The document provides information on electrostatic discharge (ESD) including its definition, causes, effects, and models. Some key points: - ESD is defined as the transfer of electrostatic charges between bodies at different potentials caused by direct contact or induced electrostatic fields. - Common causes of ESD include walking on carpets, improper grounding of equipment, and low humidity conditions. - ESD events can damage electronic components by surging voltages as high as 25,000 volts through devices. This can cause failures in integrated circuits. - Three models of ESD are described: the human body model which involves discharge through the human body's capacitance and resistance; the machine model which

1. ELECTRO STATIC DISCHARGE
AWARENESS AND CONTROL
An extensive course on

2. Examples :
Lightning
Zapping

3. An atom is made up of charges
 An atom is made up of
charges.
 In its stable state, the
size of the positive
charge at the centre
(nucleus) of an atom is
balanced by the size of
all the negative charges
of the electrons, making
it neutral overall.
 The electrons whirl
around the centre like
planets.

4. Creating a charge imbalance
 When an atom loses an
electron, it has a charge
imbalance.
 Since this atom has lost
an electron, which is a
negative charge, the
atom is now a positive
charge.
 When it gains an extra
electron, an atom
becomes a negative
charge.
Electron “lost”

5. A discharge
 This movement of
charges is called a
discharge.
 When something which has
a charge imbalance is
brought close to or touches
something else, a stream of
charges might move, to try
to bring the atoms back to
their stable balanced
condition.
This powerful, rapid
movement of charges
can damage electronic
components.
Let’s see it
again!

6. WHAT IS ESD?
ELECTRO STATIC DISCHARGE IS DEFINED AS THE
TRANSFER OF ELECTRO STATIC CHARGES
BETWEEN BODIES AT DIFFERENT POTENTIAL
CAUSED BY DIRECT CONTACT
OR INDUCED ELECTRO STATIC FIELD.
ESD EVENT
IT IS AN UNPLANNED OCCURANCE OF ELECTRO- STATIC
DISCHARGE

7. What is ESD—Electrostatic Discharges
(ESD) are the most severe form of
Electromagnet Interference (EMI). The
human body can build up static charges
that range up to 25,000 volts. These
build-ups can discharge very rapidly into
a electrically grounded body, or device.
Placing a 25,000-volt surge through any
electronic device is potentially damaging
to it.

8. Moving people
Improper grounding
Unshielded cables
Poor connections
Moving machines
Low humidity (hot and dry conditions)
The most common causes of ESD are:

9. Figure 13-14: Power Transmission System

10. Figure 13-15: Grounds on IC Chips

11. Some devices used to remove solder from circuit boards
and chips can cause high static discharges that may
damage the good devices on the board. The device in
question is referred to as a solder-sucker, and is
available in antistatic versions for use with MOS devices.
To avoid damaging static-sensitive
devices, the following procedures will
help to minimize the chances of
destructive static discharges:

12. Triboelectric generation
Basic Principles (2)

13. When two materials are in intimate contact, they share
electrons which are at their surfaces.
When materials are in contact

14. The triboelectric
charge of two
materials in
contact.

15. When two materials are in intimate contact, they share
electrons which are at their surfaces.
When materials are in contact
It is possible for electrons to be “stolen” from one
material by nuclei in the other material, because they
have a stronger force

16. When these materials are separated, electrons are
removed from one material and are transferred to the
other material.
When the materials are
separated Electrons “lost”
Electrons “gained”

18. When the materials are
separated Electrons “lost”
Electrons “gained”
When these materials are separated, electrons are
removed from one material and are transferred to the
other material.
This action takes place with all types of materials. With
insulators, the charges remain at the points of contact.
A charge spreads all over an ungrounded conductor.

19. The triboelectric
charge when two
materials placed in
contact are then
separated.

20. This action takes place with all types of materials. With
insulators, the charges remain at the points of contact. A charge
spreads all over an ungrounded conductor.
When the materials are separated
Electrons “lost”
Electrons “gained”
The loss and gain of these electrons creates an
imbalance of negative and positive charges on the
surface of each material.

