It is well understood that static electricity has been with us forever. Our awareness of problems associated with static electricity probably originated with the invention of gun powder when, no doubt, there were some mysterious ignitions that took place during chemical blending operations that could not be explained at the time.
The manifestation of static electricity problems in an industrial setting likely began with Gutenberg’s invention of the automatic printing press in 1440.1 Paper and velum (two different materials) sticking together had to be an issue. Somewhere along the line, it was likely observed that a fire burning in the vicinity of the printing press could magically make the paper less sticky. Flame treatment was used in industrial printing presses back then and in newspaper printing presses well into the 1950s, and perhaps even longer in some areas.
Static control has been practiced in munitions, modern pyrotechnics, petroleum processing, and other industries dealing with explosive and flammable materials for a long time. The grounding of process tools, equipment, and personnel has been practiced since Ben Franklin’s time.
The industry we are primarily dealing with today, electronics, did not report any significant static electricity-related issues until the later stages of the 1960s. Changes in the resistance values of some shipments of carbon resistors appear to be the first reported issue associated with static electricity in any electrical or electronic-related products. The development of metal-oxide-semiconductor (MOS) devices caused many issues in the early days of modern electronics manufacturing. Early advances in disk drive technology and the manufacture of read-write heads were almost brought to a stand-still in companies due to the fallout from static damage.
The Origins of Modern Static Control Efforts
Our review of the history of modern static control begins in the late 1960s. The first materials used for static control then were carbon-filled conductive plastics and organically treated plastics that created low charging materials (known as antistatic materials at the time). These materials were distinctly different in performance and application requirements. When these material types were used in combination for packaging electronic parts for storage and shipment, they made a highly effective static control packaging product. But this happened infrequently due to the competition between the companies that made these materials.
Grounding systems for people were already available, with innovators coming up with new concepts in wrist straps and shoe grounding devices. Varieties of these systems and concepts had been used for a long time in munitions and chemical processing facilities, but they were somewhat cumbersome and uncomfortable to use in the typical electronics assembly operation. The new designs were lighter in weight and easier to use, so they became the first line of static control in the growing electronics industry.
Special worksurfaces and flooring materials began to enter the marketplace in the middle 1970s and helped to establish what we know today as the electrostatic protective area or EPA. At about the same time, standards for military and defense-related applications entered the market, which helped support the development of industry specifications for the workplace and packaging materials. Damage to electronic parts was becoming a significant reliability issue in the later part of the 1970s. In fact, the first EOS/ESD Symposium was convened in Denver in 1979 to discuss the issues of the time, predominantly those dealing with military electronics.
Packaging innovations eventually led to the invention of transparent static shielding films used to make protective static discharge shielding bags. By the early 1980s, these film materials became ubiquitous throughout the electronics industry, and the need for further electronics packaging standardization become more obvious. In response, several industry groups emerged around that time. Leading the way was the Electronics Industry Association (EIA), which established the Packaging of Electronics for Shipment committee (PEPS). The EIA PEPS Committee ultimately drafted EIA-541–1988, Packing Material Standards for ESD Sensitive Items, the first commercial standard devoted to packaging materials used in the storage and shipment of ESD susceptible electronic devices.
The Role of the ESDA in Standards Development
The EOS/ESD Association, Inc. (ESDA) was formed in 1982, following the success of the initial EOS/ESD Symposiums. The founding members of the ESDA naively believed that the Association and its annual Symposium would be needed for just a few years, after which it could be disbanded. But this turned out not to be the case, and plans are now in the works for the 44th EOS/ESD Symposium, currently scheduled for September 2022.
The ESDA formed its own Standards Committee in 1982 and immediately started work on Standard #1, Wrist Straps, since that was viewed as the front line of protection at the time. That standard served as the foundation for the development of other standards, standard test methods, standard practices, and advisory documents over the ensuing 40 years that have helped establish specifications for most of the products used for static protection and mitigation. And the emergence of automated handling and assembly operations has required the development of new ESD control standards and test methods to manage static electricity developed within such equipment.
The period from the late 1980s to the late 1990s saw a massive amount of work in standardization. Just about all the static control products available today were the subject of some level of standards activity during that period. Over time, many of the ESDA’s standards, test methods, standard practices, and technical reports have been reviewed and revised several times since their original release. Today, the standards development effort within in the ESDA is still going strong, with the participation of 200 active members worldwide.
The Shifting Landscape of Static Control Efforts
During the same period, the electronics industry shifted major portions of its manufacturing activities to locations around the world. Large factories employing thousands of people for manual assembly operations were established. But there was a steep learning curve in efforts to produce high reliability in device fabrication (wafer fabs), circuit board assembly, and equipment assembly. Large offshore factories with huge numbers of employees required extensive training, massive installation of electrostatic protection products and materials, and frequent travel by corporate-based management and technical staff to oversee product control and maintain quality.
The development of local expertise to manage static control issues became a priority in the late 1990s to the early 2000s, and many of the current members of the ESD Association represent companies and operations from outside of the U.S. Arguably, the most far-reaching static control standards activity occurred in 1995 when the U.S. Department of Defense (DoD) formally asked the ESD Association to take the lead in the development of a new, state of the art, ESD control program standard for commercial and military users. That effort ultimately led to the introduction of ANSI/ESD S20.20–1999, Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices), which was quickly adopted by the DoD and several branches of the military.
