1、NASA HANDBOOK NASA-HANDBOOK 8739.21 National Aeronautics and Space Administration Washington, DC 20546 Approved: 2010-06-18 WORKMANSHIP MANUAL FOR ELECTROSTATIC DISCHARGE CONTROL (EXCLUDING ELECTRICALLY INITIATED EXPLOSIVE DEVICES) Measurement System Identification: Metric APPROVED FOR PUBLIC RELEAS
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3、UMENT HISTORY LOG Status Document Revision Approval Date Description Baseline - 2010-06-18 Initial Release This document is derived from GSFC-WM-001BJWL4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 4This page intentionally left b
4、lank. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 6This page intentionally left blank. Provided by IHSNot for ResaleNo reproductio
5、n or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 7TABLE OF CONTENTS 1 SCOPE . 11 1.1 Purpose . 11 1.2 Applicability 11 2 APPLICABLE DOCUMENTS . 12 3 DEFINITIONS . 13 4 GENERAL . 16 4.1 Configuration Control 16 4.2 Implementation 16 4.3 Records 17 5 ESD CONTROL PROGRAM 18 5.1
6、General . 18 5.2 Electrostatic Discharge (ESD) Technical Overview 1518 5.3 ESD Sensitivity Levels 19 5.4 Declaring the Model and Class Required 20 5.5 Personnel Safety 15. 21 5.6 ESD Control Program Manager/Coordinator (Required by ANSI/ESDA20.20) . 21 5.7 ESD Program Monitor . 21 5.8 ESD Protected
7、Areas (EPA) 22 5.9 Temporary, Provisional and Intermittent-Use EPAs . 23 5.10 ESD Control Program 24 5.11 Audits and Inspections . 24 6 TRAINING AND CERTIFICATION PROGRAM 26 6.1 General . 26 6.2 Training Program . 26 6.3 Certification of Training Levels 27 6.4 Record Maintenance 28 6.5 Maintenance o
8、f Training and Certification 29 7 ESD CONTROL REQUIREMENTS FOR FACILITIES . 30 7.1 General . 30 7.2 Compliance 30 7.3 Traceability 30 7.4 Identification and Access - ESD Areas 30 7.5 Temporary Use of ESD benches for Non-ESDS Work . 32 7.6 Prohibited Materials and Activities . 32 7.7 ESD-Protective W
9、ork Surfaces . 33 7.8 ESD-Protective Floor Surfaces 34 7.9 Personal Grounding Devices . 35 7.10 Integrity Testing of Personal Grounding Devices . 36 7.11 Equipment and Facilities . 36 7.12 Hand Tools, Equipment, and Fixtures . 39 Provided by IHSNot for ResaleNo reproduction or networking permitted w
10、ithout license from IHS-,-,-NASA-HDBK 8739.21 87.13 Protective Packaging 40 7.14 Temperature Chambers and Cooling Agents . 41 7.15 Cleaning and Cleaning Agents 41 7.16 Electrostatic Survey Meters, Voltmeters, and Monitors 41 7.17 Clothing Requirements 42 7.18 Orbit Replaceable Units (ORU) Requiremen
11、ts 1642 8 ESDS ITEM HANDLING . 44 8.1 General . 44 8.2 Special Requirements for Highly Sensitive Items . 44 8.3 Receiving, Internal Handling, and Shipping 46 8.4 Equipment Level Test, Maintenance, AND INSTALLATION 47 8.5 Identification and Marking 47 9 ASSURANCE PROVISIONS . 49 9.1 Surveillance . 49
12、 9.2 ESD Protected Area “PASS” Certification Requirements 49 9.3 ESD Protected Area “FAIL” Requirements 49 10 FORMS . 50 11 REFERENCES 51 LIST OF APPENDICES APPENDIX A ESD Protected Area Verification Test Procedure 52 APPENDIX B Example of an ESD Control Program Certification Log 56 APPENDIX C Examp
13、le of an ESD Protected Area Test Log . 57 APPENDIX D Example of Certification/Verification Sticker 58 APPENDIX E Example of Failed ESD Protected Area Sign 58 APPENDIX F Example of Completion of Training Certificate . 59 APPENDIX G Example Check Log 60 LIST OF FIGURES Figure 7-1: Typical ESD Grounded
14、 Workstations (Courtesy of JSC) . 33 Figure 7-2: Workstation Common Point Ground (Courtesy of JSC) . 33 Figure 7-3: Main Service Box 37 Figure 8-1: Sensitive Electronic Device Caution Symbol (with safely dissipating electrostatic charges over its surface or volume; or providing shielding from ESD sp
15、ark discharge or electrostatic fields. ESD-Protective Packaging Packaging with ESD-protective materials to prevent damage to ESDS items during storage or transport. ESD Protected Workstation See ESD Protected Area. ESD Sensitive (ESDS) Items Electrical and electronic parts, assemblies and equipment
16、which are sensitive to ESD voltages or electrostatic fields. Electrostatic Field A voltage gradient between an electrostatically charged surface and another surface of a different electrostatic potential. Ground A mass such as earth, a ship, or a vehicle hull, capable of supplying or accepting a lar
17、ge electrical charge. Groundable Point Any point with low impedance to ground where grounding may be attached. Usually it is the common point ground. Hard Ground A connection to earth ground either directly or through low impedance. Human Body Model An electrostatic discharge circuit that meets the
