Category Archives: Test and Monitoring Equipment

The importance of Periodic Verification – Part 1

Today we want to talk about a subject many users forget about when it comes to ESD protection: periodic verification.
Whilst many people understand the basic concepts of ESD and as a result insist on a properly equipped ESD Protected Area (EPA), they then forget all about it. They use the same products day-in, day-out, year after year, without knowing if their products are actually still working properly.
So today we want to look at the most common products in your EPA that you should be checking on a regular basis. And because there are quite a few product groups to discuss, we have split this post in 2 parts – we don’t want to scare you away with a never-ending blog post…

Why periodic verification?
Each component in an ESD protected area (EPA) plays a vital part in the fight against electrostatic discharge (ESD). If just one component is not performing correctly, you could damage your ESD sensitive devices potentially costing your company money. The problem with many ESD protection products (think wrist straps!) is that you can’t always see the damage. Just by looking at a coiled cord that has no visibly damage to the insulation you would not know if the conductor on the inside is damaged. That’s where periodic verification comes into play.
ESD protected area (EPA) products should be tested:

  1. Prior to installation to qualify product for listing in user’s ESD control plan.
  2. During initial installation.
  3. For periodic checks of installed products as part of IEC 61340-5-1 Edition 1 2007-08 clause 5.2.3 Compliance verification plan.

It’s #3 we will be focusing on in this 2-part series.

Worksurface Matting
The purpose of ESD bench matting is to ensure that when charged conductors (conductive or dissipative) are placed upon the surface, a controlled discharge occurs and electrostatic charges are removed to ground. However, this only occurs if the ESD work surface is actually connected to ground. If the matting is out-of-spec, not grounded at all, the stud on the mat has become loose or the ground cord has become disconnected, charges cannot be removed.
Many companies use a daily checklist, which includes the operator having to verify that ground cords are firmly connected.
Remember to regularly clean your bench matting to maintain proper electrical function (e.g. Reztore Surface and Mat Cleaner). Do not use cleaners with silicone as silicone build-up will create an insulative film on the surface.
The company’s compliance verification plan should also include periodic checks of work surfaces measuring:

  • Resistance Point-to-Point (Rp-p) and
  • Resistance-to-ground (Rg).

Using Surface Resistance Tester 99026Testing a working surface using 99026

Surface resistance testers can be used to perform these tests in accordance with EN 61340-5-1 Electrostatics and its test method IEC 61340-2-3; if these measurements are within acceptable ranges, the worksurface matting and its connections are good.

Wrist Straps
As discharges from people handling ESD sensitive devices cause significant ESD damage, the wrist strap is considered the first line of ESD control.
Before handling ESD sensitive items, you should visually inspect the wrist strap to see if there are any breakages etc. The wrist strap should then be tested while worn using a wrist strap tester. This ensures all three components are checked: the wrist band, the ground cord (including resistor) and the interface with the wearer’s skin. Records of each test should be kept. Wiggling the resistor strain relief portion of the coil cord during the test will help identify failures sooner. Analysis and corrective action should take place when a wrist strap tester indicates a failure.

Using Combo Tester 99031Checking wrist straps using 99031

It is recommended that wrist straps are checked at least daily. An even better solution to daily wrist strap checks is the use of continuous monitors. They will alarm if the person or work surface is not properly grounded.

A note on worksurface matting and wrist straps: if you are using earth bonding points, earth bonding bars etc. to ground the operator and/or bench matting, remember to inspect and test those regularly as well (every 6 months for example).

Keep your eyes peeled for our follow-up post.

4 Reasons you should consider Continuous Monitoring

Wrist straps are considered the first line of ESD Control. They are used to link people to ground which ensures that that the operator is kept at the same potential as surfaces, objects and ESD sensitive devices. Wrist straps need to be visually inspected and checked (while worn) on a daily basis – BEFORE handling any ESD sensitive item. This will alert the operator if their wrist strap has developed a fault and as a result does not ground them any longer.
An alternative to periodic testing is the use of continuous monitors. Per ESD Handbook TR 20.20 paragraph 5.3.2.4.4 Test Frequency, “Because wrist straps have a finite life, it is important to develop a test frequency that will guarantee integrity of the system. 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.

