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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