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Developing a good ESD control program requires more than just putting ESD controls into place, it requires a plan to verify that the controls are working as intended.

Companies make significant investments in ESD control, in an effort to greatly reduce the chance that electronic components are damaged or destroyed by electrostatic discharges.  Significant dollars are spent on ESD control elements such as work surfaces, packaging, flooring, ionization, testing and monitoring, smocks and grounding.  These control elements are often selected after careful consideration and assurance that they will perform as designed.  Industry standards, such as ANSI/ESD S20.20 and IEC 61340-5-1 include test methods to assure that the ESD control elements will perform, even in challenging conditions (such as low humidity).  Many companies select ESD control products that can demonstrate that they meet the requirements listed in the standards.

Compliance Verification

Once the ESD control elements have been selected and installed, regular testing must be conducted to verify that they are still functioning as intended.  Broken wires, contaminated surfaces and worn-out materials can all lead to the failure of the control elements.   However, these failures will not be detected if regular testing does not occur.

ESD TR53 Compliance Verification

The ESD Association has published a compliance verification document that details how to test each ESD control element to verify that it is still functioning as intended.   (ESD TR53 Compliance Verification).  This document is referenced in ANSI/ESD S20.20 ESD Association Standard for the Development of an Electrostatic Discharge Control Program for Protection of Electrical and Electronic Parts, Assemblies, and Equipment (Excluding Electrically Initiated Explosive Devices).  

ESD TR53 provides requirements for test equipment to be used and outlines procedures for conducting the test to verify compliance to the S20.20 standard.  There are step by step instructions on how to conduct the test.   What TR53 does not provide however, is guidance on how to discover the causes for test failures.

Compliance Verification Training

Most companies have a dedicated person, or persons, to conduct regular testing of the ESD control elements.   It is important that someone in the factory understands not only how to correctly perform the testing, but to understand the potential failure mechanisms for materials that do not meet the established limits.  Is it worn out materials, broken wires, contaminated or compromised surfaces, or could it even be a test instrument failure?

TR53 Certified Auditor Training

Training programs exist that provide extensive training on how to audit your ESD controls to verify that they are functioning correctly.   The training goes in depth on the operation of test instruments, correct procedures for testing and trouble shooting when the measurements do not meet expectations.

Once such training program is the TR53Certified Auditor Training developed and taught by Ron Gibson of Advanced Static Control Consulting (ASCC).   This program was established over 10 years ago and has trained and certified hundreds of people around the world.   The ESDA has recognized this program as an official certification program for TR53.  

Transforming Technologies, in cooperation with ASCC and Prostat Corporation, will be hosting this training May 24-26 in Ann Arbor, Michigan.  There is a full day of classroom training, followed by a full day of hands-on training, learning the proper way to use the instruments and how to trouble shoot when there are measurement issues.   In order to have a quality ESD control program it is critical that the company has at least one person who understands how to make compliance verification measurements.

For more details, click on the link to the training.

https://www.prostat-university.com/registration-schedule-details.aspx?schedule_ID=104&utm_source=hs_email&utm_medium=email&_hsenc=p2ANqtz–24ExRYNZP_Zk0Qcv74fZ2ijxdsyQgJ17W5pdltxf0EtFDiT7LULcWEz-kLIYyLUMCTRJS

The wrist strap is the most common and effective method for removing voltage from operators working with static sensitive devices. Unfortunately, over time, soil build up or mechanical issues can cause a wrist strap to fail.  Therefore, wrist straps must be tested regularly with an ESD Test Station to assure that people are not transferring voltage sensitive devices and causing ESD damage.

Many common ESD Testers have a both a High Limit and a Low Limit for wrist straps:

High Limit

Industry standards (ANSI/ESD S20.20) requires a wrist strap to have a resistance of less than 35 megohms. Anything above that, and you will receive a “high fail” alarm from the ESD tester. When the resistance of a wrist strap is too high, excess voltage may build up on the body and could cause an ESD event. The high fail can be can be caused by:

1. High skin resistance (have the operator use an electronics approved lotion).
2. Soiled or poorly fitted wrist band (check that the band is snug and not overly worn).
3. Broken coil cord.  It is possible that the wire inside the cord has been damaged.

