Static Control

“My footwear tester doesn’t work, heel grounders fail high, help?”

Image scsstaticcontrol February 14, 2022 0

We occasionally hear from customers who have ESD footwear (Foot Grounders or ESD Shoes) that is failing high on their ESD footwear tester (personnel grounding tester). There is often an assumption that the issue is a faulty tester or out of spec footwear. However, most of the time the problem turns out to be as simple as a “bad match”. This is between the upper resistance setting of the footwear tester and the resistance of the ESD footwear.

The first step in identifying the cause of the problem is to identify the upper limit setting of the tester being used.

Upper Test Limits of ESD Testers

The upper limit settings on SCS footwear testers are:

ESD Footwear Tester	Upper Resistance Limit
770030 Combo Tester	100 megaohm or 1 x 10⁸ ohms (factory set)
770758 Series Dual Combination Tester	The upper limit is 1 gigaohm or 1 x 10⁹ ohms however the factory setting 35 megaohm or 3.5 x 10⁷ ohms
SmartLog Pro	The upper limit 1 gigaohm or 1 x 10⁹ ohms however the factory setting 35 megaohm or 3.5 x 10⁷ ohms

Identifying the Resistance of the ESD Footwear

The next step is to identify the resistance of the ESD footwear being used, both by itself and with a person wearing the footwear.

Heel Grounders/Foot Grounders

Test Method 1 – Resistance of the Foot Grounder

Using a surface resistance tester and its alligator clip, clip the lead to the foot grounder tab
Clip the other lead to the cup material

This test will tell you the overall resistance of the tab, resistor (if there is one), and the cup material

If the foot grounder tab to cup resistance exceeds the upper limit of the footwear tester it’s very likely that you won’t pass on the tester.

Test Method 2 – Resistance of the Foot Grounder and Person Together

Use test method from TR53-01-15, 8.3.2 Meter, which has been summarised below:

Use a surface resistance tester, a handheld electrode and a foot electrode
Have the person hold the handheld electrode connect to one lead
Have the other lead connected to the foot electrode
Place one foot on the foot electrode making sure your other foot is not on an ESD floor or the electrode

This test will tell you the overall resistance of the whole foot grounder and person.

If the result is higher than the upper limit of your footwear tester you will not pass at the tester.

ESD Shoes

When we hear about ESD Footwear failing regularly at the personnel grounding tester, more often than not it is ESD Shoes that are failing rather than foot grounders.

Test Method 1 – Resistance of the ESD Shoes Using Foot Plate Electrode

Place the shoe on a metal plate.
Put the 5 lb weight from the surface resistance meter inside the shoe.
Place the other weight on the metal plate next to the shoe.
Lean on the weight inside the shoe and test.

This will give the resistance of the shoe itself from inside the shoe to the bottom of the shoe.

Test Method 2 – Resistance of the ESD Shoe Using Two 5 lb Electrodes

Put one of the 5 lb weights from the surface resistance meter inside the shoe.
Put the other weight on the sole of shoe, make like a sandwich
Press the Test

See what the resistance of the shoe is using either of these methods and compare it to the testers upper limit.

Perform the TR53 test below, see what the resistance is of the person and ESD shoe while the shoe is being worn.

The same test from TR53 used for foot grounders above can also be used for ESD Shoes. This will provide you with the total resistance is of the person and ESD shoe.

Conclusion

The tests above will identify a clear discrepancy between footwear resistance and tester settings, but there can also be other factors in play. These factors should be considered when the footwear resistance and the tester settings are close to being the same.

Tester accuracy
Test voltage
Weight of personnel
Sock thickness and material
Humidity

Any questions regarding this post, please get in contact.

Shop the Test Equipment Used

770760

Resistance Pro Meter Kit

Large OLED Display
Internal Memory
Measurement Stability Modes
Resistance Range: 1.0 x 10³ to 1.0 x 10¹² Ohms
Under Load Test Voltages (10V or 100V ±5%)
- Meets ANSI/ESD S20.20 resistance testing requirements for product qualification and compliance verification
Made in the United States of America

Learn More

770765

Handheld Electrode

Meets resistance measurement requirements of TR53, ANSI/ESD STM97.1 and more
Compatible with the Following SCS Meters:
- 770760 Resistance Pro Meter Kit
- 701 Analog Surface Resistance Megohmmeter Kit
- SRMETER2 Surface Resistance Meter
Made in the United States of America

Learn More

A Minute with Miranda – EM Aware Monitor on SMT Assembly Line

Image scsstaticcontrol January 6, 2020 0

Welcome back to “A Minute with Miranda.” This week we will be covering how the EM Aware Monitor provides continuous monitoring to detect and measure ESD Events in your STM machine.

