In the United States, the rules for ESD testing are introduced by the ESD Association and adopted by the American National Standards Institute (ANSI). Hence, the standards are “ANSI / ESD” standards.• Mats
• Wrist Straps and Heel Grounders
The current over-arching standard is ANSI / ESD S20.20 2014. In addition to this document, there are many more specific ESD Association Standard Test Methods that you should use when creating your ESD Control Program Plan.
1. ESD Mat Requirements
Since static exists on the surface of an object, what we want to test anti static mats for is their ability to dissipate static on their top surface or work surface.
Hence the title ANSI / ESD S4.1 Worksurfaces – Resistance Measurements. The standard recommends us to perform two types of tests on the top surface of a mat used for static control: a resistance top-to-top (RTT) test, and a resistance-to-groundable point (RTG) test. You can perform both tests with an ESD meter kit.
As they state in section 8.0, “these guidelines represent a range of resistance that has generally been proven to provide protection in the manufacturing environment.”
2. ESD Workstation Grounding Requirements
The standard governing workstations
It covers the range of ways that wrist straps, personnel, and mats can be electrically bonded (grounded).
You should connect all grounded equipment to an electrical outlet. Electrical outlets follow the piping to the Earth underneath the building. When you are wearing the wrist strap standing on a mat, you are connected to the outlet electrically. The electrical field underneath the building is now in balance with you.
3. ESD Smock Test Methods and Definitions
Garments used for ESD Safety are defined in ANSI / ESD S20.20 2014 as either a “Static Control Garment” (surface resistance of < 1 x 1011 ohms); a “Groundable Static Control Garment” (surface resistance of < 1 x 109 ohms); or a “Groundable Static Control Garment System” (surface resistance of < 3.5 x 107 ohms).
An ESD meter kit is used to perform resistance top-to-top (RTT), and point-to-groundable point (RTG) tests across the panels of an ESD garment.
4. How to Check ESD Grounding of Wrist Straps and Foot Grounders
The ESD test equipment, like the combo tester, is itself typically set up to meet the requirements of ESD TR53‘s Wrist Strap and Footwear sections.
The testing, therefore, looks for a reading from the wrist strap system of less than 3.5 x 107 (35,000,000) ohms, and a reading from the foot grounder of less than 1 x 109 (1 billion) ohms.