The Role of ESD
In ordinary circumstances, static electricity is little more than an annoyance. However, in an increasingly technological and integrated age, that familiar static shock we receive when walking across a carpet can be costly or even dangerous. This same static shock, referred to as electrostatic discharge (ESD), can ignite flammable mixtures and damage electronic components. Static electricity can also attract contaminants in clean environments or cause products to stick together.
ESD and ESD damage play a role in many of today’s industries as technology becomes more complex and vital. The cost of ESD-damaged electronic devices alone ranges from only a few cents for a simple diode to several hundred dollars for complex hybrids. Loss of production time in web processing industries due to static attraction is significant. When associated costs of repair and rework, shipping, labor, and overhead are included, the opportunities for significant improvements in reducing losses to ESD and static electricity become evident.
According to industry experts, “ESD control, other than a dramatic increase in sales, is the single most profitable opportunity for industry under today’s economic conditions. Independent consultants have found that ESD costs the average electronics manufacturer 4 to 8 percent of total annual corporate revenue.”1 Also “internal studies in telecommunications and other electronic firms have revealed losses equal to, or in excess of, 10 percent of annual revenues. At an estimated average impact of 6.5 percent of revenues, this means that the international electronics industry is losing in excess of $84 billion (USD) every year based on production data from 1997 through 2001.”1 According to the Electrostatic Discharge (ESD) Technology Roadmap, produced by EOS/ESD Association, the devices of today and in the future will be more sensitive to ESD than those used from 1997 to 2001. Indeed, since the mid-90’s, ESD immunity levels of electronic devices have steadily declined. By 2020, it is estimated that device sensitivities will be below 125V CDM for the most sensitive devices.2
What is ESD?
Static electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material. This imbalance of electrons produces an electric field that can be measured and that can influence other objects even at a distance. Electrostatic discharge is defined as the transfer of charge between bodies at different electrical potentials.
Electrostatic charge is most commonly created by the contact and separation of two materials. For example, a person walking across the floor generates static electricity as shoe soles contact and then separate from the floor surface. In the same manner, an electronic device sliding into or out of a bag, magazine, or tube generates an electrostatic charge as the device’s housing and metal leads make multiple contacts and separations with the surface of the container. While the magnitude of electrostatic charge may be different in these two examples, static electricity is generated in both situations.
Just as the circumstances and objects in the above examples differ, so do the results. The first example may end in the person experiencing a small shock when they reach the door and touch a metal door knob. In the second situation, however, the outcome can be far more lasting. Electrostatic discharge can change the electrical characteristics of a semiconductor device, degrading or destroying it. Electrostatic discharge also may upset the normal operation of an electronic system, causing equipment malfunction or failure.
Another problem caused by static electricity occurs in cleanrooms. Charged surfaces can attract and hold contaminants, making removal from the environment difficult. When attracted to the surface of a silicon wafer or a device’s electrical circuitry, these particulates can cause random wafer defects and reduce product yields.
Electrostatic damage to electronic devices can occur at any point from manufacture to field service. Devices handled in uncontrolled surroundings or with poor ESD control practices can experience damage.
ESD damage can occur as either a catastrophic failure or a latent defect. Catastrophic failure is defined as a device’s circuitry being permanently damaged causing the device to fail. The ESD event may have caused a metal melt, junction breakdown, or oxide failure. Catastrophic failures usually can be detected when the device is tested before shipment. If, however, the ESD event occurs after testing, the damage will go undetected until the device fails in operation.
A latent defect is more difficult to identify. A device that is exposed to an ESD event may be partially degraded, yet continue to perform its intended function. However, the operating life of the device may be reduced dramatically. A product or system incorporating devices with latent defects may experience premature failure after the user places them in service. Such failures are usually costly to repair and, in some applications, may create personnel hazards.
As early as the 1400s, European and Caribbean forts were using ESD control procedures and devices to prevent ESD ignition of black powder stores. By the 1860s, paper mills throughout the United States employed ESD control measures such as basic grounding of equipment and steam drums, ionization techniques, and other creative means to dissipate static electricity.
The age of electronics brought with it new problems associated with static electricity and electrostatic discharge. Electronic devices became smaller and faster and their sensitivity to ESD increased. Today, ESD impacts productivity and product reliability in virtually every aspect of the electronics environment. Many aspects of ESD control in the electronics industry also apply in other industries, such as cleanroom applications, graphic arts, textiles, plastic, and fuel refining.
How to Control ESD
Controlling ESD in the electronics environment can appear to be a formidable challenge. However, the task of designing and implementing ESD control programs can be simplified with knowledge and understanding. Essentially, one must assess the existing process and the threat that ESD possess, then evaluate and select appropriate ESD control measures.
