TOPIC_3_ESD

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Malaysian Institute of Aviation Technology

ESD

Electrostatic Discharge

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Electrostatic discharge(ESD) is the sudden andmomentary electric current that flows between two objects atdifferent electrical potentials caused by direct contact orinduced by an electrostatic field.

he term is usually used in the electronics and otherindustries to describe momentary unwanted currents thatmay cause damage to electronic e!uipment.

ESD is a serious issue in solid state electronic " such asintegrated circuits.

#ntegrated circuits are made from semiconductor materialssuch as silicon and insulating materials such as silicon

dio$ide.

Either of these materials can suffer permanent damagewhen subjected to high %oltages& as a result there are now anumber of antistatic de%ices that help pre%ent static buildup.

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'auses of ESD

hen two objects rub together" they create friction.

by*product of friction is heat.

+ ,esult of the increased molecular acti%ity brought

about by electrons mo%ing bac- and forth between thetwo surfaces.

ur bodies are constantly in motion. hen we mo%e

against another material" li-e carpet" we create friction.+ ,esults in rapid mo%ement of electrons" some of which

remain in our bodies.

+ his e$change of electrons builds up a charge withinour bodies

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/uilt*up electrons inside us are see-ing anoutlet0* Such as a door-nob

hen we ma-e contact with another

electrically conducti%e material" the electrons

jump from our body to the other material.

So static electricity is the buildup of an+ electrical charge within an object" such as a person"

the discharge of which is in the form of electricity.

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12 D#S'1,3E 144E56

/ecause different materials recei%eddifferent le%els of charge

Show using riboelectric Series table7ir7 1uman hands

7 3lass

7 Sil-

7 4aper

7 ood

7 48'

7 Silicon

#ncreasingly

positi%e

#ncreasingly

negati%e

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Electricity can be de%eloped electrostatically byfriction between 9 surface

:agnitude and polarity of the charges depend

on the different le%els of charge (electron)between material touches" friction force andhumidity of the surrounding air.

ESD is the transfer of electrostatic charge

between 9 bodies at different potentials %iadirect contact or when induced by electrostaticfield

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Malaysian Institute of Aviation Technology12 ESD #S #:4,56

ur bodies constantly generate andrelease static electricity.

lmost e%ery time we touch something"we discharge some amount of staticelectricity.

he human body can feel an electrostaticdischarge of ;

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Malaysian Institute of Aviation TechnologyESD Damage

Damage is not always immediately

apparent.

+ 4artial damage can result in intermittent

errors in the computer because some pulses

still flow properly while others don=t.

+ >sers will complain of errors and problems

that are not always duplicable.

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Malaysian Institute of Aviation Technology4re%enting ESD Damage

Ensure that any electrostatic buildup in your

body is discharged immediately to the

ground" you must pro%ide a direct groundpath from your body.

>se special electrostatic dissipati%e

products.+ Slow the transference of electrostatic energy"allowing it to dissipate before damaging

components.

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+ 'reate an ESD wor-station or en%ironmentto reduce ESD damage.

+ good ESD wor-station should incorporatethe components such as0

ESD wristband or an-le strap

ESD floor or table mats

ESD garments

ESD glo%es or finger co%erings

#ncrease humidity

nti*static bags

Static discharger

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Malaysian Institute of Aviation TechnologyESD ,5#53 S#35

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Malaysian Institute of Aviation TechnologyESD ristband or n-le Strap

ESD wristband or an-le strap ttached to wrist with wire leading to a metal

clip which is attached to grounded object

'an be grounded to %arious items0+ ESD mat+ ESD floor mat

+ :etal table or chair leg

+ ,emo%ed computer case Separated from any components you might touch

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Malaysian Institute of Aviation TechnologyESD ?loor or able :at

ESD ?loor or able :at ?loor mat placed where you stand

+ >nderside has contacts that pro%ide outlet for ESD to

the ground beneath

+ ?loor and underneath mat should be -ept free of dirtand debris

able mat is placed on your wor- surface

+ 4ro%ide route to ground through0

'ontacts underneath to contact metal table or

3rounding strap that runs from mat to a grounding source

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Malaysian Institute of Aviation TechnologyESD 3arments

ESD 3arments orn o%er your clothing and pro%ides a

ground wire that can be attached to an

ESD floor or table mat. :ade of a static dissipati%e

material that slows ESD to gi%e

it time to be discharged toground through the ground wire.

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Malaysian Institute of Aviation TechnologyESD 3lo%es or ?inger 'o%ering

ESD 3lo%es or ?inger 'o%ering orn on the hand or fingers that will come in

contact with sensiti%e components.

'an be made of one of the followingmaterials0

+ 8inyl

3ood for anti*ESD wor-

+ Special substances to dissipate

or pre%ent ESD transference.

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Malaysian Institute of Aviation Technology#ncreasing 1umidity

ESD buildup is greatly reduced in a humid en%ironment.

+ e$ample humidifier

cti%ity @

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Malaysian Institute of Aviation Technologynti*static /ags

'omputer components are shipped inspecial plastic bags.

Storing components in these bags will

reduce the ris- of ESD damage to thecomponent

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Malaysian Institute of Aviation Technologyypes f nti*static /ags

Electrically conducti%e bags

+ >sually blac- or gray" coated with a metallic or

carbon layer" or with a metallic wea%e.

:etal helps conduct ESD across surface of bag to

ground %ery !uic-ly

'arbon slows ESD transference" routing the

charge to the ground

+ /ags can be used o%er long periods

of time without losing effecti%eness

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Electrically Dissipati%e /ags

+ >sually pin-" coated with a substance thatslows the transference of ESD long enough

for it to be conducted safely to the ground.+ 8ery little protection might actually be afforded

to the components inside.

+ nti*static properties of the

bag degrade o%er time.

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Malaysian Institute of Aviation TechnologyStatic Discharger

hey are used on aircraft to allow the continuoussatisfactory operation of onboard na%igation and radiocommunication systems.

n aircraft" static dischargers are used on the trailingedges of wings and other surfaces.

During ad%erse charging conditions (air friction)" they limitthe potential static buildup on the aircraft and controlinterference generated by static charge.

Static dischargers are not lightning arrestors and do notreduce or increase the li-elihood of an aircraft being struc-

by lightning. Static dischargers are subject to damage or significant

changes in electrical resistance as a result of lightningstri-e to the aircraft" and should be inspected after alightning stri-e to ensure proper static discharge operation.

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Static dischargers are fabricated with a wic- of wire or aconducti%e element on one end" which pro%ides acontinuous low resistance discharge path between theaircraft and the air.

hey are attached on some aircraft to the trailing edgesof ailerons" ele%ators" rudder" wing" horiHontal and%ertical stabiliHer tips..

n smaller aircraft static dischargers are typically

constructed out of glass*reinforced resin surrounding awo%en metal conductor.

hese are fragile and easily damaged by inattenti%eoperators.

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portion of static dischargerStatic dischargers on the wingletand

aileronof an EasyIetirbus ;@*@

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