SCS is excited to announce a brand new video series discussing real-life ESD problems and solutions. This is a great educational resource for anybody new to ESD or just wanting to learn more about best practices.
Each episode will focus on one issue commonly found in an ESD Protected Area – at the same time we will present solutions so you know how to tackle the problem should you ever face it in your own factory.
A new episode will be published each week so make sure you subscribe to our YouTube channel to get notified when a new video is available. Episodes 1 and 2 are now live so don’t waste a second longer and catch-up now:
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.
Welcome back to “A Minute with Miranda.” This week we will be covering how to perform the Rtt and Rtg test on an ESD Worksurface Mat.
Before using a worksurface mat in an EPA environment, you need to verify that the mat will meet the ANSI/ESD S20.20 Worksurface Requirements. For both the Rtt and Rtg test the worksurface should test between 1 x 106 to less than 1 x 109 ohms. The test should be performed in accordance to the ANSI/ESD S4.1 Standards.
SCS worksurface mats meet the ANSI/ESD STM4.1 and ANSI/ESD S20.20 required limit of 1 x 10^6 to less than 1 x 10^9 ohms for Rtt and Rtg and the recommendations of ANSI/ESD S4.1.
View our complete SCS Static Worksurface mat offering here.
Welcome back to “A Minute with Miranda.” This week we will be covering how to launder your ESD Smocks.
SCS Static Control Smocks should be laundered periodically for proper operation. Smocks should be washed by hand or with a standard household washing machine using cold or warm water with a non-ionic liquid detergent. Avoid using bleach, fabric softeners or dry detergents as these can contaminate the conductive fibers and make the garment insulative .
After washing the smocks they should either be hung dry or tumbled dry at low heat. High heat can degrade the conductive fibers within the garment and degrade the ESD properties.
With normal wearing and washing conditions, SCS Static Control Smocks will maintain their ESD properties for a minimum of 100 washings.
SCS Smocks meet the requirement for Groundable Static Control Garment System per ANSI/ESD S20.20 required limit of less than 3.5 x 107 ohm Rtg tested per ANSI/ESD STM2.1 and ESD TR53.
The best way to keep electrostatic
sensitive devices (ESDs) from damage is to ground all conductive objects and
remove insulators from your ESD Protected Area (EPA). This is not always
possible because some insulators are “process-essential” and are necessary to
build or assemble the finished product. The only way to control charges on
these necessary non-conductive items is the use of ionization systems.
However, if an ionizer is out of balance,
instead of neutralizing charges, it will produce primarily positive or negative
ions. This results in placing an electrostatic charge on items that are not
grounded, potentially discharging and causing ESD damage to nearby sensitive
It is therefore essential to regularly
clean your ionizers and verify they function correctly. Below we have put
together a list of tasks you need to perform with your ionizers on a regular
ionization devices will require periodic maintenance for proper operation.
Maintenance intervals for ionizers vary widely depending on the type of
ionization equipment and use environment. Critical clean room uses will
generally require more frequent attention. It is important to set-up a routine
schedule for ionizer service. Routine service is typically required to meet
quality audit requirements.” (ESD Handbook TR20.20 section 22.214.171.124
Maintenance / Cleaning)
EIA-625, recommends checking ionizers every
6 months, but this may not be suitable for many programs particularly since an
out-of-balance may exist for months before it is checked again. ANSI/ESD S20.20
section 126.96.36.199 Compliance Verification Plan Requirement states: “Test equipment shall be selected to make
measurements of appropriate properties of the technical requirements that are
incorporated into the ESD program plan.”
Under normal conditions, an ionizer will
attract dirt and dust (especially on the emitter points). To maintain optimum
neutralization efficiency and operation, cleaning should be performed on a
Wipe the case with a soft cloth and
deionized water. Fully squeeze the wiping cloth or sponge to remove any excess
liquid. If a stronger cleaning solution is required, dab a soft cloth with
mixture of isopropyl alcohol and deionized water (70% IPA and 30% DI water).
2. Emitter Points
The emitter points should be cleaned using
specific emitter point cleaners or a swab dampened with Isopropyl alcohol.
Below are general instructions on how to clean emitter points. However, each
unit is slightly different so always refer to the ionizer’s manual.
Turn the unit OFF and unplug the power cord.
Open the top screen by loosening the screw and swinging the grill to one side.
Clean the emitter points using the an emitter point cleaner or a swab dampened with Isopropyl alcohol.
Re-attach the top screen.
Plug in the power cord and turn the unit ON.
Verify the performance of the ionizer by using a charged plate monitor or ionization test kit (see below).
