3 static awareness seminar. types of esd failures to electronic devices catastrophic failure u...
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3
Static AwarenessSeminar
Types of ESD Failures to Electronic Devices
Catastrophic FailureCatastrophic Failure Device no longer operates Represents 10%10% of ESD failures
Intermittent / Walking WoundedIntermittent / Walking Wounded Device is operational, but erratic and
will cause additional service calls Represents 90%90% of ESD failures
Static Damaged Mos Transistor
DRAIN SOURCE
GATEOXIDE LAYER
Cost of Cost of ESD damage damage increases by increases by ten (10)ten (10) fold at every process fold at every process levellevel
Component Level
Board Level
System Level
Field Service Level
$5
$500
$50
$5000
Where do you need static protection ?
• Incoming inspection and test• Stores and storage• Transfer carts• Kitting• Manual and automated
insertion• Wave soldering• Equipment assembly and
test• Packaging and shipping• Repair stations• Field service
DEFINITION OF STATIC DEFINITION OF STATIC ELECTRICITYELECTRICITY
The electrification of materials through physical contact and separation, and the various effects that result from the positive and negative charges so formed.
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MAJOR PROBLEMS MAJOR PROBLEMS CAUSED BY STATICCAUSED BY STATIC
Dust and Lint Attraction Material Handling Problems Damage to Products Product Malfunction Fire and Explosion Hazards Shock to Personnel
Ranking of Semiconductor Failure Causes
EOS/ESD is the #1 Cause ofSemiconductor Failure
Source : Semiconductor Reliability News, March 1993
EOS/ESD 59%
Electrical testing 3%
Oxide/passivationfailure 3%
Conductor failure 3%
Die fracture 4%
Lead short/open 7%
Wire bonds 15%
Others 6%
SEMICONDUCTOR SEMICONDUCTOR DEVICE SENSITIVITIESDEVICE SENSITIVITIES
Device Type
MOSFET VMOS NMOS GaAsFET EPROM CMOS GaAsFET JFET SAW Op-AMP Schottky Diodes Film Resistors Bipolar Resistors ECL SCR SChottky TTL
Threshold Susceptivity (Volts)
10 - 10030 - 180060 - 10060 - 2000100+200 - 300025 - 50140-7000150-500190-2500300-2500300-3000300-7000500+500-1000500-2500
HUMAN PERCEPTIONS HUMAN PERCEPTIONS OF ESD OF ESD
At 3000 volts, you can ESD
At 5000 volts, you can ESD
At 10000 volts, you can ESD
Typical Electrostatic Voltages
ELECTROSTATIC VOLTAGES
10 TO 20 PERCENTRELATIVE HUMIDITY
65 TO 90 PERCENTRELATIVE HUMIDITY
MEANS OFSTATIC GENERATION
WALKING ACROSS CARPET
WALKING OVER VINYL FLOOR
WORKER AT BENCH
VINYL ENVELOPES FOR WORKINSTRUCTIONS
COMMON POLY BAG PICKED UP FROM BENCH
WORK CHAIR PADDED WITHPOLYURETHANE FOAM
35,000
12,000
6,000
7,000
20,000
18,000
1,500
250
100
600
1,200
1,500
OWEN J. McATEERMILITARY ELECTRONICS/COUNTERMEASURES
ELECTROSTATIC ELECTROSTATIC DISCHARGE (ESD)DISCHARGE (ESD)
Billions of Dollars $$$ are wasted each year because of ESD damage.
Millions of dollars in PC Board float is the result of ESD damage.