In today’s post we will highlight 4 benefits of continuous monitoring which may help you decide to move away from daily wrist strap checks.
But first a little reminder of what continuous monitors actually are: Continuous monitors come in different styles and sizes but are intended to be kept on your workstation. Some units just ‘sit’ on your bench; others are attached to your working surface matting; some can even be attached underneath the workbench so they don’t take away valuable workspace. Operators connect their wrist strap to the unit to allow for real-time continuous monitoring. If the wrist strap fails, the unit will alarm. Many continuous monitors also feature a parking stud providing a means for the operator to disconnect when leaving their workstation.

There are two different types of continuous monitors available:

  • Single-wire continuous monitors allow the use of any standard, single-wire wrist strap and coil cord. The monitor / wrist strap system life-cycle costs are significantly lower than dual-wire systems. While they would not be suitable for the most critical applications, single-wire continuous monitors are an economical way to monitor both the operator’s wrist strap and/or workstation surface.
  • Dual-wire constant monitors provide true continuous monitoring of wrist strap functionality and operator safety according to accepted industry standards. Dual-wire continuous monitors provide redundancy because even if one dual-wire wrist strap conductor is severed, the operator still has a reliable path-to-ground with the other conductor.

1. Instant Feedback

Imagine this scenario: you come to work in the morning, you test your wrist strap, it passes and you start work on your ESD sensitive devices. 3 hours later, when you come back from your tea break, you test your wrist strap again and it fails. What to do? You don’t know if the wrist strap only just failed or if it failed right after your first test in the morning. How do you know if the devices you worked on all morning have been damaged? You don’t – after all, latent defects are not visible and failures may only occur at a later time. Using continuous monitoring while working on those ESD sensitive devices will alert the operator as soon as their wrist strap fails. The faulty wrist strap can be replaced with a new model from stock and everyone is happy – no ESD sensitive devices damaged and no unhappy customers.

zero-volt-monitor-solo
The EMIT Zero Volt Monitor (50579) in Use

Continuous monitors provide operators with instant feedback on the status and functionality of their wrist strap. The instant an operator’s wrist strap or cord fails, the monitor will issue audible and visual (LEDs) alarms alerting the user and supervisor of the problem. Full time continuous monitoring is superior to periodic or pulsed testing, and can save a significant amount of money in testing costs and rejected product. Periodic testing only detects wrist strap failures after ESD susceptible products have been manufactured. The costs of dealing with the resulting catastrophic failures or latent defects can be considerable. “A properly grounded wrist strap will keep a person’s body voltage to approximately + 10 V. The main advantage to a constant [or continuous] monitor is the immediate indication that the employee receives if the wrist strap falls open. With an unmonitored system, the employee will not be aware of a wrist strap failure until the start of the next shift. This has reliability benefits for an ESD program as it might help reduce or eliminate ESD damage.” [CLC/TR 61340-5-2:2008 User guide Annex B.1.3 Constant monitors].

2. Monitor Operator AND Workstation

An option available with most continuous or constant monitors is the ability to monitor working surface ground connections. “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. The monitor however, will not detect insulative contamination on the worksurface.” [ESD TR 12-01 Technical Report Survey of Constant (Continuous) Monitors for Wrist Straps]
When the monitor is connected to an ESD Mat working surface, the amount of current that flows is a function of the total resistance between the monitor and through the working surface to ground. When the resistance of the working surface is below a pre-set threshold*, the monitor will indicate good. Conversely, if the resistance level is high when compared to the monitor’s reference*, the unit will alarm. This is an integrating resistance measuring circuit, therefore it is relatively insensitive to externally induced electromagnetic fields.

multi-mount-monitor
Installing the Charleswater Multi-Mount Monitor (99129) to ground the worksurface

For units that also monitor the connection of a worksurface to protective earth, it is also possible to reduce or eliminate the checking of the worksurface as part of the periodic audit of the process.” [CLC/TR 61340-5-2:2008 User guide Annex B.1.3 Constant monitors].