18、set model values by conforming to waveform criteria specified in ESD-STM 5.1, characterizing the discharge from the fingertip of a typical human being. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 15Insulative Material A material
19、 having a surface resistivity 1012ohms/square or a volume resistivity 1011ohms-cm.Kit A prepared package of parts with instructions for assembly and/or wiring a component or chassis. Level B Instructor An individual who is certified to train operators and ESD program monitors. Certified Level B Inst
20、ructors are qualified to perform the duties of an ESD program monitor. Machine Model An electrostatic discharge simulation test based on a discharge network consisting of a charged 200 Pico farad capacitor at (nominally) zero ohms of series resistance. Actual series resistance and inductance are spe
21、cified in terms of the current waveform through a shorting wire. The simulation test approximates the electrostatic discharge from a machine. (See ESD STM 5.2) Operator An individual who is trained and certified to perform tasks in an ESD protected area. Organization A NASA center, support contracto
22、r, supplier, department, group or team. Part An element of a component, assembly, or subassembly which is not normally subject to further subdivision or disassembly without destruction of its designed use, e.g., a module, IC, resistor, etc. Soft Ground A connection to ground through impedance suffic
23、iently high to limit current flow to safe levels for personnel (normally 5 milliamperes). Impedance needed for a soft ground is dependent upon the voltage levels which could be contacted by personnel near the ground. By this definition a hard ground protected by a functional GFCI is considered a sof
24、t ground. Static Dissipative A property of a material having surface resistivity 105but 1012ohms per square or a volume resistivity 104but 1011ohms-cm Subcontractor An individual or concern that enters into a purchase agreement under a Government prime contract. Surface Resistivity. The surface resi
25、stivity is an inverse measure of the conductivity of a material. Surface resistivity of a material is numerically equal to the surface resistance between two electrodes forming opposite sides of a square. The size of the square is immaterial. Surface resistivity applies to both surfaces and material
26、s with constant volume conductivity and has the value of ohms per square. System A system is a functional subdivision of a spacecraft generally composed of two or more components designed to perform an operation. An instrument is considered a system. Verification The act of performing the tests and/
27、or inspections required in Table 7-1 and reviewing ESD protected areas for compliance to the requirements of this Manual. Triboelectric Pertaining to electricity generated by friction. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21
28、 164 GENERAL 4.1 CONFIGURATION CONTROL 4.1.1 This document is a controlled document and is controlled by NASA Headquarters OSMA configuration management procedures. 4.1.2 Requests for technical changes arep processed in accordance with NASA Headquarters OSMA configuration management procedures. 4.2
29、IMPLEMENTATION 4.2.1 ESD Control Program Plans which conform to the recommendations in this handbook include requirements related to facility preparation and certification, records management, assignment of responsible personnel, manager and operator training, assessment of the sensitivity of the ha
30、rdware to be handled, and declaration and use of special processes and criteria as applicable. It is intended that recommendations herein, made using language such as “is”, “are”, “should”, and “will”, will be converted to “shall” statements in the local ESD Control Program Plans. 4.2.2 Suppliers sh
31、ould provide a central ESD Point of Contact (POC) that can advise and assist operators, Program Monitors, contractors, subcontractors and other authorized personnel in the proper and effective implementation of the provisions of this handbook. This person can be the ESD Control Program Manager that
32、is required by ANSI/ESDA S20.20-2007 2. 4.2.3 The methods described in this handbook for developing an ESD Control Program Plan are implemented directly by operators, Program Monitors, Audit Teams, Audit Coordinators, and Program Managers. 4.2.4 The needed ESD Protected Area (EPA) certification leve
33、l and associated ESD event model are determined by the hardware designer based on the most sensitive piece-part to be handled. The recommended default EPA certification level is HBM Class 1A (See Table 5-1). Where the Human Body Model (HBM) does not provide sufficient protection for the hardware, th
