A Trusted UK Supplier Of ESD Control Products Since 1986
As you are reading this article, you may be familiar with Electrostatic Discharge (ESD) or work in an organisation with an Electrostatic Protected Area (EPA). In this instance, it is likely you have come across ESD matting. Although, have you ever wondered what exactly is ESD matting and why is it used? Then this article is a perfect introduction to ESD matting for you.
Static sensitive components are threatened by static electricity in many industries including those of flat panel manufacturing and electronic assembly. Electrostatic discharges (ESDs) can generate stray sparks that can cause irreversible damage to static sensitive components such as printed circuit boards. It is therefore imperative to use the right static control equipment.
Several methods are available to prevent static electricity from damaging your electronic components. To eliminate electrical buildup, it is a good idea to start from the ground up. To ensure ESD safety, all ESD safety plans must include ESD mats. ESD mats are the core assets of an ESD Control Plan. Let’s find out why…
ESD mats are just like ordinary placemats – they are used on flat surfaces like workbenches and tables. They are a typical integral part of the ESD workstation, particularly in areas where hand assembly occurs. It is important that each bench, or work surface, is covered with the proper ESD material and is properly connected to Earth using a system of cords and Earth Bonding Points (EBPs).
Most workstations will use pliable ESD matting to cover the bench and be the ESD work-surface on which to handle ESD sensitive (ESDS) items. The mat needs to be grounded and best practice is to use metal grounding hardware snaps and ground cords connecting the work-surface mat to the common point ground. The entire bench-top should be covered by the ESD mat. It is possible that without this ground, the mat would protect the item being worked on initially, but it would then transfer the ESD to the following item, the person holding it, or even back to the item it was originally intended to protect.
An ESD protective work surface is usually dissipative on the surface with a conductive layer either underneath (2-layer matting), or buried between two dissipative layers (3-layer matting). Although conductive materials are the quickest to ground a charge, they can also cause damage by discharging too rapidly.
Walking alone can create static electricity. However, ESD matting can help to disperse this electricity. These mats have electrically conductive carbon fibres throughout. Consequently, the ESD flows at a slower rate across the surface of the mat which in turn neutralises it. There is also matting available which is appropriate to use on workbenches, trolleys and other surfaces. We will cover the electrical properties of an ESD mat in greater detail later on.
If you need a large workspace or a dedicated ESD workstation, you should consider purchasing rolls of ESD matting or getting custom-sized mats. You should ensure that all mats, no matter their size or quantity, are properly grounded.
Furthermore, ESD mats can increase worker safety as well as provide further neutralisation of potential electrostatic discharge as well as cushioning, easing fatigue for the standing worker while working on electronic devices. An ESD flooring mat also reduces the risk of slipping on slippery floors.
It is important to remember that not all ESD mats are tested equally. Ideally, the mats you are buying should be IEC certified for your company’s protection, so you are sure you are getting the protection you need.
Antistatic mats help to protect static sensitive components from electrostatic discharge. They are engineered to drain static charge from items placed on their surface. A secondary benefit of ESD mats is that they serve to protect the surface of the ESD sensitive devices from wear and tear. They do this by slowing down the flow of static charge, which neutralises the static electricity and moves the charge into the grounded mat, away from the electronic components being worked on.
The performance of ESD matting is based on the material its constructed with, as well as its electrical properties and ability to withstand heat, chemicals and mechanical abrasion. Generally, anti-static mats have a low electrical resistance of between 0.1 and 1000 MegaOhm (MΩ). The use of anti-static matting prevents the build-up of electrostatic charge in the body by dissipating this charge and thus prevents a sudden discharge between electrically charged objects on contact. A wide variety of sizes are available for these mats, which are typically placed on the floor or a work surface.
As with other forms of static safety equipment, ESD mats serve two purposes. First, they disperse static electricity of individuals and objects, and second, they prevent the buildup of static electricity in the workplace. Their use, together with grounding wristbands, antistatic clothing, antistatic tools, and antistatic packaging, helps reduce the possibility of an electrostatic discharge.