*The resistance threshold limits can vary between brands and models (and can sometimes also be adjusted by the user) so make sure you do your homework before committing to a particular unit and check the limit meets your individual requirements.

3. Detect Initial Flex Fatigue

Unlike wrist strap testers, continuous monitors detect split-second failures when the wrist strap is still in the “intermittent” stage. This is prior to a permanent “open” which could result in damage to ESD sensitive components.

usecontmont1
The Jewel Mini Workstation Monitor (99135) in Use

Wrist strap checkers are usually placed in a central location for all to use. Wrist straps are stressed and flexed to their limits at a workstation. While a wrist strap is being checked, it is not stressed, as it would be under working conditions. Opens in the wire at the coiled cord’s strain relief are sometimes only detected under stress.” [ESD TR 12-01 Technical Report Survey of Constant (Continuous) Monitors for Wrist Straps]

4. Eliminate Need for Periodic Testing

Many customers are eliminating periodic touch testing of wrist straps and are utilising continuous monitoring to better ensure that their products were manufactured in an ESD protected environment. Continuous monitors eliminate the need for users to test wrist straps and log the results; by their function, these monitors satisfy the EN 61340-5-1 test logging requirements. “There are also other process benefits from using constant monitors such as the elimination of the need to maintain daily test logs and a reduction in the time for employees to make the daily test.” [CLC/TR 61340-5-2:2008 User guide Annex B.1.3 Constant monitors].

paperpile
No more Paper Logs!

So when using constant monitoring, operators:

  • Don’t have to waste time queuing at a wrist strap test station before each shift.
  • Don’t have to remember to complete their daily test logs.

It’s also harder to ‘cheat’ with continuous monitors. We’re not saying, your employees would do naughty things like that but we’ve seen it all before: operators ‘pretending’ to perform a wrist strap check, operators failing a wrist strap test and still recording a pass etc. There are always options to bypass a system, but it’s definitely harder when continuous monitors are used.

So should you now run-out and equip all your users with continuous monitors? As with most things in life, the answer is not that simple: it depends! If your company manufactures products containing ESD sensitive items, you need to ask yourself “how important is the reliability of our products”? Sooner or later a wrist strap is going to fail. If your products are of such high value that you need to be 100% sure your operators are grounded at all times, then you should consider a continuous monitoring system.

Deal of the Week – 20% Off Surface Resistance Meter Kits!

http://www.charleswater.co.uk/DealWeek.aspx

Check this link weekly for special pricing on overstock items.

Discover deep discounts on high quality Charleswater ESD Control Products.

Save on your regular stocking orders.

Current Deal of the Week

20% Off Surface Resistance Meter Kit

Surface Resistance Test Kit


99105 – Surface Resistance Meter Kit
99106 – Surface Resistance Meter
99108 – Leads for Surface Resistance Meter, Pair
99109 – Electrodes for Surface Resitance Meter, Pair

  • Digital Compliance Verification Surface Resistance Meter Kit
    Measures resistance point-to-point (Rp-p) or surface to ground (Rg) of working surfaces, flooring, garments, packaging, and other materials in accordance with EN 61340-5-1 per IEC 61340-2-3
  • Meter measures ambient temperature and relative humidity
    Available when required for test records
  • Colour coded LED and digital LCD read-out
    Easy to read, no interpretation needed; can easily be used for quick go/no go checks
  • Made in the United States of America

Use code C101 at checkout. Valid for online orders only.

Buy Now

Deal of the Week – 25% Off Jewel® Mini Monitor

http://www.charleswater.co.uk/DealWeek.aspx

Check this link weekly for special pricing on overstock items.

Discover deep discounts on high quality Charleswater ESD Control Products.

Save on your regular stocking orders.

Current Deal of the Week

25% Off Jewel® Mini Monitor

Jewel® Mini Monitor

99135 – Jewel Mini Monitor Workstation, Sapphire, 220VAC

  • Improved Banana Jack
    Creates a more consistent connection and helps to prevent accidental disconnects with operator’s wrist strap banana plug.
  • Small size – 70mm x 53mm
    Takes up minimal worksurface area.
  • Two 10mm threaded studs installed on bottom of unit
    Permanently snap monitor flush on mat.
  • Two 10mm push and clinch sockets included
  • Power Adapter, 24 VAC

Use code C101 at checkout. Valid for online orders only.

