A

Air Conductivity - The ability of air to conduct an electric current under the influence of an electric field or fields.

Air Ion - A cluster of several airborne molecules (i.e., water and local particulation) that are bound by polarization forces to a charged (typically singly) nitrogen or oxygen molecule.

Antistat, Agent - A substance that is part of or topically applied to a material to render the material surface static dissipative.

Auxiliary Ground - A separate supplemental grounding conductor for use other than general equipment grounding.

B

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

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.

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 through bleeding, recombination, induction, or "neutralization" of a net electrostatic charge.

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

Cold Work station - A work area that has items, assemblies, black boxes, or systems to which no power is caused by electrostatic discharge.

Conductor - A material which contains movable electric charges.

Conductive - A material which has an electrical resistivity below 1x10⁵ Ohms/sq.

Current - The flow of charge known as amperage (amp) or (A) given in units of Coulombs per second.

D

Decay Time - The time required for an electrostatic potential to be reduced to a given percentage of its initial value.

E

ESD - (ElectroStatic Discharge) - The rapid, spontaneous and usually uncontrolled transfer of an electrical charge between two conductors induced by a strong electrostatic field.

ESD Sensitivity - Electrostatic Discharge Susceptibility.

ESDS - ElectroStatic Discharge Susceptibility.

Equipment Ground - The ground point at which the equipment grounding conductor is bonded to any piece of equipment, at the equipment end of the conductor.

EOS - Electrical OverStress is a transient or steady state electrical condition that exceeds the specifications and/or capabilities of a device. Both the magnitude and duration of an EOS event can vary. Examples of mild EOS are oxide ruptures and junction damage with signs of visual stress. Severe EOS may include massive vaporization of bond wires or aluminum interconnects and carbonizing of plastic packages.

F

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 - Also known as Faraday Shield or Screen. A network of parallel wires connected to a common conductor at one end to provide electrostatic shielding without affecting electromagnetic waves. The common conductor is usually grounded. A conductive enclosure that attenuates an electrostatic field.

Field Induced Charging - A charging method using electrostatic induction.

Foot Grounder - A ground strap used for mobility that connects the bodies foot to ground (ESD floor) via a conductive tab between the sock and insole connected to a conductive outer wear (rubber cup) that is positioned on the bottom sole of the shoe. Foot grounders come in different styles: heel grounders, toe grounders, ball (of the foot) grounders and sole (combination heel and ball) grounders.

G

Ground - 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.

Ground Cord - A ground cord connects two conductors together to bring at the same potential, usually ground. Most of the wrist strap ground cords are coiled to retain excess cord length when not in use. Standard ground cords have a built in 1 megohm resistor for operator safety.

H

Hard Ground - A connection to ground through a wire or other conductor that has an negligible resistance to ground.

I

Ionization - The process by which a neutral atom or molecule acquires a positive or negative charge. The dissociation of an atom or molecule into positive and/or negative particles.

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

J

Junction Damage - Electrical Overstress damage to a semiconductor junction.

L

Latent Failure - A malfunction that occurs following a period of normal operation.

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.

N

Neutralize - To eliminate an electrostatic field by recombining positive and negativity charges.

O

Ohm - Unit of resistance. Symbolized by the Greek capital letter omega (O). It is defined as the resistance, at 0^o C, of a uniform column of mercury weighing 14.451 grams. One ohm is the value of resistance through which a potential difference of one volt will maintain a current of one ampere.

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.

P

Paschen's Law - The sparking potential between two terminals in a gas is proportional to the pressure times the spark length. For a given voltage, this means the spark length is inversely proportionate to the pressure.

Parallel - Also called a shunt. Connected to the same pair of terminals, so that the current can branch out over two or more paths.

Plasma - A highly ionized gas. The fourth state of matter (it does matter). 99% of all matter in the universe is in a plasma state. Lightning, neon lights and fire are natural examples of plasma on Earth.

Q

Q - Symbol for quantity of electrical charge.

Quality Control - The control of variation of workmanship, processes, and materials in order to produce a consistent, uniform product.

R

R - Symbol for resistance, resistor or reluctance.

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).

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.

S

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 material that can conduct an electrical charge and has an inherent resistivity range between 1x10⁴ ohms and 1x10¹¹ ohms Sometimes referred to as electrically dissipative.

Static Electricity - "Static electricity" appears when two dissimilar materials are placed into intimate contact and then separated. This is a charge separation or an IMBALANCE between quantities of positive and negative particles. During contact electrification it is usually only the negative electrons which are moved. As negative particles are pulled away from the positive particles, equal and opposite areas of imbalance are created. In one place you'll have more protons than electrons, and this spot will have an overall positive charge. Elsewhere you'll have more electrons than protons, for an overall negative charge. "Static electricity" exists whenever there are unequal amounts of positive and negative charged particles present. It doesn't matter whether the region of imbalance is still or is flowing; only the imbalance is important. All solid objects contain vast quantities of positive and negative particles whether the objects are electrified or not. When these quantities are not exactly equal and there is a tiny bit more positive than negative (or vice versa), we say that the object is "electrified" or "charged," and that "static electricity" exists. When the quantities are equal, we say the object is "neutral" or "uncharged." "Charged" and "uncharged" depends on the sum of opposite quantities. Since "static electricity" is actually an imbalance in the quantities of positive and negative, it is wrong to believe that the phenomena has anything to do with lack of motion, with being "static." In fact, "static electricity" can easily be made to move along conductive surfaces. When this happens, it continues to display all it's normal characteristics as it flows, so it does not stop being "static electricity" while it moves along very non-statically! In a high voltage electrical system, the wires can attract lint, raise hair, etc., even though there is a large current in the wires and all the charges are flowing. And last, when any electric circuit is broken and the charges stop flowing, they do not turn into "static electricity" and begin attracting lint, etc. A disconnected wire contains charges which are not moving, yet it contains no "static electricity!"

W

Wrist Strap - A device which electrically connects to the human skin, at the wrist via a mechanically contacting wrist band, to a ground cord, usually tied connected to power ground. It is your first line of defense in ESD control. The wrist strap's main purpose is to keep the human body's skin at ground potential (or the same potential as the devices being handled) via conduction. The wrist strap keeps the body at ground potential when properly employed and minimizes the chance of making contact with controlled conductors at different potentials. There are many types of wrist straps available. U.L. approval for wrist strap kits only include units with at least 1 megohm serial resistance between the operator and ground.

Z

Zap - A layman's term for an electrical discharge or electrostatic discharge, ESD.