34、e Machine Model (MM) or the Charged Device Model (CDM) should be considered when designing the ESD protected area. (See 5.7). For areas required to protect extremely sensitive devices see paragraph 8.2. 4.2.5 Use of the guidelines herein facilitates compliance to NASA Agency-level ESD requirements h
35、owever it does not supersede or preclude Project review and approval of suppliers ANSI/ESD S20.20-complient ESD Control Program Plans. It is the Projects responsibility for assuring that local ESD Control Program Plans meet the requirements of ANSI/ESD S20.20 as well as Project-specific requirements
36、. However, it is recommended that Projects utilize this document as a benchmark against which suppliers plans are evaluated. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 174.3 RECORDS Records required by the processes described h
37、erein should be retained per Table 4-1 below. Table 4-1: Record Retention *NRRS NASA Records Retention Schedules (NPR 1441.1) Record Title Record Custodian Retention Training records Office of Human Resources and/or Supervisor. NRRS 3/33G1* - Destroy 5 years after employee discontinues or completes
38、training. ESD workstation records Laboratory Manager or owning project manager when there is no Program Manager NRRS 8/109* -Temporary- Destroy/delete when between 2 & 15 years old. Do not retain longer than life of program/project plus 5 years. Temporary/Intermittent Workstation records Project Man
39、ager NRRS 8/109* Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 185 ESD CONTROL PROGRAM 5.1 GENERAL 5.1.1 The intent of this ESD Control Program Guide meets or exceeds the requirements of ANSI/ESD S20.20 as well as the NASA ESD Wor
40、kmanship requirements for processing ESD sensitive equipment. 5.1.2 Proper control of ESD is critical at every process step that an electronic part may see, from part manufacturing through testing and shipment, to incorporation on printed wiring boards, electronic modules, and directly into boxes. 5
41、.2 ELECTROSTATIC DISCHARGE (ESD) TECHNICAL OVERVIEW 155.2.1 ESD is the sudden transfer of electrical charge between two objects at different potentials. Almost everyone has experienced ESD. One example occurs when you, wearing shoes, walk across a carpet and touch a conductive object, such as a meta
42、l doorknob. The “zap” that you feel and hear is a form of ESD. 5.2.2 The human body or other conductive objects can become electrostatically charged if not properly grounded. If this charge comes in contact with or passes near an ESD sensitive (ESDS) device, ESD damage can occur. Charge is not local
43、ized on the surface of a conductor, but is spread out uniformly over the conductors surface. Thus, very low voltages are capable of damaging ESDS devices. 5.2.3 Cathode ray tubes and other high voltage electric devices can create high electrical field potentials. Moving an ESDS device through such a
44、 field can induce current to flow through the device, thus causing damage even if the device does not come into contact with the charged surface. In addition, grounding a device that has become charged in an external electrostatic field can cause damage. 5.2.4 The physical structures on modern devic
45、es are extremely small and continue to shrink in size as technology advances. Very small charges accumulated on conductive elements of a device can exceed the breakdown potential of the insulating layers or the air gaps between them, causing the device to destroy itself. The presence of mechanical d
46、amage, such as fine scratches or contaminants within and on the surface of the device, tends to increase its ESD sensitivity. 5.2.5 Conductive, static dissipative, and insulative materials in the work place can become charged due to the triboelectric effect. These must be controlled to below damagin
47、g potentials through the use of grounding in the case of conductive and dissipative materials, or through the use of air ionization for insulative materials. 5.2.6 Where the static safe work place is in a clean room, the requirements of contamination control may place restrictions on the approaches
48、that might ordinarily be available for controlling ESD. 5.2.7 The smallest ESD event most people can detect is about 2,000 volts. This same voltage, when applied to an ESDS device, can result in catastrophic failure. Some parts are severely damaged by ESD events of tens of volts. Thus, many damaging ESD events are not noticeable by human detection alone. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-HDBK 8739.21 195.2.8 Three general ESD damage failure modes can be