The purpose of an ESD protective working surface is to prevent damage from electrostatic discharge to components and assemblies that are ESD sensitive.
There are two ways in which an ESD protective working surface protects:
1. Antistatic surfaces limit the generation of static electricity below potentially damaging levels by providing low-charging (antistatic) working surfaces.
2. Electrostatically discharging objects that have been placed on the surface of the workpiece.
Antistatic mats are divided into two categories, work surface/bench mats and floor mats:
ESD work surface mats, also known as table top mats or bench mats, have a smooth or lightly textured embossed surface. The embossed surface helps to reduce the reflective properties of the matting, reducing glare and therefore aiding workers with complicated electronic assembly tasks. Bench mats tend to come in light colours for easy visibility of smaller components.
They are available in single layer vinyl homogeneous material, two layer rubber material and three layer with homogeneous vinyl top and foamed vinyl on the back with a carbon layer in the middle. Compared to floor mats, they tend to be much thinner. ESD bench mats are designed to be used with other ESD controls such as ESD wrist straps and grounding points.
ESD floor mats, or underfoot ESD mats, have a heavy textured embossing or grooves to improve traction and prevent workers from slipping. They have an anti-fatigue cushioned surface for increased ergonomic safety to help reduce stress on the body for long periods of standing. Colour-wise, the floor mats are usually designed with dark colours to hide dirt and scuffs from worker’s shoes or production equipment. ESD floor mats are much larger and thicker than table mats to help absorb wear and tear. Floor mats have more durability than table mats and, because of their strong formation, they often last longer too.
ESD floor mats are designed to work as part of a wider ESD protection scheme. When using ESD floor mats, you should always ensure to use ESD footwear or heel straps in conjunction with the floor matting to provide a path to ground. This allows full grounding and Earthing so you can be sure you are static-free when moving around the EPA.
Work surfaces for ESD protection can be categorised as conductive or dissipative.
According to most standards, a conductive working surface is one with a surface resistance of less than 1 x 10^(4) ohms. Those materials that conduct electricity ground a charge the fastest, however, too much discharge can harm them.
Those materials are classified as dissipative if they have a resistance of 1 x 10^(4) or less, but not more than 1 x 10^(9) ohms. Using dissipative materials is recommended when handling electronic components, as they dissipate charges more slowly. Surfaces used for benchtop working are most often made with dissipative materials.
The topmost important part of an ESD Control Program is personnel grounding. However, most people think that working surfaces are important too. In order for a mat to work properly, a must must be able to conduct electricity so the range of conductivity is vital.
If the mat’s resistance is too low, static transfers to the mat and a spark is created causing an electrostatic discharge (ESD) which will in turn damage static sensitive electronic components or devices.
If the mat’s resistance is too high, static transfers slowly and any items placed on the mat will not lose their charge. When the item is removed from the mat, the static charge will be capable of discharging to other items.
ESD protective worksurfaces with a resistance to ground of 1.0 x 106 to 1.0 x 109 provide a surface that is at the same electrical potential as other ESD control items at the workstation. They also provide an electrical path to ground for the controlled dissipation of any static charges on materials that contact the surface. The ESD protective worksurface also helps define a specific work area in which ESDS items are to be handled. The ESD protective worksurface is connected to the common point ground.
ESD matting can be measured in three ways:
Resistance To Ground (RTG): The main measurement, and the one we’ll focus on most in the examples below. RTG measures the resistance given between the most heavily used part of the ESD mat and the electrical ground.
Resistance to Groundable Point (RTGP): This functions like RTG with one difference. It measures the resistance between a single point on the mat’s surface and the grounding point of the work surface.
Resistance Point to Point (RTP): Surface resistance from one part of the mat’s surface to another point ten inches apart.
Before choosing your matting, there are three types of materials you need to familiarise yourself with first.
The type of matting material you opt for can provide you with different benefits, whether it be a more cost-effective solution or provide better static dissipation. Generally, antistatic mats are available in a vinyl or rubber material.