With normal handling, the emitter points
should not require replacement during the life of the unit.
Per ESD TR53 section 188.8.131.52.1 “The best practice is to measure the offset
voltage and discharge times, clean the unit, including emitter points and air
filters if present, offset voltage to zero (if adjustable), and then repeat
offset voltage and discharge time testing. If the unit does not meet offset
voltage specifications or minimum established discharge time limits, further
service is indicated. Manufacturers should provide details on service
procedures and typical service intervals.”
Most companies will assign a number or
otherwise identify each ionizer and setup a Compliance Verification /
Maintenance / Calibration schedule. If the ionizers all test good, the data can
justify lengthening the calibration period. If ionizers require adjustment, the
calibration period should be shortened. Although ESD TR53 does not advise a
test frequency, JESDD625-A (Revision of EIA-625) recommends ionizers be tested semi-annually,
noting to use “S3.1 except the number of
measurement points and locations may be selected based on the application.”
Verification should be performed in
accordance with the ESD Association ionization standard ANSI/ESD STM3.1.
Below are general instructions on how to
verify your ionizer’s offset voltage and discharge time. Always refer to the
User Guide accompanying your Charge Plate Monitor or Ionization Test Kit for
proper operation and setup.
1. Testing Ionizer Offset Voltage:
The required limit per ANSI/ ESD S20.20 is
less than ± 35 volts. Check your ionizer’s operating manual or consult with the
ionizer manufacturer to determine what the offset voltage should be for your
Charge Plate Monitor (CPM)
Position the ionizer and charge plate monitor as shown below.
Set the CPM to Decay/Offset mode.
Set the CPM to decay and offset voltage mode with a starting charge at either + or – 1 KV and a stopping charge at either + or -100 Volts.
Start the decay/offset test sequence on the CPM. This will take a few seconds.
Record the decay time, and offset voltage as displayed on the CPM.
your Charge Plate Monitor for Overhead and Benchtop Ionizers
Ionization Test Kit
Zero the charge plate by touching it with a grounded object. This
can either be the finger of a grounded person or some other item which is
connected to electrical ground. In either case, zeroing the charge plate should
make the display on the field meter read zero.
Hold the meter approximately one foot (30.5 cm) in front of the
Monitor the display. The value displayed is the offset balance of
the ionizer, which is the difference between the number of positive and
negative ions being emitted.
2. Testing Ionizer Discharge Time:
The required limit per ANSI/ESD S20.20 is
“user defined”. Please refer to the ionizer’s operating manual or consult with
the ionizer manufacturer to determine what this discharge time should be.
Charge Plate Monitor (CPM)
Set the CPM to Decay/Offset mode.
Set the CPM to decay and offset voltage mode with a starting charge
at either + or – 1 KV and a stopping charge at either + or -100 Volts.
Start the decay/offset test sequence on the CPM. This will take a
Record the decay time, and offset voltage as displayed on the CPM.
Ionization Test Kit
After charging the plate of the ionization test kit, hold the field
meter approximately one foot (30.5 cm) away from the ionizer.
Monitor the display of the meter to see how quickly the 1.1 kV
charge is dissipated to 0.1 kV.
The speed at which this occurs (the discharge time) indicates how
well the ionizer is operating.
Repeat this procedure for both a positively and a negatively charged
Some ionizers offer adjustment options
(e.g. trim pots) which allow modification of the offset voltage.
However, if your ionizer is out of balance
(and cannot be adjusted) or if the discharge time is out of specification, the
ionizer will require service/repair by an authorized company.
Ionization is one of the best methods of
removing charges from insulators and as a result plays an important role in
Remember though: ionizers require periodic
cleaning of emitter pins and verifying of the offset voltage and discharge
time. Otherwise, instead of neutralizing charges, the ionizer will primarily produce
positive or negative ions. The ionizer will therefore place an electrostatic
charge on items that are not grounded, potentially discharging and causing ESD
damage to nearby sensitive items.
Setting up an ESD-safe workstation is often
more challenging than it first appears. There are many methods of controlling
ElectroStatic Discharge (ESD), and typically, it requires a combination of
these to curb all static problems. Unfortunately, there is no single method
that will fill all requirements.
Wrist straps and work surface mats are probably the most familiar to everyone, draining charges from operators as well as from the product being worked on. But what if the static charge in question is on an insulator? Electronic products, by nature, will normally consist of conductors and insulators. Insulators at the workstation can be found on the product itself, tools being used, tapes for masking, even circuit boards. A static charge on an insulator cannot be drained by grounding, as you could with a conductive material.
