Electrostatic discharge testing, also known as ESD testing is an essential test for many anti static equipment and products. But before we delve into this, let’s find out what exactly is ESD? ESD is the sudden transfer of electricity between two electrically charged objects. These objects or surfaces would be typically made from insulative materials. This electrostatic transfer can be caused by contact, dielectric breakdown or an electrical short. As a result of this, an ESD event is most likely to occur. When an ESD event happens in the presence of manufacturing of electronics, it can be extremely harmful as it slowly damages the components on the circuit board. And even though the damage is slow, the latent damage to the component will eventually lead to the component failing. You can read more about ESD through Electrostatic Discharge: Causes, Solutions, and Products That Are ESD-Safe | Bondline. Manufacturers of electronic devices are required to devise appropriate ESD countermeasures that satisfy the standards of each electronic device, and various tests and standards have been enacted for each purpose and product. Below, we will talk in more depth about ESD Testing Instruments: Why ESD testing is important, what it is exactly, types of ESD test equipment, how it can help workplaces and more. Keep reading!
When trying to maintain an Electrostatic Protected Area (EPA), monitoring the effectiveness of your equipment is paramount. Regular testing of EPA’s and ESD protection systems such as wrist straps, foot grounders, work surfaces and floors have now become a requirement of the latest ESD Standard IEC 61340-5-1. Investing in ESD testing equipment that can signify when devices no longer hold their antistatic qualities helps to safeguard both your employees’ safety and that of your equipment. By testing your antistatic equipment on a regular basis, it enables you to identify any immediate problems with your equipment meaning that these issues can be dealt with in a timely-manner. The sooner you are able to pinpoint a problem with your antistatic equipment, the better you can act upon this to prevent further damage or damage from occurring in the first instance. Ultimately, saving you time, money and costly replacements.
a) 0.9 meh-ohm is checking that you don’t have a short circuit to ground, which could be dangerous. It has been calculated that 0.75 meg-ohm will offer protection against 250v a.c. (500v d.c.)
b) 35 meg-ohm ensures that you are not too resistive to ground.
It is important to note that if you fail a test, you shouldn’t try to fiddle with it. Instead, you should find out what is wrong, for example, see whether it is dirty, damaged, if you have dry skin or there is no resistor. Investigating into the problem will save you time and enable you to come to a solution. If you were to cheat the test, you would be cheating on your own responsibility!
Briefly, ESD testing is the process of checking a device’s resistance to electrostatic discharge. Known to be caused when two electrically charged objects come into contact with one another, there is a sudden flow of electricity creating a visual spark or discharge. While they are not lethal on their own, the sudden release of energy renders devices and equipment dysfunctional.
ESD testing is an electromagnetic compatibility test (EMC test). ESD testing simulates various electrostatic impacts that equipment might experience either during transit or operation. An electrostatic discharge test determines whether a product is in compliance with its ESD protective area and procedures.
ESD can be transferred through the air or contact. The most common test of ESD is called human body method (HBM). The test simulates the effect on an electronic component of a human discharging electrical energy onto it. This energy is a static buildup.
There are two ESD test methods. One is the air method and the other is the contact method. The air method ESD testing involves moving a charged generator or discharge object such as an ESD gun towards the device being tested. There are many variables that can impact ESD testing. These include humidity, the speed of the discharge object towards the test device and temperature. ESD events are much more common in low temperature and low humidity environments.
The contact method ESD testing helps eliminate the impact of environmental effects such as temperature and humidity. This test method involves an ESD generator being in direct contact with the device to be tested. This contact is in place throughout the entire test. While this test method is generally consistent across environmental conditions, contact ESD rarely occurs naturally.
An ESD test confirms that the equipment correctly operates per the test requirement and the manufacturer’s operating procedures. ESD testing is generally part of a larger EMC test plan for product certification compliance.
Your Electrostatic Protected Area (EPA) plays a crucial part in your business as it provides a static-safe area for both operators and static-sensitive items. Since it is the very core to your static control routine, you must ensure you check workstations, floor mats, ESD ground connections and ionisers monthly. Additionally, you should also check any ESD control instrument you have annually. This will allow you to identify any problems with your equipment so you can solve the issue in a timely-manner with little or no damage.
Resistance to ground for the following should be:
The commonly used devices in testing for ESD are ESD guns, otherwise known as ESD simulators. Similar to its ioniser counterparts, these simulators are compact and hand-carried to make it accessible for users and to be used in different situations and locations. ESD guns are programmable; users can detect voltages which range from 16kV to 30kV. It can be further altered depending on the situation and needs of the testing. It was made to be agile and flexible to meet international standards of ESD testing.
Depending on your needs, budget and specifications, you can select and choose the appropriate ESD testing instruments for your business. In choosing, you should be mindful that the test instrument must be able to conduct various tests, one in which is the Human Body Model test which will be discussed below.
The easiest and most common method used by test engineers and electricians alike. This is normally designed to test items and equipment that are not for commercial use. From the name itself, the human body, the test accounts for the built up electrostatic charges in the body which have been accumulated by daily activities. Some of these include rubbing of shoulders, toes, or feet. If the equipment reacts to the static energy in the skin, it will create a tingling sensation making a sudden surge of energy between person to person or object to a person.
Calibrating your ESD testing instruments is a vital process as it determines the instruments’ accuracy. The process involves obtaining a reading from the instrument and measuring its variation from the reading obtained from a standard instrument. Calibration of an instrument also involves adjusting its precision and accuracy so that its readings come in accordance with the established standard.
