With the economy steadily improving, many companies are looking for ways to increase profits and overall performance within their particular industry. The electronics industry is no exception. Many electronics companies are working towards improved quality and reliability at the same rate as improving the performance of the products they manufacture. In the latter part of 2005, the ESD Association released an “ESD Technology Road Map” in an effort to create awareness within the global electronics industry of some remarkable changes that are right around the corner.

The “Road Map” points out, in dramatic fashion, that numerous mainstream electronic parts and components will soon reach assembly factories without the same level of ESD protection installed just a few years ago. The manufacturing industry may have become a bit complacent in the past few years since many design schemes offered very good levels of ESD protection. However, the ever increasing demands for enhanced performance, speed, storage capacity, and bandwidth, along with a reduction in physical size has led to the necessary removal of on-chip protection.

Nowhere is this more evident than in the world of wireless communication devices and other portable electronic equipment. The features crammed into a pocket sized cell phone are truly amazing and many more are on the way. As consumers demand and are granted more features, manufacturers must adapt to handling increased ESD susceptibility in their parts.

The ESD Association Standards Committee is “charged” with keeping pace with the industry demands for increased performance, and is not too far away from offering the ability to determine process capability as it relates to ESD with all its peripheral ramifications. The existing Standards, Standardized Test Methods, Standard Practices and Technical Reports assist in the design and monitoring of the Electrostatic Protected Area (EPA). Most of the existing documents relate to controlling electrostatic charge on personnel and stationary work areas. However, with the ever increasing shift to automated handling, the need to evaluate and monitor what is going on inside of process equipment is growing daily. A shift is being made from Human Body Model device susceptibility as the major concern, to Charge Device Model considerations in the typical factory.

Table 1: Types of ESD Association Documents

While there has always been significant issue with machine processing, there have been very few tools available to give the ESD coordinator in the factory a methodology to conduct meaningful evaluations. Next year, this annual update should include Standards and other procedures that will allow a company to determine the level of ESD sensitivity that their process can handle reliably.

There is absolutely no question that the existing ESD Association Standards such as ANSI/ESD S20.20 (Program Development) and ANSI/ESD S541 (Packaging for Shipment) are important to industry. These documents are downloaded from www.esda.org in excess of 948 times per month. The new ESD Technology Road Map has had over 6400 downloads since it was released. The industry is paying attention. The factory Certification Registrars report strong interest in Certification to S20.20 and the world of consultants in this area report that inquiries for assistance are at an unprecedented level in recent months. Individual education also seems of interest once again with numerous individuals attempting to qualify as Certified ESD Control Program Managers.

A recently introduced educational opportunity is the ESD Device Design Professional Certification program (see Conformity, June 2005). Similar to the ESD Program Manager Certification in concept, candidates take a required number of tutorials related to electronic device and testing technologies, show work in the field and potentially write an exam (still in the planning phase). For details on this and the Program Manager Certification program, see the ESD Association web site.

A large percentage of the certification program requirements are based on Standards and the other related documents produced by the ESD Association Standards Committee. Recently released documents include a major revision of ANSI/ESD S6.1 Grounding. This important standard offers significant information related to setting up an ESD controlled environment, choosing an appropriate grounding system and advising what to do in the event a ground is not readily available.

New Standardized Test Methods include ANSI/ESD STM 11.13-2004 Two Point Resistance Measurement and ANSI/ESD STM 11.31-2001 Bags. A new Standard Practice document released this past year includes ANSI/ESD SP 15.1-2005 In-Use Resistance Testing of Gloves and Finger Cots. Recent guidance and informational Technical Reports are also available covering the following subjects: cleanrooms and air ionizers. An international version of S20.20 should be released for use by the International Electrotechnical Commission (IEC) during 2006.

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:

• They help assure consistency of ESD sensitive products and consistency of ESD control products and services.

• They provide a means of objective evaluation and comparison among competitive ESD control products.

• They help reduce conflicts between users and suppliers of ESD control products.

• They help in developing, implementing, auditing, and certifying ESD control programs.

• They help reduce confusion in the marketplace.

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.

General 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. First, there are those that provide ESD program guidance or requirements, such as ANSI/ESD S20.20-1999 Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices); ANSI/ESD S6.1-2005 Grounding—Recommended Practice; and ANSI/ESD S1.1-1998 Wrist Straps. These documents are classified as standards as they all have specific requirements that must be met.

A second group of documents is called standard test methods. These documents contain procedures that can be used to evaluate device sensitivity or ESD control products, materials, or processes. The procedures called out in a standard test method should provide similar test results when tested by two separate labs. Standard test methods include documents such as ESD STM5.1-2001 Device Testing—Human Body Model (HBM) Component Level and ESD STM11.3.2004 Two Point Resistance Measurement.

The third category of documents is called standard practices. 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.

