Credits

1
Credits
ELECTROSTATIC DISCHARGE (ESD) AWARENESS TRAINING
Prepared by CAPT JESSE D. S. MORGAN,
III Additional Slides by JULIUS
BRODBECK Technical Assistance by Steve Gerken
and Mike Manders AF ESD Control Center Materials
Integrity Branch Materials and Manufacturing
Directorate Air Force Research Laboratories AFMC
2
What is ESD?

• Electrostatic Discharge (ESD) is the discharge of
  stored static electricity.
• Some circuits today are sensitive to as little as
  25 volts. Typically humans begin to feel a
  static discharge at 3500 volts.
• You can damage a circuit without feeling it!

3
Notes Included
ELECTROSTATIC DISCHARGE (ESD) CONTROL TRAINING
For those viewing this on their computer, most of
the slides have their Notes pages filled in
which amplify the information provided on the
slides. Version 3a 9/5/03
4
Overview

• Extent of ESD Damage
• Directives
• Definitions
• Summary of ESD Principles
• Tribocharging
• Effects of Humidity
• Controlling Body Voltage
• Packaging
• Marking, Labeling, and signs
• ESD Worksurfaces
• Air Ionization
• Grounding
• The Role of Capacitance
• Reference

5
ESD Damage, 1st of 7
Extent of ESD Damage
Photo taken on a Microscope of ESD damage
6
A DEMO on a MOSFET
A 3N157 MOSFET is lying on a circuit board
to illustrate the relative size of the all metal
package.
7
An ESD Shock is applied
8
Microscopic Postmortem
There is no visible damage at 150 power !
9
2500 Magnification
At 2500 power, damage to a via is seen.
10
Susceptibility
Extent of ESD Damage
Susceptibility of Various Devices Exposed to ESD
Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.39
11
Telephone Systems
Extent of ESD Damage
Estimate of Telephone System ESD Costs
160
150
160
129
140
120
94
100
Cost in Millions
80
60
40
43
43
20
35
25
0
78
79
80
81
Year
Range of ESD Damage
Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.17
12
Published ESD Losses
Extent of ESD Damage
1980 Delco Electronics study on Auto
22M Electronics Product ESD Failures 1983 ATT
HIC Shop ESD Losses 39 1984 USAF Missile
Guidance Video Board 492,000 ESD Failures
(250 Failed) 1984 USAF Depot ESD failures
788,000 1985 Early IBM Printer Module ESD
Failures 62
Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.19
13
Air Forces ESD Estimate
Extent of ESD Damage
Estimate of Failures Due to ESD
1988 USAF, A Review of EOS/ESD Field Failures
in Military Equipment.
Up to 12 of the Failures could be ESD.
Capt Thomas Green 1988 EOS / ESD Symposium
Proceedings
14
Damage in Manufacturing
Extent of ESD Damage

• EOS/ESD Damage During Manufacturing.
• Data from 23 designs from High Reliability
  Facility.
• Out of 1193 Processing Failures.
• There were 414 EOS/ESD Failures.
• At Another Plant 1607 Devices Were Analyzed.
• The Conclusion in 1993 was.
• 25.8 of the product rejected by this.
• facility was damaged by the cumulative.
• effects of EOS and ESD, all of which.
• were avoidable.
• Basic ESD Seminar prepared by Burt Unger for
  the ESD Association, Rome, NY, P.20

15
Repair Cost vs Discovery
Extent of ESD Damage

• REPAIR COSTS

Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.16
16
Directives, 1st of 6
Directives

• Air Force Policy Directive 21-1 and 21-3
• Compliance with AF T.O.s is mandatory
• T.O. 00-25-234, General Shop Practice
  Requirement for the Repair, Maintenance, and Test
  of Electrical Equipment.
• ANSI/ESD S20.20, Development of an ESD Control
  Program is replacing Mil-Std-1686
• MIL-HDBK-263B, Electrostatic Discharge
• Local Operating Instructions

17
Authorize Time Money
Directives

• The following Air Force documents authorize
• AF time and money for ESD Control as indicated
• Section 7 of T.O. 00-25-234)?
• AF Policy Directive 21-3
• AF Policy Directive 21-1
• AFI 21-116
• AFI 24-202

