A Guide to ESD Wrist Strap Testing and Monitoring

Introduction

A fundamental aspect of an effective static control program is conducting a Quality Process Audit. This audit serves as a daily maintenance check of the program. For instance, it involves the daily testing of anti-static wrist straps and footwear, as well as verifying the integrity of electrical grounds. Operators should carry out these checks on a daily, weekly or monthly schedule. An anti static wrist strap, or grounding bracelet, is one of the most common and effective ways to remove static charge on personnel. However, it is also the type of static control device that is most likely to fail over time. Several ways an anti static strap can fail include: a dirty cuff interior, a damaged wire in the cord, high skin resistance and improper wear of the strap (placed over clothing or too loose). If the wrist strap fails, the ESD charge on an operator will increase and may cause electrostatic damage to the electronic component without the operator even realising. This is why it is important that actions are taken to assure that the operator is properly grounded when wearing an ESD wrist strap. Fortunately, there are several ways you can test your anti static wrist strap. Keep on reading to find out the types of devices available for ESD wrist strap testing and how often they should be tested.

Types of Personnel Grounding Testers

ESD Wrist Strap Testing Meter

One of the simplest ways to assure your ESD wrist strap system is working correctly is to use an ESD wrist strap test meter. The ESD wrist strap testing meter assesses the resistance of the fitted anti static wristband and cord (including the operator) and provides a pass or fail indication. The ESD wrist strap testing device offers a cost-effective solution for testing anti static wrist straps. As it is compact and portable, the device is ideal for use at workstations, small laboratories and for supervisors to spot-check workers and ensure compliance.

ESD Wrist Strap Test Station

There are also test stations for testing your anti static wrist bands. ESD wrist strap test stations have wall-mountable units that are generally supplied with a wall plate which attaches to a wall. The tester is then mounted on to the wall plate. Like the meter, the test station will assess the resistance of the fitted wrist strap and cord and provide a pass or fail indication.

Additionally, there are test stations that can come with footwear test plates to allow you to check the continuity of fitted ESD shoes or heel straps as well as anti static straps and cords. Single footplates will require the operator to test each foot separately one after the other. Dual footplates, on the other hand, feature a split footplate which allows the unit to check both feet independently at the same time. This can be an efficient time-saver if you have many operators in your company who are required to verify their personnel grounding devices.

Despite how many times an operator tests, there is a risk that the anti static wrist strap will fail at some point during a shift. Constant Monitors can stop this risk.

Constant Monitoring

If a wrist strap fails the test at the start of a shift, you may wonder “when did the failure happen and how much product was handled after the failure?”  Constant monitors, or continuous monitors, are designed to continuously monitor whether the wrist strap, cord or bench mat is disconnected while simultaneously verifying the Earth to ground system is correctly working. Should any part of the wrist strap system fail, lights will illuminate, and a buzzer will sound immediately if there is any disconnect from the operator to ground. This will alert the operator to not handle the product until the issue is fixed.

Constant monitors check the wrist strap at the work location, eliminating the chance of a working wrist strap but a faulty ground attachment. They can eliminate the need for recording and storing test results and some devices will also monitor the work surface such as bench mats to check that it is still connected to ground.

How Often Should ESD Wrist Straps Be Tested?

If you are not using a constant monitor, an anti static wrist band should be tested at least once a day before handling any static sensitive electronic devices. This quick check can determine that no break in the path-to-ground has taken place. It is imperative for wrist straps to be worn while the operator is being tested. By doing so, this provides the best way to test all three components:

• The anti static wrist band
• The grounding cord (including the resistor)
• The interface (contact) with the operator’s skin.

ESD wrist strap testing frequency can also depend on the amount of risk exposure that can occur between tests. Typical test programs recommend that wrist straps that are used daily should be tested daily. Although, if the products that are being manufactured are of high value, then a continuous monitor should be considered. Using a test program will provide the operator with useful data they can use to help them make the choice of how often the wrist strap should be tested and which wrist straps have the most useful service life.

Summary

Anti static wrist straps are the most common method for eliminating static charge from operators handling static sensitive electronic components and devices, however they need to be tested frequently to ensure they are functioning correctly. ESD Wrist Strap Test Stations and Test Meters can check wrist strap functionality, but there is still a risk of wrist strap failure in between tests. Constant Monitors solve this problem and can provide assurance that the system is working as designed and the static sensitive electronic components and devices are being handled safely at all times. It is recommended to test an anti static electricity bracelet at least daily with a wrist strap test station or meter, especially if the wrist strap is used daily. However, if the product is of great value, then a constant monitor should be used for more reliable testing.

Shop Our ESD Wrist Strap Testing Devices

Protect your ESD sensitive products from static damage with ESD wrist strap testing. At Bondline Electronics Ltd, we stock a wide range of testing devices including ESD wrist strap test meters, test stations and constant monitors. If you would like more advice or guidance on testing anti static wrist straps, please get in touch with our friendly sales team on +44 (0)1793 511000 or email us at sales@bondline.co.uk where we’d be happy to help.

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