21. When the materials are separated
Electrons “lost”
Electrons “gained”
When the surfaces are rough, this intimacy and
separation is assisted by rubbing the materials
together.

22. When the materials are separated
Electrons “lost”
Electrons “gained”
The size of the charge (imbalance) depends on the
intimacy of the contact, how fast they were separated,
the humidity and the kinds of materials

23. When the materials are separated
Electrons “lost”
Electrons “gained”
The drier the air (lower relative humidity, RH)
the higher the generated charge

24. The creation of a
charge when
materials are
separated is termed
“triboelectric
charging”

25. Charging by Induction
Basic Principles

26. Charging by induction
The presence of this very strong force causes
similar charges on the surfaces of nearby
conductors to be repelled.
The charge imbalance on a surface produces
an electric field.

27. Charging by induction
If the conductor is grounded while it is still
influenced by the electric field, these repelled
charges go to earth, thus maintaining a charge
balance in the areas of the conductor that are not
affected by the electric field.

28. Charging by induction

29. Walking on carpet
Thoughts and theories

30. Walking across carpet
 Walking across a
carpet creates a
charge
imbalance on the
lower surface of
shoes.

31. A strong electric field
 This charge imbalance
creates a strong electric
field that emanates in all
directions.
 The material in the sole of
shoe enables a strong
field to influence charges
within foot.

32. An induced charge
 Since the body is relatively
conductive, the charges that
are repelled from the lower
regions of my foot set up a
charge throughout the rest of
my body.
 But the body still has a
balanced charge overall (it
has not lost or gained any
charges).

33. Contacting a source of
charges  While you are still
on the carpet (still
influenced by the
electric field on the
sole of your
shoe),you briefly
touch a metallic
object (a chair,
table, door knob,
metal stapler, etc.)
 This enables
charges to be
provided by the
metallic object.

34. Charging through the air
 This movement of
charges is thus
producing an overall
charge imbalance in
my body, since I was
previously neutral
overall.
 If the charge imbalance on my body is large enough, I do
not need to touch the object, as the imbalance could allow
a movement of charges through the air.

35. An overall charge imbalance
 Therefore, after
that brief
encounter with the
metallic object, my
body now has an
overall charge
imbalance.

36. Removing that charge
 The only way to remove the possibility of
damaging an ESD-sensitive device or
assembly is to remove the overall charge
imbalance on my body.
 This is done by connecting my body to
the ready source of charges that is at
the same reference potential as the item
I wish to handle - using a wrist strap or
foot strap.

37. ELECTROSTATIC DISCHARGE PROCESS
1. Charge is generated on the surface of an
insulator.
2. This charge is transfered to a conductor by
contact or induction.
3. The charged conductor comes near a metal
object (grounded or ungrounded) and a discharge
occurs.
4. When a discharge occurs to an ungrounded
object, the discharge current flows through the
capacitance between the object and ground.

38. STATIC GENERATION
THE STATIC CHARGE IS GENERATED BY IMBALANCE
IN THE MOLECULAR STRUCTURE BY RUBBING;
CAUSING STRIPPING OF NEGATIVELYCHARGED
ELECTRONS WITH ONE MATERIAL GETTING PASITIVE
CHARGE AND OTHER NEGATIVE
CAUSE FOR STATIC CHARGE
 FRICTION
 SEPERATION
 INDUCTION

39. CAUSES FOR ESD GENERATION
 WALKING ON SYNTHETIC SURFACE
 RELATIVE MOVEMENT ON CHAIR
 TABLE, COMPUTER, PLASTIC PARTS NYLON OR
SYNTHETIC CLOTHES
 CLEANING WITH COMPRESSED AIR
 CLEANING WITH SOLVENT
ESD

40. FACTORS:
 TYPE OF MATERIAL
 RELATIVE HUMIDITY
 TYPE OF CLOTHING
 SPEED AND MANNER OF WALKING
 BODY RESISTANCE

41. RECORDED ESD ACCIDENTS
 In 1937, The German flying boat Hinderburg arriving in
Lakehurst, New Jersey, caught fire while anchoring at its
landing mast.
 In 1970’s, in USA, a space craft launching rocket exploded
during the fueling operation, killing 3 engineers.
 In January, 1985, during the assembly of a missile in
Germany, the motor case made of Kelvar, got rubbbed
against the cushioning in its container. The ESD generated
caused the highly flammable propellant to catch fire and the
motor exploded, killing 3 people.
 3 to 30% of Integrated Circuits manufactured every year
die in “infancy” due to ESD.