18
Mandatory Compliance
Directives

• AIR FORCE POLICY DIRECTIVE 21-3, Technical
  Orders
• Says Compliance with Air Force T.O.s is
  mandatory
• Includes TO 00-25-234
• AIR FORCE POLICY DIRECTIVE 21-1 Managing
  Aerospace Equipment Maintenance
• Defines Aerospace Equipment as Equipment used
  and maintained to meet the Air Force mission. It
  includes aircraft, missiles, space equipment,
  communications, electronic equipment, avionics,
  engines, training equipment, support equipment,
  aerospace ground equipment, sound suppresser
  systems, test, measurement and diagnostic
  equipment and major-end-items of all equipment

19
AFI 21-116
Directives
AIR FORCE INSTRUCTION 21-116 Maintenance and
Management of Communication Electronics Para
5.17.4.3.7.9, under responsibilities of the
Maintenance Support Representative (MSR)
requires Compliance with Electrostatic
Discharge practices, where applicable. (TO
00-25-234) TECHNICAL ORDER 00-25-234, General
Shop Practice Requirements for the Repair,
Maintenance, and Test of Electrical
Equipment Says The provisions contained
herein are applicable to Air Force and
contractual personnel engaged in repair,
maintenance, or test of Aerospace Electronic
Equipment
20
Supply is to Comply
Directives
ESD Control in Supply
AIR FORCE INSTRUCTION 24-202 Preservation and
Packaging Chapter 2 (Packaging Operations),
paragraph 2.4 Packaging Line Layout should
include At least one electrostatic discharge
(ESD) protective workstation where trained
personnel can package sensitive (ESDS) items.
This must include a conductive work surface and
personnel grounding devices. TO 00-25-234,
Section VII, contains detailed information about
ESD protective workstations. Post signs
prohibiting entry of unauthorized personnel and
static-producing materials in areas designated
for packaging ESDS items
21
Supply AFI 24-202
Directives
AIR FORCE INSTRUCTION 24-202 Chapter 3,
Preserving Supply and Equipment Items, para
3.2, Electrostatic Discharge Sensitive Items
says 3.2 Never handle ESD-sensitive items,
regardless of condition, without their protective
packaging except at a grounded ESD
workstation. 3.2.1. Use care in opening ESD
items. ESD bags are usually constructed with
enough extra material to allow for at least one
additional heat seal, thereby facilitating reuse
in the maintenance activity. 3.2.2. Identify ESD
items by Type Cargo Code 3 on DD Form 1348-1A,
and by special interior and exterior
sensitive-electronic-device caution label .
22
Electrical Definitions
Definitions

• Conductors - Materials that permit the
  free
• movement of electrons.
• Electrons - Small negatively charged
  particles
• Electric Current - Movement of free electrons
• Insulators - Materials that impede the
  free
• movement of electrons.
• Negative Charge - A surplus of electrons
• Positive Charge - A deficiency of electrons
• A Proton - A positively charged
  particle
  
  

Ms. Kim Wagner, Hill AFG, OO-ALC / TIUBA
23
Resistance Classification
Definitions
Classification Sheet Resistivity
Ohms / Square is done with special electrodes and
converted to a number that is about 10 X more
than is obtained by 7.8 a Work Surface Test
Procedure.
24
ESD Physics, 1st of 6
ESD Physics

• Tribocharging
• Separation of surfaces
• Tape
• Binder Pages
• Rubbing of surfaces together
• Footwear against the floor
• Clothing against anything it touches
• Flow of fluids
• Fuel, oil and water

25
Ben Franklin Painting
Ben Franklin was surely protected by the Angels
during his foolish kite stunt, or should we say
shunt?
Ms. Kim Wagner, Hill AFG, OO-ALC / TIUBA
26
At the Molecular Level
ESD Physics
Both Molecules are Electrically Neutral
Both Molecules are Electrically Charged
27
Charge, Attract Repel
ESD Physics
Opposite Charges Attract
Charges
Like Charges Repel
28
Electric Field Demonstrations
ESD Physics