Finally, the last category of standards documents includes advisories and technical reports. These types of documents are used to provide educational information to potential users. 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.

Following is a list of the current ESD Association Standards documents:   ANSI/ESD S1.1-1998 Wrist Straps This document establishes test methods for evaluating the electrical and mechanical characteristics of wrist straps. It includes improved test methods and performance limits for evaluation, acceptance, and functional testing of wrist straps.   ANSI/ESD STM2.1-1997 Garments This standard test method provides test methods for measuring the electrical resistance of garments used to control electrostatic discharge. It covers procedures for measuring sleeve-to sleeve and point-to-point resistance.   ANSI/ESD STM3.1-2000 Ionization Test methods and procedures for evaluating and selecting air ionization equipment and systems are covered in this standard. The document establishes measurement techniques to determine ion balance and charge neutralization time for ionizers.   ESD SP3.3-2000 Periodic Verification of Air Ionizers This standard practice provides test methods and procedures for periodic verification of the performance of air ionization equipment and systems (ionizers).   ANSI/ESD S4.1-1997 Worksurfaces—Resistance Measurements This standard establishes test methods for measuring the electrical resistance of worksurface materials used at workstations for protection of ESD susceptible items. It includes methods for evaluating and selecting materials.   ANSI/ESD STM4.2-1998 ESD Protective Worksurfaces—Charge Dissipation Characteristics This standard test method provides a test method to measure the electrostatic charge dissipation characteristics of worksurfaces used for ESD control.   ANSI/ESD STM5.1-2001 Electrostatic Discharge Sensitivity Testing—Human Body Model (HBM) Component Level This standard test method updates and revises an existing standard. It establishes a procedure for testing, evaluating and classifying the ESD sensitivity of components to the defined Human Body Model (HBM).   ANSI/ESD STM5.2-1999 Electrostatic Discharge Sensitivity Testing— Machine Model (MM) Component Level This standard establishes a test procedure for evaluating the ESD sensitivity of components to a defined machine model (MM). It also provides a system of classifying the sensitivity of these components.   ANSI/ESD STM5.3.1-1999 Charged Device Model (CDM)—Component Level This standard test method establishes the procedures for testing, evaluating, and classifying the ESD sensitivity components to a defined charged device model.   ANSI/ESD SP5.3.2-2004 Sensitivity Testing Socketed Device (SDM) Component Level This standard practice provides a test method for generating a “Socketed Device Model” (SDM) test on a component integrated circuit (IC) device. ANSI/ESD SP5.4-2004 Transient Latch-up Testing—Component Level Supply Transient Stimulation This standard practice was developed to instruct the reader on the methods and materials needed to perform transient latch-up testing.   ANSI/ESD SP5.5.1-2004 Electrostatic Discharge Sensitivity Testing Transmission Line Pulse (TLP) Component Level This standard practice defines a method for pulse testing to evaluate the voltage current response of the component under test   ANSI/ESD S6.1-2005 Grounding This standard specifies the parameters, materials, equipment and test procedures necessary to choose, establish, vary and maintain an Electrostatic Discharge Control grounding system for use within an ESD Protected area for protection of ESD susceptible items, and specifies the criteria for establishing ESD Bonding.   ANSI/ESD S7.1-2005 Resistive Characterization of Materials—Floor Materials Measurement of the electrical resistance of various floor materials such as floor coverings, mats, and floor finishes is covered in this document.   ANSI/EOS/ESD S8.1-2001 Symbols—ESD Awareness Three types of ESD awareness symbols are established by this document. The first one is to be used on a device or assembly to indicate that it is susceptible to electrostatic charge. The second is to be used on items and materials intended to provide electrostatic protection. The third symbol indicates the common point ground.   ANSI/ESD STM 9.1-2001 Footwear—Resistive Characterization This standard defines a test method for measuring the electrical resistance of shoes used for ESD control in the electronics environment. A companion document covering foot grounders is in the draft stage.   ESD SP9.2-2003 Footwear—Foot Grounders Resistive Characterization (not to include static control shoes) This standard practice was developed to provide test methods for evaluating foot grounders and foot grounder systems used to electrically bond or ground personnel as part of an ESD Control Program. Static control shoes are tested using ESD STM9.1.   ESD SP10.1-2000 Automated Handling Equipment (AHE) This standard practice provides procedures for evaluating the electrostatic environment associated with automated handling equipment.   ANSI/ESD STM 11.11-2001 Surface Resistance Measurement of Static Dissipative Planar Materials This standard defines a direct current test method for measuring electrical resistance of static dissipative planar materials used in packaging of ESD sensitive devices and components.   ANSI/ESD STM11.12-2000 Volume Resistance Measurement of Static Dissipative Planar Materials This standard test method provides test methods for measuring the volume resistance of static dissipative planar materials used in the packaging of ESD sensitive devices and components.   ANSI/ESD STM11.13-2004 Two Point Resistance Measurement This standard test method measures the resistance between two points on a material’s surface without consideration of the material’s means of achieving conductivity. This test method was established for measuring resistance where the concentric ring electrodes of ESD Standard Test Method 11.11 cannot be used.   ANSI/ESD STM11.31-2001 Bags This standard provides a method for testing and determining the shielding capabilities of electrostatic shielding bags.   ANSI/ESD STM12.1-1997 Seating—Resistive Measurement This standard provides test methods for measuring the electrical resistance of seating used to control ESD.   ESD STM13.1-2000 Electrical Soldering/Desoldering Hand Tools This standard test method provides electric soldering/desoldering hand tool test methods for measuring the electrical leakage and tip to ground reference point resistance and provides parameters for EOS safe soldering operation.   ANSI/ESD SP14.1-2004 System Level Electrostatic Discharge (ESD) Simulator Verification This standard practice was developed to provide guidance to designers, manufacturers, and calibration facilities for verification and specification of the systems and fixtures used to measure simulator discharge currents.   ANSI/ESD SP15.1-2005 In-Use Resistance Testing of Gloves and Finger Cots This standard practice provides test procedures for measuring the intrinsic electrical resistance of gloves and finger cots.   ANSI/ESD S20.20-1999 Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) This standard provides administrative, technical requirements and guidance for establishing, implementing and maintaining an ESD Control Program.   ANSI/ESD STM97.1-1999 Floor Materials and Footwear—Resistance Measurement in Combination with a Person This standard test method provides for measuring the electrical resistance of floor materials, footwear and personnel together, as a system.   ANSI/ESD STM97.2-1999: Floor Materials and Footwear—Voltage Measurement in Combination with a Person This standard test method provides for measuring the electrostatic voltage on a person in combination with floor materials and footwear, as a system.   ANSI/ESD S541-2003 Packaging Materials for ESD Sensitive Items This standard defines the packaging properties needed to protect electrostatic discharge sensitive (ESDS) electronic items through all phases of production, transport and storage. The document discusses application requirements and references the testing methods for evaluating packaging and packaging materials for those properties.

