ESD Control Guide
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Introduction
Many electronic components and assemblies used in high technology products can be damaged or degraded by the sudden exchange of static electrical charges. This Electrostatic Discharge, or ESD, is the reason industries handling susceptible electronic components must take steps to minimise ESD risk.
As industry experts, we offer an extensive selection of Electrostatic discharge control equipment for any workplace environment. Brands range from RS Pro, our high quality, professionally approved own range, to SCS, Charleswater, Menda, EMIT, Electrolube, Vermason and other market-leading brands.
Sections in this guide
Causes and Risks of ESD
When two items are at different levels of electrostatic charge, i.e. one positively and one negatively charged, they will want to come into balance. If the items are in close enough proximity there can be a rapid, spontaneous transfer of electrostatic charge from one to the other. This is called Electrostatic Discharge or ESD.
As electronic technology advances, electronic circuitry gets progressively smaller. As the size of components is reduced, so is the microscopic spacing of insulators and circuits within them. Their sensitivity to ESD is increased.
This sensitivity means circuitry can be more easily damaged by the simple action of touching the product after moving across a room or workshop.
Static charge can build up on a person as explained below.
In dry air conditions, certain flooring materials are particularly susceptible to the build up of static charge. Flooring construction and its electrical resistance also play a part.
Risks of ESD
ESD is the hidden enemy in a high-tech manufacturing environment. Modern electronic circuitry can be burned or melted when subject to an ESD event which is, in effect, a miniature lightning bolt.
Two types of risk to electronic equipment can occur:
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Catastrophic failure Catastrophic failure causes a permanent fault. The ESD event may have caused a metal melt, junction breakdown or oxide failure. Normal inspection is able to detect a catastrophic failure. |
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Latent defect A latent defect is linked to an ESD event that causes partial degradation. This defect may not be detected by normal inspection and the device can continue to perform as it should. The defect can then cause intermittent or permanent failure at a later time. |
ESD Standards
EN 61340 Part 5-1: Protection of electronic devices from electrostatic phenomena is the standard most companies use to build their ESD control plan.
The standard uses a Human Body Model to simulate discharges from a person and increasingly tests an electronic device at higher and higher discharges until it fails. This establishes the device's withstand voltage.
ESD Sensitive Components
The electronic components in the chart below can be damaged by the electrostatic voltages shown.
| ESD Class | Voltage Rating (V) | Device Names |
|---|---|---|
| Class 0 | 0 to 99 | SAW, JFETS, CCDs, Precision voltage regulator diodes, OP AMP, Thin film resistors, Integrated circuits, Hybrids utilizing class 1 parts, VHSI, CSCRs. |
| Class 1 | 200 to 1,999 | SAW, JFETS, CCDs, Precision voltage regulator diodes, OP AMP, Thin film resistors, Integrated circuits, Hybrids utilizing class 1 parts, VHSI, CSCRs. |
| Class 2 | 2,000 to 3,999 | JFETs, Ics, VHSIC, Precision resistor networks (type RZ), Hybrids utilizing class 2 parts, Low power bipolar transistors. |
| Class 3 | 4,000 to 15,999 | JFETS, OP AMPS, Ics, All other microcircuits not included in class 1 or 2, Small signal diodes, General purpose silicon rectifiers, Opto-electronic devices (LEDs, phototransformers, opto couplers), Resistor chips, Piezo electric crystals, Hybrids using Class 3 parts. |
ESD Control Plan
How to set up an ESD control plan in your company
Any business working with ESD sensitive items should set up ESD prevention and control measures in the form of a Control plan, according to EN 61340 Part 5-1.
Every company will have different processes so each will require its own plan. Steps to set up your Control plan are as follows:
Hover over the steps to begin creating your own ESD Control Plan.
1Define what you are trying to protect
Identify any ESD susceptible items that your company handles. Treat any device that you receive in ESD packaging as a susceptible item.
2Become familiar with the industry standards for ESD control
Read BS EN 61340-5-1 for guidance if you manufacture, process, assemble, install, package, label, service, test, inspect, transport or handle susceptible items.
3Select a grounding/equipotential bonding system
Eliminate differences in potential in your ESD protected area by connecting ESD control elements and personnel to a protective earth, functional earth or an equipotential bonding system.
