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Air Force ElectroStatic Discharge Training slides

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					ELECTROSTATIC DISCHARGE (ESD)                 Credits

     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
                                                        1
                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!

                                                   2
         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                      4
                                     ESD Damage, 1st of


      Extent of ESD Damage                   7



Photo taken on a Microscope of ESD damage


                        Micro Wire




                                                    5
             A DEMO on a MOSFET
 A 3N157 MOSFET is lying on a circuit board to
illustrate the relative size of the all metal package.




                                                         6
An ESD Shock is applied




                          7
         Microscopic Postmortem

There is no visible damage at 150 power !




                                        8
           2500 Magnification

At 2500 power, damage to a via is seen.




                                          9
              Extent of ESD Damage                                                       Susceptibility




Susceptibility of Various Devices Exposed to ESD
   Device Type                                       Range of ESD
                                                     Susceptibility (Volts)
   MOSFET                                               100 - 200
   JFET                                                 140 - 1,000
   CMOS                                                 250 - 2,000
   Schottky Diodes, TTL                                 300 - 2,500
   Bipolar Transistors                                  300 - 7,000
   SCR                                                  600 - 1,000
    “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.39                    10
               Extent of ESD Damage                                             Telephone Systems




Estimate of Telephone System ESD Costs
                                                                  160
                                                    150
          160
                                     129
          140
          120
                       94
          100
           80
           60
           40
                                                    4              4
           20                         35
                                                    3              3
                       25
           0
                       78           79 Year 80         81
                                   = Range of ESD Damage
                                                                                                11
  “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.17
              Extent of ESD Damage
                   Published ESD Losses
1980 Delco Electronics study on Auto                                        $22M
     Electronics Product ESD Failures

1983 AT&T 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
                                                                                        12
              Extent of ESD Damage                           Air Force’s ESD Estimate




        Estimate of Failures Due to ESD
1988 USAF, A Review of EOS/ESD Field Failures
     in Military Equipment.
                                           IC Design
                                           Fabrication and
  Up to 12 %             17%               Assembly
                                     25%   Electrical
  of the                                   Overstress
  Failures          6%                     (EOS)
                                           Electrostatic
  could be                                 Discharge (ESD)
  ESD.              6%
                                           EOS or ESD

Capt Thomas Green
1988 EOS / ESD                             Retest OK
Symposium                      46%
Proceedings
                                                                                13
              Extent of ESD Damage                                            Damage in Manufacturing




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              14
            Extent of ESD Damage                                            Repair Cost vs Discovery




                        REPAIR COSTS
                                  Hewlett
   Level where                    Packard                       Gould
   Fault was                      Commercial                    Military
   Discovered                     Product                       System

   Device                          $1                           $5

   Board                           $5                           $50

   System                          $50                          $1,500

   Field                           $500                         $10,000
                                                                                                  15
“Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.16
              Directives                     Directives, 1st of 6




 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
                                                             16
             Directives
       Authorize Time & Money
 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
                                                 17
                   Directives
             Mandatory Compliance
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”
                                                                  18
                    Directives                                 AFI 21-116




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”

                                                                            19
                     Directives                            Supply is to Comply




               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”

                                                                          20
                         Directives                                   Supply & AFI
                                                                        24-202




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 .
                                                                                     21
                     Definitions                             Electrical
                                                            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
                                                                          22
                 Ms. Kim Wagner, Hill AFG, OO-ALC / TIUBA
                  Definitions                              Resistance
                                                          Classification




 Classification               Sheet Resistivity
• Conductive                 100-105 Ohms/Square
• Static Dissipative         105 to 1012 Ohms/Square
• Insulative                 Greater than 1012 Ohms/Square

     Section 7 of AF T.O. 00-25-234
• Conductive                 100-106 Ohms
• Static Dissipative         106 to 109 Ohms
• Insulative                 Not Defined

 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.                               23
           ESD Physics                       ESD Physics, 1st
                                                  of 6




• 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
                                                           24
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   25
             ESD Physics               At the Molecular Level




Both Molecules are     Both Molecules are
Electrically Neutral   Electrically Charged
                                                          26
             ESD Physics               Charge, Attract &
                                            Repel




                     Opposite Charges Attract

     Charges               +

                                   -
             +


Like Charges Repel   +

                                                     27
              ESD Physics
     Electric Field Demonstrations

•   Around insulators
          Styrofoam    +
         * Teflon       -
• Around human body standing on an insulator
       * With wrist strap
       * Without wrist strap
• Absent around grounded conductors
                                               28
                         ESD Physics                                                     Charge Distribution




