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
Auxiliary Ground - A separate
supplemental grounding conductor for use other than
general equipment grounding.
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
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
. 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
Charge Density - The charge
per unit area on a surface, or charge per unit volume in
Cold Work station - A work area that has
items, assemblies, black boxes, or systems to which no power is caused by
Conductor - A
material which contains movable electric charges.
Conductive - A
material which has an electrical resistivity below 1x105
Current - The flow
of charge known as amperage (amp) or (A) given in units
of Coulombs per second.
Decay Time - The time required for an
electrostatic potential to be reduced to a given percentage of its initial
ESD - (ElectroStatic
Discharge) - The rapid, spontaneous and usually uncontrolled transfer of an
electrical charge between two conductors induced by a
strong electrostatic field.
- Electrostatic Discharge Susceptibility.
- 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.
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.
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.
Hard Ground - A connection to
ground through a wire or other conductor that
has an negligible resistance to ground.
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
Junction Damage - Electrical Overstress
damage to a semiconductor junction.
Latent Failure - A malfunction that
occurs following a period of normal operation.
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
Neutralize - To
eliminate an electrostatic field by recombining positive and negativity
Ohm - Unit of
resistance. Symbolized by the Greek capital letter omega (O).
It is defined as the resistance, at 0o 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
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.
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
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
Q - Symbol for quantity of electrical
Quality Control - The control of
variation of workmanship, processes, and materials in order to produce a
consistent, uniform product.
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.
- 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
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.
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
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
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
Zap - A layman's term for an electrical
discharge or electrostatic discharge, ESD.