Buy Now

New Limit Comparator for Testers Available at Charleswater.co.uk!

Limit Comparator for Testers

Use to perform periodic calibration testing of the:
Dual Independent Footwear Tester
Dual Independent Footwear and Wrist Strap Tester
SmartLog V4™
SmartLog V5™

Frequency of recalibration should be based on the critical nature of those ESD sensitive items handled and the risk of failure for the ESD protective equipment and materials. In general, Charleswater recommends that calibration be performed annually.

Use the Limit Comparator to calibrate our new SmartLog V5

Item Description Price
50424 Limit Comparator for Testers $224.10
“A compliance verification plan shall be established to ensure the organization’s fulfilment of the requirements of the plan. Compliance verification records shall be established and maintained to provide evidence of conformity to the technical requirements.” [EN 61340-5-1 Edition 1.0 2007-08 clause 5.2.3 Compliance verification plan]

Continuous Monitors: What’’s Better – Single-Wire Impedance or Dual-Wire Resistance Monitors?

Dual-Wire Continuous Monitor

Fred Tenzer on Continuous Monitor History and Preference

By Fred Tenzer

First off, both technologies work fine, but one needs to understand the technologies to understand the shortcomings of each. Let me start with the following basic historical information that will make my “preferences” more clear. If you choose to just know the answer, scroll to the bottom, but I believe this information will be very helpful to you in making your decision. All the technologies will also monitor the worksurface ground circuit and while there are some differences, the worksurface part of the monitoring system is NOT discussed below.

History

When people realized that Operator Grounding was the foundation of an ESD Control Program, wristbands and coil cords came into big time use. The first ESD Association Standards meeting was in 1982 and the first standard written produced by the ESD Association was for wrist straps. The weakest part of the system was the coil cord and testing was developed for bending or flex life testing. The minimum flex life was established at 16,000 flex cycles and in the mid-1980’s that was tough to achieve.

Thus, monitoring technology was initially developed to detect initial flex fatigue while it was still in the “intermittent” stage, which is prior to a permanent open being created. Touch testing would almost never detect this “intermittent” failure mode. In addition, if a wrist strap system was touch-tested twice a day and an operator passed at 1:00 PM on Monday and failed at 8:00 AM on Tuesday, all the work that had peen performed at that station after 1:00 PM on Monday would now be suspect and would be a cause for more detailed quality inspections by many companies. Therefore, while discovering an operator grounding problem was good, it was also costly due to increased Quality Control. Thus, monitoring of the “operator ground system” grew in customer desirability and has resulted in technology improvements by some of the manufacturers and inventors of monitoring technology.

Single-Wire Monitoring Technology

Originally, simple “AC capacitance” single-wire monitors were developed. There were many shortcomings of this technology, all stemming from mostly “false negatives” (unit indicating the operator was grounded when he was not) and “false positives” (alarms going off when they shouldn’t). This technology is still around today and is purchased by some because of its low cost, around £25-£35 per operator and a lack of knowledge by the End User. A big plus is being able to use any standard single-wire wrist strap.

Wave Distortion Single Wire Continuous Monitor

The next level in single-wire evolution was “impedance” technology. However, since the capacitance and therefore the impedance of the circuit will also vary with such things as the person’s size, clothing, shoe soles, conductance of the floor, chair, table mat etc. these monitors often have to be adjusted or tuned to a specific installation and operator. Again, there were resulting “false positives” and “false negatives” though this was an improvement over the simple “capacitance” technology. This technology is also still around; the driver is low cost, £30 -£45 per operator.

The top of single-wire monitoring technology is called “Wave Distortion”. What this technology looks at is not the impedance level, but at the waveform generated by the circuit. Current will leak voltage at various points due to the combinations of resistance and capacitive reactance. There is a negligible amount of inductive reactance from the coil cord. By monitoring these “distortions” or phase shifts the Wave Distortion Monitor will determine if the circuit is complete i.e.; the wearer is in the circuit and the total equivalent DC resistance is within specifications given a range of installations. This technology is very reliable, (virtually no “false positives” or “false negatives”) and response time is very fast (<50 ms). In addition, the wrist strap open circuit test voltage is very low at 1.2 volts peak-to-peak @ 1-2 Micro Amps. Thus, a very low voltage is applied to the operator. The cost for this technology is £75 – £90 per operator.