Around 2000, DNV, an ISO 9001 Certification Body, proposed that the ESDA adopt a facilities audit program in connection with ANSI/ESD S20.20,
eventually leading to the ESD facility certification program. Today, there are several hundred certified facilities around the world. Other certification programs were developed subsequently to that initial effort, most notably the ESD Certified Professional Program Manager certification and the ESD TR53 Certified Technician certification.
The Emergence of Static Control Measurement Tools
As the electronics industry created standards and materials to control static electricity, measurement tools were needed to validate the materials and to evaluate the manufacturing processes. Original validation equipment typically consisted of a high resistance meter, called a megger, and an electrostatic field meter. The megger was designed for measuring the electrical system to ground (or insulation) resistance. The typical voltages first used for measurement were 500 to 1000 volts. As materials to control static electricity and the standards to measure them were further developed, resistance measurement voltages were revised to 10 and 100 volts to create more measurement sensitivity and to help ensure that the materials and products could perform their intended function in an EPA.
The evaluation of static control materials at low relative humidity also has become a requirement to make sure the product maintains its specifications and performance attributes at the lowest environmental moisture condition expected. Electrostatic voltmeters were developed along with a device called a charge plate monitor to measure ionization.
The Challenges of Automated Production
The emphasis today in comparison to the early days relates to automated electronics processing. It is well understood that personnel must be grounded all the time when handling unprotected susceptible items. The most significant change in the grounding of personnel has been the increased reliance on footwear and flooring. Wrist straps are still used by the millions every year since they are a requirement for seated operations in the ESD Control Program development standards ANSI/ESD S20.20 and IEC 61340-5-1, Electrostatics-Part 5-1: Protection of Electronic Devices from Electrostatic Phenomena – General Requirements.
Footwear and flooring test methods now have significant importance since mobile personnel are required to operate and maintain automated process equipment and assembly lines. The electrical resistance to ground and voltage of personnel while in motion are important considerations for the modern EPA. The instrumentation for measuring and recording voltage on people has become arguably the most essential tool in the ESD control practitioner’s toolbox.
Testing device susceptibility to ESD events has been the subject of standardization for well over 50 years. For a long time, separate industry standards existed for the evaluation of the human body model (HBM). Today, the HBM requirements and specifications have been harmonized into a single harmonized HBM standard through a joint effort between the JEDEC Solid State Technology Organization and the ESDA.2
Similarly, the susceptibility of devices during automated handling have been harmonized in a joint charged device model (CDM) standard.3 The ESD susceptibility test method known as machine model (MM) has been dropped as a device qualification standard since the damage mechanism is much the same as HBM, only at a lower threshold.
Over the last 5-8 years, there has been further development to connect device testing specifications and susceptibility levels to what happens in the factory during production. What is called process assessment has become one of the important activities of the ESDA standardization activity. The effort is providing test methods and techniques for the evaluation of electrostatic charging and ESD events within automated handling equipment. One technical report is now available,4 and a standard practice5 was released in 2021.
These documents, along with new measurement tools such as the high impedance contact voltmeter and event detector devices, will provide knowledgeable practitioners with valuable tools and insight for the evaluation of automated handling equipment capabilities. The question “What device sensitivity/susceptibility level can my process handle?” will be easier to answer using the new documents and new tools.
Conclusion
The physics of electrostatics has not changed over the decades, but the ability to measure and protect from the phenomenon certainly has. Materials science and innovation have led to vast improvements in products used to control static electricity in the workplace. ESD standards and test methods have brought a level of understanding into an area that was once considered black magic.
Endnotes
- Childress, Diana, Johannes Gutenberg and the Printing Press, Minneapolis: Twenty-First Century Books, 2008
- ESDA/JEDEC Joint Standard – For Electrostatic Discharge Sensitivity Testing – Human Body Model (HBM) Device Level, ESD Association, 7900 Turin Road, Bld. 3, Rome, NY 13440, 315-339-6937, http://www.esda.org
- ESDA/JEDEC Joint Standard – For Electrostatic Discharge Sensitivity Testing – Charged Device Model (CDM) Device Level, ibid ESD TR17.0-01-14 ESD Association Technical Report – For Electrostatic Discharge Process Assessment Methodologies in Electronic Production Lines – Best Practices Used in Industry
- ESD Association Standard Practice – For the Protection of Electrostatic Discharge Susceptible Items – Process Assessment Techniques, ibid (not published at time of this writing but coming soon)
David Swenson has been a member of the ESD Association since 1984 and has served in several key Association leadership positions over his long career. He has received numerous Association and industry awards for his work, most recently the EOS/ESD Symposium David F. Barber Sr. Memorial Award in 2018. Swenson is also the convener of Joint Working Group 13 between TC101 and TC40 (Capacitors and Resistors).
John Kinnear is an IBM senior engineer specializing in process and system technology, and facility certification in accordance with ANSI/ESD S20.20. He has been a member of the ESDA for more than 30 years. Kinnear also serves as the appointed technical advisor to the U.S. National Committee/IEC technical committee 101, where he works to support the international adoption of ANSI/ESD S20.20.