DAMAGE MODESDAMAGE MODESCatastrophic Failure Device no longer operates Are mostly caught in-house Represents 10% of ESD failures
Intermittent / Walking Wounded Device is operational, but erratic and will
cause additional service calls Most expensive static problem Represents 90% of ESD failures
DAMAGES CAUSED BY DAMAGES CAUSED BY ESDESD
PROPERTIES OF STATIC PROPERTIES OF STATIC ELECTRICITYELECTRICITY
A charged surface has electrical potential energy (voltage)
A charged surface emanates an electric field
A charged surface can produce kinetic energy (current)
STATIC CHARGE STATIC CHARGE GENERATORSGENERATORS
Work surfaces Floors Chairs Clothing Papers and work order holders Packaging materials PERSONNEL
DEVICE FAILURE CAN DEVICE FAILURE CAN HAPPEN AT ANY LEVELHAPPEN AT ANY LEVEL
Single device Circuit board Product assembly Field service
STATIC GENERATIONSTATIC GENERATION
Triboelectric charging Induction Changes in capacitance
TRIBOELECTRIFICATIONTRIBOELECTRIFICATION
Static Charge can be generated by contact and separation of dissimilar surfaces.
Static Charge on contacting surfaces can be increased with addition of friction or rubbing.
INDUCTIONINDUCTION Process of separating charges on a
material through space at a distance by the influence of an electric field.
A conductor in the presence of an electric field can acquire a charge and hold it.
Non-conductors are polarized and able to be attracted to charged surfaces (like dust to a TV screen).
CHANGES IN CHANGES IN CAPACITANCECAPACITANCE
Voltage on an object is greatly affected by the capacitance of the object.
Capacitance can change in the environment due to position of the object relative to other objects in the area.
Increase capacitance, reduces voltage. Decrease capacitance, increases voltage.
MATERIALS MATERIALS CHARACTERISTICSCHARACTERISTICS
Conductors Allow the flow of electrons
Non-conductors or Insulators Resist the flow of electrons
FACTORS AFFECTING FACTORS AFFECTING STATIC CHARGE STATIC CHARGE GENERATIONGENERATION
Intimacy of contact Speed of separation Conductivity of materials Position on Triboelectric
series
MATERIALSMATERIALS
AirAsbestosGlassMicaHuman HairNylonWoolFurLeadSilkAluminumPaperCotton
SteelWoodAmberHard RubberBrass SilverSulfurPolyesterPolyurethanePolyethylenePolypropylenePVCTeflon
Increasing Positive
Increasing Negative
HOW STATIC IS GENERATED
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Contact and Separation of Materials
5,000 Volts
4,00
0V
3,00
0V2,
000V
STATIC FIELD EMANATES FROM CHARGED OBJECT
Fundamentals of Static• VOLTAGES associated
with static charges can be created by :
1. Triboelectric charging
2. Induction
3. Changes in capacitance
• SCIENTIFIC BASIS :
1. Coulomb’s Law* like charges repel* opposite charges attract
2. V = Q/C
V = voltage in volts
Q = charge in coulomb
C = capacitance in farads
Typical Voltage Variations Monitored on a Person with No
Wrist Strap
0
500
1000
1500
VoltagePulseHeight
OperatorWalking
OperatorSat Down
Feet Raised
FeetLowered
OperatorStands Up
OperatorSat Down
850 v(max)3200 v/sec
5000v/sec 3800 v/sec
1400 v(max)
1550v(max)
Time
SOLUTIONS TO STATIC SOLUTIONS TO STATIC PROBLEMSPROBLEMS
Prevention of Charge Generation Neutralization of Charge Dissipation of Charge Shielding
PREVENTIONPREVENTION
Static cannot be totally prevented ..........
Only Limited !!!!!
PREVENTIONPREVENTION
The property of Antistaticity is related to Prevention of static charge generation -
Providing surface lubricity and slightly conducting properties usually results in low charging properties.
DISSIPATIONDISSIPATION
Removal of Charge from Conductors
Rate of dissipation controlled by resistance to ground
Slow rate of dissipation preferred by most
DISSIPATIONDISSIPATION
Device damage models have helped determine the need for dissipative worksurfaces.
Human Body ModelCharged Device ModelMachine Model
Human Body ModelHuman Body Modeloxide layer
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static discharge
Charged Device ModelCharged Device Model
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discharge
tweezers
DISSIPATIONDISSIPATION
Dissipation is the most important control property in electrostatics.
