ANSI ESD S20.20-2007 - FOIA and eLibrary website! - NASA

ANSI/ESD S20.20-2007level in the real world. The assumption for this test model is that the device itself has becomecharged and rapid discharge occurs when the charged device’s conductive leads contact aconductive surface, which is at a lower potential. An issue with the preparation of a CDM teststandard is the availability of suitable instrumentation to measure the discharge event. Thewaveform rise time is often less than 200 picoseconds. The entire event can take place in lessthan 2.0 nanoseconds. Although very short in duration, current levels can reach several tens ofamperes during discharge.Table 4. ESD Susceptibility Test References for DevicesESDModelHBMESD Standards and Methods for Susceptibility Testing of DevicesANSI/ESD STM5.1MIL-STD-883 Method 3015MIL-STD-750 Method 1020MIL-PRF-19500MIL-PRF-38535MMCDMANSI/ESD STM5.2ANSI/ESD STM5.3.1Assembly, Equipment and Design Hardening1. Assembly, Equipment and Design Hardening GuidanceAssemblies and equipment should have protective circuitry or techniques to meet the desireddesign goals. Determining the ESD susceptibility of assemblies and equipment may be based onsimulation modeling, or actual testing. Table 5 provides a quick reference for various testmethods associated with assembly and equipment susceptibility testing.2. Direct Contact, Non-Operating Assembly, Body/Finger or Hand/Metal TestsThis model can be used to verify that assemblies will not be damaged during non-operatingconditions by direct contact to input, output and interface connections. This threat applies to alltypes of assemblies (see Table 5).3. Direct Contact Operating Equipment Hand/Metal TestThis model can be used to verify that operating equipment will not be damaged (or nonrecoverablefaults will not be injected) by direct contact to operator accessible points andexposed surface areas during the normal maintenance process. This threat is limited toequipment subject to operator adjustments or maintenance activities during operation (seeTable 5).4. Indirect Contact, Operating Equipment Furniture Model TestThis model can be used to verify that operating equipment in a home or office environment willnot be damaged (or non-recoverable faults will not be injected) by indirect contact during normalactivities performed within the proximity of the equipment. This threat applies to all electronicequipment in a home or office environment (see Table 5).Copyright 2010 by ESD Association. Licensed, by agreement, for enterpise-wide use to NASA.No other reproduction or transmission in any form is permitted without written permission of the ESDA.For inquiries or to report unauthorized use, contact info@esda.org.10