1. Compliance Verification Testing of Installed ESD Protective Products
9/05
©Copyright 2011 DESCO INDUSTRIES INC.

2. ESD TR53 Compliance Verification
Use ESD Association Technical Report ESD TR Compliance Verification of ESD Protective Equipment and Materials. Can be purchased from TR53 includes equipment, test procedures and troubleshooting tips to periodically verify the performance of ESD protective equipment and materials.
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3. ESD Protected Area Clearly Identified
“Caution signs indicating the existence of the Protected Area shall be posted and clearly visible to personnel prior to entry to the EPA [ESD Protected Area]. NOTE: An EPA can consist of a single workstation, entire room or building.”
Ref: ANSI/ESD S20.20 section 8.3.
Report Visual Observations
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4. ESD Protected Area Clearly Identified
Attention Sign
Aisle Tape
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5. Access to ESD Protected Area Controlled
“Access to the EPA shall be limited to personnel who have completed appropriate ESD training Untrained individuals shall be escorted by trained personnel while in an EPA.” Ref: ANSI/ESD S20.20 section 8.3.
Report Visual Observations
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6. Wrist Strap & Footwear Tester
SmartLogX3
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7. Check Ground
“The AC equipment ground is the preferred ground connection because all electrical equipment (e.g., soldering irons,' scopes, etc.) at the workstation is already connected to this ground.” Ref: ESD Handbook ESD TR20.20 section 5.1.3
Check AC outlet properly wired with AC Outlet Analyzer
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8. AC Outlet Analyzer and Wrist Strap Tester
Check Ground
AC Outlet Analyzer and Wrist Strap Tester
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9. Check Ground Points < 1 Ohm
Can use ohmmeter or (as an indicator) Megohmmeter (note: if has resistor expected measurement 1 megohm +/- 20%)
Suggest extension cord with AC Outlet Analyzer to connect to AC equipment ground and use Surface Resistance Megohmmeter without 5# Electrodes.
Plug one lead into wrist strap ground jack and sensing lead into electrical ground
At 10 volts, look for lowest reading if no resistor or about 1 x 10^6 ohms if there is a resistor.
Report Rtg
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10. Check Ground Points < 1 Ohm
Ohmmeter
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11. No Resistor in Mat Ground Cord
“a direct connection from the ESD technical element to the common point ground or common connection point is acceptable and recommended.
Note: Manufacturers may add resistance to the grounding conductors for purposes other than ESD (e.g. current limiting).
… The typical added resistance in grounding conductors is 1 megohm”
Ref: Grounding ANSI/ESD S6.1 section 5.3.3
“The grounding conductors (wires) from wrist straps, worksurfaces, flooring or floor mats, tools, fixtures, storage units, carts, chairs, garments and other ESD technical elements may or may not contain added resistance. Where added resistance is not present, a direct connection from the ESD technical element to the common point ground or common connection point is acceptable and recommended.
Note: Manufacturers may add resistance to the grounding conductors for purposes other than ESD (e.g. current limiting). Added resistance is acceptable for the purposes of controlling ESD provided electrostatic accumulation does not exceed specific EPA requirements. The typical added resistance in grounding conductors is 1 megohm, although other values may be specified.” [Grounding ANSI/ESD S6.1 section ESD Technical Element Conductors]
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12. Rtg and Rtt Resistance
The most important resistance measurement is resistance to ground or Rtg. How well the material conducts charges to ground; whether material is or can be grounded
Rtg or Resistance to ground The resistance in ohms measured between a single electrode placed on a surface and ground.
Rtt or Point-to-point resistance (or top to top) The resistance in ohms measured between two electrodes placed on any surface.
The best test is a system test Rtg resistance to equipment ground, not to ground point on mat which is resistance to groundable point Rtgp
Surface Resistivity is independent of location if the material is homogenous. Theoretically, Resistivity is 10 times greater than Resistance, i.e. 10^7 ohms Rtt, Surface Resistivity should measure 10^8 ohms. Note: ohms/square is not correct.
The proper unit of measure for Surface Resistivity is ohms.Confusion is one of the reasons that the ESD Association has recently made this change. Until recently, the unit of measure for Surface Resistivity was ohms / square.