• Around insulators
• Styrofoam
• Teflon -
• Around human body standing on an insulator
• With wrist strap
• Without wrist strap
• Absent around grounded conductors

29
Charge Distribution
ESD Physics
30
Retention of Charges
ESD Physics
Retention of Charges After Separation of Surfaces
GROUNDED CONDUCTOR GROUNDED
CONDUCTOR no charge
no charge
GROUNDED CONDUCTOR INSULATOR
no charge
charged
INSULATED CONDUCTOR INSULATOR
charged
charged
INSULATOR INSULATOR
charged charged
Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.28
31
Tribocharging
Tribocharging
Triboelectric Series
Nickel, Copper Brass, Silver Gold,
Platinum Polyester
Celluloid Saran
Polyurethane
Polyethylene
Polypropylene PVC
Silicon
Teflon

Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.32
32
Amount Rate of Charge
Tribocharging

• Amount of Charge Generated
• - Relative position in triboelectric series
• - Intimacy of contact
• - Rate of separation
• - Coefficient of friction
• Rate of Discharge
• - Conductivity of materials
• - Relative humidity
• Moisture on surface

Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.37
33
Effects of Humidity
Varies with Season Location and and Time

• Winter, Low Humidity, High Static
• Extra caution is necessary
• The colder it gets, the more electrostatic
  discharge
• Summer, High Humidity, Low Static
• Exception is Lightening
• Difficult to demonstrate static events
• Desert Areas and at High Atmospheres
• These places have low humidity
• Static is a problem year around

34
Voltage Humidity
Effects of Humidity
Voltages at Various Humidities
Means of Static Generation
Electrostatic Voltages Refer to Table
7-2 in T.O. 00-25-234 10
40 55 R.H. R.H.
R.H.
Person Walking Across Carpet
35,000 15,000 7,500 Person Walking
Across Vinyl Floor
12,000 5,000 3,000 Worker at a
Bench (No wrist Strap!) 6,000
500 400 White Styrofoam packing
120,000
50,000 15,000 Common plastic bag picked up
from bench 60,000 25,000
10,000
Notice that with higher humidity, the charging
potentials decrease significantly but are still
at damaging levels.
Basic ESD Seminar prepared by Burt Unger for
the ESD Association, Rome, NY, P.38
35
ESD Control Work Areas

• T.O. 00-25-234, Section VII Requires

• ESD Control Work Area Survey
• The Work Area Survey (performed by the ESD POC)
  defines the ESD work area and identifies the
  necessary ESD control items required for that
  work area.
• Keep Two Basic Rules in Mind
• Handle all ESD Sensitive items at an approved
  static control workstation.
• Transport and store all static sensitive
  components, circuit boards, assemblies and
  systems in static shielding (Faraday Cage)
  packages or containers.

36
ESD Control Work Areas

• T.O. 00-25-234, Section VII Requires

• ESD Control Work Area Certification
• The Work Area Certification is an evaluation by
  the ESD POC to ensure an ESD work area meets the
  requirements of the Work Area Survey.
• The appropriate certification document (letter
  signed by ESD POC) shall be posted at the
  entrance to the ESD work area or in a readily
  accessible file.

37
Controlling Body Voltage

• Wrist Straps

• Purpose
• An ESD control wrist strap is used to prevent
  body
• voltage from damaging ESD sensitive items.
• Use
• Typically, an ESD control wrist strap should be
  worn anytime you are handling an ESD sensitive
  item.
• Testing Requirement
• Single conductor wrist straps shall be tested
  prior to first use each day per person.

38
Controlling Body Voltage

• Wrist Straps

• Advantages
• Drains body voltage to ground
• An economical ESD solution
• Can be used almost anywhere
• Prevents body voltage buildup
• Adjustable size and cord length
• Light weight
• Ease of use

39
Wrist Straps
Controlling Body Voltage

• Wrist Straps

• Disadvantages
• You have to remember to use them.
• Requires testing !
• You dont know when they are working !
• You have to test them periodically
• Reasons for test failures
• They frequently do not make good
• body contact because
• Body hair, Dry skin, Loose fit
• Worn Cuff, Broken cord, etc.