To continue reading Click Here

EMIT Smartlog V5™ Data Acquisition System – ESD Data at your Fingertips

The patented* SmartLog V5™ system is designed for fast, frequent and accurate testing of ESD personnel grounding items. The SmartLog V5™ records ESD test data and exports it to a central PC or server in real-time where it can be managed and reported using TEAM5 Software.

  • Single-wire and Dual-wire Wrist Strap Compatible
  • Embedded CCD Barcode Scanner
  • Ethernet Communication
  • Adjustable Resistance Limits
  • Programmable Test Requirements
  • Compatible with Proximity Readers
  • Embedded relay terminal for use with electronic


TEAM5 Software

TEAM5 is the most powerful and accurate ESD Test Acquisition Software on the market. Use TEAM5 to automate and manage the ESD test data collected by the SmartLog V5™.
Click here to learn more.
Item Description List Price
50762 Smartlog V5™, Europe, w/o Software £2,294.72
50763 SmartLog V5™, Euro, 10MM Adapter, w/o Software £2,294.72
50764 Reader Only, SmartLog V5™, HID ProxPoint Plus £   370.28
50765 Reader Only, SmartLog V5™, HID iClass £   383.04
50491 TEAM5 Enterprise Software with 1 Year Service £3,886.16
50493 TEAM5 Software with 1 Year Service £   623.36

*US Patent 6,078,875
“Compliance verification records shall be established and maintained to provide evidence of conformity to the technical requirements. The test equipment selected shall be capable of making the measurements defined in the compliance verification plan.” [EN 61340-5-1 Edition 1.0 2007-08 clause 5.2.3 Compliance verification plan]
Click HERE for Printable Version | Request a Demo HERE | See list of sales reps and distributors HERE
All Items & programs are available through your participating distributor | Submit your questions HERE

Advantages of Using Continuous Monitors per EN 61340-5-1 and User guide -2

Leading companies use continuous monitors as a cost effective component in satisfying some of the audit and check requirements of EN 61340-5-1.

Wrist strap testing “Where continuous monitoring is used, no additional testing is required.” [EN 61340-4-1, per A.5.2]

“The wrist band will normally be worn for several hours at a time so it needs to be comfortable while making good contact with the skin. It is a good idea to check the wrist strap every time it is applied. Constant on line monitors can be used so that any breaks will be immediately found.” [EN 61340-5-2 clause 5.2.7]

“A properly grounded wrist strap will keep a person’s body voltage to approximately + 10 V.  The main advantage to a constant [or continuous] monitor is the immediate indication that the employee receives if the wrist strap falls open. With an unmonitored system, the employee will not be aware of a wrist strap failure until the start of the next shift. This has reliability benefits for an ESD program as it might help reduce or eliminate ESD damage.

There are also other process benefits from using constant monitors such as the elimination of the need to maintain daily test logs and a reduction in the time for employees to make the daily test. For units that also monitor the connection of a work surface to protective earth, it is also possible to reduce or eliminate the checking of the work surface as part of the periodic audit of the process.

Constant monitors might be implemented by an organization due to high reliability requirements imposed by customers.” [CLC/TR 61340-5-2:2008 User guide Annex B.1.3 Constant monitors]

“In many EPAs [ESD protected areas] constant monitor wrist straps are used. These fall into two categories, dual wrist band and single wrist band. The dual wrist strap type using a split band is used with a two core cord.

The dual wrist strap type normally works using the resistance bridge method.

The single wrist strap type uses a single strap for both grounding and monitor purposes and has an a.c. signal injected which is used for monitoring purposes. This type has the advantage of using the simpler single wrist strap.” [EN 61340-5-1 A.5 Wrist straps]

See selection of Charleswater Continuous Monitors.

Introducing the New EMIT Zero Volt Monitor Solo!

