From ESD It’s hardly front-page news that change is a dominant force in today’s electronics industry. Economic pressures, higher density devices, new technologies, and increasing reliance on out-sourcing are only a few of the indicators of change. When change is accompanied by today’s stagnant economy, the double whammy intensifies the pressure to reduce product losses caused by electrostatic discharge (ESD).
By some accounts, electrostatic discharge (ESD) control may provide the largest potential profit opportunity available to the electronics industry. Independent consultants have claimed that ESD costs the average electronic manufacturer 4 to 8 percent of total annual corporate revenues, depending on product designs and device sensitivity. With an estimated average negative impact of 6.5 percent of revenues, this means the international electronics industry is losing in excess of $84 billion (USD) every year based on 1997-2001 production data.[1]
As companies face the complex challenge of reducing ESD losses, they look for legitimate ways to evaluate and compare competing brands and types of products. They need objective confirmation that their ESD control program provides effective solutions to their unique ESD problems. Contract manufacturers and OEMs require mutually agreed-upon ESD control programs that reduce duplication of process controls.
That’s where ESD standards come into play, playing an ever-increasing role in reducing marketplace confusion in the manufacture, evaluation, and selection of ESD control products and programs. They help define the ESD sensitivity of the products manufactured and used and the performance requirements for various ESD control materials, instruments, and tools. They provide guidance in developing programs that effectively address ESD process control. And, as the industry and its needs change, ESD standards also undergo transformation and refinement.
Who uses standards and why? Who uses ESD standards? The list is quite broad: manufacturers, purchasers, and users of ESD sensitive devices and products; manufacturers and distributors of ESD control products; certification registrars; and third party testers of ESD control products.
Why use ESD standards? The reasons are numerous:
In the United States, the use of ESD standards continues to be voluntary. However, their use can be written into contracts or purchasing agreements between buyer and seller. In much of the rest of the world, the use of standards, where they exist, is compulsory.
Types Of Standards As recently as 1990, there were relatively few reliable ESD standards and many of them were developed for applications other than electronics. In this new century, the landscape has changed significantly with an increasing number of ESD standards developed specifically for the electronics industry.
ESD Association standards can be categorized into four main groups:
1. Standards (S): Precise statements of a set of requirements to be satisfied by a material, product, system or process that also specifies the procedures for determining whether each of the requirements is satisfied. These include documents providing ESD program guidance or requirements. Two examples of Standards documents would be ANSI/ESD S20.20-1999 Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices); ANSI/ESD S6.1-1999 Grounding—Recommended Practice and ANSI/ESD S1.1-1998 Wrist Straps.
2. Standard Test Methods (STM): Definitive procedures for the identification, measurement, and evaluation of one or more qualities, characteristics, or properties of a material, product, system or process that yields a reproducible test result. Standard test methods include documents such as ESD STM5.1-2001 Device Testing—Human Body Model (HBM) Component Level and ESD STM7.1-2001 Resistive Characterization of Materials—Floor Materials.
3. Standard Practices (SP): A standard practice contains procedures similar to those found in a standard test method with one difference. The procedure is not sufficiently developed to ensure that two labs will get the same result when the procedure is followed. In many cases, a document is released as a Standard Practice so that industry can start to use it. The working group that issued the standard practice continues their efforts to make the test method repeatable and reproducible with the goal of eventually elevating the document to a standard test method.
4. Technical Reports (TR): Collections of technical data or test results published as an informational reference on a specific material, product, system, or process. A good example is TR20.20. This document is a companion publication to ANSI/ESD S20.20-1999 and provides detailed, background information on the requirements of the standard as well as a wealth of information on ESD control issues.
Tables 1 and 2 provide a listing of ESD Association standards and advisory documents.
Who are the primary standards developers? Although there are a number of organizations such as IEST (Institute of Environmental Sciences and Technology) , IDEMA (International Disk Drive Equipment and Materials Association), and JEDEC (JEDEC Solid State Technology Association, formerly the Joint Electron Device Engineering Council) involved in ESD standards development, the ESD Association has become the focal point for the development of ESD standards in recent years. An ANSI-accredited standards development organization, the Association is charged with the development of ESD standards and test methods. The association also represents the United States on the International Electrotechnical Commission’s Technical Committee 101-Electrostatics. The ESD Association has published 27 standards documents and 16 technical reports covering material and program requirements, electrostatic sensitivity, and test methodology for evaluating ESD control materials and products.