The SCS EM Aware Monitor is a continuous monitor for three key parameters that allow you to verify your ESD process in an automated insertion machine; ESD events, change in static voltage field, and ionizer balance. The thresholds for all three of these parameters are fully adjustable by the user. The EM Aware Monitor is a miniature radio receiver tuned to detect and measure the unique waveform generated by an ESD event. The EM Aware Monitor meets the Continuous Monitor requirements of ANSI/ESD S20.20 in accordance with ESD TR1.0-01 and ANSI/ESD STM3.1. It meets the recommendations of ESD Handbook ESD TR20.20 which includes “if the products that are being produced are of such value that the knowledge of a continuous, reliable ground is needed, then continuous monitoring should be considered or even required.”

View the full range of SCS EM Aware Monitors here

A Minute with Miranda – WS Aware Continuous Monitor on SMT Line

Image scsstaticcontrol December 6, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be covering how the WS Aware provides continuous monitoring for an operator at an SMT line.

The SCS WS Aware Monitor is a continuous monitor for operators, ESD Worksurfaces and metal tools. It will continuously monitor the path-to-ground integrity and body voltage of two operators. It also monitors the path-to-ground integrity of two metal tools. In addition, it continuously monitors for electromagnetic interference (EMI) on two metal tools, which may cause electrical overstress (EOS) damage. The WS Aware Monitor eliminates the need for periodic testing and record keeping of wrist straps.

Per ESD Handbook ESD TR 20.20 section 5.3.2.4.4 “Typical Test programs recommend that wrist straps that are used daily should be tested daily. However, if the products that are being produced are of such value that knowledge of a continuous, reliable ground is needed, then continuous monitoring should be considered or even required.”

View the full range of SCS WS Aware Monitors here.

A Minute with Miranda – WS Aware Workstation Overview

Image scsstaticcontrol November 4, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be covering how the WS Aware Monitor provides for continuous monitoring of an ESD Workstation setup.

The SCS WS Aware Monitor is a dual workstation continuous monitor for operators, ESD Worksurfaces and metal tools. It will continuously monitor the path-to-ground integrity and body voltage of two operators. It also monitors the path-to-ground integrity for two conductive or dissipative worksurfaces and two metal tools. It also continuously monitors for electromagnetic interference (EMI) on two metal tools which may cause electrical overstress (EOS) damage. The WS Aware Monitor eliminates the need for periodic testing and record keeping of wrist straps.

Per the ESD Handbook ESD TR20.20 section 18.4.2 “Some continuous monitors can monitor worksurface ground connections. A test signal is passed through the worksurface and ground connections. Discontinuity or over limit resistance changes cause the monitor to alarm. Worksurface monitors test the electrical connection between the monitor, the worksurface, and the ground point. However, the monitor will not detect insulative contamination on the worksurface.”

View the full range of SCS WS Aware Monitors here.

A Minute with Miranda – WS Aware Continuous Monitoring a Wrist Strap

Image scsstaticcontrol October 7, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be covering how to use the WS Aware Monitor for continuous monitoring of SCS wrist straps when at an ESD Workstation.

The SCS WS Aware Monitor is a dual workstation continuous monitor for operators, ESD Worksurfaces and metal tools. It will continuously monitor the path-to-ground integrity and body voltage of two operators. The WS Aware Monitor eliminates the need for periodic testing and record keeping of wrist straps. The WS Aware Monitor features operator body voltage detection. It will alarm if the operator generates or comes into contact with voltage that would be dangerous to an ESD susceptible item. Per the ESD Handbook ESD TR20.20 section 5.3.2.4.4 “Typical test programs recommend that wrist straps that are used daily should be tested daily. However, if the products that are being produced are of such value that knowledge of continuous, reliable ground is needed, then continuous monitoring should be considered or even required.”

View the full range of SCS WS Aware Monitors: https://staticcontrol.descoindustries…

A Minute with Miranda – Cleaning an ESD Worksurface Mat

Image scsstaticcontrol September 27, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be covering how to properly clean an ESD Worksurface Mat.

