What is ESD wrist strap tester?

An ESD wrist strap tester is a device used to test the performance and reliability of electrostatic discharge (ESD) protective wrist straps.

As a portable battery-powered tool, ED698 is ideal for use in small workshop or by supervisors to conduct spot checks on employees and ensure compliance. The green LED will illuminate to signify a successful test, provided the resistance measured across the circuit is between the specified 800 kilohm and 9 megohm thresholds.

ESD wrist strap testing procedure

The operator wears the wrist strap and inserts its snap into the ESD wrist strap tester’s jack. Then touch the metal plate until the test completes. A green light indicates a passed test, while a red light indicates a failed test.

In addtion, ESD footwear testers can perform supplementary testing on the electrical resistance of heel grounders and ESD shoes worn by employees in ESD protected area.

How often should esd wrist straps be tested?

EESD (Electrostatic Discharge) wrist straps should typically be tested daily to ensure their effectiveness in grounding. This recommendation is based on industry common standards and guidelines, includes:

Fundamentals of Electrostatic Discharge: In Part 3, titled “Basic ESD Control Procedures and Materials” the document states, “Wrist straps have several failure mechanisms and therefore should be tested on a regular basis. Either daily testing at specific test stations or using a continuous monitor at the workbench is recommended.”

ANSI/ESD S1.1-2021: In Annex A.3, titled “Frequency of System Testing,” the standard states, “The wrist strap system should be tested daily to ensure proper electrical resistance.”

What is an ESD wrist strap?

ESD wrist strap, also called ESD wrist band and ESD bracelet, is a anti static device designed to quickly and effectively dissipate static electricity from the human body to ground in ESD sensitive area.

An ESD wrist strap is a device primarily made up of an anti-static elastic band, a movable buckle, a spring coil cord, a protective resistor, and a plug or clamp. By establishing direct contact with the skin, it forms a conductive pathway that enables the safe dissipation of static electricity from the human body to the common ground.

How must an ESD grounding wrist strap be worn?

Common Mistakes in Wearing an Anti-static Wrist Strap

Do you frequently encounter situations where your ESD wrist strap malfunctions and fails to work properly? However, in most cases, this is due to the incorrect ways of wearing the ESD wrist strap. By becoming aware of these common mistakes in wearing, you can ensure the proper functionality of the ESD wrist strap.

How do you ground an ESD wrist strap?

It is recommended to use a professional ESD grounding device in EPA, and insert the grounding terminal of the wrist strap into the grounding device socket. If using an alligator clip, it should grip the bare part of the ESD grounding wire.

If there is no professional ESD grounding wire in your work area, you can clip the wrist strap to the metal part of the workbench or large equipment in the work area to achieve local equipotential connection. The metal part should be clean and unpainted, as a painted surface would not provide a proper connection.

The Importance of ESD Wrist Straps in Sensitive Work Environments

In the manufacturing of electronic products, semiconductor production, and maintenance of medical equipment, static electricity can potentially cause serious damage to the devices. ESD (Electrostatic Discharge) wrist straps ensure that personnel working with these ESD sensitive devices to not trigger equipment malfunctions or damage due to human body static electricity. In flammable and explosive work environments, static electricity can also pose a risk of fire or explosion. The use of ESD wrist straps can eliminate this potential safety hazard and ensure the safety of personnel.

Types of ESD wrist strap tester

• Single-wire ESD wrist strap tester: used to test the ground resistance of the single-wire wrist strap.
• Dual-Wire  ESD wrist strap tester: can test both the ground resistance and current of the dual-wire wrist strap.
• Combo Tester: specially designed to test the ground resistance of all grounding devices included wrist strap, footwear and garments.