Vinyl is the most widely used material for table top or work surface applications. Vinyl mats are cost-effective, easy to cut to size and provide excellent static-dissipation overall.
Rubber is generally used where high resistance to heat and chemicals is required. Mats made from rubber are resistant to hot solder, whereas a vinyl mat would melt. Compared to vinyl matting where the mats can change and become harder in cold conditions, rubber matting remains in its same form, staying stable; its ESD properties cannot change. Rubber mats are generally cheaper to manufacture. Therefore, they tend to be a cost-effective matting solution.
Anti static mats can be made from solid sheets, multiple layers and suspended particles, offering differing electrical performance. There are four common structures for vinyl and rubber mats:
Homogenous or solid mats are made of a single layer polymer mix and therefore consist of the same material throughout. These mats provide good mechanical service with electrical performance normally limited to about 10^(9) to 10^(10) RTG.
Three layer vinyl mats are constructed with a conductive metal/carbon inner layer that sits between a vinyl top surface and a foam backing. The conductive layer improves the electrical properties by acting as a fast track to move the static charge to ground. The foam back layer provides a cushioning effect, making it easier to pick up parts.
Two layer vinyl mats typically combine the foam used in three layer vinyl mats and dissipative vinyl from the solid mats. As they contain no metallised layers, they provide average electrical performance.
Two layer rubber mats, generally consisting of a static dissipative surface layer and a conductive backing, provide the same electrical performance as the three-layer vinyl mats. However, out of the two, the two layer rubber mats have a greater tolerance to heat and chemicals. This type of material does come with a cost premium.
ESD mats are used in environments that are electrostatically sensitive or where static electricity is a risk. This includes:
ESD mats are commonly used in static controlled areas where employees frequently interact with ESD-sensitive products; they are also necessary for employees who occasionally need to interact with these environments, such as back-office staff who sometimes need to access a cleanroom or manufacturing facility.
In cases where extended periods of standing are required, some ESD mats may incorporate “anti-fatigue” features, such as extra foam, to provide a more comfortable work environment.
1) The ESD Table Mat should be placed on your workbench when assembling general electronics. For workers who are doing electrical work or handling chemicals, ESD rubber mats are a good option. Static electricity is dissipated by the mat, which provides a route to the ground for static electricity buildup.
2) A ground snap is attached to your table mat to connect your ESD ground cord. Make sure the ring terminal of your ground cord is connected to a grounding receptacle nearby. You can accomplish this task by placing the outlet cover plate screw through the ring terminal.
3) Install your ESD wristband and insert the banana plug coil cord into the receptacle of the common point ground. The coil cord connects the wristband to the user. Wristbands are attached to the Ground Wire over the Coil Cord. With the coils, the wristbands can be easily moved.
4) Lay your floor mat before your workbench to prevent the buildup of static electricity. Static electricity builds up in the mat, which allows it to be discharged to the ground.
5) Connect the ground snap of your floor mat to the ground snap of your Low Profile ESD Ground Cord. The ring terminal must be connected to the grounding receptacle as described in step 2. To keep the shoes connected to the floor mat, wear ESD Heel Straps when standing on the ESD mat. If safety shoes are worn, the ESD heel straps need not be worn.
Bondline Electronics Ltd are a leading UK supplier of ESD control products since 1986. They specialise in providing the highest quality ESD consumables at competitive prices, including ESD matting.
Bondline offer an extensive range of ESD worktop mats and ESD floor mats, including:
And more…
If you are finding that you still require more guidance around ESD matting, we’d be happy to help you. Our team is always on hand to answer any technical questions you may have. We also offer guidance and advice across our full product range.
Please get in touch with a member of our team on +44 (0)1793 511000 or send us an email to sales@bondline.co.uk and we can direct you to the best person to speak to. For more information on ESD mats, take a look at our ESD matting guidebook.
On selected products if ordered before 1pm
Dedicated account manager to help your ordering process
Great value on premium quality products
