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Author:Some Material: 2013, EOS/ESD Association, Inc., Rome, NYImages: 2016 VARIOUS AUTHORS


WHAT IS ESD?Electrostatic discharge is the rapid movement of a charge from one object to another object.As you walk across the carpet, you may not realize that you are generating several thousand volts of electrical charge that will cause severe damage to electronic components or entire circuit card assemblies. This shock, or release of energy, is what is known asElectrostatic Dischargeor anESD Event.

When your finger comes close to a door knob or your computer screen, you may feel a slight shock.

You may not realize it, but every time that you touch an electronic piece of equipment, you may feel nothing, but a sensitive electronic component could either be destroyed or become unstable.Sometimes the results of anESD Eventwill not show up for weeks or even months in electrical components.Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge


Static electricity is a charge at rest. Static charges are caused by surfaces separating, friction, and movement of materials against surfaces (such as a shoe brushing against the floor). Nearly any time two materials are rubbed together there is anelectric charge.Picking up a circuit board from a table, or our clothing rubbing as we walk, sit and work, are all examples of movement that can create static charge. One object, or surface, picks up additional electrons from the surface that it is separated from, and becomes negatively charged. The surface that had given up the electrons then becomes positively charged. As electrons transfer, the absence or surplus of electrons creates an electrical field known asstatic electricity.

Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge


Static chargesaccumulate on the surface ofconductors- the skin of a person, the surface of a conductive tote box, and anInsulative surface- practically all plastics and textiles. Both conductors and insulators may become charged with static electricity.These static charges "stay put". They cannot move because there is not path to ground. The charge is called "static" - not moving. A static charge will stay in place on the surface of an object until it has a chance to move. When a non-grounded conductor of static charges, a person or an object, comes close to a ground plane, the charge will "jump" from, a point on the non-grounded conductor to the grounded object, causing anESD event.As you walk across the carpet and touch a metal door knob, the electrostatic charge that is built up on your body is discharged through the doorknob.A charged object is surrounded by an electrostatic field. A charge from an electrostatically charged object can charge a component without actually touching the component. It may "jump" from the conductor to the electronic component from several feet away.This process is known as induction.When a charged insulator comes close to a conductive object, the charge can be induced onto the conductor, which can then rapidly discharge to other conductors - an ESD event.Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge

Copyright 2016 Micki Delaney. All rights reserved.INTRO| 5THE COST OF ESD

TRAININGESD Electrostatic DischargeElectrostatic discharge (ESD) costs the electronics industry millions of dollars annually in damaged and degraded parts. A study in Semiconductor Reliability News estimated that approximately 60% of device failures are EOS/ESD caused.To many people, Electrostatic Discharge (ESD) is only experienced as a shock when touching a metal doorknob after walking across a carpeted floor or after sliding across a car seat. However, static electricity and ESD has been a serious industrial problem for centuries.Despite a great deal of effort during the past thirty years, ESD still affects production yields, manufacturing cost, product quality, product reliability, and profitability. The cost of damaged devices themselves ranges from only a few cents for a simple diode to thousands of dollars for complex integrated circuit


Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge

2013, EOS/ESD Association, Inc., Rome, NYControlling electrostatic discharge (ESD) in the electronics manufacturing environment is a formidable challenge. However, the task of designing and implementing ESD control programs becomes less complex if we focus on just six basic principles of static control. In doing so, we also need to keep in mind the ESD corollary to Murphys law, no matter what we do, static charge will try to find a way to discharge.1.0DESIGN IN PROTECTIONThe first principle is to design products and assemblies to be as resistant as reasonable from the effects of ESD. This involves such steps as using less static sensitive devices or providing appropriate input protection on devices, boards, assemblies, and equipment. For engineers and designers, the paradox is that advancing product technology requires smaller and more complex geometries that often are more susceptible to ESD. The Industry Council on ESD Target Levels and the ESD Associations Electrostatic Discharge (ESD) Technology Roadmap, revised April 2010, suggest that designers will have less ability to provide the protection levels that were available in the past. Consequently, the ESD target levels are reduced to 1000 volts for Human Body Model robustness and 250 volts for robustness against the Charged Device Model, with tendency to reduce these values further. Those target values are considered to be realistic and safe levels for manufacturing and handling of todays products using basic ESD control methods as described in international industry standards as e.g. ANSI/ESD S20.20 or IEC 61340-5-1. When devices with lower ESD target levels must be used and handled, application-specific controls beyond the principles described here may be required.2.0DEFINE LEVEL OF CONTROL NEEDEDWhat is the most sensitive or ESD susceptible ESDS you are using and what is the classification of withstand voltage of the products that you are manufacturing and shipping? In order to get an idea of what is required, it is best to know the Human-Body Model (HBM) and Charged-Device Model (CDM) sensitivity levels for all devices that will be handled in the manufacturing environment. ANSI/ESD S20.20 and IEC 61350-5-1, both published in 2007, define control program requirements for items that are sensitive to 100 volts HBM; future version of those standards will most likely address also items that are sensitive to 200 volts CDM. With documentation, both standards allows requirements to be tailored as appropriate for specific situations.


Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge

3.0IDENTIFY & DEFINE ELCTROSTATIC PROTECTED AREAS (EPAs)Per Glossary ESD ADV1.0 an ESD protected area is A defined location with the necessary materials, tools and equipment capable of controlling static electricity to a level that minimizes damage to ESD susceptible items. These are the areas in which you will be handling ESD sensitive items and the areas in which you will need to implement the basic ESD control procedures including bonding or electrically connecting all conductive and dissipative materials, including personnel, to a known common ground.

EPA AREA 2013, EOS/ESD Association, Inc., Rome, NY


Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge

4.0REDUCE ELECTROSTATIC CHARGE GENERATIONIf projections of ESD sensitivity are correct, ESD protection measures in product design will be increasingly less effective in minimizing ESD losses. The fourth principle of control is to reduce electrostatic charge generation and accumulation in the first place. Its fairly basic: no charge no discharge. We begin by eliminating as many static charge generating processes or materials, specifically high-charging insulators such as common plastics, as possible from the EPA work environment. We keep conductive/dissipative materials at the same electrostatic potential using equipotential bonding or attaching to equipment ground. Electrostatic discharge does not occur between materials kept at the same potential. In the EPA, ESD control items should be used in place of more common factory products such as worksurface mats, flooring, smocks, etc. which are to be attached to ground to reduce charge generation and accumulation. Personnel are grounded via wrist straps or a flooring/footwear system. While the basic principle of controlling static electricity to a level that minimizes damage should be followed, complete removal of charge generation is not achievable.

2013, EOS/ESD Association, Inc., Rome, NY


Copyright 2016 Micki Delaney. All rights reserved.TRAININGESD Electrostatic Discharge

5.0DISSIPATE & NEUTRALIZEBecause we simply cant eliminate all generation of electrostatic charge in the EPA, our fifth principle is to safely dissipate or neutralize those electrostatic charges that do occur. Proper grounding and the use of conductive or dissipative materials play major roles. For example, personnel starting work may have a charge on their body; they can have that charge removed by attachment to a wrist strap or when they step on ESD flooring while wearing ESD control footwear. The charge goes to ground rather than being discharged into a sensitive part. To prevent damaging a charged device, the magni