Conformity Magazine - November 2007 - (Page 22)

ESD Open Forum The Charged Device Model Provided by the ESD Association Q: A: Does CDM have a defined Class Zero? The CDM ANSI/ESDA standard, STM-5.3.1 Charged Device Model (CDM)--Component Level, does not have a defined Class Zero (0), but the lowest class (C1 <125 volts) in the document is being used (established or not) by the ESD community to represent class Zero. The C represents the fact that it is a CDM classification. The HBM ANSI/ESDA STM standard has a Class Zero (0) which is specified as < 250 volts, but must not be equal to 250 volts, so be aware of the simple mathematical difference. © Photographer: Scott Rothstein | Agency: Dreamstime.com Q: A: What is the ESD threshold voltage for future electronic chips in terms of CDM? As you are aware, the consumers’ insatiable desire to have things work faster and take up less space in turn forces manufacturers to require their design engineer to continuously improve their designs. So the smaller ESD protection feature sizes of the components, the circuits and the chips result in reduced ESD threshold susceptibility. The ESDA ESD Technology roadmap (www.esda.org) shows the device ESD sensitivity trends from 1980 to 2010 for all three ESD models of HBM, MM and CDM. The table below, taken from the roadmap, shows what the roadmap predicts for CDM by the year 2010. The worst case threshold will be down to 10 volts and possibly lower. CDM ESD roadmap Max V – the best Min-V – the worst Year 2000 1000 V 400 V Year 2005 800 V 200 V Year 2010 600 V 10 V that it is measuring, but is also indirectly proportional to the capacitance, which changes with distance. The 1 inch is for all intent and purposes an arbitrarily accepted number used in industry to gauge the approximate strength of a field, but not to be used for ESD device threshold measurements, nor for calculations, which is an almost “exact” science. If you were to move the FVM further or closer (to the device in the field) than 1 inch, the measured voltage would change. Secondly, the design strategy used by CDM ESD designers to protect their circuits from very fast transients (a combined << 200 pico-second rise time and <<10 nano-second pulse width) due to charge build up on the device bears little relationship mathematically to the actual field in which the device is placed. No correlation exists as yet. An empirical equation needs to be developed, and data collected, or vice versa. The design focus is mostly on the transient behavior of Q: A: 22 For the case of CDM, if industry experts say the future CDM threshold would be X voltage, then would it mean that, when measured with a field voltage meter at 1 inch distance, the reading shown should be not more than the X value in order to prevent damage due to CDM? Long question, but good question. This assumption is incorrect because firstly the simple physics says that the voltage measured by the field voltage meter (FVM) is not only proportional to the charge associated with the field CONFORMITY NOVEMBER 2007 Figure 1: Rise time dependent triggering behavior (Bart et. al.) http://Dreamstime.com http://www.esda.org

Table of Contents Feed for the Digital Edition of Conformity Magazine - November 2007

Conformity - November 2007 Contents Editor’s Note Commission Sets Date, Terms for 700 MHz Auction FCC Reaffirms Roaming Obligations Commission Moves to Improve USF Management FCC Proposes Fines for Violations of E911 Handset Requirements Commission Levies $1 Million Plus Fines for Unsolicited Fax Advertisements GR-3150 - Lithium Battery Certification Levels Based on Criteria for General Product, Safety, and Performance, Part 2 ESD Open Forum Machinery Field Evaluation for the United States Validation, Verification, and Immunity Testing Techniques for EMC for Functional Safety Thermal/EMC Simulation Addresses New Mechanical Design Challenges Product Safety Equipment Buyer’s Guide FCC Releases Report on Telephone Numbering Resource Utilization Canada Still Has PCS Spectrum to Assign Updated Standards List for the EU’s Medical Devices Directive Updated Standards List for EU Directive on Active Implantable Medical Devices Call for Papers for the 2008 EOS/ESD Symposium Announced Mobile Phone Use in Hospitals May Be Dangerous CPSC Actions in the News IEC Standards Update UL Standards Update Telcordia Standards Update From Our “You Can’t Make This Stuff Up” Department Product Reviews Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - November 2007

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.