Table 2: ESD Association Standards Documents

Who are the primary standards developers?

Although there are a number of organizations such as IEST, IDEMA, and JEDEC 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.

ESD Association Advisory documents are not standards, but provide general information for the industry or additional information to aid in better understanding of association standards.   ESD ADV1.0-2004 Glossary of Terms Definitions and explanations of various terms used in Association Standards and documents are covered in this Advisory. It also includes other terms commonly used in the electronics industry.   ESD ADV11.2-1995 Triboelectric Charge Accumulation Testing The complex phenomenon of triboelectric charging is discussed in this Advisory. It covers the theory and effects of tribocharging. It reviews procedures and problems associated with various test methods that are often used to evaluate triboelectrification characteristics.   ESD ADV53.1-1995 ESD Protective Workstations This advisory document defines the minimum requirements for a basic ESD protective workstation used in ESD sensitive areas. It provides a test method for evaluating and monitoring workstations.   ESD TR 20.20-2000 ESD Handbook Provides guidance that can be used for developing, implementing, and monitoring an electrostatic discharge control program in accordance with ANSI/ESD S20.20. It also includes Glossary of Terms (ESD ADV1.0-2003). This document was formerly ESD ADV2.0.

Traditionally, 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.

Summary

The ever changing and dynamic electronics world will face additional challenges as discussed in the “ESD Technology Road Map.” The technical and manufacturing communities will need to monitor processes to make sure they are capable of handling parts with greater ESD sensitivity than they have had to deal with in recent years. Keeping up with the changes in the electronics industry is a task that the ESD Association Standards Committee must face on nearly a daily basis - a daunting task for a volunteer organization. g

ESD standards are available from the following sources:

• ESD Association, 7900 Turin Road, Building 3, Rome, NY 13440. Phone: 315-339-6937; fax: 315-339-6793; email: info@esdsa.org; website: http://www.esda.org.

• International Electrotechnical Commission, 3, rue de Varembe, Case postale 131, 1211 Geneva 20, Switzerland. Fax: 41-22-919-0300; website: http://www.iec.ch.

• Military Standards, Naval Publications and Forms Center, 5801 Tabor Avenue, Philadelphia, PA 19120.

References

1. “ESD Control: A Profitable Opportunity in Tight Economic Times,” Stephen A. Halperin, Threshold, January/February 2003 (Rome, NY: ESD Association) 8-9.

The ESD Association is the largest industry group dedicated to advancing the theory and the practice of ESD avoidance, with more than 2000 members worldwide. Readers can learn more about the association and its work at www.esda.org. Special thanks to Dave Swenson for his assistance in preparing this article.