             NONCONDUCTOR                                       CONDUCTOR

            ++--++--++++                                   +++++++++++
            +++ - ++--- ++                                 +++++++++++
Before      ---- ++++--- -                                 +++++++++++
             Can have Random                                Will have Uniform
and          Charge Distribution                            Charge Distribution
             (Mixed Shown)                                  (Positive Shown)

After       ++--++--++++
grounding   +++ - ++--- ++
            ---- ++++--- -

            Does not Discharge                               Complete Discharge
                                                                                                               29
            “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.27
                           ESD Physics                                            Retention of Charges




  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
                                                                                                     30
  “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.28
               Tribocharging                                                        Tribocharging




             Triboelectric Series
+                                   Nickel, Copper
      Glass
        Human Hair               Brass, Silver
         Nylon                    Gold, Platinum
             Wool                   Polyester
              Lead                     Celluloid
               Aluminum                  Saran
                                             Polyurethane
                 Paper
                                               Polyethylene
                   Cotton
                                                 Polypropylene
                    Steel
                                                  PVC
                       Wood
                                                   Silicon
                         Sealing Wax                Teflon                               -
                          Hard Rubber


    “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P.32          31
                     Tribocharging                                              Amount & Rate of
                                                                                    Charge




      • 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                 32
           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
                                                    33
                    Effects of Humidity                                                       Voltage &
                                                                                              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
                                                                                                          34
      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.

                                                              35
      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.




                                                               36
     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.


                                                               37
     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

                                            38
       Controlling Body Voltage            Wrist Straps



• Wrist Straps
  • Disadvantages:
     • You have to remember to use them.
     • Requires testing !
        • You don’t 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.
                                                     39
      Controlling Body Voltage         Adjustable Cuffs




• Wrist Straps

    T.O. 00-25-234 requires that
    all wrist straps have adjustable
    diameter cuffs.

    Metal wrist strap cuffs have
    not been approved.


                                                     40
   Controlling Body                      Wrist Strap
                                          Warning


   Voltage


     WARNING

The personnel wrist strap shall not be
  worn when working on energized
  parts, assemblies and equipment.

                                                       41
      Controlling Body
                                                                    Current,
                                                                   Physiologic
                                                                     Effects

      Voltage
Effect of Electrical Current on Humans
 Current Values (Milliamperes)                       Effect
    AC                        DC
 25 TO 400 HZ

           0-1                   0-4           Perception
           1-4                  4-15           Surprise
          4-21                 15-80           Reflex Action
         21-40               80-160            Muscular inhibition
      40-100                160-300            Respiratory block
    Over 100               Over 300            Usually fatal


         (Ref. MIL-STD-454) Also in Table 7-4 of TO 00-25-234
                                                                                 42
      Controlling Body Voltage          Wrist Strap
                                         Testing




Wrist Strap Testers, Electrical Aspects


Table 7-3 ITEM    Passing Range      Output
                     Ohms             Volts

     61            8x105 to 1x107     8 - 13


 Don’t use an Ohmmeter to test wrist straps.

                                                      43
         Controlling Body Voltage
                                              Non-Linear
                                              Resistance




       Skin Resistance is Non-Linear
      VERY
      MOISTURE
      DEPENDENT.

      LOTIONS
      SOMETIMES
      REQUIRED           DC VOLTS
A DMM puts out less than a volt when measuring
ohms; therefore, a good cuff will test as defective.
                                                           44
     Controlling Body Voltage             Continuous
                                           Monitors




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
                                                       45
   Controlling Body Voltage        Dual Wire Cords




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




                                               46
    Controlling Body Voltage        Footwear
                                     Testing




• 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                               47
      Controlling Body Voltage
                                         Footwear/Floor
                                            System




  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!
                                                      48
                   Packaging                      Packaging, 1st of 8




        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.
                                                                  49
                  TO 00-25-234 Chapter 7, 7-5.b
           Packaging           Objectives




 ESD Packaging Objectives
– Provides Shielding

– Immune to Tribocharging

– Allow charge transfer from
 package exterior to an ESD
 protective worksurface
                                            50
                   Packaging                      Types 1, 2, & 3




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                                         51
                      Packaging           Type 1, details




• 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.                                         52
                  Packaging                    Type 2, details




• 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.
                                                                 53
                  Packaging                 Type 3, Details




• 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
                                                              54
                    Packaging   Materials to Avoid




• Avoid Unnecessary
 Charge Generators

  – Styrofoam materials



  – Clear Polyethylene and
   Polypropylene films
   and bags

                                                     55
             Packaging                 Packaging, Demos




• Demonstrate the Properties of
 the three types of bags:

 – Transparency                 This is not a
                                Faraday Cage !
 – Tribocharging
 – ESD Shielding
 – EMI Shielding
 – Puncture Resistance
 – Vapor and water Resistance

                                                          56
                   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


                                                              57
     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.


