The power of lightning is in your hands. Not the hands of Thor or Zeus or whatever lightning-casting being—but yours! The average human body, at rest, produces around 100 W of power. When you shuffle along a carpeted floor and touch a doorknob, you feel a spark of static electricity. This is the simplest form of electrostatic discharge (ESD). To protect electronic components from the static coming from our skin, ANSI/ESD S1.1-2021: Wrist Straps addresses various requirements for ESD wrist straps (also known as anti-static wrist straps).
What are ESD Wrist Straps?
An electrostatic discharge takes place when there is a charge transferring between bodies of differing electrical potentials. While ESDs can pose hazards to living things (such as in explosive environments), they are rarely more than a momentary nuisance. However, for electrical equipment, like printed circuit boards (PCBs), these bursts of static can be destructive.
Professionals prevent electrostatic discharges with dissipative materials and grounding, the latter of which can be accomplished with wrist strap systems. Wrist straps, as detailed in ANSI/ESD S1.1-2021, consist of a wristband and a ground cord that provides an electrical connection of a person’s skin to ground. The ground cord grounds the wearer by completing the electrical circuit between the wristband and the ground.
About ANSI/ESD S1.1-2021
ANSI/ESD S1.1-2021, an American National Standard, provides electrical and mechanical test methods and performance limits for product qualification, acceptance testing, and system testing of wrist straps. It contains helpful figures throughout it text to aid the user with its information and test methods.
This document assists personnel working with ESD sensitive supplies and assemblies by testing wrist straps and wrist strap systems used to ground. Please note, however, that it does not address monitoring systems and garments.
ANSI/ESD S1.1-2021 was developed by the 1.0 Wrist Strap Subcommittee and published by the EOS/ESD Association, an ANSI-accredited standards developing organization (SDO) dedicated to advancing the understanding of electrical overstress (EOS) and the theory and practice of electrostatic discharge avoidance.
Changes to ANSI/ESD S1.1-2021
ANSI/ESD S1.1-2021 revises and supersedes the 2013 edition of the same standard. As outlined in Informative Annex E of the document, the current version went through the following changes to keep its information current:
- Changed limits in Table 1: Product Qualification to match ANSI/ESD S20.20 (“less than” instead of “less than or equal to”).
- Used unit N for breakaway force instead of kg.
- Added Figure 1: Wrist strap.
- Updated Figure 2: Wristband Resistance Test Fixture.
- Added Figure 3: Set-up for Wrist Strap Continuity and Resistance Test – Alternative Method.
- Added Figure 4: Set-up for Wristband Resistance Test – Interior Resistance.
- Added Figure 5: Measurement Set-up to Determine the Breakaway Force.
- Added Figure 6: Tensile Tester Example.
- Renumbered Section 6.11 to Section 6.1.2: Wrist Strap Continuity and Resistance Test – Alternative Method as an alternative test method of Section 6.1.1: Wrist Strap Continuity and Resistance Test Using the Test Fixture.
- Aligned ground connections of cord and wristband throughout the document.
ANSI/ESD S1.1-2021: Wrist Straps is available on the ANSI Webstore.