Conformity Magazine - April 2008 - (Page 33)

at their customer sites “dead on arrival,” even after putting their products through design verification and/or production testing. Although they went through burn-in, temperature cycling, vibration and shock testing individually, they could not uncover all the design weaknesses and weed out manufacturing defects. A new approach in which temperature cycling and vibration testing is conducted concurrently has been proven to be more effective. This process is called environmental stress screening (ESS). How the System Works The ESS system discussed in this article has a chamber with doors on each side that open and close, and an electromechanical shaker with a skewed table in the center of the chamber. The system enables the operator to conduct thermal cycling evaluations on a given product while imposing vectored vibration input on all 3 axes, providing an effective and efficient method of screening. Figure 5 shows the exploded view of the accordion assembly when it is pulled apart. The system uses a temperature chamber with openings on each side. Printed circuit boards (PCBs) are loaded in between support plates and are pushed together on standoffs, similar to their mounting in a finished product. Compressed air shaft collar locks are employed to hold the PCBs in position, and these specialized collar locks hold the shaft, and lock in the PCBs tightly on the standoffs. Movement of the PCBs is done with a hovercraft transport system. An accordion fixture holds the PCBs in place, and the hovercraft moves them in and out of the sides of the chamber. The PCBs are easily loaded on the accordion fixture from either side of the chamber. The hovercraft transport system on the accordion fixture makes it easy to move the fixture from the loading table to the chamber. Once the units are in the chamber, the doors close and the units are quickly fastened by vacuum onto the shaker table and are then vibrated at cold and hot temperatures. While screening is being performed on one group of boards, new boards are being unloaded and reloaded outside the chamber. Once the screened PCBs are done, the boards are unloaded and the new PCBs are moved into the chamber for screening. The process is then repeated. There are 2 main ESS systems available today; the combined temperature chamber with an electromagnetic, skewed shaker table, and the pneumatic hammer shock table system. These We’re in your neighborhood Let us pick up and deliver –– or calibrate your equipment at your site With six regional labs, it’s easy to access Agilent’s calibration services. And when we calibrate your instruments, you can be sure they retain “like new” performance and accuracy. Turnaround time from local cal centers is normally ﬁve business days, and if you’re within a two-hour radius, pick up and delivery are free. Or when downtime is critical, our Volume Onsite Calibration Service brings Agilent’s expertise to your site. Either way, you get thorough high quality calibrations with all adjustments included, plus comprehensive data reports, minor repairs, and advice on available hardware upgrades — at no extra cost. Remove all doubt Your instruments restored to like-new performance, returned on time • Premier measurement expertise • NIST-traceable metrology • A2LA-accredited calibrations available For more information, send email to service-info@agilent.com or call 1-800-829-4444 and we’ll connect you to your local cal center: Arlington Heights, IL Chelmsford, MA Bethlehem, PA Durham, NC Irvine, CA Richardson, TX www.agilent.com/ﬁnd/CAL_LAB © Agilent Technologies, Inc. 2008 Calibration_ComformHalf.indd 1 April 2008 Conformity 33 3/17/08 11:14:29 AM http://www.agilent.com/find/CAL_LAB

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

Conformity Magazine - April 2008 NewsBreaks Editor’s Note Mandatory Analog Cellular Service Ends FCC Releases Quarterly Reports on Consumer Inquiries and Complaints New Standards List Released for The EU’s Low Voltage Directive FDA Issues Notification on Unretrieved Device Fragments FDA Offers Guidance on Waivers for In-Vitro Diagnostic Devices ESD Open Forum Emerging Issues in Standards Challenges in Testing Design Fundamentals Focus on... New Products Product Reviews Premarket Approval Application Guidance Issued by FDA New Jersey Enacts Electronic Waste Recycling Regulations A New U.S. Standard for Workstation and Computer Design Might the CPSC Hold Retailers Accountable for Safe Products? CPSC Loses “Sole Toy Tester” CPSC Actions in the News IEC Standards Update UL Standards Update Telcordia Standards Update From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - April 2008

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