Lower Limit

Most wrist strap testers also test for low resistance (typical low fail is less than 750K ohms) , to assure that the 1 megohm resistor is present and performing as intended.  The purpose of the 1 megohm resistor is for safety: to limit the amount of current that could be transferred through the body. The 1 megohm resistor is designed to limit the current to 250 microamps at 250 Volts rms AC, which is below the perception level of humans. A “low fail” result can be caused by

1. The person is connected to ground via another path, i.e., touching a grounded metal structure.
2. The most common cause of a fail low is a shorted resistor in the wrist strap coil cord. Replace the coil cord with a new one and repeat the test.

Summary
If an ESD Wrist Strap fails high, it means the wrist strap’s resistance is too high and is not removing voltage efficiently. If it fails low, the wrist strap may have an issue with the 1 meg resistor, which is a safety concern. Either way, the wrist strap or coil cord should be replace to ensure you are protected from damaging ESD.

Air ionization is used to reduce the charge from process essential insulators and isolated conductor that cannot be grounded.   ESD sensitive devices can be damaged when they contact charged conductors or if they are grounded in the presence of an electrostatic field.  Air ionization creates a cloud of positive and negative ions that neutralize the charge on objects that cannot be effectively connected to ground.

Two of the more popular types of ionizers used today are AC and Steady State DC.  While both technologies are effective in neutralizing charges, AC Technology offers some distinct advantages.  Both technologies use power supplies to apply high voltage to sharp emitter points.  Positive high voltage creates positive ions and negative voltage creates negative ions.   Both AC and DC ionizers require air flow to effective move the ions away from the emitter points and to the target area.

DC Ionizers

DC Technology incorporates dedicated negative and positive power supplies as well as negative and positive emitter points for creating a balance of ions.  The high voltage applied to the emitter points causes wear and particle attraction, however the wear is not equal between the two polarities.  The voltage must be adjusted to one emitter point to assure equal ion production, which requires a more costly voltage monitoring circuit in the ionizer.  DC ionizer emitter points also require more frequent cleaning as oppositely charged particles are attracted to the emitter points and the balance of ion output needs to be monitored more frequently.

AC Ionizers

AC Ionizers use a single power supply that switches between positive and negative voltage and each emitter point produces both positive and negative ions.  Alternating positive and negative voltage to each emitter point creates even wear and significantly less particle attraction, which makes maintaining even balance much easier and less expensive. 

Transforming Technologies offers a variety of high quality, high performance AC ionizers with ion balance of ±10 volts, which is well below the industry standard of <±35 volts.   Styles range from Benchtop (BFN series, IN series), Overhead (BFN, IN), Ionizing guns (BFN, IN), Nozzles (IN) and bars (Scion).  View the Transforming Technologies website to see our complete range of ionization.

In a world full of static, you need to protect your sensitive electronics from being destroyed. Transforming Technologies offers an extensive selection of static control products, such as ionizers, matting and more to keep your products safe. But what about your personnel?  Grounding your workers is an essential function of an ESD Program.  These products are grouped into a category called Personal Grounding.  View all of our personal grounding products on our website. Contact 419-841-9552 for more information!

Typical ESD products found in manufacturing environments include grounding straps, table matting and ESD jackets. But did you know that common, everyday items such as trashcans or pens, can be a potential threat to your static sensitive items? Transforming Technologies provides ESD safe versions of products that are commonly overlooked products in ESD protected areas.

ESD Product Accessories Include:

• Labels
• Tapes
• Pens
• Signs
• Trash Cans
• Curtains
• Badge Holders
• Sheet Protectors

View all of our ESD Accessories on our website.

Contact 419-841-9552 for more information!

Transforming Technologies is proud to supply Warmbier brand ESD products. Wolfgang Warmbier is Europe’s premier brand of ESD products. Their ESD Test Instruments are precision engineered products that provide powerful ESD testing and reporting. With a built-in market of European owned manufacturers, Wambier products are highly sought after in North America.

We stock the following products in the USA:

• PGT120 ESD Tester
• Resistance Meters
• Walking Test Kits
• Audit Kits
• Field Meters

View all of our Warmbier Products on our website.

Contact 419-841-9552 for more information!