Square is a dimensionless unit; it only signifies that the measurement is resistivity and not resistance. It is the geometrical constant in converting a 4 point probe measurement into surface resistivity typically when measuring silicon wafers (or other materials in FAB labs) and was erroneously adopted for ESD control. The square is independent of the area measured, it could represent a square millimeter or a square kilometer....in both cases, if the material measured is homogenous then the results should be identical, that is independent of area.
Per ESD Handbook ESD TR20.20 section “resistivity. For surface treated materials, the conventional way to describe the electrical property has been ohms/square. As discussed in the literature, this terminology is incorrect. The actual measurement is ohms only. Details of this discussion may be found in the book, Electrostatics, by Professor Niels Jonassen, Technical University of Denmark.”
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13. Worksurfaces 10^6 – 10^8 Ohms Use Megohmmeter Test Kit
Worksurfaces, Shelves, and Cart storage surfaces in EPA
S20.20 specifies no lower limit, however, ANSI/ESD S4.1 recommends in the manufacturing environment a resistance range of over or equal to 1 x 10^6 to less than 1 x 10^9 ohms.
Report Rtg resistance mat to equipment ground
If fails or if measures close to 1 x10^6 ohms (perhaps measuring resistor in ground cord) measure Rtt with two 5# electrodes about 10” apart measuring mat resistance itself.
If 1 megohm resistor is in ground cord Rtg would measure 10^6 ohms even with a very conductive worksurface
S20.20 specifies no lower limit, however, per S4.1 recommends a resistance range of over or equal to 1 x 10^6 to less than 1 x 10^9 ohms.
Report Rtt of the material itself.
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14. Worksurfaces 10^6 – 10^8 Ohms Use Megohmmeter Test Kit
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15. Use Megohmmeter Test Kit
For Rtg use Surface Resistance Megohmmeter with one 5# electrode
For Rtt use Surface Resistance Megohmmeter with two 5# electrodes
Measure at 10 volts; if over 10^5 then at 100 volts
Desco will change test voltage automatically, and has a switch to set only at 10 volts
Some other equipment use a manual switch
The best test is a system test Rtg resistance to equipment ground, not to ground point on mat which is resistance to groundable point Rtgp
For a mat then the resistance in series is measuring the mat material, the mat ground snap, its connection to the ground cord, and the integrity of the wire in the ground cord, and its connection to equipment ground (likely the ground of an AC electrical outlet).
If fail high, other troubleshooting might include testing each component separately using an ohmmeter..
Using an extension cord and an AC Outlet Analyzer is due to the fact that often it is difficult to find an assessable AC electrical outlet. Once you find one, use it to make numerous measurements. Just don’t drag the extension cord over parts and products.
Typically a banana plug does not fit securely in the ground of an AC electrical outlet. By using an AC Outlet Analyzer, you immediately test that the outlet is wired correctly while having a snug banana jack.
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16. Worksurfaces 106 – 108 Ohms Use Megohmmeter Test Kit
For Rtg use Surface Resistance Megohmmeter with one 5# Electrode
Suggest using a extension cord with AC Outlet Analyzer to connect sensing lead to AC equipment ground
Place the one 5# electrode on mat’s center or most worn area; measure Rtg at 10 volts; if over 10^5 at 100 volts
Measure at least one of each type or color mat and laminate.
If fail high, measure Rtt with two 5# electrodes about 10” apart before and after cleaning (first allow to dry).
Report Rtg (& Rtt if fail)
The best test is a system test Rtg resistance to equipment ground, not to ground point on mat which is resistance to groundable point Rtgp
For a mat then the resistance in series is measuring the mat material, the mat ground snap, its connection to the ground cord, and the integrity of the wire in the ground cord, and its connection to equipment ground (likely the ground of an AC electrical outlet).
If fail high, other troubleshooting might include testing each component separately using an ohmmeter..
Using an extension cord and an AC Outlet Analyzer is due to the fact that often it is difficult to find an assessable AC electrical outlet. Once you find one, use it to make numerous measurements. Just don’t drag the extension cord over parts and products.
Typically a banana plug does not fit securely in the ground of an AC electrical outlet. By using an AC Outlet Analyzer, you immediately test that the outlet is wired correctly while having a snug banana jack.
