Conformity Magazine - July 2008 - (Page 27)

ESD Open Forum standards only require a minimum of three samples to be tested, but we have tested a total of 18 samples with only one failure. Why should this product’s classification be lowered to 1C (1000 – 2000 V) instead of Class 3A (4000 – 8000). The existing HBM standards allows for repeating HBM tests at the fail voltages with fresh new samples. This step in the test method was added to make sure the failures were not due to some type of wear out failure mechanism [3]. If the new samples pass the new tests, then the HBM tests can continue. If the additional testing shows that the product passes at much higher HBM stress levels until repeatable failure occur, then the classification level will be the highest level reached. In your case, since the repeatable failures did not occur to > 4000 V, the HBM standards allow you to rank your product as a Class 3A product. References 1. Industry Council on ESD Target Levels, “White Paper 1: A Case for Lowering Component Level HBM/MM ESD Specifications and Requirements,” www.esda.org. INEMI, “2005 Packaging Roadmap Overview,” www.conformity.com/1901. ANSI/ESD STM5.1-2007 or JESD22-A114E A: 2. 3. © Tryatna Anto | Dreamstime.com For example if the 64-pin IC component has one pin fail below 2000 V, the pin failure rate would be 1.56% risk of occurrence, while 2 pin failure on a 512 pin IC component would have a 0.4% risk of occurrence. The probability numbers change even more if the probability of the exact pin combination is included. Since the number of different pin combinations for the 500-pin IC component versus the 64-pin IC component is 11 versus 3, the above probabilities would be even lower for the high pin component. None of these probability factors are considered in the existing HBM standard test methods. The probability that a specific pin combination would receive an ESD discharge event becomes much lower as the pin count increases; this information is currently being ignored. Are the existing HBM standard test methods too restrictive? The best answer, in my opinion, is yes; especially for high pin count IC components with multiple independent power supplies. About the Author This article was prepared on behalf of the ESD Association by Michael Chaine, who has worked since 1998 at Micron Technology, Inc, in Boise, Idaho, where he serves as a Section Manager in the R&D Reliability Group. Mike is currently working in the area of on-chip ESD protection design for all advanced DRAM and FLASH technologies. Mike holds a BSEE degree from Arizona State University, and is a former member of the ESDA Board of Directors, He currently chairs two different IC device test work groups for the ESDA, the component levels Human Body Model (HBM) WG5.1 and Socketed Device Model (SDM) WG5.3.2. About the ESD Association Founded in 1982, the ESD Association is a not for profit, professional organization dedicated to furthering the technology and understanding of electrostatic discharge. The Association sponsors educational programs, develops ESD standards, holds an annual technical symposium, and fosters the exchange of technical information among its members and others. Additional information may be obtained by contacting the ESD Association, 7900 Turin Rd., Bldg. 3, Rome, NY 13440-2069 USA. Phone: 315-339-6937. Fax: 315-339-6793. Email: info@esda.org. Website: www.esda.org. Q: During the product qualification HBM tests, we stressed a total of 2 IC components from three different wafer lots for a total of 6 parts. Five out of six IC components passed all HBM pin combinations at 4000V, but one device had functional failures at 1500 V. The product was retested with a larger sample size of 12 additional IC components and none of these parts failed. The HBM JULy 2008 Conformity 27 http://www.esda.org http://www.conformity.com/1901 http://Dreamstime.com http://www.esda.org

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

Conformity Magazine - July 2008 Contents Editor's Note FCC Adopts 6 Million Dollars in DTV Enforcement Orders Commission Enforcement Bureau Adopts V-Chip Consent Decree FDA Seeks 2 Million Dollars from Medical Device Manufacturer FDA Answers Questions About CFLs and UV Radiation EPA Issues Energy Star Specs for TV, Video Boxes Canada Unveils Sweeping Product Safety Legislation How the Evolution of CISPR Standards Continues to Shape the Requirements for Anechoic Chambers ESD Open Forum Reach Compliance for Non-EU Article Manufacturers The iNARTE Informer Preamplifier Considerations for Emission Measurement Systems Effective Shielding in Medical Electronics Applications Product News Focus On...Power Components Buyer's Guide Updated Standards List for the EU's ATEX Directive EOS/ESD Symposium Set for September CPSC Actions in the News Researchers Work to Develop Non-Flammable Batteries Safety Link Launches Redesigned, Enhanced Web Site IEC Standards Update UL Standards Update Product Reviews Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - July 2008

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