The ESD Control Program Handbook. Jeremy M. Smallwood

hours about technical issues, and how best to write a standard test method, that could be understood and reproduced by anyone with reasonable technical ability and expected to produce results which would agree with others who had done the same. In international standards, we would first have to agree on a test method acceptable to the participating National Committees. There could be several to choose from already in use amongst the standards from the participating countries. Naturally each National Committee expert would favor a particular approach, especially if it was already adopted within their country. Mostly, of course, these would produce different results due to different conditions and methodologies. We would discuss these at length amongst a group of international experts whose cultures and experiences could be very different, and English often not their mother tongue. The resulting methodology would have to be acceptable in the very different climates, conditions, and working practices in Japan, UK, USA, Canada, Scandinavia, France, Germany, Italy or wherever the participating experts were from. In most cases the end product would have to be translatable into the expert's mother language for publication. We found that some common ways of writing in English can be difficult to translate or may be unclear in other languages. English phrases or words can even mean different things to an American or a UK English speaker – leading to long discussions about the best wording for a single sentence!

      In the early 2000s the ESD Association standards were becoming widely accepted in the electronics industry, and their use spreading from North America to other areas of the world. Encouraged by ESDA standardization experts working with IEC TC101, the decision to rewrite IEC 61340‐5‐1 with an unofficial harmonization with ANSI/ESDA S20.20 was a landmark decision by the IEC TC101 Working Group 5 revising this standard. Subsequent further harmonization has simplified the task of the ESD Coordinator, especially in multinational companies.

      As time goes on, the components commonly handled in electronics facilities are becoming more susceptibility to ESD damage. The variety of facilities and processes in which they are handled, stored or transported grows greater. This means that there is an increasing necessity for the person developing, implementing and maintaining an ESD control program to understand, analyze and specify effective protection against ESD risks.

      Part way through writing this book, I realized I was trying to write the book I would have liked to find when I first got into the subject of ESD control in the electronics industry. This book aims to help the reader understand the principles and practice of ESD control to the point where they can make the decisions needed to develop an effective and optimized ESD control program compliant with the current ESD control standards. To do this one needs to understand the purpose of ESD control equipment and materials, and how to specify and test that it does the job intended. If the reader wishes to improve their knowledge further, the references and bibliography given should give them a good starting point. Perhaps most importantly, I hope this book will help the reader find that an initially mysterious set of practices is actually based on sound engineering principles that they can learn to apply with confidence.

Acknowledgments

      I would like to acknowledge my debt to all the experts in the field of ESD control and standardization who through discussions and published work have contributed to the current state of my understanding. I am also indebted to all my clients and course attendees who have challenged me to clarify, explain and justify effective ESD control techniques applied in many different situations.

      I would especially like to thank David E Swenson for his comments on the text and for contributing photographs and other material, and for writing the Foreword, as well as for many enlightening discussions over the years. Dave performed the extraordinary feat of reading and commenting on almost all the draft Chapters at least once. This helped enormously in picking up my mistakes and typographic errors, adding or clarifying important points and generally improving my work.

      Several other friends and colleagues have also very kindly read and commented on Chapters of this book and encouraged me in this work. Special thanks are due to Rainer Pfeifle, Charvakka Duvvury and Christian Hinz who each reviewed and commented on various Chapters in detail. Bob Willis also contributed comments, and Charles Cawthorne kindly provided me some photographs from his own ESD training materials. Lloyd Lawrenson kindly allowed me to use Kaisertech facilities for some of my photography. I'm indebted to Lisa Pimpinella of the ESD Association for arranging permission for me to include figures from the 2016 ESD Association Electrostatic Discharge (ESD) Technology Roadmap.

      Last, but definitely not least, I would like to thank my wife Jan for her good‐natured tolerance of my absent mindedness and lack of communication when engrossed in my work, and my daughter Alia for helping improve some of my photographs in preparation for publication in this book.

1 Definitions and Terminology

As with any specialist subject there are many terms that are the “jargon” of the subject that can be confusing to the newcomer. There are also terms that have specific meanings in the context of these standards but may have different meanings in common parlance. The intention here is not to give strict and rigorous academic definitions, but to assist the newcomer to the field to understand the following chapters.

      Sometimes a range of meanings is common in different industries. For example, the terms conductive, static dissipative, insulative or insulating, and antistatic can mean many different things to different people from different industry areas or in the context of different standards or electrostatic discharge (ESD) control product types. In most cases, only the meaning common in ESD control, and in particular in the context of the IEC 61340‐5‐1 and ANSI/ESD S20.20 and related standards, is emphasized here.

      The task of supervising an ESD control program is often given to personnel from many technical and educational backgrounds. For this reason, the minimum of prior technical knowledge is assumed in this book.

      Despite this, some of the terms used in this document are defined with basic mathematical relationships given where appropriate. This is because simple mathematics often helps to clarify the subject and, in some cases, may be essential to helping the user understand how to specify aspects of an ESD control program. In many cases, these aspects, and their practical importance and application, are discussed further in Chapter 2.

1.1 Scientific Notation and SI Unit Prefixes

      In electrostatics and ESD work, we often have to deal with very large or very small numbers. For example, the resistance of a material may be measured to be 10 000 000 000 Ω. For convenience and clarity, we use scientific notation and SI unit prefixes as shorthand for numbers (http://physics.nist.gov/cuu/Units/prefixes.html).

In scientific notation, the number is rewritten in the form a × 10^b, where a lies between 1 and 10, and b is the number of decimal places a must be shifted to get the full number. This is probably most easily understood by examples of resistance and capacitance (Table 1.1). Sometimes, when the number a is simply 1, it is omitted.

Table 1.1 Examples of use of scientific notation and SI prefixes.

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Value	Scientific notation	SI prefix
150 Ω	1.5 × 102 Ω	150 Ω
22 000 Ω	2.2 × 104 Ω	22 kΩ
35 000 000 Ω	3.5 × 107 Ω	35 MΩ