                                                               58
         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.                  59
       Marking, Labeling, & Signs          Marking & Signs, 1st of 4




• 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.




                                                                  60
       Marking, Labeling, & Signs              Unit Pack Label




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



                    ATTENTION
                   STATIC SENSITIVE DEVICES
                         HANDLE ONLY AT
                   STATIC SAFE WORK STATIONS




                                                                 61
        Marking, Labeling, & Signs       Shipping Container Label




• 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.



                                                               62
       Marking, Labeling, & Signs        ESD Work Area Sign




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

             ATTENTION
         STATIC SAFEGUARDED
              WORK AREA




                                                              63
           ESD Worksurfaces                          ESD Worksurfaces, 1st
                                                            of 4




• 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
                                                                             64
             ESD Worksurfaces                    Permanent Type




• 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 AF’s static dissipation, and resistance.
        tests.


                                Refer to items 1 - 12
                                    in Table 7-3


                                                                  65
              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.




                                                      66
                 ESD Worksurfaces                 Cleaning them




• 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.
                                                                  67
             ESD Worksurfaces                            Scrim Layer Functions




• 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

              Insulative, Protective, Transparent Paper Layer
              Humectants, Metal particles, Salts, Ionic Materials
              The Colored Decorative Paper
              Layer
              The Conductive Scrim layer, usually carbon doped paper
              Cardboard Layer #1 for strength and thickness
              Cardboard Layer #2 for strength and thickness                  68
                                     Air

       AIR IONIZATION             Ionizers,
                                  what they
                                     do


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
                                              69
            AIR IONIZATION                      When to use Ionizers




• 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
                                                                       70
                Grounding                     Grounding, 1st of 5




• View of Open Outlet Box Showing Equipment
  Grounding Conductors.
                                        Equipment
                                        Grounding
                                        Conductors




         Third Wire
         “Ground”


                                                                    71
             Grounding                           Wiring Verification Test




•photo




 Utility Wiring Verification Test is done first.
           Par. 7-5.e(3)(b) of T.O. 00-25-234.                       72
                 Grounding                    Utility Ground Check




• Utility Ground Wiring Verification Check,
  Par. 7-5.e(3)(c)
• Item 66 of
 Table 7-3




                                                                     73
                   Grounding                  Bench Ground Check




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




                                                                   74
               Grounding       Common Point Ground




• USE AN OHMMETER TO CHECK
 CONTINUITY FROM THE CPG TO:

 WRIST STRAP
 PLUG-INS,

 BENCH
 DRAWERS,

 BENCH MATS,


 SHELF MATS
                                                75
The Role of Capacitance



 CAPACITANCE
 A KEY PLAYER IN ESD




                          76
    The Role of Capacitance          Capacitance Equations




   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                       77
             The Role of Capacitance            Parallel Plate Example




  Parallel Plate Capacitance

                            d        A
             A                   C = --- 0K
                                     d
                                 C = Farads
• Capacitance becomes larger     A = meters2
 as the distance becomes less.   d = meters
• Let Q (coulombs) remain        0 = 8.85 x 10-12 f/m
 constant.                       K = dielectric constant
• The Voltage goes down
 as the capacitance goes up.      V=Q/C
                                                                     78
          The Role of Capacitance                  Your 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 ?


                                                                      79
         Reference              Reference, 1st of 4




• Measuring Charge, Coulombs




Faraday Cup      Electrometer



                                                      80
        Reference
      Energy Equations

E = 1/2 C V 2      E = 1/2 Q V

        E = 1/2 Q 2 / C

        E = energy in Joules
        C = Capacitance in Farads
        V = Volts DC
                                    81
              Reference
            Numerical Prefixes
    FACTOR        PREFI X      SYMBOL
       12
    10            t era        T
       9
    10            gi ga        G
       6
    10              e
                  m ga         M
       3
    10            ki l o       k
       -3
    10              i
                  mlli         m
       -6
    10              i
                  m cro        u
       -9
    10            na no        n
       - 12
    10            pi c o       p

Examples:   1 nanocoulomb = 1 x 10 -9 coulombs
            10 picofarad = 10 x 10-12 farads     82
                 Reference
              Useful Derived Units
QUANTITY              NAME      SYMBOL EXPRESSION
force                 Newton      N    Kg/m/s-2

charge                coulomb     Q    A/s
energy                joule       J    N/m
power                 watt        W    J/s
field strength                    E    N/C - V/m
voltage potential     volt        V    J/C
capacitance           farad       C    Q/V

resistance            ohm             V/A
bulk resistivity                  P     - m
surface resistivity               Ps   Square
                                                    83
    ANY Questions???


Rome Site ESD Contacts See
         Next slide




                              84
               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

                                             85

				
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