ESD Compliance for Class 0 Components

ESD sensitivity of a component can be derived from various classification models, but these sensitivity levels are guidelines only.

Q: What are the requirements for Class 0 ESD compliance?

A: Class 0 usually refers to the human body model (HBM) ESD sensitivity of a component. Each of the three device testing methods (human body model, machine model, and charged device model) includes a classification system for defining the component sensitivity to the specified model. A sensitivity classification system for HBM is shown in Table I. Such classification systems have a number of advantages. For example, they allow easy grouping and comparing of components according to their ESD sensitivity, and the classification gives an indication of the level of ESD protection required for the component.

A fully characterized component should be classified using all three models. These classification systems and component sensitivity test results function as guides, however, and should not necessarily be viewed as absolutes. The events defined by the test data produce narrowly restrictive data that must be considered carefully and used judiciously. The ESD sensitivity models represent discrete points used in an attempt to characterize ESD vulnerability. The data points are informative and useful, but to arbitrarily extrapolate the data into a real-world scenario can be misleading. The true utility of the data is in comparing one device with another and providing a starting point for developing an ESD control program.

The ESD Association's new ESD control program standard, ANSI/ESD S20.20-1999, provides guidance for developing and implementing programs to protect products that are susceptible to damage by electrostatic discharges >= 100 V HBM. These products would include some Class 0 components.

For Further Reference

ESD-STM5.1-1998, "Sensitivity Testing, Human Body Model (HBM)," ESD Association, Rome, NY.

ANSI/ESD-S20.20-1999, "Development of an Electrostatic Discharge Control Program," ESD Association, Rome, NY.

MIL-STD-883, "Method 3015, Microcircuits, Electrostatic Discharge Sensitivity Classification," Department of Defense, Philadelphia, PA.

MIL-STD-750, "Method 1020, Test Methods for Semiconductor Devices, Electrostatic Discharge Sensitivity (ESDS) Classification," Department of Defense, Philadelphia, PA.

MIL-PRF-19500, "General Specification for Semiconductor Devices," Department of Defense, Philadelphia, PA.

MIL-PRF-38535, "General Specification for Integrated Circuits (Microcircuits) Manufacturing," Department of Defense, Philadelphia, PA.

Q: What is some recommended reading for best practices to fix and prevent ESD problems in new and existing electronic designs?

A: Several papers on ESD design solutions have been presented at the EOS/ESD Symposium and the International Reliability Physics Symposium (IRPS) over the past several years. The ESD Association has recently published a bibliography of significant device and design papers from past EOS/ESD symposia. That list can be found on the ESD Association's Web site, http://www.esda.org. A bibliography of papers from IRPS proceedings can be found at http:// www.irps.org. In addition, two books on the subject are ESD in Silicon Integrated Circuits, by Ajith Amerasekera and Charvaka Duvvury, and Basic ESD and I/O Design, by Sanjay Dabral and Timothy Maloney. Both are available from the ESD Association, 7900 Turin Rd., Bldg. 3, Ste. 2, Rome, NY 13440; tel: 315/339-6937; fax: 315/339-6793. IRPS materials are available through the IEEE Customer Service Center, 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08855-1331; tel: 800/678-4333 or 732/981-0060; fax: 732/981-9667; e-mail: storehelp@ieee.org.

To submit your questions to the ESD Help Desk or to browse the archives of past questions and answers, go on-line at http://www.ce-mag/esdhelp.html. Information on the ESD Association may be found at http://www.eosesd.org.

Class	Voltage Range
Class 0	<250 V
Class 1A	250 to <500 V
Class 1B	500 to <1000 V
Class 1C	1000 to <2000 V
Class 2	2000 to <4000 V
Class 3A	4000 to <8000 V
Class 3B	>=8000 V
Table I. ESDS Component sensitivity classification–Human Body Model (per ESD STM5.1-1998).

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