Ionizers deliver a balanced stream of positive and negative ions and are used primarily to control static charges on insulating materials such as standard plastic. Transforming Technologies carries a wide variety of ionization products for use in industries such as electronics assembly, cleanroom, semiconductor, flat panel display, medical device manufacturing and pharmaceutical.  Ionizers are the ideal solution to dust and contamination, process lockup, spray painting, static shocks, quality control, and much more.

View all of our anti-static ionizers on our website.

Contact 419-841-9552 for more information!

SRM200 is a very useful tool for checking surface resistance and resistance to ground for ESD compliance and static control.

The instrument can be used on work surfaces, floors, chairs, carts, clothing and packaging materials, etc. With the additional “two-point probe” adapter also Rpp measurements can be done on small areas like in cavities of vacuum formed trays. The measured value is displayed with LED display that indicates whether the value is conductive, dissipative or insulating. All readings can be stored in the instrument and can by using the included software easily transferred to PC via USB cable. The measurements can be performed either with the built-in measurement electrodes (fitted with conductive rubber for good conductivity) on the underside of the instrument or together with lightweight travel electrodes. Performed measurements with external measuring electrode met the requirements of ANSI ESD S20.20 and IEC61340-5-1. SRM 2000 also has integrated temperature and humidity sensor. The SRM200 is available in the North America from Transforming Technologies:

Warmbier SRM200 Pocket Digital Surface Resistance Verification Kit

For more information, call 419-841-9552 for email info@transforming-technologies.com.

With the Covid-19 virus on everyone’s mind, companies are asking how to properly clean and sanitize ESD rubber table mats in a way that will not affect their static control performance.

So for the past several weeks, we tested two common cleaning agents known to control the Covid-19 virus; Isopropyl Alcohol (IPA) and Lysol.  The is concern is that repeated use of IPA or Lysol will degrade the ESD performance of rubber mat material, leaving sensitive components at risk.  We found that after 36 applications,  the ESD performance of table mats were not affected by disaffecting with IPA or Lysol.   For our testing, samples of our most popular rubber table mat, the MT4500 series, were sprayed twice daily, allowing the cleaning agent to stand for five minutes prior to wiping per the manufacturer’s instructions.   The mats resistance properties were tested daily, and after 16 working days of applications, the mats showed no change in their physical or ESD control properties. In some cases, the surface resistance readings improved. We suggest that users of our 2 layer ESD mats use an EPA approved cleaning agent to help prevent the spread of the Covid 19 virus but to perform regular compliance verification testing for any long term affects on the material.

For testing questions, download our guide on how to properly test ESD mats, or call us at 419-841-9552 or schedule a 15 minute meeting with a  static control expert to learn more.

A Surface Resistance Meter is an instrument that measures electrical resistance of an object. It is an important tool in manufacturing, as well as static control and ESD prevention programs because it can be used to evaluate materials and classify them as conductive, dissipative and insulative.  Surface resistance meters are also commonly used to test the effectiveness of ESD control products such as auditing an ESD worksurface.

A quick internet search reveals many types with a wide range of capabilities and accessories. It can be difficult to choose which meter is right for your application.

Use our guide below to help with your decision.  The following are topics we will cover in this article:

1. Accuracy

2. Test Range

3. Results Display

4. Voltage

5. Temperature and Humidity

6. Electrodes

7. Memory

8. Summary 

 

1 . Accuracy:  Verification vs Qualification

Not all resistance meters are created equal.  Meters may be designed for quick measurements to confirm specifications (verification) while some meters are designed for more rigorous testing that requires more accurate measurements (qualification). How accurate your meter needs to be will depend on the type of testing you will be doing. Choosing a meter with higher accuracy will be a more expensive investment,  it will ensure quality measurements no matter what testing required. Below is a table that show a variety of meters with a range of functions. “Travel” meters are excellent for quick measurements and are very portable. Lab Grade meters

SRM110 Entry Level “Travel” Meter	SRM200 Mid Level “Travel” Meter	Metriso B530 Entry Level “Lab Grade” Meter	Metriso 3000 High Level “Lab Grade” Meter

 

2. Test Range

The minimum test range required for ESD purposes is 10^3 ~ 10^12 which covers conductive, dissipative and insulative items.  Entry level meters will only have this range and will display “Less Than 10^3” for low resistance and” Greater Than 10^12” for high resistance items. More accurate resistance meters will have a larger test range.  The  Metriso 3000 has a test range from 1 Ohm ~ 1.2Tera Ohm  (1.2 x 10¹² ohm).  The larger test range is important depending the material being tested.