40
Adjustable Cuffs
Controlling Body Voltage

• Wrist Straps

T.O. 00-25-234 requires that all wrist straps
have adjustable diameter cuffs. Metal wrist
strap cuffs have not been approved.
41
Wrist Strap Warning
Controlling Body Voltage
WARNING
The personnel wrist strap shall not be worn when
working on energized parts, assemblies and
equipment.
42
Current, Physiologic Effects
Controlling Body Voltage
Effect of Electrical Current on Humans
(Ref. MIL-STD-454) Also in Table 7-4 of TO
00-25-234
43
Wrist Strap Testing
Controlling Body Voltage
Wrist Strap Testers, Electrical Aspects
Dont use an Ohmmeter to test wrist straps.
44
Non-Linear Resistance
Controlling Body Voltage

• Skin Resistance is Non-Linear

VERY MOISTURE DEPENDENT. LOTIONS SOMETIMES REQUIR
ED
A DMM puts out less than a volt when
measuring ohms therefore, a good cuff will
test as defective.
45
Continuous Monitors
Controlling Body Voltage
Wrist Strap Continuous Monitors

• Resistance Measurement Type
• The system resistance is continuously
• monitored during use.
• Resistance Range 0.8 to 10 Meg ohms

• Voltage Sensing Type
• Body Voltage is monitored continuously.
• Acceptable Voltage Range 0 to /-10V

46
Dual Wire Cords
Controlling Body Voltage

• Wrist Strap Continuous Monitors
• Both types require dual wire cords
• and special wrist strap cuffs.

47
Footwear Testing
Controlling Body Voltage

• Footwear Testing
• Refer to ESD STM97.1-1999
• Demonstrate Footwear Test with
• Integrated wrist strap / footwear tester
• Portable Flooring Megger
• Demonstrate the Footwear Test
• Combat Boots
• ESD Shoes
• Stocking Feet

48
Footwear/Floor System
Controlling Body Voltage

• Lab Data on Max Body Voltage
• Without Wrist Strap Actual Lab Data
• On Nylon Carpet At 10 RH
• With Combat Boots - 840 V
• With ESD Shoes 215 V
• On ESD Carpet
• With Combat Boots 558 V
• With ESD Shoes 41 V
• Good ESD control requires a
• complete system approach!

49
Packaging, 1st of 8
Packaging

• SUMMARY OF ESD CONTROL.
• STRATEGIES.
• RULE 1.
• Handle all ESD Sensitive items at an ESD.
• Workstation.
• RULE 2.
• Transport and store all ESDS items ( both.
• reparable and serviceable) in static.
• shielding and non-charge generating.
• packages or containers.

TO 00-25-234 Chapter 7, 7-5.b
50
Objectives
Packaging

• ESD Packaging Objectives
• Provides Shielding
• Immune to Tribocharging
• Allow charge transfer from package exterior to
  an ESD protective worksurface

51
Types 1, 2, 3
Packaging

• Mil-Prf-81705D for ESD Protective,
  Heat-Sealable, Barrier Materials
• A Navy Spec 3 Sep 98
• Three Types
• Type I Not transparent, Water-vapor proof, ESD
• protective, EMI and ESD
  shielding. Heavy duty.
• Type II Transparent, Waterproof, ESD protective
  and
• dissipative. Pink Poly fits
  here.
• Type III Transparent, Waterproof, ESD protective
  and
• static shielding

52
Type 1, details
Packaging

• EMI/Static Shield Bag (Type I)
• Top of the Line, heavy duty outer wrap.
• Required for long
• term storage.
• Protects from
• water vapor
• Electromagnetic
• Fields.
• ESD Protective.

53
Type 2, details
Packaging

• Pink Poly Bags (Type II).
• Pink Polyethylene reduces tribocharging.
• Does not provide.
• good ESD protection.
• Is used to protect.
• from physical damage.
• Shown Zip Lock Bubble.
• Wrap.