Before you begin to use your newly purchased ESD test instruments, you would want to ensure that they have been calibrated so that the instruments perform correctly and efficiently. Usually, you will find that the supplier has conducted calibration of the devices and will issue a certificate for this. If they haven’t, then it is best recommended that you find a reputable company who can conduct a calibration for you. It is important to note that calibration of all test equipment is recommended on a regular basis (annually).
Wrist Strap Tester – This device can come as either a portable or wall mounted unit. With a simple plug in, it tests the effectiveness of the user’s wrist strap in grounding the ESD charge. These products display the results through a colour system, green for a pass and red if the ESD wrist strap has failed the test. Not only can you find solely wrist strap testers, but you can also find combined wrist strap and footwear testers. This type of tester is particularly used when both ESD foot grounding and ESD wrist straps are employed in the EPA.
Testing For ESD Shoes – Due to heavy use, footwear will degrade over time, often losing their antistatic properties. Testing your ESD footwear is vital to ensure a safe EPA environment. The testing equipment for shoes often comes as an add on to the wrist strap ESD testing stations. This will pass footwear that is within the range of 750 Kilohms – 100 Megohms.
Surface Resistivity Meter – This type of device can usually be found in the form of a handheld, portable meter or as part of a kit. Devices of this nature are used when attempting to measure both point to point ESD resistance or the surface resistivity. Surface resistivity tools are incredibly accurate with a static dissipative range of 10 to 100 volts. Simply place the square probe where you require testing, press a button and wait for the results!
Constant Monitors – Constant Monitors are designed to continuously monitor whether the wrist-strap, bench mat or the Earth is disconnected whilst simultaneously checking the Earth to ground system is working correctly. Should any part of the ESD system fail, a red LED indicator will illuminate and a buzzer will sound. This part of the system should be checked using the appropriate test equipment before continuing with manufacture. In short, Constant Monitors give a constant and sustained reading for the grounded connection of the device. You can therefore rest assured that a grounded connection is present through the entirety of the production process when connected.
Electrostatic Field Monitors – These devices are compact and handheld that allow you to measure static charges around your workplace. Alongside the single meter option, you can alternatively purchase a whole kit. These meters are optimal for low light and confined spaces, utilising an ESD field monitor ensures accurate measurements for your EPA environment.
For more information on ESD Testing Instruments, please get in touch with our team!
The personnel grounding tester is a wrist strap and/or footwear tester to check personnel grounding systems before entering an EPA. It is highly recommended that you check wrist straps and footwear twice a day to ensure they are working correctly. If they are not functioning the way they should then you need to stop using them and find out why. If you continue to use them while they are not working, a static potential could generate and dissipative onto the operator or environment, posing a high risk to the static sensitive device.
ESD is not just present across all equipment, items and products in manufacturing companies or factories. The friction of the shoes and floor also creates and leaves huge amounts of static energy to the ground. The built up static energy is activated when conductors are induced. The wind is a major vehicle of such conductors like carbon and graphite. These elements then make the floors gain electrical conductivity.
ESD flooring used with approved footwear, may be an alternative to the wrist strap system, in this case the standard is more restrictive and one of the following conditions must be met:
It is possible to test floors, one of which is the use of a Megohmmeter with one lead attached to the ground and one electrode held by the person wearing ESD footwear standing on the factory’s protective floor. It is imperative that you check the “footwear/flooring system” twice a year to ensure it is functioning correctly. Detecting if a floor is ESD-immune is important as it can cause major disruptions and damage to electronics. Too much exposure to the gradual decrease in function of the device. After detection, it is easier to manage it with the use of ESD flooring or footwear combinations. These floorings will prevent and manage the accumulation of ESD on the flooring.
When you test for ESD in your workplace, you are ensuring that your equipment remains up to the task of grounding the electrostatic charge efficiently. Bondline’s equipment is calibrated to ensure the best testing results. Here is how a regular ESD testing procedure will help your business:
Highlight Dangers – From both a moral and business perspective, investing in an ESD testing procedure keeps your workplace healthy and happy and yet reduces the damage electrostatic discharge can cause by testing correctly with the right testing equipment.
Spot Faulty ESD Equipment – Products degrade over time through use. Regular ESD testing ensures that you spot faulty equipment in time, enabling you to replace them quickly for your employees.
Monitor Static Charge – Help to identify exactly where static charge is being emitted from your workplace. Know exactly where you need to either clean or put in place antistatic measures to maintain your EPA.
Bondline is a leading supplier of UK manufactured ESD test equipment since 1986. Bondline offer a huge range of ESD testing devices including Wrist Strap Testers, Surface Resistivity Meters, Constant Monitoring and Field Meters. All of Bondline’s test instruments are manufactured to the very highest quality allowing qualification to council directives 89/336/EEC and are CE approved.
Alongside purchasing your ESD Testing Instruments from Bondline, Bondline will conduct a full calibration and issue certification of calibration for the test instruments, traceable to national standards.
While Bondline have a range of readily to purchase ESD Testing Instruments on their website, Bondline can also offer bespoke customisation for these devices. Customisation can include private labelling, custom logos and colours on request. Additionally, Bondline can also provide their test equipment with specific ranges to conform to many standards in the electronics industry. If you would like a custom-made ESD testing product, please make an enquiry to Bondline.
To get a quote or expert advice, contact us at ESD Testing Devices | Bondline Electronics Ltd or fill in the form below.
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