ELECTROSTATIC DISCHARGE ESD AWARENESS TRAINING Credits Prepared by

ELECTROSTATIC DISCHARGE (ESD) AWARENESS TRAINING Credits 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 Ø Ø Ø Ø 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, 1 st of Extent of ESD Damage 7 Photo taken on a Microscope of ESD damage Micro Wire 5

A DEMO on a MOSFET A 3 N 157 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 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 150 Cost in Millions 160 129 140 120 100 160 94 80 60 40 20 0 25 78 35 43 43 79 Year 80 81 = Range of ESD Damage “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P. 17 11

Extent of ESD Damage Published ESD Losses 1980 Delco Electronics study on Auto Electronics Product ESD Failures $22 M 1983 AT&T HIC Shop ESD Losses 39% 1984 USAF Missile Guidance Video Board ESD Failures (250 Failed) $492, 000 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 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 13

Extent of ESD 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 Level where Fault was Discovered Hewlett Packard Commercial Product Gould Military System Device $1 $5 Board $5 $50 System $50 $1, 500 Field $500 $10, 000 “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P. 16 15

Directives, 1 st of 6 Ø Air Force Policy Directive 21 -1 and 21 -3 “Compliance with AF T. O. s is mandatory” Ø T. O. 00 -25 -234, General Shop Practice Requirement for the Repair, Maintenance, and Test of Electrical Equipment. Ø ANSI/ESD S 20. 20, Development of an ESD Control Program is replacing Mil-Std-1686 Ø MIL-HDBK-263 B, Electrostatic Discharge Ø 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)? µ AF Policy Directive 21 -3 µ AF Policy Directive 21 -1 µ AFI 21 -116 µ 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 -1 A, and by special interior and exterior sensitive-electronic-device caution label. 21

Definitions Electrical Definitions Ø Conductors - Materials that permit the free movement of electrons. Ø Electrons - Small negatively charged particles Ø Electric Current - Movement of free electrons Ø Insulators - Materials that impede the free movement of electrons. Ø Negative Charge - A surplus of electrons Ø Positive Charge - A deficiency of electrons Ø A Proton - A positively charged particle Ms. Kim Wagner, Hill AFG, OO-ALC / TIUBA 22

Definitions Classification Sheet Resistivity • Conductive • Static Dissipative • Insulative 100 -105 Ohms/Square Resistance Classification 105 to 1012 Ohms/Square Greater than 1012 Ohms/Square Section 7 of AF T. O. 00 -25 -234 • Conductive • Static Dissipative • Insulative 100 -106 Ohms 106 to 109 Ohms 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, 1 st 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 Both Molecules are Electrically Neutral At the Molecular Level Both Molecules are 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 ++--++++ - ++--- ++ ---- ++++--- - +++++++++++ and Can have Random Charge Distribution (Mixed Shown) Will have Uniform Charge Distribution (Positive Shown) After grounding ++--++++ - ++--- ++ ---- ++++--- - Before Does not Discharge Complete Discharge “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P. 27 29

ESD Physics Retention of Charges After Separation of Surfaces GROUNDED CONDUCTOR no charge INSULATOR charged INSULATED CONDUCTOR charged INSULATOR charged “Basic ESD Seminar” prepared by Burt Unger for the ESD Association, Rome, NY, P. 28 30

Tribocharging Triboelectric Series + Glass Human Hair Nylon Nickel, Copper Brass, Silver Gold, Platinum Polyester Wool Celluloid Lead Saran Aluminum 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 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 Refer to Table 7 -2 in T. O. 00 -25 -234 Electrostatic Voltages 10% 40% 55% 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, 000 500 400 120, 000 50, 000 15, 000 60, 000 25, 000 10, 000 White Styrofoam packing Common plastic bag picked up from bench 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 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 Voltage Wrist Strap Warning WARNING The personnel wrist strap shall not be worn when working on energized parts, assemblies and equipment. 41

Controlling Body Voltage Current, Physiologic Effects Effect of Electrical Current on Humans Current Values (Milliamperes) AC Effect DC 25 TO 400 HZ 0 -1 0 -4 1 -4 4 -15 4 -21 15 -80 21 -40 80 -160 40 -100 160 -300 Over 100 Over 300 Perception Surprise Reflex Action Muscular inhibition Respiratory block 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 61 Passing Range Ohms Output Volts 8 x 105 to 1 x 107 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 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 +/-10 V 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 STM 97. 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 • On Nylon Carpet • With Combat Boots • With ESD Shoes Actual Lab Data At 10 % RH - 840 V 215 V • On ESD Carpet • With Combat Boots • With ESD Shoes Good ESD control requires a complete system approach! 558 V 41 V 48

Packaging • Packaging, 1 st 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. TO 00 -25 -234 Chapter 7, 7 -5. b 49

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-81705 D 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, Demos • Demonstrate the Properties of the three types of bags: – Transparency – Tribocharging – ESD Shielding This is not a Faraday Cage ! – 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, NASM 5501/31 & 32 Formerly Mil-C-5501/31 A & 32 A – 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, 1 st 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, 1 st 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 IONIZATION Air 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, 1 st of 5 • View of Open Outlet Box Showing 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 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 (p. F) = 10 -12 F 77

The Role of Capacitance Parallel Plate Example Parallel Plate Capacitance A d • Capacitance becomes larger as the distance becomes less. • Let Q (coulombs) remain constant. • The Voltage goes down as the capacitance goes up. A C = --- 0 K d C = Farads A = meters 2 d = meters 0 = 8. 85 x 10 -12 f/m K = dielectric constant 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, 1 st 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 Examples: 1 nanocoulomb = 1 x 10 -9 coulombs 10 picofarad = 10 x 10 -12 farads 82

Reference Useful Derived Units 83

ANY Questions? ? ? Rome Site ESD Contacts See Next slide 84

ESD Contacts • Rome Site 1 Lt Christopher Lowe x 2276 • • • Ron Ziminski Bob Macior 1 Lt Christopher Lowe Steve Tyler Charlene Booth Linda Dittmar Julie Brichacek John Rooks Bill Lipe x 4450 x 2480 x 2276 x 3618 x 2203 x 2684 x 4995 x 2618 x 4878 RIB RIE RIF RIG RIK RIO RIS RIT RY 85