The following steps are essential to an effective ESD control program:
Understand the specific manufacturing process thoroughly
Hire or train personnel who understand the process and have ESD expertise
Select and implement ESD controls that meet the specific needs of the process and the devices being handled.1
How EOS/ESD Association, Inc. Can Help
As the forerunner in ESD standards and specifications development, the EOS/ESD Association
provides the guidance companies need to establish ESD control programs. The EOS/ESD Association is an internationally recognized, American National Standards Institute (ANSI) accredited standards development organization and has published over sixty documents covering electrostatic discharge in the electronics environment. EOS/ESD Association, Inc. standards cover test methodologies for evaluating ESD control materials and the ESD sensitivity of electronic components. Test methods are consolidated into complete ESD control programs. By harmonizing the requirements and test methods for ESD control, the EOS/ESD Association is creating a common methodology for industry and military users. More than 150 volunteers work on standards projects, including cooperative efforts with U.S. military agencies and governmental units, and European standards development bodies. These volunteers work to define effective standards and guidelines applicable to the electronics industry. The EOS/ESD Association helps meet the above goals of establishing effective ESD control programs through:
Education—increasing the pool of qualified ESD professionals by offering a wide range of education available internationally, from initial ESD training through maintaining skills with up-to-date research.
Certification—providing the educational opportunities for personnel to become proficient in the problems and solutions related to ESD. Qualified certification facilitates standardization of necessary ESD control skills.
Standards—developing standards that deal with each facet of the ESD issue with nearly 20 working groups who, as part of EOS/ESD Association Standards Committee, work year-round to update and create new standards and technical documentation in areas that include workstations, garments, transient latch-up, floor materials, packaging, ionization, and the human body model.
Research—providing support documents such as technical reports and advisory documents to help ensure understanding and effective use of association standards.
Standards provide guidance, help eliminate confusion, and promote the development of effective ESD control programs. Standards aid in program development by
Helping to develop, implement, audit, and certify ESD control programs
Defining the sensitivity of the products manufactured and used
Defining the performance requirements for various ESD control materials, instruments, and tools
Providing a means of objective evaluation and comparison among competitive ESD control products
Reducing marketplace confusion in the manufacture, evaluation, and selection of ESD control products and programs
Reducing conflicts and enhancing understanding between users and suppliers of ESD control products.
S20.20: Electrostatic Discharge Control Program Standard
The standard ANSI/ESD S20.20-2014 Electrostatic Discharge Control Program for Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) encompasses the basic principles of ESD control.3 Proven as an effective standard, ANSI/ESD S20.20-2014 was adopted for use by the US Department of Defense and has become the worldwide standard of choice for developing and implementing an ESD control program. ANSI/ESD S20.20-2014 covers the requirements necessary to design, establish, implement, and maintain an ESD control program to protect electrical or electronic parts, assemblies, and equipment susceptible to ESD damage from human body model (HBM) discharges greater than or equal to 100 V.
Each year EOS/ESD Association holds the EOS/ESD Symposium, an international technical forum that features the latest research and technology presented by industry professionals from around the globe. Symposium is the world’s premier event for ESD education and provides basic, intermediate, and advanced tutorials. To further facilitate education and the exchange of ideas, symposium offers workshops set up as interactive sessions for in-depth discussions. Symposium exhibits of ESD control products and services bring together a diverse selection of ESD technology and solutions. The Symposium also brings together leading device technical exerts to share knowledge of IC chip protection methods and solutions to counter the very advanced emerging technology developments that are leading to highly sensitive electronic product applications and thus in-turn requiring development of sophisticated programs like S20.20.
Education and Certification
A key proponent in a successful ESD control program is qualified and knowledgeable personnel. To effectively control ESD damage, employees must understand both the particular process of production and ESD. Through education and certification, the EOS/ESD Association provides, employers can be more confident in the qualifications of their employees. Just as standards help to reduce confusion, so does certification help ensure qualified ESD professionals.
Using ANSI/ESD S20.20-2014 as its foundation, EOS/ ESD Association, Inc. trains and certifies qualified certification bodies to perform detailed facility audits and confirm ESD control program effectiveness. Acceptable programs receive ANSI/ESD S20.20-2014 certification from the EOS/ESD Association approved certification bodies. The ESD facility certification audit focuses on the key elements of an ESD program: documentation, training, ESD control element selection and function, purchasing (ESD related contracts), calibration, nonconforming product, and documentation control. An ESD program that is certified as complying with ANSI/ESD S20.20-2014 provides an assurance that is passed on to customers.
ESD Control Benefits
ESD is a very real and costly problem that needs to be treated as a priority for the sake of product and process quality and customer and workplace safety and satisfaction. ESD control measures can provide returns that are hundreds to possibly thousands of times the original investment.1 According to industry experts, ESD losses are often budgeted. “If these budgeted ESD related costs are reduced by 80 percent, the average organization can add approximately 5 percent to their bottom line.”
At the outset the problems related to ESD can seem overwhelming and establishing ESD control measures appears to be a daunting task. However, EOS/ESD Association exists to define the dangers and solutions to ESD. Through standards research and education opportunities, EOS/ESD Association, Inc. has already set groundwork to guide the successful implementation of ESD control measures in nearly all areas of industry.