ANSI ESD S20.20-2007 - FOIA and eLibrary website! - NASA

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ANSI/ESD S20.20-2007Table 1. Grounding / Equipotential Bonding RequirementsTechnical Requirement Implementing Process Test Method Required Limit(s)Grounding / BondingSystemEquipment GroundingConductorANSI/ESD S6.1 < 1.0 ohm impedanceAuxiliary Ground ANSI/ESD S6.1< 25 ohms to theEquipment GroundingConductorEquipotential Bonding ANSI/ESD S6.1 < 1.0 x 10 9 ohms 11 The maximum resistance between any ESD technical element and the common connection point.8.2 Personnel GroundingAll personnel shall be bonded or electrically connected to the grounding / equipotential bondingsystem when handling ESDS items. The personnel grounding method(s) shall be selected fromTable 2.NOTE: Use of a garment to achieve personnel grounding shall be documented in the ESD ControlProgram Plan. The garment shall be electrically conductive from one sleeve to the next and mustalso meet the system resistance requirements defined in Note 2 in Table 2.When personnel are seated at ESD protective workstations, they shall be connected to thegrounding / equipotential bonding system via a wrist strap system.For standing operations, personnel shall be grounded via a wrist strap system or by a flooringfootwearsystem. When a flooring-footwear system is used, one of the two following conditionsshall be met:A. When the total resistance of the system (from the person, through the footwear andflooring to the grounding / equipotential bonding system) is less than 3.5 x 10 7 ohms,Method 1 shall be followed (see Table 2).B. When the total resistance of the system (from the person, through the footwear andflooring to the grounding / equipotential bonding system) is greater than 3.5 x 10 7ohms and less than 1 x 10 9 ohms, Method 2 shall be followed (see Table 2).Table 2. Personnel Grounding RequirementPersonnelProduct Qualification 1Compliance VerificationGroundingTechnicalTest Method Required Limit(s) Test Method Required Limit(s)RequirementWrist Strap ANSI/ESD S1.1System 2 (Section 5.11)Flooring / FootwearSystem – Method 1Flooring / FootwearSystem – Method 2(both required)ANSI/ESDSTM97.1ANSI/ESDSTM97.1ANSI/ESDSTM97.2< 3.5 x 10 7 ohms< 3.5 x 10 7 ohms< 10 9 ohms< 100 voltsESD TR53Wrist Strap SectionESD TR53Flooring SectionESD TR53Footwear SectionESD TR53Flooring SectionESD TR53Footwear Section< 3.5 x 10 7 ohms< 3.5 x 10 7 ohms< 3.5 x 10 7 ohms< 1.0 x 10 9 ohms< 1.0 x 10 9 ohms1Product qualification is normally conducted during the initial selection of ESD control products and materials. Any of thefollowing methods can be used: product specification review, independent laboratory evaluation or internal laboratoryevaluation.2 For situations where an ESD garment is used as part of the wrist strap grounding path, the total system resistanceincluding the person, garment and grounding cord shall be less than 3.5 x 10 7 ohms.Copyright 2010 by ESD Association. Licensed, by agreement, for enterpise-wide use to NASA.No other reproduction or transmission in any form is permitted without written permission of the ESDA.For inquiries or to report unauthorized use, contact info@esda.org.4
ANSI/ESD S20.20-20078.3 ESD Protected Areas (EPAs)Handling of ESDS parts, assemblies and equipment without ESD protective covering orpackaging shall be performed in an EPA. Caution signs indicating the existence of the EPA shallbe posted and clearly visible to personnel prior to entry to the EPA.NOTE: An EPA can consist of a single workstation, entire room or building.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.In order to mitigate field-induced CDM damage, the ESD program shall include a plan for thehandling of process-required insulators. If the field exceeds 2,000 volts/inch, steps shall be takento either:A) Separate the insulator from the ESD-sensitive device by a distance of 30 cm (12 inches);orB) Use ionization or other charge mitigating techniques to neutralize the charge.NOTE: The accurate measurement of electrostatic fields requires that the person making themeasurement is familiar with the operation of the measuring equipment. Most hand held metersrequire that the reading be taken at a fixed distance from the object. They also normally specify thatthe 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 beremoved from the workstation or any operation where unprotected ESDS items are handled.An EPA shall be established wherever ESDS products are handled. However, there are manydifferent ways to establish ESD controls within an EPA. Table 3 lists some optional ESD controlitems which can be used to control static electricity. For those ESD control items that areselected for use in the ESD Control Program, the required limits and test methods for that itembecomes mandatory.5Copyright 2010 by ESD Association. Licensed, by agreement, for enterpise-wide use to NASA.No other reproduction or transmission in any form is permitted without written permission of the ESDA.For inquiries or to report unauthorized use, contact info@esda.org.
Page 1 and 2: ANSI/ESD S20.20-2007Revision of ANS
Page 3 and 4: ESD Association Standards Committee
Page 5 and 6: ANSI/ESD S20.20-2007CAUTIONNOTICEEl
Page 7 and 8: ANSI/ESD S20.20-2007This document w
Page 9 and 10: ESD Association StandardANSI/ESD S2
Page 11: ANSI/ESD S20.20-2007The ESD Control
Page 15 and 16: ANSI/ESD S20.20-20078.4 PackagingES
Page 17 and 18: ANSI/ESD S20.20-2007ANNEX B - ESD S
Page 19 and 20: ANSI/ESD S20.20-2007Table 5. ESD Su
Page 21: ANSI/ESD S20.20-2007Industry Standa

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