To effectively remove charges from insulators, we need to make the surrounding air more conductive. We have all seen a balloon cling to a wall because of a static charge, and we know that, after a period of time, it will drop. That is because the air is somewhat conductive and the charge eventually drains off. The problem with this concept is that it takes too long. The more conductive the air is, the faster the charge will be neutralized.
The method most frequently used to increase
the conductivity of the air is ionization.
Ionizers are useful in preventing
electrostatic charge generation, ElectroStatic Discharge, ElectroStatic
Attraction, as well as preventing equipment latch-up. Per ANSI/ESD S20.20
section 184.108.40.206. Protected Areas Requirement states: “Ionization or other
charge mitigating techniques shall be used at the workstation to neutralize
electrostatic fields on all process essential insulators if the electrostatic
field is considered a threat.”
do Ionizers work?
Most ESD workstations will have some
insulators (e.g. product plastic housing) or isolated conductors (e.g. PCB
board components not in contact with ESD worksurface) that cannot be removed or
replaced. These should be controlled using ionization.
Ionizers create great numbers of positively
and negatively charged ions. Fans help the ions flow over the work area. If
there is a static charge present on an item in the work area, it will be
reduced and neutralized by attracting opposite polarity charges from the air.
Ionization can neutralize static charges on
an insulator in a matter of seconds, thereby reducing their potential to cause
The charged ions created by an ionizer
neutralize charges on process
neutralize charges on non-
neutralize isolated conductors
does Ionization fit into an ESD Control Program?
Ionization is just one component of your
ESD Control Program. Before utilizing ionization, you should follow the
fundamental principles of ESD Control:
Ground all conductors
(including people) using conventional grounding methods (e.g. wrist straps or
Remove all insulators, e.g.
coffee cups, food wrappers etc.
“Air ionization is not a replacement for
grounding methods. It is one component of a complete static control program.
Ionizers are used when it is not possible to properly ground everything and as
backup to other static control methods. In clean rooms, air ionization may be
one of the few methods of static control available.” (ESD Handbook ESD TR20.20
Ionization, section 220.127.116.11 Introduction and Purpose / General Information)
Ionizers can be critical to
reduce induction charging caused by process necessary insulators
Ionizers can be critical in
eliminating charges on isolated conductors like devices on PCBs
Ionization can reduce
ElectroStatic Attraction (ESA) and charged particles clinging and contaminating
It is recommended to use ionizers with feedback mechanisms, so you’re notified if the offset voltage is out of balance.
Ionizers should be pieces of equipment that
have serial numbers and are included in the company’s maintenance and
calibration schedules. This is particularly critical to ensure that the offset
voltage or balance is within acceptable limits. Otherwise, instead of
neutralizing charges the out of balance ionizer will charge insulators and
isolated conductors. The user, depending on the value and function of their
products, must determine the appropriate frequency of maintenance and
The best way to keep electrostatic
sensitive devices (ESDs) from damage is to ground all conductive objects and
remove insulators. This is not always possible because some insulators are
“process-essential” and are necessary to build or assemble the finished product.
The only way to control charges on these necessary non-conductive items is the
use of ionization systems. Applications include:
eliminating charges on process
neutralizing workstations where
ESDS are handled,
removing charged particulates
to create a static free work area.
In today’s connected world, we are surrounded by home monitoring networks, fitness trackers and other smart systems. They all use an IoT platform to keep us up to-date with the current temperature in our house or the number of steps we have taken in a day. There are many different applications of IoT: Consumer, Commercial, Industrial, and Infrastructure, but is there a way to use this incredibly smart technology to improve ESD Control? Let’s take a look!
What Is The Internet of Things (IoT)?
The Internet of Things (IoT) is used everywhere today – from medical devices, to vehicles, to homes and more! Simply put, IoT:
Connects “things” in the physical world to the internet using sensors.
Collects data for these “things” via sensors.
Analyses the collected data and provides a deeper insight into the “things”.
Another broad definition provided for IoT is:
“The Internet of Things (IoT) is the network of physical devices, vehicles, home appliances, and other items embedded with electronics, software, sensors, actuators, and connectivity which enables these things to connect and exchange data, creating opportunities for more direct integration of the physical world into computer-based systems, resulting in efficiency improvements, economic benefits, and reduced human exertions.” [Source]
As mentioned previously, there are many different applications for IoT, but The Industrial Internet of Things (IIoT) applies specifically to manufacturing and industrial processes.
It has slightly different requirements compared to consumer IoT products but the principle is the same: smart machines (incorporating various sensors) accurately and consistently capture and analyze real-time data allowing companies to pick-up problems as soon as (or even before) they appear.
