Conformity Magazine - December 2008 - (Page 20)

current FCDM testers. We predict that there will be increased interest in some form of cc-TLP to replace FCDM testing. Machine Model (MM) Machine model testing will likely continue to experience a slow decline in use. There is no active effort within either ESDA or JEDEC to update the test method documents. JESD47E [6], the JEDEC document specifying stress tests that should be done to integrated circuits for qualification, has not recommended MM testing for a number of years. Even in the automobile industry, where MM has always been popular, it is not required. AEC-Q100-Rev-F requires that either HBM or MM be done, whereas CDM must be done. The Industry Council, in its white paper on recommended passing levels for HBM and MM, downplayed testing with machine model. Many companies, however, have extensive history of MM results for which they have developed confidence. It is unlikely that MM testing will be discontinued suddenly. System-Level Testing Most system-level testing is done using the IEC 61000-4-2 test method, in which systems are tested using a hand-held ESD gun. Discussion of system-level ESD testing waveforms and the test setup can be found in [8] and [9]. A new update to this standard is promised, but it is not likely that the new update will result in major changes in how systems are supposed to be tested. The changes are likely to concentrate on improving the measurement and definition of the stress waveform. We believe that some of the biggest changes in ESD testing will be in those areas where IEC 61000-4-2 is being applied outside of its intended scope. IEC 61000-4-2 specifically states that one is not to do contact discharge with the ESD gun onto the pins of system connectors, such as Ethernet ports or USB ports. If the connector has a metal shell, contact discharge should be done directly to the metal shell. If the connector has an insulating shell, air discharge should be done to the region of the connector. Despite this, there are regular reports of contact discharge being performed directly to the pins of a system. The motivation is often to measure some form of robustness due to the cable discharge event (CDE). CDE occurs when a cable becomes charged due to friction and then discharges as it is plugged into a system. This is a common event, but there is no generally accepted test method. A number of companies have internal test methods, but none has been made available to the industry. The result is an undisciplined approach to defining robustness for this real world stress. The ESDA Working Group 14 is currently working on a test procedure for CDE that should be available for industry review within the next year. It is hoped that this test procedure will provide a common test procedure for the industry. A second area where IEC 61000-4-2 is used outside of its scope is the testing of components. OEMs need their products to pass system-level ESD testing, and they are increasingly looking toward their suppliers to help them in this effort. OEMs are increasingly asking their suppliers to provide components that pass a high level of IEC 61000-4-2 stress, often 8 kV contact discharge and 15 kV air discharge. This is being requested despite the fact that IEC 61000-4-2 does not cover the testing of components. IEC 61000-4-2 does not specify the following important test parameters for component testing: • How to apply stress; • Required test fixtures; • Grounding for the ESD gun and component under test; • Pins requiring stress; • Should the component be powered during the test; • Should the component be functioning during the test; • The definition of failure; • How to verify the component was stressed. 20 Conformity DeCember 2008 http://www.okaya.com http://www.okaya.com

Table of Contents Feed for the Digital Edition of Conformity Magazine - December 2008

Conformity Magazine - December 2008 Contents Editor's Note FCC Warns Regulatory Fee Payers About Potential "Phishing" Commission Prowls the Web to Enforce Its Regulations First DTV Rollout Initiated in Wilmington, NC New Standards List Released for the EU's Directive on the Safety of Toys ESD Association Call for Papers ESDA. JEDEC Announce Standards Development Cooperation Commission Releases Data on Local Telephone Competition The Future of ESD Testing ESD Open Forum Emerging Issues in Standards: China RoHS: One Year and Counting Challenges in Testing: Revisiting 10-Meter and 3-Meter Radiated Emission Measurements Design Fundamentals: Meeting the Shielding Challenges of Injection-Molded Plastics Focus On...Microwave Absorbers Buyer's Guide FDA Recalls Automated External Defibrillators FDA Revises Guidance on Medical Device Tracking Guidance Document Safety of Passive Implants Released FDA Offers Guidance on Marketing Diagnostic Ultrasound Systems EU Commission Issues Correction on Machinery Directive Standards Other CPSC Actions in the News Product Reviews IEC Standards Update UL Standards Update Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - December 2008

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