charge (voltage) produced by a triboelectric event. Low levels of humidity produce higher voltage

I

Impedance - n. Symbol Z A measure of the total opposition to current flow in an alternating current circuit, made up of two components, ohmic resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance. Impedance is measured in ohms.

Inductive Charging - The transfer of an electric charge to an object when it is momentarily contacted to ground in the presence of an electric field.

Input Protection - Structures, devices or networks connected at the input terminals of an item to prevent electrostatic discharge damage.

Insulative - Materials that have a surface resistivity of greater than 1 X 1012 Ohm/Sq Eg Anything that isn't metal, silicon, water, carbon, people.

Insulated Conductor - A conductor encased within material of composition and thickness that is recognized as electrical insulation.

Insulative Material - A material having a surface resistivity of at least 1 x 1012 ohms/square or 1 x 1011 ohm- cm volume resistivity.

Ionization - The process by which a neutral atom or molecule acquires a positive or negative charge.

Ion - a charged particle, usually of air or nitrogen. The charge can either be positive (+) or negative (-). A positive charge is the result of missing electrons. A negative charge is the result of extra electrons.

Ionizer - A device which is designed to generate positive and/or negative air ions.

Isolated Conductor - A non-grounded conductor.

Isolated Ground Receptacle - A grounding type receptacle in which the equipment grounding conductor contact and terminal are electrically isolated from the receptacle mounting means.

J

Junction Damage - Electrical Overstress damage to a semiconductor junction.

Laminar Flow Hood Ionization - These devices or systems provide local area ionization coverage in vertical or horizontal laminar flow hoods or benches.

L

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

M

Machine Model - An electrostatic discharge simulation test based on a discharge network consisting of a charged 200 picofarad capacitor and (nominally) zero ohms of series resistance. Actual series resistance and inductance are specified in terms of the current waveform through a shorting wire. The simulation test approximates the electrostatic discharge from a machine.

Machine Model electrostatic Discharge - An event meeting the criteria specified in ESD-S5.2-1994.

Main Bonding Jumper - The connection between the grounded circuit conductor and the equipment grounding conductor at the service.

Monitor, Charge(d) Plate - An instrument used to measure the charge neutralization properties of ionization equipment.

N

Neutralize - To eliminate an electrostatic field by recombining positive and negative charges, either by conducting the charge to ground or by introducing an equal opposite charge.

Nuclear Ionizer - A device that creates ions usually by alpha emissions which strip electrons from gas molecules to form equal numbers of positive and negative ions in gases.

O

Offset Voltage - The observed voltage on the isolated conductive plate of a charged plate monitor that has been placed in an ionized environment.

Ohm/Sq - Standard measurement of surface resistivity that defines if a material is a conductor, dissipator, or insulator

Ohm's Law - The voltage across an element of a dc circuit is equal to the current in amperes through the element, multiplied by the resistance of the element in ohms. Expressed mathematically as E=IxR. The other two equations obtained by transposition are I=E/R and R=E/I.

Ohms per square - A unit of measurement of resistance by topological shape known as resistivity. A resistor topology can be considered to consist of continuous squares. The value of a resistor is equal to the number of squares times the ohms per square. The ESDA has now adopted the unit for resisitivity as just ohms.

Outlet - 1. A receptacle that is connected to a power supply and equipped with a socket for a plug. 2. A point on a wiring system at which current is taken to supply utilization equipment.

Output Protection - Structures, devices or networks connected at the output terminals of an item to prevent electrostatic discharge damage.

Oxide Punch-through - Dielectric breakdown of an oxide layer, as in a semiconductor device.

P

Passive Ionizer - A device, usually a sharp grounded needle point, that discharges surfaces in the immediate vicinity by creating a conductive path of air ions.

Peak Offset Voltage - For pulsed ionizers, the maximum value of the offset voltage for each polarity, as the ionizer cycles between positive and negative ion outputs.

Personnel Grounding Device - An electrostatic discharge protective device designed to ground any electrostatic charge accumulated on a person. NOTE: The resistance to ground of a personnel grounding device must be high enough to avoid causing an electrical shock hazard.

Planar Material - An item with a surface sufficiently large and flat to conform to the surface resistance measuring electrode described in EOS/ESD-S11.11-1993.

R

R - Symbol for resistance, resistor or reluctance.

Receptacle - A contact device installed at the outlet for the connection of an attachment plug.

Resistance - The property of conductors which - depending on their dimensions, material, and temperature - determines the current produced by a given difference of potential; that property of a substance which impedes current and results in the dissipation of power in the form of heat. The practical unit of resistance is the ohm.

Resistivity - Referring to the measurment of the resistance of a material to electric current either through its volume or on its surface. The unit of volume resistivity is ohm-centimeter; the unit of surface resistivity is the ohm.

rfi - (radio-frequency interference)-Radio frequency energy of sufficient magnitude to have a possible influence on the operation of other electronic equipment. Also known as EMI (electromagnetic interference).