Internet of Things (IoT) and Industry 4.0
IoT helped push the 3rd industrial revolution (machine automation) one step further. “Cyber Physical Systems (CPS) dominate the manufacturing floor, linking real objects with information processing, and virtual objects via the internet. The goal is to converge Operational Technology (OT) and Information Technology (IT).” [Source]
The 4th industrial revolution is also referred to as “Industry 4.0”. “At the very core Industry 4.0 includes the (partial) transfer of autonomy and autonomous decisions to cyber-physical systems and machines, leveraging information systems”. [Source]
Industry 4.0 as fourth industrial revolution [Source]
So, how can companies use the power of IoT and create accessible, real-time feedback on the status of their ESD Control Protected Area (EPA) and ESD control items?
Industry 4.0 IoT Platforms in ESD Control
ESD damages can be extremely costly – especially when it comes to latent defects that are not detected until the damaged component is installed in a customer’s system. Conventional ESD control programs incorporate periodic verification checks of ESD control products to detect any issues that could result in ESD events and ESD damage. The problem is that ESD control products (and the EPA as a whole) are not constantly monitored.
Take an ionizer for example: if a company uses ionization to handle process-essential insulators, the ionizers need to be fully reliable at all times. If an ionizer passes one check but is found to be out of balance at the next, the company faces a huge problem: nobody knows WHEN exactly the ionizer failed or if contributed to a charged insulator potentially causing ESD damage.
The Industry 4.0 IoT platform will be a game changer when it comes to creating a reliable and dependable ESD control program. Sensors collecting vital ESD information like field voltage, Electromagnetic Interference (EMI), temperature, humidity etc. in an EPA will help detect potential threats in real-time allowing supervisors to act even before an ESD threat occurs.
Advantages of Internet of Things (IoT) in ESD Control
Here is a (by no means exhaustive) list of advantages, IoT can bring to ESD Control:
The day in an EPA can be busy. Taking the time to capture and record measurements of ionizers, wrist straps, work surfaces, automated processes etc. can be disruptive and is prone to errors. IoT allows data to be collected automatically without any input from users. This helps to increase the accuracy of data and allows operators and supervisors more time focusing on their actual jobs.
Supervisors have all the essential data in one place right in front of them and can make informed decisions; they can provide feedback and give suggestions in case of an ESD emergency. IoT allows to pinpoint areas of concern and prevent ESD events.
IoT continuously monitors processes and provides a real-time picture of them – no manual checks required. If a potential threat is detected, warnings will show-up immediately. There is no need to worry about potentially damaging sensitive devices because the next scheduled check of ionizers, wrist straps etc. has not been completed yet.
The number one reason for adapting an ESD control program is to reduce costs by:
Enhancing quality and productivity,
Improving customer satisfaction,
Lowering repair, rework and field service costs and
Reducing material, labor and overhead costs.
Reduced Workload and Increased Productivity
IoT pushes all the above even further with the additional benefits of:
Reduced workload for operators: Data is collected remotely without any input from users. Operators are not disrupted in their day-to-day activities.
Reduced workload for supervisors: Supervisors don’t have to collect and analyze data from personnel testers, field meters, monitors etc. The system does it for them and will highlight any issues.
Further increases in productivity and cost reductions: An ESD program can be managed better and with fewer resources.
Static Management Program (SMP): the next generation of ESD Process Control – more information
IoT will no doubt change ESD control and the way EPAs are monitored. Quantifiable data allows companies to see trends, become more proactive and improve the efficiency of their ESD process control system. IoT will support organizations’ efforts to make more dependable products, improve yields, increase automation and provide a measurable return on investment. Not only will this benefit users and supervisors, but the company as a whole.
SCS Static Management Program (SMP) is the only smart ESD system on the market that continuously monitors your entire ESD process control system throughout all stages of manufacturing. SMP captures data from SCS workstation, equipment and ESD event continuous monitors and provides a real-time picture of critical manufacturing processes.
For more information on how to continuously monitor your ESD control program and/or improve an existing program, request a free ESD/EOS Assessment or SMP demo at your facility by one of our knowledgeable local representatives to evaluate your ESD program and answer any ESD questions!
Have you ever walked across a car park on a bright cold winter’s day only to get zapped by your car’s door handle? It’s commonly known that these ‘zaps’ are much more common in cold dry weather. It begs the question: if there are less ‘zap, will using air humidifiers in a manufacturing environment prevent ESD damage of sensitive components? Let’s find out!