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17. Worksurfaces Troubleshooting ESD Mat Cleaner
Static dissipative solution cleans & restores ESD properties
Does not contain silicone which will leave a insulative film
Report observations and Rtg or Rtt before and after cleaning allowing time to dry
Cleaners will have some alcohol as a carrier. As the alcohol evaporates, it cools the surface and thus condenses moisture on the surface. Recommended "dry time" is ~20 minutes from cleaning to retest
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18. Worksurface Troubleshooting Check if Properly Grounded
“Grounding / Equipotential Bonding Systems shall be used to ensure that ESDS items, personnel and any other conductors (e.g., mobile equipment) are at the same electrical potential.” Ref: ANSI/ESD S section 8.1
Use ohmmeter to ensure electrical continuity between components in path to ground
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19. ESD Seating < 10^9 Ohms Use Megohmmeter Test Kit
Use Surface Resistance Megohmmeter with one 5# Electrode
Suggest extension cord with AC Outlet Analyzer to connect sensing lead to equipment ground
Place the one 5# electrode on various seating surfaces
Measure Rtg at 10 volts; if over 10^5 at 100 volts
Can measure with two 5# Electrodes; one on seating and one to known good ESD Floor
Report resistance measurements.
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20. ESD Seating Troubleshooting
If high Rtg, measure ESD Floor Rtg to determine if floor is high
If high, check if conductive casters are dirty
If high, use ohmmeter to ensure electrical continuity between components in path to ground
Note: if measuring Seating back surface ensure that you are holding insulative surface of 5# Electrode (or wear insulative gloves) otherwise could create a secondary path to ground through the person performing the test
To check Seating, can place a highly conductive plate under casters and measure Rtt from Seating surface to plate
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21. Storage Shelves & Cart Shelves Electrically Connected & Grounded
Less than 10^9 ohms Rtg; 10^6-10^8 if unprotected ESD sensitive items (ESDS)
Mats and Shelves worksurfaces to be grounded
Use Surface Resistance Megohmmeter with one 5# electrode same test as worksurface
Can measure with two 5# Electrodes to a known good ESD Floor
If shelf material is unknown, measure Rtt with two 5# electrodes about 10” apart
Report resistance measured
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22. ESD Flooring Less Than 10^9 Ohms Rtg
Per Floor standard ANSI/ESD S7.1 section “Perform a minimum of five tests per contiguous floor surface material or a minimum of five tests per 5,000 square feet (464.5 m2) of floor material, whichever is greater. A minimum of three of the five tests should be conducted in those areas that are subject to wear or that have chemical or water spillage or that are visibly dirty.”
Report Rtg and Rtt if measured
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23. ESD Floor <10^9 Ohms Use Megohmmeter Test Kit
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24. ESD Floor Less Than 10^9 Ohms Rtg
Use Surface Resistance Megohmmeter with one 5# Electrode
Suggest extension cord with AC Outlet Analyzer to connect sensing lead to equipment ground
For 3 of 5 tests, place the one 5# electrode on areas that are subject to wear or that have chemical or water spillage or that are visibly dirty. Measure Rtg at 10 VDC; if over 10^5 at 100 VDC
If fail high, measure Rtt with two 5# electrodes about 3 feet apart before and after cleaning (first allow to dry). If tiles, place electrodes on different tiles.
Report Rtg and Rtt if measured
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25. Flooring-Footwear System Less Than 35 megohms Rtg
Use Surface Resistance Megohmmeter with one 5# Electrode
Suggest extension cord with AC Outlet Analyzer to connect sensing lead to equipment ground
Place the one 5# electrode on bare palm of person wearing ESD footwear standing on ESD Floor;
Measure Rtg at 10 VDC; should be < ^7 ohms (35 megohms) resistance in series thru person – ESD Footwear – ESD Floor to ground.
Report Rtg
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26. Personnel Grounding Guideline
ESD TR20.20 Figure 14 Relationship Body Voltage and Resistance to Ground
120
100 80
Body Voltage 60 40 20
Per ESD Handbook ESD TR20.20 Personnel Grounding section “System Requirements, Electrostatic charge can accumulate on the body through simple movement. The charge results in an electrostatic potential or voltage between the body and ground: This voltage can be damaging to ESDS devices. The procedures outlined within ANSI/ESD S20.20 are designed to protect devices sensitive to HBM voltages of 100 volts or greater. To maintain body voltage to less than 100 volts, the body must be electrically connected to ground.