In the past, the U.S. military spearheaded the development of specific standards and specifications with regard to ESD control in the United States. Today, however, U.S. military agencies are taking a less proactive approach, relying on commercially developed standards rather than developing standards themselves.
The international community, led by the International Electrotechnical Commission (IEC), has also taken an active role in standards development. Europe’s CENELEC has issued a European electrostatic standard, EN 61340-5-1 Protection of Electronic Devices from Electrostatic Phenomena—General Requirements that was adopted as a European Norm.
Trends In Standards Development: Organizational Cooperation Perhaps one of the more intriguing trends in ESD standards development has been the increasing organizational cooperation between various groups. One such cooperative effort occurred between the ESD Association and the U.S. Department of Defense, which resulted in the association preparing ANSI/ESD S20.20, a standard that has been adopted by the Department of Defense as a successor to MIL-STD-1686.
Similarly, the ESD Association recently completed work on a new packaging standard as a replacement for EIA 541-1988. The new document, ANSI/ESD S541-2003: Packaging Materials for ESD Sensitive Items, was approved as a full standard in February of 2003.
Internationally, European standards development organizations and the ESD Association have developed working relationships that result in an expanded review of proposed documents, greater input, and closer harmonization of standards that impact the international electronics community. The IEC and the ESD Association are now working together to more closely align and harmonize the IEC and European standards with S20.20.
For users of ESD standards, this increased cooperation will have a significant impact. First, we should see standards that are technically improved due to broader input. Second, we should see fewer conflicts between different standards. Finally, we should see less duplication of effort.
Trends In Standards Development: New And Updated Documents A second major trend in standards development is the continuing process of creating new standards and the fine-tuning of existing standards to meet the technological advances and changing needs of the industry.
The Advent of S20.20 Perhaps the key standards document to be introduced into the ESD marketplace in recent years is ANSI/ESD S20.20-1999 Protection of Electrical and Electronic Parts, Assemblies, and Equipment (Excluding Electrically Initiated Explosive Devices). Designed to help answer the questions “How do I convince my customers my ESD control program adequately protects the products I provide them?” and “How do I demonstrate that a single ESD control program will work for all of my customers?” ANSI/ESD S20.20-1999 outlines the basic requirements necessary to design, establish, implement, and maintain an ESD control program. The standard itself provides broad program guidance while allowing the user the flexibility to develop a specific, individualized program within the framework of S20.20.
What makes S20.20 unique is that programs developed and based on it are third-party auditable. Using S20.20 as a program guideline, a manufacturer not only has a means for developing and implementing a program that meets its specific needs, but also has an ISO-level certifiable program that can demonstrate to their customers that they have a functioning ESD program in place. Contract manufacturers who previously faced a myriad of differing control programs to satisfy their customers’ varying requirements will now have the opportunity to implement a single auditable program.
The ESD Association announced the mechanism for a third-party facility audit based on S20.20 in the fall of 2000. The S20.20 facility certification program is similar to ISO 9000, with certified registrars independently assessing a company’s ESD control program and issuing a formal S20.20 certification. This assessment of a company’s ESD control program can be performed in conjunction with a company’s ISO 9000 audit or as a separate audit.
Other Standards Documents In addition to the recent release of ANSI/ESD S541, the ESD Association continues to work on updating existing documents as necessary as well as developing new ones to meet industry needs. Standards covering floor materials, footwear, static dissipative planar materials, bags, and HBM testing continue to be reviewed and updated. The Association recently released a draft standard regarding floor materials, DSTM7.1-2004 Floor Materials—Characterization of Materials.
Summary As the electronics industry continues to face technological advances, the propagation and fine-tuning of ESD standards to meet these advances will result in an increase in the technical references that will help improve ESD control programs. There will be recommendations and procedures to help set up effective programs. There will be test methods and specifications to help users of ESD control materials evaluate and select products that are applicable to their specific needs. And there will be guidelines for vendors of ESD products and materials to help them develop products that meet the real needs of their customers. n
References 1. “ESD Control: A Profitable Opportunity in Tight Economic Times,” Stephen A. Halperin, Threshold, January/February 2003 (Rome, NY: ESD Association) 8-9.
About The ESD Association With more than 2000 members throughout the world, the ESD Association is the largest industry group dedicated to advancing the theory and the practice of ESD avoidance. Readers can learn more about the association and its work at www.esda.org. Special thanks to Michael Brandt for his assistance in preparing this article.
Table 1: ESD Association Standards
Table 2: ESD Association Advisory Documents
Table 3: Sources of Standards © Copyright 2007 Conformity |