42. Device sensitivity to Electrostatic Discharge
At higher
magnificat
ion the pit
in the area
between
the base
and
emitter
becomes
more
obvious

43. Device sensitivity to Electrostatic Discharge
At this
magnific
ation see
the 1/2 of
the width
of the
material
has been
destroyed
.

46. 40 – 50% EQUIPMENTS HAVE
FAILED IN THE FIELD
DUE TO ESD
Statistics

47. SENSITIVE CONSTITUENTS FAILURE MODES
MOS STRUCTURES SHORT
BIPOLAR JUNCTIONS LEAKAGE
FILM RESISTORS VALUE SHIFT
METALIZATION STRIPES OPEN
FIELD PERFECT STRUCTURES OPERATIONAL
PIEZOELECTRIC CRYSTALS DEGRADED
CLOSELY SPACED CONDUCTORS DEGRADED

48. • PLASTICS
• CONDUCTORS
• FURNITURES
• VINYL FLOOR
• COOLING FANS WITH PLASTIC BLADES
• PRINTERS/COPIERS
• PAPER
• NYLON & WOOLLEN GARMENTS
• COMPRESSED AIR GUN
ESD SOURCES
MAN MADE:

49. NATURAL:
• HUMAN BODY
• MOVEMENT OF CLOUDS

50. PACKING HANDLING MATERIALS:
COMMON POLYTHENE BAGS, WRAPS,ENVELOPES
COMMON BUBBLE PACK FOAM
COMMON PLASTIC TRAYS, PLASTIC TOTE BOXES, VIALS
TYPICAL CHARGE GENERATORS
ASSEMBLY, CLEANING, TEST & REPAIR AREA ITEMS:
SPRAY CLEANERS
COMMON SOLDER SUCKERS
COMMON SOLDER IRONS
SOLVENT BRUSHING ( SYNTHETIC BRISTLES)
CLEANING, DRYING
TEPARATURE CHAMBERS

51. ESD VOLTAGE MEASUREMENT
ELECTROSTATIC VOLTAGE
MEANS OF STATIC GENERATION 10% RW 40% RW 55% RW
PERSON WALKING ACROSS CARPET
PERSON WALKING ACROSS VINYL
FLOOR
WORKER AT A BENCH
CERAMIC DIPS IN PLASTIC TUBE
CERAMIC DIPS IN VINYL SET UP TRAYS
CIRCUIT AS BUBBLE PLASTIC
COVER REMOVED
CIRCUIT AS PACKED IN FOAM
LINED SHIPPING BOX
35000 15000 7500
12000 5000 3000
6000 800 400
2000 700 400
11500 4000 2000
25000 20000 7000
21000 11000 5500

52. REASONS FOR DISBELIEF
ESD DAMAGE : WHEN UNNOTICED?
HUMAN SENSE OF FEELING OF STATIC AT 4000V
MUCH MORE HIGHER THAN SENSITIVITY OF
COMPONENTS
 HARDLY ANY PHYSICAL DAMAGE
 ESD FAILURES CONSIDERED AS GENERAL COMPONENT FAILURE
 FAILURE MAY NOT BE INSTANT. (LATENT FAILURE)

53. GUIDE TO STATIC CONTROL MATERIALS
SURFACE RESISTIVITY-OHMS PER SQUARE
INSULATOR
MATERIALS IN THIS RANGE ARE NOT
EFFECTIVE FOR STATIC CONTROL
1012 To 10 15

54. 1010 To 10 12
ANTISTATIC
THESE MATERIALS DO NOT GENERATE
AND SUPPORT HIGH STATIC CHARGES.
BUT DISCHARGE RATES ARE TOO SLOW
FOR MOST INDUSTRIAL APPLICATIONS.
SURFACE RESISTIVITY-OHMS PER SQUARE
GUIDE TO STATIC CONTROL MATERIALS