4Determine a personnel grounding method for operators
Seated operators must use a wrist strap, however standing workers can use a foot grounding system. In some cases both grounding methods will be used.
5Establish and identify your ESD Protected Area (EPA)
Define all departments which will be EPAs. Identify and control access using signs, floor marking and access control measures.
6Select ESD control products to use in your EPA
Consider products such as work surfaces, flooring, seating, ionisation, shelving, trolleys and clothing.
7Develop a Packaging plan for materials handling and storage
When moving ESD susceptible devices outside a protected area, what packaging will you use?
8Use proper markings for ESD susceptible items, system or packaging
9Implement a Compliance Verification plan
Document the steps you will take to review, verify, analyse, evaluate and improve your ESD programme. Compliance verification records should be kept.
10Develop a Training plan
Your training plan should specify how personnel who handle or contact ESD sensitive items will undergo training in ESD awareness and prevention.
11Make the ESD Control plan part of your internal quality system
Your ESD control plan should include a list of ESD control items used in the EPA, the Compliance Verification plan and the Training plan.
ESD Product Selection Guide
Click to expand and read about the key considerations for each control selection.
ESD Packaging, Storage & StationeryView products
ESD Packaging, Storage & Stationery - For transport outside an ESD Protected Area (EPA), protection is achieved by enveloping the device in a material with a shielding layer, such as a shielding bag. The envelope is frequently referred to as having the effect of a Faraday Cage. An ESD packaging material will also often provide mechanical protection or protection against contamination by dust or humidity (e.g. moisture barrier or shielding bubble bags).
When storing products inside an EPA (on grounded surfaces), use conductive bags or containers to store your ESD sensitive items. Conductive materials have a low electrical resistance so electrons flow easily across the surface. Charges will go to ground if bags or containers are handled by a grounded operator or are stored on a grounded surface.
ESD-Safe Cabinets, Drawers & InsertsESD Testing & Monitoring EquipmentView products
ESD Testing & Monitoring Equipment - Our testing and monitoring range consists of three equipment types. Test meters comprise a group of units for testing the integrity of ESD control products, from Surface Resistivity testers to Wristband testers.
Continuous monitors eliminate time spent carrying out frequent integrity checks, as ESD integrity is monitored continuously through the day. Testers and auditors covers products used to confirm the accuracy of test meters.
Testing and monitoring can be viewed as two distinct families: personnel testing and EPA (ESD Protected Area) testing.
The personnel testing family offers a choice of wrist strap and/or footwear testers or test stations, for testing personnel grounding systems before entering an EPA. Other testers are designed for use inside the EPA to test resistances in-situ. This helps reduce queues at the test station at the beginning of a shift. They can also be used to monitor personnel grounding on a continuous basis (continuous monitors).
The EPA testing family consist of equipment to measure electrical resistance and electrostatic fields. Resistance meters are used to qualify an EPA whereas electrostatic field meters help locate electrostatic charges, identify insulative materials or serve to balance ionisers.
ESD Testing and monitoring equipmentIonisers View products
Ionisers - Bench top ionisers benefit from the ability to be moved easily between workstations. However, care should be taken to ensure that items normally on the bench will not obstruct the flow of ionised air.
Overhead ionisation was established to solve the problem of items on a bench blocking the flow of ionised air. In addition, the downward airflow is more consistent over the entire bench. Overhead ionisers are ideal for areas where bench space is limited.
Forced air ionisers use compressed air or nitrogen to neutralise static charges in localised areas – they are a quick point-and-shoot option.
The main advantage of this type is the ability to provide a strong air blast to help dislodge contamination, while the ionisation in the air stream eliminates the static attraction of the particles at the same time.
IonisersESD Personal Grounding & ESD Clothing View products
ESD Personal Grounding & ESD Clothing - For people who work mainly sitting down, grounding is best achieved with the use of a wristband connected to an extendible coiled cord, also known as wrist strap. It, in turn, is connected to an earth bonding point (EBP) or continuous monitor.
ESD gloves allow any charges to travel to ground through the wearer. They protect the hands from sharp edges and they protect components and assemblies from body oils and perspiration.