  • Single Station Continuous Dual-Wire Monitor
    Continuously monitors the ground integrity and charge generation of one operator and supervisor as well as the ground integrity for one ESD worksurface and one optional tool, eliminating the need for periodic testing and record keeping of wrist straps
  • Patented* Dual Polarity Technology
    Provides Real-Time Continuous Monitoring for Operator Path-to-Ground and Presence of 1 Meg Resistor True continuous monitoring (versus pulsed) instantaneously detects broken cords, intermittent faults, dry skin, loose bands and low resistance.
  • Dual Polarity Technology
    Steady-State DC Dual Polarity Signal yields virtually zero voltage on the operator
  • Operator Charge Detection Alarm
    Alarms if the operator generates or comes in contact with a voltage that would be dangerous to an ESD susceptible item
  • RS-485 Communication Ports
    Use with EMIT SIM Software for test data acquisition and management
  • User Adjustable Features
    Use the internal DIP switches to enable / disable test circuits and modify the operator test voltage, operator charge detection voltage and worksurface resistance limit
  • NIST Calibrated with Certificate
    Calibrated with accepted procedures and standards traceable to the National Institute of Standards and Technology. For more information on calibration of EMIT products see Calibration
Item Description Price
50579 ZVM Solo, Europe $334.97

“A properly grounded wrist strap will keep a person’s body voltage to approximately + 10 V. The main advantage to a constant [or continuous] monitor is the immediate indication that the employee receives if the wrist strap falls open. With an unmonitored system, the employee will not be aware of a wrist strap failure until the start of the next shift. This has reliability benefits for an ESD program as it might help reduce or eliminate ESD damage.

There are also other process benefits from using constant monitors such as the elimination of the need to maintain daily test logs and a reduction in the time for employees to make the daily test. For units that also monitor the connection of a work surface to protective earth, it is also possible to reduce or eliminate the checking of the work surface as part of the periodic audit of the process.

Constant monitors might be implemented by an organization due to high reliability requirements imposed by customers.” [CLC/TR 61340-5-2:2008 User guide Annex B.1.3 Constant monitors]

*US patents 6,052,053 and 6,205,408

Click HERE for Printable Verison | Sign Up HERE | Request a Demo HERE | See list of sales reps and distributors HERE
All items & programmes are available through your participating distributor | Submit your questions HERE

SmartLog V5™ Data Acquisition System – ESD Data at your Fingertips

The patented* SmartLog V5™ system is designed for fast, frequent and accurate testing of ESD personnel grounding items. The SmartLog V5™ records ESD test data and exports it to a central PC or server in real-time where it can be managed and reported using TEAM5 Software.

  • Single-wire and Dual-wire Wrist Strap Compatible
  • Embedded CCD Barcode Scanner
  • Ethernet Communication
  • Adjustable Resistance Limits
  • Programmable Test Requirements
  • Compatible with Proximity Readers
  • Embedded relay terminal for use with electronic locks, turnstiles and light fixtures
  • 5 Year Warranty

TEAM5 Software
TEAM5 is the most powerful and accurate ESD Test Acquisition Software on the market. Use TEAM5 to automate and manage the ESD test data collected by the SmartLog V5™. Click here to learn more.

Item Description List Price
50762 SmartLog V5™, Europe, w/o Software $3,633.00
50763 SmartLog V5™, Euro, 10MM Adapter, w/o Software $3,633.00
50764 Reader Only, SmartLog V5™, HID ProxPoint Plus $580.00
50765 Reader Only, SmartLog V5™, HID iClass $600.00
50491 TEAM5 Enterprise Software with 1 Year Service $6,166.77
50493 TEAM5 Software with 1 Year Service $1,000.00


*US Patent 6,078,875
“Compliance verification records shall be established and maintained to provide evidence of conformity to the technical requirements. The test equipment selected shall be capable of making the measurements defined in the compliance verification plan.” [EN 61340-5-1 Edition 1.0 2007-08 clause 5.2.3 Compliance verification plan]

Click HERE for Printable Verison | Sign Up HERE | Request a Demo HERE | See list of sales reps and distributors HERE
All items & programmes are available through your participating distributor | Submit your questions HERE