Ringing- Distortion in the form of a damped oscillatory waveform superimposed on the main waveform.

rms - The "root-mean-square" value of ac voltage, current, or power. Calculated as 0.707 of peak amplitude of a sine wave at a given frequency.

Room Ionization - ionization systems which provide large area coverage with air ions.

S

Shunting Bar - A device that shorts together the terminals of an electrostatic discharge susceptible item forming an equipotential surface. Spark - An electrical discharge of very short duration, normally between two conductors separated by a gas (such as air).
Static Control (or, electrostatic Discharge Control) - 1. adj. - electrostatic discharge protective. 2. n. - Generic term for measures taken to diminish the effects of electrostatic discharge.
Static Decay Test - A procedure in which an item is first charged to a specified voltage, then allowed to dissipate to a specified voltage while measuring the duration of the discharge.

Standard - Latest ESD standard is IEC 61340-5-1 and IEC 61340-5-2.

Static Control (or, electrostatic Discharge Control) - 1. adj. - electrostatic discharge protective. 2. n. - Generic term for measures taken to diminish the effects of electrostatic discharge.

Static Decay Test - A procedure in which an item is first charged to a specified voltage, then allowed to dissipate to a specified voltage while measuring the duration of the discharge.

Static Dissipative - A property of a material having a surface resistivity of at least 1 x 105 ohms/square or 1 x 104 ohm-cm volume resistivity but less than 1 x 1012 ohms/square surface resistivity or 1 x 1011 ohm-cm volume resistivity.Static Electricity - See electrostatic charge.Static Parameters - Those measured with the component in a non-functioning condition, and may include, but are not limited to: input leakage current, input breakdown voltage, output high and low voltages, output drive current, and supply current. Step Stress Test Hardening - A process whereby a component subjected to increasing electrostatic discharge voltage stress is able to withstand higher stress levels than a similar component stressed at a single lower voltage level. Note: As an example, a component may fail at one thousand volts if subjected to a single stress, but fail at three thousand volts if stressed at progressively higher voltages, starting at a low level, for example 250 volts.Step Stress Testing - A test consisting of increasing stress levels applied sequentially to a sample for periods of equal duration.

Surface Resistance - The ratio of DC voltage to the current flowing between two electrodes of specified configuration that contact the same side of a material. This measurement is expressed in ohms.

Surface Resistivity (rs) - For electric current flowing across a surface, the ratio of DC voltage drop per unit length to the surface current per unit width. In effect, the surface resistivity is the resistance between two opposite sides of a square and is independent of the size of the square or its dimensional units. Surface resistivity is expressed in ohms/square. When using a concentric ring fixture, resistivity is calculated by using the following expression, where D1 = outside diameter of inner electrode, D2 = Inside diameter of outer electrode, and R = measured resistance in ohms:

T Tests - Daily
Wrist Straps and Curly Cords
Heel Straps/Footwear
Garments
Ionisers
Grounding points undamaged
Clean Floors and Benches
Storage facilities earthed
Testers in good working order

Tests - Weekly
Check no fields greater than 100V
Check earth bonding
Tests - Monthly
Signs and Labels
EPA boundaries
Grounding Systems

Tests - Six Monthly
Register of trained personnel

Training
Guides/handbooks/standards available and up to date

Tests - Yearly
EPA area audited for certification

Topical Antistat - An antistat that is applied to the surface of a material for the purpose of making the surface static dissipative or to reduce triboelectric charging.

Triboelectric Charging - The generation of electrostatic charges when two materials make contact or are rubbed together, then separated. (See also Triboelectric series.)

Triboelectric Series - A list of materials arranged so that one can become positively charged when separated from one farther down the list, or negatively charged when separated from one farther up the list. Note: The series' main utility is to indicate likely resultant charge polarities after triboelectric generation. However, this series is derived from specially prepared and cleaned materials tested in very controlled conditions. In everyday circumstances, materials reasonably close to one another in the series can produce charge polarities opposite to that expected. This series is only a guide.

V

Vertical Laminar Flow - Non-turbulent air flow in a vertical direction.

Voltage Suppression - Reduction of the voltage (V) of a charged object by increasing its capacitance (C) rather than by decreasing its charge (Q), in accordance with the formula V = Q/C. Note: Voltage suppression typically occurs when a charged object is brought closer to ground.

Volume Resistivity rv) - The ratio of the DC voltage per unit thickness to the amount of current per unit area passing through a material. Volume resistivity is given in ohm-centimeters.

W

Worksurface Groundable Point - A point on the worksurface that is intended to accommodate an electrical connection from the worksurface to an appropriate electrical ground.

Worksurface Ionization - ionization devices or systems used to control static charges at a work station. Note: This type includes benchtop ionizers, overhead worksurface ionizers, and laminar flow hood ionizers.

Wristband - Fabric or metal band that grounds the operator via contact with the skin. Resistance to ground should be no less than 1 meg Ohm (safety) and no greater than 35 meg Ohm (European standard).

Z

Zap - (colloquial term) See electrostatic discharge.