55. GUIDE TO STATIC CONTROL MATERIALS
SURFACE RESISTIVITY-OHMS PER SQUARE
STATIC DISSIPATORS ( PARTIALLY CONDUCTIVE)
MATERIALS MOST SUITABLE FOR
STATIC CONTROL WORK SURFACES,
FLOORING AND FLOOR MATS, SEALING,
OVERALLS
106 To 10 9

56. GUIDE TO STATIC CONTROL MATERIALS
SURFACE RESISTIVITY-OHMS PER SQUARE
CONDUCTIVE
MATERIALS FOR CONTAINERS AND HANDLING
EQUIPMENT.BELOW 104 OHMS PER SQUARE
EFFECTIVE STATIC SHIELDING IS
POSSIBLE,OPERATOR SAFELY WILL BE
COMPROMISED IF THE EARTH PATH THROUGH
BENCH MATS, FLOOR MATS AND FLOORING LESS
THAN 5 X 104 OHMS AND MAINS POWERED
EQUIPMENT’S IN USE.
101 To 10 4

57. OBJECTIVES OF ESD CONTROL
 PREVENTING STATIC CHARGE GENERATION
DISSIPATING THE DEVELOPED CHARGE
NEUTRALISING DEVELOPED CHARGE FOR A CHARGE
FREE ZONE
CONTROLLING OF ESD
WORK SURFACE
AIR
HUMAN BODY
FLOOR

58. DO’S
 MINIMISE HANDLING.
 KEEP PARTS IN ORIGINAL PACKING UNTILL READY
FOR USE.
 USE ESD PROTECTIVE CONTAINERS AND BAGS.
 DISCHARGE STATIC BEFORE HANDLING DEVICE BY
TOUCHING NEARBY GROUNDED SURFACE.
 HANDLE DEVICES BY THE BODY.
 TOUCH THE ESD PROTECTIVE PACKAGE BEFORE
TOUCHING INSIDE OF DEVICE.
 KEEPA DUST FREE WORK AREA.

59. DONT’S
 TOUCH THE LEADS OF DEVICE.
 SLIDE ES DEVICES OVER ANY SURFACE.
 PUT MASKING TAPE ON PROGRAMMABLE IC’S.
 STORE OR CARRY SENSITIVE COMPONENTS OR
ASSEMBLIES IN PLASTIC BAGS.
 STORE SENSITIVE COMPONENTS IN
THERMOCOLE/PLASTIC FOAM.
 HANDLE ES DEVICES IN “NON ESD CONTROLLED”
ENVIRONMENT.

60. ESD MODELS
ESD MODELS HAVE BEEN DEFINED TO DESCRIBE
THE EFFECTS ON ESD SENSITIVE DEVICES:
 HUMAN BODY MODEL
 CHARGED DEVICE MODEL
 MACHINE MODEL

61. Human Body Model (HBM)
 The basic human body model consists of body capacitance
and resistance. The charge is stored in the body capacitance
and the discharge occurs through the body resistance.
 When a charged person handles or comes in close proximity
to an ESD sensitive part, the part may be damaged by direct
discharge or by an electro static field.
    
   
<0.1mH Rb
Vb
Cb
Cb : 50 to 350pF
Rb : 150 to 10KOhms
Vb : 3 to 20 KV

62. Human Body Model (HBM)

63. HUMAN BODY CAPACITANCE AND RESISTANCE
 o
50-100pF
50pF
100pF
100pF
Rb
o

64. TYPICAL ESD CURRENT WAVE FORM
. . . . . . . ..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
t
tf=100nSec
tr=1nSec
40A
I

65. Machine Model
A discharge similar to the HBM
event also can occur from a
charged conductive object, such as
a metallic tool or fixture.
.

66. Charged Device Model
The transfer of charge from an ESDS device is
also an ESD event. A device may become
charged, for example, from sliding down the feeder
in an automated assembler. If it then contacts the
insertion head or another conductive surface, a
rapid discharge may occur from the device to the
metal object. This event is known as the Charged
Device Model (CDM).