Foot grounders or conductive shoes are used for earthing mobile personnel. This personnel grounding method can only function when used in conjunction with suitable ESD flooring.
Garments are used to control electronic charges generated by personnel working in EPAs. They form a conductive grid around the upper body so that any electrostatic fields are held within the garment.
ESD Grounding Wrist Straps & Cord SetsESD Matting View products
ESD Matting - For electronics manufacturing, the ESD Standard recommends a resistance to ground (RG) for working surface matting of 1 x 104 to less than 1 x 109 ohms. The bench mat needs to be grounded using a ground wire from the surface connecting to the common point ground which in return is linked to ground, preferably equipment ground. Best practice is that ground connections use firm fitting connecting devices such as metallic crimps, snaps and banana plugs to connect to designated ground points. The use of alligator clips is not recommended.
ESD floor matting is an integral part of a flooring / footwear system which is a personnel grounding alternative for standing or mobile workers. Any static charges will quickly and effectively drain through the foot grounders or shoes and ESD floor to Ground. The ESD Standard requires the resistance of the person/footwear/flooring to be less than 3,5 x 107 ohms (resistance in series of operator plus footwear plus floor). It is therefore recommended to use conductive flooring (RG < 1 x 106 ohms) as the resistance can increase with dirt.
ESD-Safe MatsESD Field Service View products
ESD Field Service - Utilising equipotential bonding and a common point ground system for connecting static control elements including operator, worksurface and equipment, field service kits are manufactured from low charging materials that limit charge generation. When properly connected, the field service kit mat will share the charge from conductive objects when they are placed on the surface.
Vacuums are designed for precise removal and collection of dry dust particles and debris from electrostatic sensitive devices.
ESD-Safe Field KitsESD Furniture View products
ESD Furniture - Chairs and workbenches explicitly designed for use in the electronics industry will prevent the build up of static by dissipating it safely to earth. ESD-safe seating will often have castors constructed of a dissipative or conductive material, enabling charge to be safely removed.
Take this into account when selecting suitable furniture for your ESD protected area, as well as the weight and size of items you will be handling or transporting.
ESD-safe trolleys should be used to transport sensitive components and our models conform to EN 61340 Part 5-1: Protection of electronic devices from electrostatic phenomena.
As static can build up anywhere on a work bench, all working surfaces of a bench should be static dissipative. That way electronics assemblies and tools can be placed anywhere without risk. If tools are placed on a non-ESD dissipative surface, attract static, and used to work on an electronics assembly, the chances of damage will rise.
Work Benches & Work TopsESD Grounding Accessories, Brushes and Probes View products
ESD Grounding Accessories, Brushes and Probes - Earth bonding point plugs or bars should be installed at each workstation and should be connected directly to a verified electrical system ground or to a verified grounding bus which is connected to the protective earth ground. Only one groundable point should be installed on a working surface. Both surfaces and wrist straps can be grounded via an Earth bonding point plug or bar.
Straight cords are used to connect fixed elements in an EPA to ground.
Various studs, snaps and kits are available to create earth grounding points on bench and floor mats which connect ground cords. The connectors must be riveted through all layers of a mat.
ESD Grounding AccessoriesESD Treatments, Lotions & Dispensers View products
ESD Treatments, Lotions & Dispensers - Operators working with soldering irons or performing cleaning tasks at their ESD workstation will be using water or some sort of cleaning agent. ESD dissipative dispensers have ESD properties embedded in the bottle and are safe to use inside an EPA.
ESD-Safe & Clean Room Treatments, Lotions & DispensersESD Labels & Posters View products
ESD Labels & Posters - The best known ESD cautionary symbol consists of a yellow hand in the act of reaching, deleted by a bar; all within a black triangle.
The 'susceptibility' symbol is intended to identify devices and assemblies that are susceptible to ESD. ESD labels using the 'susceptibility logo are used as follows:
ESD labels using the 'protection' symbol should appear on ESD protective products such as shielding bags and boxes as well as on portable items such as field service mats, trolleys and garments.
The letter underneath indicates the primary function of the item:
Every EPA needs to be identified as such. Signs and posters are designed to attract attention and deliver a clear message to personnel and visitors.
ESD Labels & PostersTechnologies we offer
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