ESD Wrist Band Tester vs. ESD Combo Tester: Weighing the Pros and Cons to Make the Right Choice

Pros & Cons of ESD Wrist Band Tester

Pros	Cons
1. Relatively simple and straightforward to use 2. More affordable compared to combo tester	1. Limited to testing only wrist bands 2. May not provide the level of accuracy and precision offered by professional test instruments 3. Only test results without test resistance value 4. Inability to save and track test data, limiting documentation and traceability

Pros & Cons of ESD Combo Tester

Pros

Cons

1. Comprehensive functionality to test wrist bands, foot grounders, ESD shoes, and ESD garments 2. Employs professional test equipment for higher accuracy and reliability of results 3. Intuitive display of digital test resistance value 4. Broader applicability across various industries and ESD management requirements 5. Ability to record test data for documentation, analysis, and compliance purposes 6. Support integration with eletectronic doorlock/turnstiles

1. Higher initial investment compared to a dedicated wrist band tester

When choosing between an ESD wrist band tester and an ESD combo tester, consider your specific ESD control needs. The wrist band tester is more cost-effective if you only need to test wrist bands without extensive data requirements. However, the ESD combo tester’s advanced capabilities for testing diverse ESD devices and managing detailed records make it the better long-term investment, despite the higher initial cost. Contact an ESD Defender expert for a tailor-made solution.

What should be the resistance of an ESD wrist strap?

As per ANSI/ESD S1.1-2021 and IEC 61340-5-1 standards, the resistance of an anti-static wrist strap should be less than 3.5 x 10E7 ohms. This ensures that the wrist strap can effectively discharge the human body’s electrical charge to the ground, while not posing a danger to the human body.

How to use ESD wrist strap?

Wear the wrist strap on your wrist, ensuring it makes direct contact with your skin. Then connect the grounding cord of the wrist strap to a known grouding point.

In addition, there are a few more points to note：
1. The resistance value of the wrist strap should be regularly checked using an ESD grounding tester/ESD wrist strap monitor to ensure it is within the range of 750 kilohms to 35 megohms.
2. Avoid wrapping the wrist strap around your wrist, as this can disrupt the grounding circuit. Keep the wrist strap loosely worn.
3. Replace the wrist strap periodically, as they can wear out over time.

ESD wrist strap tester calibration

Electrostatic wrist strap testers require regular calibration to ensure the accuracy and reliability of their measurements. Additionally, industry standards like ANSI/ESD S20.20, IEC 61340-5-1, and JEDEC JESD-625B mandate periodic calibration of test equipment to ensure test result compliance with the relevant standards.

Click here to see a wrist strap calibration tutorial video.

Do wireless wrist strap really work?

Compared to conventional wrist straps, wireless wrist straps are gaining popularity due to their convenience and unrestricted mobility. The vendors of these wireless wrist straps claim that they can dissipate static electricity without the need for a ground wire connected to a grounding circuit. However, is this claim truly accurate?

While the portability and freedom of movement offered by wireless wrist straps may be appealing, the effectiveness of these devices in adequately dissipating static electricity has been called into question. NASA engineers have conducted extensive testing and found that these wireless wrist straps fail to prevent charge buildup or effectively drain accumulated charge, thereby not meeting the necessary product qualification requirements.

The experiment demonstrates that，contrary to the assertions of vendors, wireless wrist straps are inadequate in maintaining the user at the same electrical potential as ESD-sensitive hardware due to their lack of a direct connection to a grounding circuit.

Furthermore, the ANSI/ESD S20.20 standard clearly stipulates that all personnel must be bonded or electrically connected to a grounding system when handling electrostatic-sensitive devices. This standard specifies that the impedance between the operator and ground should be less than 35 megohms. However, wireless wrist straps lack the controlled, high-resistance path to ground, which undermines the fundamental purpose of an ESD wrist strap – to protect the work piece from electrostatic discharge events. As a result, the use of wireless wrist straps not only fails to provide the necessary controlled, high-resistance grounding path to safeguard the work piece, but also does not meet the compliance requirements of the ANSI/ESD S20.20 standard.