…there must be some degree of assurance that the body voltage remains below 100 volts when connected in series with a resistance to ground. This resistance is a key factor in limiting the voltage observed on the body. For a given body movement. the voltage achieved increases with resistance. Tests conducted by the International Electrotechnical Commission (lEC) have shown that a resistance of 40 x 10^6ohms or less is necessary to limit body voltage to less than 100 volts. Figure 14 shows the relationship between body voltage and resistance to ground. The limit provided within ANSI/ESD S20.20 is 35 x 10^6 ohms, which is approximately a 10% safety margin.” 1 10 20 40
Resistance (megohms)
Data used to set Resistance Limit in Combination with a Person < 35 megohms
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27. Flooring-Footwear System Charge Generation Less Than 100V
Use Charged Plate Monitor to measure electrostatic charge on a person wearing ESD Footwear on ESD Floor.
With person connected to isolated conductive plate via a wrist strap and bulldog clip, and moving feet, report highest peak voltage
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28. Charged Plate Analyzer
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29. Flooring-Footwear System Demonstration
Need both ESD flooring and footwear
To demonstrate can use Human Body Model Fixture & Ionization Test Kit
Try regular athletic shoes on ESD floor and then with ESD Footwear
Ground equipment and hold Fixture portion
Have person moving feet or walking.
Note peak voltage
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30. Human Body Model Fixture & Ionization Test Kit
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31. Flooring-Footwear System Charge Generation Less Than 100V
Charged Plate Monitor for more accurate reading
Human Body Model Fixture & Ionization Test Kit for indication or demonstration purposes
Dance 6-step recommended in ANSI/ESD 97.2, or as people normally walk in the facility
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32. ESD Protected Area Clear of Insulators
All nonessential insulators, such as those made of plastics and paper must be removed from the ESD workstation. Less than 2,000 volts or kept 12” from ESDS
Visual – Are non-essential insulators present?
Measure what charge can be generated on item
Use Static Field Meter to measure ability to charge after rubbing item with hand or on your clothing.
Report voltage; report observations of closest distance to ESD Sensitive component or assembly
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33. Digital Field Meter
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34. Measuring ElectroStatic Field Tips
Static Field Meter may have oscillating light beam to position 1” away from surface.
Typically display ElectroStatic field in kilovolts (so 1.20 would be 1,200 volts)
Static Field Meter to be grounded
Technician to be grounded
Measured charge on items smaller than 3" x 3“ only an indication
“In order to mitigate field-induced CDM [Charged Device Model] damage, the ESD program shall include a plan for the handling of process-required insulators. If the field exceeds 2,000 volts/inch, steps shall be taken to either:
A) Separate the insulator from the ESD-sensitive device by a distance of 30 cm (12 inches); or
B) Use ionization or other charge mitigating techniques to neutralize the charge.”
NOTE: The accurate measurement of electrostatic fields requires that the person making the measurement is familiar with the operation of the measuring equipment. Most hand held meters require that the reading be taken at a fixed distance from the object. They also normally specify that the object has a minimum dimension of fixed size in order to get an accurate reading.
“All nonessential insulators such as coffee cups, food wrappers and personal items shall be removed from the workstation or any operation where unprotected ESDS items are handled.” [ANSI/ESD S section 8.3]
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35. ESD Protected Area Clear of Insulators - Resistance
Can measure Rtg with item between 5# electrode and ESD mat
Use Surface Resistance Test Kit sensing lead to AC equipment ground & one 5# electrode on item on ESD mat. Note: paper absorbs moisture so may not interfere with path-to-ground, but measure with & without
Report resistance Rtg
Ideally, all insulators or non-conductors should be removed from the ESD protected workstation. Per ANSI/ESD S541 Packaging standard and Glossary ADV1.0 an insulator has a resistance of 1 x 10^11 ohms or greater.
If one allows insulators to be placed upon a properly grounded ESD worksurface, lots of money is being wasted as the path to ground of items placed on the mat may be blocked.