Dissipation includes grounding of people, worksurfaces and flooring.
Electrical system ground preferred over a separate system or building ground.
IONIZATIONIONIZATION
Creation of free charge in gases (usually air).
Coulombs Law dictates that opposite charges attract.
Ionization cancels out static charges, one for one on surfaces.
Ionization must be balanced, otherwise a charge can be added to a surface.
SHIELDINGSHIELDING
Shielding is used to protect electrostatic susceptible items when they are being transported between Static Protected Areas.
Shielding is a requirement for most classes of components in Military and commercial specifications.
4 RULES OF STATIC 4 RULES OF STATIC CONTROLCONTROL
Handle all static sensitive items at a static safeguarded work station.
Transport all static sensitive items in static protective containers.
Test and monitor the static control process.
Make sure every party in the supply chain follows then above 3 rules.
RULE 1 - STATIC RULE 1 - STATIC SAFEGUARDED WORK SAFEGUARDED WORK AREAAREA
Provides bonding and grounding for all conductors used in the area, including people.
Provides neutralization of charge on the necessary non-conductors used in the area.
RULE 1 - SOLUTIONSRULE 1 - SOLUTIONS
Worksurface Materials Flooring Materials Wrist Straps Shoe Grounding Ionization
OHM’S LAW
VOLTS
OHMS= AMPS
EXAMPLE:
120 VOLTS
1,000,000 OHMS
= 120 MICROAMPS
RULE 2 - RULE 2 - TRANSPORTATIONTRANSPORTATION
Products must be protected when they are moved from the static safeguarded work station.
RULE 2 - SOLUTIONSRULE 2 - SOLUTIONS
Flexible packaging - shielding bags Rigid containers - tote boxes,
trays, card carriers
RULE 3 - TEST RULE 3 - TEST EQUIPMENTEQUIPMENT
Tester for Wrist/Shoe Strap.
“Megger” (high voltage meter) for worksurfaces and flooring.
“Charge Plate” for Ionization.
RULE 4RULE 4
Make sure everyone that is in the supply and distribution system follows the first 3 Rules.
Conduct audits on suppliers for conformance to Operating Procedures if necessary.
STANDARDIZATION IN STANDARDIZATION IN STATIC CONTROLSTATIC CONTROL
Standards setting organization exist in the US, Europe, and Internationally.
The most active organizations are : ESD Association, EIA, JEDEC.
The US Military also has many standards related to Static Electricity.
ESD ASSOCIATION TEST ESD ASSOCIATION TEST METHODSMETHODS
Individual ProductsWrist straps, flooring, table mats etc.
Measurement TechniquesResistance, Shielding, Charge Generation
AdvisoriesGuidelines, Practices, Procedures, Definitions
EIA - Electronic Industry EIA - Electronic Industry AssociationAssociation
Packaging of Electronic Products for Shipment - EIA 541Specifications for materials used in packaging materials
ESD Standard 625
PREREQUISITES FOR A PREREQUISITES FOR A SUCCESSFUL STATIC SUCCESSFUL STATIC CONTROL PROGRAMCONTROL PROGRAM
A full commitment on the part of top management
ESD control compliance on all suppliers A comprehensive in-house ESD control
program Advise your customers on proper
handling Select a professional and knowledgeable
static control vendor
Benefits of a total static Benefits of a total static control programcontrol program
Reduced IC and PC board rejects Reduced field service calls More competitive service contract due to lower warranty costs Reduced circuit board float resulting from increased IC and PC board
reliability $$ Savings proportion example:
5 PC boards in inventory per 1 PC board in the field can be reduced to:
3 PC boards in inventory per 1 PC board in the field Reduced physical space requirements for PC Savings = return on investment capital invested Improved customer satisfaction (goodwill) and assure customer re-
orders. Increase share of marketplace with high quality and reliable products Improve profits