54
Type 3, Details
Packaging

• Static Shielding Bag (Type III)
• Transparent, Local use, Shielding bag
• Reduces need to open bags
• Water proof
• (not vapor proof)
• Protects from
• Electrostatic fields
• (not magnetic fields)
• Dissipates a Charge

55
Materials to Avoid
Packaging

• Avoid Unnecessary Charge Generators
• Styrofoam materials

• Clear Polyethylene and
• Polypropylene films
• and bags

56
Packaging, Demos
Packaging

• Demonstrate the Properties of the three types
  of bags
• Transparency
• Tribocharging
• ESD Shielding
• EMI Shielding
• Puncture Resistance
• Vapor and water Resistance

This is not a Faraday Cage !
57
Packaging

• When does ESD susceptibility stop?
• When ESD sensitive items are properly packaged in
  ESD control packaging materials.
• When the level of assembly or packaging is such
  that a complete electrostatic shield (Faraday
  Cage) exists around the item.
• Faraday Cage Examples
• ESD Shielding Bag/Pouch, Conductive Tote Box
  (with lid), Conductive Case/Enclosure

58
Cabinets, Shelves, Work Surfaces

• Cabinets, Shelves, Work Surfaces Requirements
• Ground cabinets, shelves, and work surfaces used
  during handling or storage of ESD sensitive
  items.
• All ESD control work surfaces, storage cabinets,
  and shelves shall be tested annually.
• Non ESD designed shelves and storage cabinets may
  require fitted ESD work surface material to meet
  this requirement.
• Cabinets and shelves used exclusively for storage
  of non ESD Sensitive items (or ESD Sensitive
  items protected by a complete Faraday Cage) do
  not require a ground connection or periodic
  testing.

59
ESD Connector Caps

• Connector Caps, NASM5501/31 32 Formerly
  Mil-C-5501/31A 32A
• They complete the Faraday Cage
• They protect against discharge to the pins.
• They keep moisture and dust out.
• They need to be conductive to work.
• Pink Poly will not work
• None of the colored ones will protect
  electronics
• They can be tested with a DMM
• There is a supply problem
• Some are not labeled correctly.

60
Marking Signs, 1st of 4
Marking, Labeling, Signs

• Equipment Label
• TO 00-25-234, Fig 7-8
• Attach on a readily visible exterior surface,
• if space is available and does not hinder
• operation of the item.

61
Unit Pack Label
Marking, Labeling, Signs

• The Unit Pack Label
• TO 00-25-234, Fig 7-11
• Attach to both sides of outermost bag.

62
Shipping Container Label
Marking, Labeling, Signs

• Shipping Container Label
• TO 00-25-234, Fig 7-12
• Attach to Fast-Pack, Intermediate Pack,
  Exterior Pack, or Shipping Container which
  contain the unit packs.

• The preferred color
• scheme is shown.

63
ESD Work Area Sign
Marking, Labeling, Signs

• ESD Work Area Sign
• TO 00-25-234, Fig 7-16
• Placed at or near the entrance to ESD
• Work Area.

64
ESD Worksurfaces, 1st of 4
ESD Worksurfaces

• TYPES OF ESD WORKSURFACES
• RIGID
• None approved at this time
• They have smooth hard surfaces, but do not
  dissipate charge at low humidity.
• CUSHIONED
• These are most commonly used.
• Available in standard 2 x 4 size (Table 7-3 item
  16)
• The 40 Roll, Item 19 in Table 7-3, does about 10
  work benches
• FOLDABLE
• These are portable and have CPG W/S

65
Permanent Type
ESD Worksurfaces

• Permanent ESD Workstation Surface.
• Glued to the wood subsurface.
• Prevents sliding and buckling of the surface.
• Durable hard rubber increases service life.
• Surface hardness is between Rigid and Cushioned.
• Passes AFs static dissipation, and resistance.
• tests.

Refer to items 1 - 12 in Table 7-3
66
ESD Worksurfaces

• What to do with a non ESD Workstation?
• Add a 2 x 4 ESD control work surface.
• Sits on top of existing surface.
• Reduces cost of replacing entire workstation
• Reference Table 7-3, item 13 in T.O. 00-25-234.