3. Result Display: How will your meter display the measurement?

Results are measured in Ohms and are sometimes displayed in powers of 10 (also known as the decade scale). The simplest readouts show values with LED lights coded with the decade scale with colors to signify conductive, dissipative, and insulative.  This readout is less accurate because the actual measurements may fall in between a decade and is rounded to the closest number. More accurate meters will display the values digitally, either in the decade scale or in Ohms. 4. Voltage: Choose The Right Voltage for Your Application Surface resistance meters use voltage to test the resistance of a material. The voltage required depends on the material you are testing and the test method. Generally for ESD testing, conductive materials (1.0 x 10⁴ ohms to <1.0 x 10⁶ ohm) are tested at 10v and materials in the dissipative range (≥1.0 x 10⁶ ohm to <1.0 x 10⁹ ohms or < 1 x 10¹¹ ohms for packaging materials) are tested at 100v. (Learn when to use 10v and 100v). Most meters will be able to test at both 10v and 100v. They may switch between the two automatically based on the material or you may have to select the voltage manually. The verification of insulative materials may call for a higher voltage, such as 500v.  There are specially designed meters for that voltage such as the Metriso 3000. Another concept to understand with resistance meter voltage is “constant voltage”. A meter that has constant voltage does not drop significantly from the selected voltage during testing. For example, when 100 volts is selected, the meter will deliver 96 and 100 volts at the probes (standard requires ±5%). Some meters, referred to as “Open Circuit”, will drop the voltage to a much lower level when the resistance of the material measured is less to protect the meter from the returning current.  A meter with constant voltage is a much more accurate tool. The Metriso 3000 is a constant voltage meter and the output voltage at the probes is displayed during testing.

5. Temperature and Humidity

The humidity and temperature affect the electrical properties of the material being tested. It is possible for a material to meet the requirements at high humidity, but fail at a lower humidity. Because of this, both the ESD Association and the European CECC recognize the environmental effects on test measurements and require them to be recorded. Some resistance meters may have the capability to test temperature and humidity built in while some do not, and external devices may be required.  When in doubt, it is best to get a meter that measures temp & humidity.  If your meter does not have that capability, we supply a tool that precisely measures temperature and humidity.

6. Measuring Electrodes

All surface resistance meters contact the material to be tested with components called electrodes. Electrodes can be built into a meter (called parallel electrodes) or can be external components.  The electrodes you require with your meter depends on the tests you will perform. Parallel Electrodes:  Two conductive rails are built into the back of the meter and are used to give fast electrical resistance measurements.  Not all meters have parallel electrodes. External Electrodes:  A variety of external electrodes can be connected to a surface resistance meter depending on the type of test.  Here is a list of some external probes:

• 5lb disk probes – Most common probe (work surfaces, floors, shelves, carts, chairs, garments)
• Two point probe – for testing small areas (component trays, component tapes, non-planar surfaces)
• Hand held probe – testing resistance through a person
• Concentric ring probe – testing volume resistance. (Packaging materials)
• Glove Probe – Testing ESD Gloves (CAFÉ probe – Constant Area Force Electrode)
• Back Rest Probe – Testing ESD Chairs
• Clamp Probe – Testing ESD Fabrics/Jackets

7. Memory

Some meters record measurements in internal memory, making reporting very convenient. Recording measurements is a nice feature, but may not be necessary for everyone. Our Metriso 3000 can store 50,000 data points and includes software to create reports. Some mid- level resistance meters can also store data, such as the Metriso SRM200.  The amount of data points required during your testing sessions will help you determine if you need internal memory.

8. Summary

The surface resistance meter you should choose will primarily depend on the type of test required. Do you require very accurate measurements to qualification testing or just simple measurements for verification? Will you taking large amounts of tests regularly? Or just periodically?  For simple testing needs, a entry level “travel” meter such as the SRM110 will be all that is required.   For higher level testing, a mid-level Travel Meter such as the SRM200  with probe accessories or a Lab Grade Testing Kit like the Metriso B530 or 3000 should be considered.

If you have any questions on Surface Resistance Meters, please contact Transforming Technologies at 419-841-9552 or email info@transforming-technologies.com. You can also fill our a Form on the Website or Chat with the link on the right.