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36. ESD Garments Compliance Verification
ESD Garment should be grounded via cord or ESD flooring/footwear. Can be tested while worn using a Wrist Strap or Footwear Tester < 3.5 x 10^7 ohms
Observe that Garment is properly worn covering all clothing with cuffs or wristband in snug contact with skin.
Can use Surface Resistance Megohmmeter with two 5# Electrodes sleeve to sleeve Rtt
Place Garment on insulative surface; place one 5# electrode on each sleeve or cuff. Measure Rtt at 10 volts; if over 10^5 ohms at 100 volts
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37. Garment on Insulative Surface
Testing ESD Garments Rtt Sleeve to Sleeve
Garment on Insulative Surface
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38. Essential Insulators Neutralized with Ionizers
“Necessary non-conductors in the environment cannot lose their electrostatic charge by attachment to ground. Ionization systems provide neutralization of charges on these necessary non-conductive items (circuit board materials and some device packages are examples of necessary non-conductors).” [ANSI/ESD S Foreword]
Test Ionizers, use Charged Plate Monitor or Ionization Test Kit
Report Offset Voltage (Balance) & Discharge Times (both polarities)
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39. Ionizer being Tested
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40. Ionizers < +/-50 Offset Voltage User Defined Discharge Times
Test ionizer as being used; do not clean.
Remove from the surface only those items that might block airflow.
Technician and Ionization Test Kit to be grounded.
If adjustable, zero reading, and then locate test fixture on worksurface furthest away from the ionizer where ESD sensitive products are handled.
Using Charging Unit, hold acorn nut & simultaneously press button to charge Conductive Plate.
With Ionizer operating at normal speed, use a stop watch or count time in seconds it takes to go from 1,000 volt reading to 100 volts.
Change polarity and repeat discharge time test -1,000 volts to -100 volts
Measure Offset Voltage or Balance reading after allowing sufficient time for reading to stabilize.
Record Discharge Times and Offset Voltage
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41. Ionizer Troubleshooting
If poor performance, remove filter & repeat test without filter in place (passing then suggests maintenance is the problem). If still fails, remove electrical power, and clean wiping emitter pins with alcohol & re-test.
Calibrate: adjust improving offset voltage [balance] to near zero
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42. Continuous Monitors Checked
Continuous monitoring devices should be functionally checked prior to use and periodically to ensure that they are operating as designed.
Use Manufacturer’s Calibration or Verification Device
Follow manufacturer’s instructions
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43. Continuous Monitor Calibration Unit
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44. Packaging / Material Handling Dissipative Preferred 10^4 – 10^10 ohms
Can use Static Field Meter to measure ability to charge after rubbing surface. Report voltage; report observations of closest distance to ESDS
Use Surface Resistance Megohmmeter with two 5# Electrodes
Place Packaging on insulative surface; place 5# electrodes 10” apart if possible. Measure Rtt at 10 VDC; if over 10^5 ohms, measure Rtt at 100 VDC
Report Voltage and/or Rtt
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45. Use Shielding Bags / Containers Outside ESD Protected Area
When not specified by [contract]… the organization shall define ESD protective packaging requirements, both inside and outside the EPA per ANSI/ESD S541.” Ref: ANSI/ESD S section 8.4
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46. In-Plant Handler
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47. Are Re-used Bags / Containers in Good Condition?
Users should be aware that some packaging materials may be humidity dependent and may have limited shelf life. They may also lose static shielding properties by crumpling, puncturing and folding.
Report: Observations
Per ESD Handbook ESD TR20.20: Under Triboelectric Charge, it states:
“It is well known that static electricity, in the form of static cling and static shocks are more prevalent when the air is dry. Heating interior air in the winter months dries out the already dry air in the higher latitudes.”
“Note: It is recognized that some hygroscopic materials (readily accepts moisture) may have results that fluctuate and do not remain within a specified minimum or maximum resistance range as the environmental conditions change.” [ANSI/ESD STM9.1
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48. ESD Packaging Properly Marked
ESD protective packaging should be marked in accordance with ESD Protective Symbol [ANSI/ESD S541]
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49. Test Per What Reference?
Compliance Verification of ESD Protective Equipment and Materials ESD TR
Recommend buying a copy from at
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50. Compliance Verification Testing of Installed ESD Products
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