67
Cleaning them
ESD Worksurfaces

• CLEANING WORKSURFACES.
• Best to use 70 / 30 IPA / water.
• Do not use any silicones !
• Do not use oils or waxes !
• Demonstrate Testing the Work Surface.
• Test Annually or sooner if desired.
• The Work Surface Test Procedure is in 7-8 a.
• A Megohmmeter and a 5 LB electrode is used.
• Test points from the surface to the CPG.

68
Scrim Layer Functions
ESD Worksurfaces

• Scrim Layer Functions
• Provides a uniform top to top resistance
• It is part of the grounding system
• Test the electrical contact from Snap to Scrim
• Use a DMM or Megger across the Snaps

69
Air Ionizers, what they do
AIR IONIZATION

• IONIZED AIR REMOVES CHARGES
• FROM JOB ESSENTIAL NON CONDUCTORS
• PACKAGING MATERIALS
• LAMINATED SCHEMATICS DRAWINGS
• AND FROM ISOLATED CONDUCTORS
• NEED TO MAINTAIN A BALANCE OF
• POSITIVE NEGATIVE IONS

70
When to use Ionizers
AIR IONIZATION

• Use When
• The Work Area Survey requires it.

• Demonstrate Value of Ionization

Ionizers require periodic testing.
Refer to 00-25-234 7-7.d.6.a
71
Grounding, 1st of 5
Grounding

• View of Open Outlet Box Showing Equipment
  Grounding Conductors.

72
Wiring Verification Test
Grounding

• Utility Wiring Verification Test is done first.
• Par. 7-5.e(3)(b) of T.O. 00-25-234.

73
Utility Ground Check
Grounding

• Utility Ground Wiring Verification Check,
• Par. 7-5.e(3)(c)

• Item 66 of
• Table 7-3

74
Bench Ground Check
Grounding

• Resistance Check from Benchs Groundable point
  to
• third wire
• ground.
• Par. 7-5.e(3)(d)

75
Common Point Ground
Grounding

• USE AN OHMMETER TO CHECK CONTINUITY FROM THE CPG
  TO
• WRIST STRAP
• PLUG-INS,
• BENCH
• DRAWERS,
• BENCH MATS,
• SHELF MATS

76
The Role of Capacitance
CAPACITANCE
A KEY PLAYER IN ESD
77
Capacitance Equations
The Role of Capacitance
CAPACITANCE EQUATIONS
Q CV C Q / V V Q / C
Q - charge in coulombs C - Capacitance in
farads V - potential in volts
Nanocoulomb (nc) 10-9 C Picofarad (pF) 10-12 F
78
Parallel Plate Example
The Role of Capacitance
Parallel Plate Capacitance
A C --- ?0K d
C Farads A meters2 d meters ?0 8.85 x
10-12 f/m K dielectric constant

• Capacitance becomes larger
• as the distance becomes less.
• Let Q (coulombs) remain
• constant.
• The Voltage goes down
• as the capacitance goes up.

V Q / C
79
Your Capacitance
The Role of Capacitance
A PRACTICAL EXAMPLE OF CAPACITANCE AT WORK

• If you have insulative shoes, your soles become
  the
• dielectric in a capacitor between you and the
• grounded floor.
• With a charge on your body lift your leg high.
• What happens in terms of the equations ?
• What happens to the voltage on your body ?

80
Reference, 1st of 4
Reference

• Measuring Charge, Coulombs

81
Energy Equations
Reference
82
Numerical Prefixes
Reference
Examples 1 nanocoulomb 1 x 10 -9 coulombs 10
picofarad 10 x 10-12 farads
83
Useful Derived Units
Reference
84
ANY Questions???

• Rome Site ESD Contacts? See Next slide

85
ESD Contacts

• Rome Site 1Lt Christopher Lowe x2276
• RIB Ron Ziminski x4450
• RIE Bob Macior x2480
• RIF 1Lt Christopher Lowe x2276
• RIG Steve Tyler x3618
• RIK Charlene Booth x2203
• RIO Linda Dittmar x2684
• RIS Julie Brichacek x4995
• RIT John Rooks x2618
• RY Bill Lipe x4878