67. ESD CONTROL DEVICES
 ANTISTATIC VINYL TABLE MAT
 CONDUCTIVE FLOOR MAT
 ESD LAMINATE
 ESD WRIST STRAP
 ESD HEEL STRAP
 ESD TOE STRAP
 COMMON POINT GROUND
 ANTISTATIC BINS/TRAYS
 PCB STORAGE RACK
 CONDUCTIVE FOAM

68. Typical Facility Areas
Requiring ESD Protection
Receiving
Inspection
Stores and warehouses
Assembly
Test and inspection
Research and development
Packaging
Field service repair
Offices and laboratories
Clean rooms

69. ESD AUDIT

70. MATERIALS CLASSIFICATION
MATERIAL SURFACE VOLUME
CLASS RESISTIVITY RESISTIVITY
SHIELDING 104 OR LESS 102 OR LESS
CONDUCTIVE 105 OR LESS 104 OR LESS
DISSIPATIVE 105 TO 1010 104 TO 109
ANTISTATIC 1010 TO 1012 ---
INSULATIVE >1015 >1014

71. ESD AUDIT
 PERSONNEL TRAINING FOR ESD PREVENTIVE
 AWARENESS TRAINING
 CERTIFICATION TRAINING
 CONTROL PROGRAM AUDIT

73. ESD TEST & MEASURING INSTRUMENTS
 STATIC CHARGE METER
WRIST STRAPAND GROUND TESTER
FOOTWEAR TESTER
SURFACE RESISTIVITY METER
STATIC SENSOR
CONTINUOUS WRIST STRAP MONITOR
CONTINUOUS WORK STATION MONITOR
TEMPARATURE AND HUMIDITY INDICATOR

74. TESTING EVALUATION
The test evaluation report consists of the following test
areas for each ESD item/s:
POINT TO POINT SURFACE RESISTIVITY TOP/BOTTOM
POINT TO POINT SURFACE RESISTIVITY IN/OUT
SURFACE TO GROUND RESISTANCE
PERSON TO GROUND RESISTANCE
STATIC CHARGE MEASURING TEST
STATIC SHIELDING TEST

75. TESTING EVALUATION
 Antistatic P.E Bags
 Static Shield Bags
 Conductive Bags
 Conductive Grid Bags
 Antistatic Aprons
 Conductive Brush
 Foot Wear

ESD Mat
conductive Mat
 Work Surface
 ESD Laminate
 Wrist Strap
 Heel Strap
 ESD Chair
The tests are generally conducted for the following item/s:

76. PERSONAL GROUNDING
Two types of Personal Grounding:
Wrist Straps
Footwear

77. WRIST STRAPS
 Daily Check with Wrist Strap Worn
 Test with a Wrist Strap tester

78. Floor
 Point to Point

79. Floor
 Resistance to Ground

80. Garments
 Point to Point

81. Garments
 Point to Ground
 May need person wearing garment
Needs to be
connected to
ground as
wor n

82. Chair
 Check all parts of Chairs to Ground
 Seat, Backrest, Armrest, Foot Rest

85. TYPES OF ESD DAMAGE
CATASTROPHIC FAILURE
UPSET FAILURE

86. SHIELDING
FARADAY CAGE
Types of Faraday Cages
• Metallized & Conductive
Shielding Bags
• Conductive tote box with cover

87. A hollow conductor
 A Faraday Cage is a
hollow conductor.
Michael Faraday

88. WORK STATION

89. Electrostatic Voltmeter (ESV)

90. Measurement of Static Electricity
Static electricity is measured in coulombs. The charge "q" on
an object is determined by the product of the capacitance of
the object "C" and the voltage potential on the object (V):
q=CV
Commonly, however, we speak of the electrostatic potential
on an object, which is expressed as voltage.

91. ESD Damage-How Devices Fail
Electrostatic damage to electronic devices can occur at any
point from manufacture to field service.
Damage results from handling the devices in uncontrolled
surroundings or when poor ESD control practices are used.
Generally damage is classified as either a catastrophic
failure or a latent defect.

93. Questions
ESD