For optimum electrical performance, the ESD worksurface mat surface should be cleaned regularly using a recommended ESD mat cleaner. Per the ESD Handbook ESD TR20.20, “Ensure that cleaners that are used do not leave an electrically insulative residue common with some household cleaners.”
We recommend using Reztore ESD Surface and Mat Cleaner. Reztore is alcohol free and does not contain silicone or other substances that will leave an insulative residue or inhibit the performance of the ESD worksurface mats.

After cleaning the ESD worksurface mat with Reztore it is recommended to test the surface to ensure that all insulative contaminates such as dirt and grime have been removed from the mat.
SCS worksurface mats meet the ANSI/ESD STM4.1 and ANSI/ESD S20.20 required limit of 1 x 10⁶ to less than 1 x 10⁹ ohms for Rtt and Rtg and the recommendations of ANSI/ESD S4.1. View the range of Reztore Alcohol Free products here.

A Minute with Miranda – ESD Packaging with Protektive Pak In-Plant Handler

Image scsstaticcontrol September 16, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be discussing how to store and ship your static sensitive assemblies within and outside of an ESD Protected Area using an In-Plant Handler.

ANSI/ESD S20.20 requires that ESD protective packaging is necessary to store, transport and protect ESD sensitive electronic items during all phases of production and shipment. Beyond the static protection, packaging also provides protection from physical damage, moisture, dust and other contaminates. Per the ANSI/ESD S541 Packaging Standard packaging that is used inside and outside of an EPA shall be low charge generating, constructed from dissipative or conductive material for intimate contact with ESD items and provide electrostatic discharge shielding.

The Protektive Pak In-Plant Handlers are constructed from an impregnated dissipative corrugated material that has a surface resistance range of 1 x 10⁶ to less than 1 x 10⁹ ohms per ANSI/ESD STM11.11. This minimizes the potential of rapid discharge or sparking. The in-plant handlers will shield ESD sensitive items from charge and electrostatic discharges with the lid in place. The partition sets are constructed from the same impregnated dissipative material and are available in over 300 cell size configurations to suit your specific packaging needs.

View the full range of Protektive Pak In-Plant Handlers here.

A Minute with Miranda – Testing an ESD Floor

Image scsstaticcontrol September 4, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be discussing how to test the point-to-point resistance (Rtt) and the resistance-to-ground (Rtg) of a Conductive ESD Floor.

ANSI/ESD S20.20 requires initial and periodic verification of an ESD Flooring System. ANSI/ESD STM7.1 outlines the test methods applicable for the Conductive flooring material. For the Point-to-Point resistance (Rtt) test the flooring will be tested with a resistance measurement meter and
2 x 5lbs cylindrical electrodes positioned 36” apart. The value for the test should be less than or equal to 1 x 10⁶ ohms.

The Resistance Point-to-Ground (Rtg) test should be conducted with a resistance measurement meter and 1 x 5lbs cylindrical electrode. One lead from the meter should be connected to the ground point and the other lead will be connected to the electrode. The test value should be less than or equal to 1 x 10⁶ ohms.

View the full range of SCS Surface Resistance Testers here.

A Minute with Miranda – Testing Resistance Point-to-Point Rpp for an ESD Smock

Image scsstaticcontrol August 22, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be discussing how to test the point-to-point resistance (or Rpp) of an ESD Smock.

ANSI/ESD S20.20 requires initial and periodic verification of ESD Control items – this includes ESD Smocks. ANSI/ESD STM2.1 outlines the test method applicable for ESD Smocks: the ESD Smock is to be placed on an insulative surface and 2 x 5lbs cylindrical electrodes are to be positioned on each cuff before taking the measurement. The Resistance Point-to-Point Rpp of the groundable smock needs to be less than 1 x 10⁹ ohms.

View the full range of SCS ESD Smocks here.

A Minute with Miranda – How to Wear a Wrist Strap

Image scsstaticcontrol August 16, 2019 0

Welcome back to “A Minute with Miranda.” This week we will be covering how to properly wear a wrist strap.

ANSI/ESD S20.20 requires seated personnel to be connected to the grounding / equipotential bonding system via a wrist strap. The total resistance of the Wrist Strap System needs to be less than 3.5 x 10^7 ohms. The key to a wrist strap is the intimate contact of the band to the skin and that the coil cord is connected to ground. Wrist straps need to be tested at least daily before handling any ESD sensitive devices.

Operators can choose between elastic and metal wristbands. Elastic wristbands are comfortable to wear and easy to adjust. Metal wristbands generally last longer and are easier to clean. View the full range of SCS Wrist Straps here.