Electrostatic Discharge Control
Electrostatic Discharge Control
NOTE 1. NASA and other government and industry partners made substantial progress last year in developing companion assurance requirements for the performance requirements found in ANSI/ESD S20.20. As the ESDA is not able to support the assurance requirements in an ESDA standard, NASA will reissue a NASA-STD-8739 document to host both minimum assurance and performance requirements for ESD control. Contact Gene.S.Monroe@nasa.gov to obtain a copy of the draft that is in development and to provide inputs/comments. .
NOTE 2. A comparison between the 1999 and the 2007 version of the document can be found at http://esda.org/s2020compare.html
NOTE 3. NASA-STD-8739.7, Electrostatic Discharge Control (Excluding Electrically Initiated Explosive Devices), was cancelled in 2002.
NOTE 4. Gap Analysis between 2014 and 2007 Versions of ANSI/ESD S20.20
Added minimum safe charge thresholds of 200 V CDM and 35 V MM to Scope concerning susceptibility of ESDS items to damage. The HBM value of 100 V remains unchanged.
Added requirement statement to Personnel Safety section: “The resistance measurements obtained through the use of these test methods shall not be used to determine the relative safety of personnel exposed to high AC or DC voltages.”
Product Qualification was added as a required element of an organization’s ESD Control Program Plan
Personnel Grounding Section reformatted. Changes include:
· removed shall statements from a note requiring documentation of garment use and electrical continuity from sleeve to sleeve;
· removed resistance values from text in favor of referencing Table 2;
· removed Method 1 for Footwear/Flooring Systems (Method 2 now simply identified as Footwear/Flooring System);
· and added requirement for garments to meet wrist strap resistance values if used for personnel grounding.
As with the 2007 version, process required insulators found with a measured field exceeding 2000 V/inch are required to be kept 30 cm (12 inches) away or to be neutralized with ionization or other charge mitigation. The 2014 version has added mitigation of insulators within 1 inch of hardware exceeding 125 V/inch and restricts the use of isolated conductors contacting ESDS items exceeding 35V.
Ionization Offset voltage (-50 V to +50 V, old value) reduced (-35V to +35V, new value); room system ionization removed, all ionization must be able to be meet the same requirements.
Added Mobile Equipment, Soldering/desoldering hand tools as optional controls (i.e. if used limits per applicable documents shall be imposed).
Note 5. Guide for Creating an ESD Safety Plan
NASA-HDBK-8739.21, Workmanship Manual for Electrostatic Discharge Control (Excluding Electrically Initiated Explosive Devices) provide text that can be used to build a site-specific ESD Safety Program Plan that is traceable to the Agency's required ESD Safety Standard, ANSI/ESD S20.20. "Shall" statements found in NASA-HDBK-8739.21 are taken directly from ANSI/ESD S20.20. All of the "should" statements in NASA-HDBK-8739.21 are provided for users who choose to convert them into requirements statements in their own local ESD Safety Program Plan. ANSI/ESD S20.20 is a requirements standard applicable to all NASA Programs and Projects. NASA-HDBK-8739.21 is not a required standard but is provided to facilitate successful use of ANSI/ESD S20.20.
NOTE 6. Training Requirements for ESD Control
Please refer primarily to ANSI/ESD S20.20 for the requirement for each organization (i.e., supplier, user, developer) who handles ESD-sensitive items to establish and implement an ESD Control Plan. ANSI/ESD S20.20 states that within the ESD Control Plan there shall be training and retraining requirements. Authors of ESD Control Plans may choose to use commercially available ESD training programs to augment training to their own specific requirements and procedures however are cautioned to avoid using externally developed ESD training as a substitute for training their own personnel to the requirements of their own ESD Control Program. This includes using ESD training developed for use within a NASA Center to train personnel working to a different Center's ESD Control Plan. Using commercially available ESD training or another NASA Center's ESD training is not a substitute for instituting an ESD Control Program or an ESD Training Program.
Dowload slides that can be used for training to a program based on NASA-HDBK-8739.21