Humidity describes the amount of water vapor in the air. There are 3 main measurements of humidity with the most common one being the relative humidity (RH). It is expressed in percent and describes “how much humidity there is in the air, compared to how much there could be. Meteorologists often use the relative humidity as a measurement to describe the weather at various places.” [Source]
At 0% the air is completely dry; at 100% it is so moist that mist or dew can form. The optimum relative humidity level is somewhere between 40% and 60%:
A lower relative humidity increases charge generation as the environment is drier.
If the humidity level is too high, condensation can form on surfaces.
Charge Generation and ElectroStatic Discharge (ESD)
The simple separation of two surfaces generates an ElectroStatic charge. Examples:
Unwinding a roll of tape
Gas or liquid moving through a hose or pipe
A person walking across a floor with heels and soles contacting and separating from the floor
The amount of static electricity generated varies and is affected by materials, friction, area of contact and the relative humidity of the environment. A higher charge is generated at low humidity or in a dry environment.
Once an item has generated a charge, it will want to come into balance. If it is in close enough proximity to a second item, there can be a rapid, spontaneous transfer of electrostatic charge. This is called discharge or ElectroStatic Discharge (ESD).
Going back to our earlier example of getting a zap from your car’s door handle:
Charge generation: you walk across the car park with your soles contacting and separating from the floor. A charge is built-up on you.
ElectroStatic Discharge (ESD): you touch the door handle. Charges move from your body to your car until both are balanced out.
Impact of relative humidity on ESD
Many people will notice a difference in the ability to generate static electricity when the air gets dryer (relative humidity decreases). Relative humidity (RH) directly affects the ability of a surface to store an electrostatic charge. “With a humidity level of 40% RH, surface resistance is lowered on floors, carpets, table mats and other areas. …the moisture in the air forms a thin protective “film” on surfaces that serves as a natural conductor to dissipate electric charges. When humidity drops below 40% RH, this protection disappears, and normal employee activities lead to objects being charged with static electricity.” [Source]
In an electronics manufacturing environment lower humidity may result in lower output from production due to an increase in ESD events during manufacturing processes.
Air Humidification and ESD
Air humidifiers are used to add moisture to the air and are commonly used in drier environments to keep humidity at a constant (optimum) level. Given that a lower humidity level increases the risk of ESD events, the obvious questions are:
Can air humidifiers replace normal ESD Control measures?
Are air humidifiers required for complete ESD protection?
Let’s address both questions:
Let’s be very clear about one thing here: air humidifiers cannot replace ESD Control measures.
As explained further above, ESD is caused by two items that are at a different electrostatic equipotential and want to equalize their charges. Adding moisture to the air using humidifiers will not stop this discharge from happening. The only thing you may achieve is a reduction in the number of ESD events. BUT: they will still happen; just walking across a carpet will generate a charge on an operator. If they then touch an ESD sensitive component, discharge will still occur and may damage the component. No humidifier will prevent this.
The only way to control electrostatic charges on a person or object is through ESD grounding – this will ensure any charges generated dissipate to earth:
For more information on how to create a ESD workstation and how to correctly ground all elements, have a look at this post.
Low air humidity can increase the number of ESD events so it may make sense to keep a factory at a higher humidity level. However, there are many other factors that come into play when choosing the ‘right’ humidity for a manufacturing environment. The recommended humidity range is usually determined by the specifications of the devices and components being assembled. Increasing the humidity in an electronics manufacturing facility can help to reduce ESD events but increased humidity can lead to other unwanted quality issues in an electronics manufacturing environment such as corrosion, soldering defects and the popcorn effect on moisture sensitive devices.
A normal range for humidity in electronics manufacturing is between 30% RH and 70% RH. Some facilities try to maintain a constant moderate RH (~50%), whereas other environments may want lower % RH due to corrosion susceptibility to humidity sensitive parts.
And remember: you will not eliminate ESD by using humidifiers and keeping humidity levels at a higher level. You need an ESD Control Program in place to avoid ESD and associated damages.
Air humidification can help reduce the number of ESD events in an electronics manufacturing environment but at the same time there are other factors (e.g. moisture sensitivity of components) that need to be considered.
A lower relative humidity level increases charge generation as the environment is drier. This will result in more ESD events which can potentially damage sensitive components. The only way to protect sensitive components from ESD damage is by having proper ESD control measures in place and connecting operators, objects and surfaces to ground. This will ensure each element is kept at the same electrical potential and any electrostatic discharge is being removed to ground.
For more information on how to get your ESD control program off the ground or improve an existing program, request a free ESD/EOS Assessment at your facility by one of our knowledgeable local representatives to evaluate your ESD program and answer any ESD questions!