I would agree with Brian in that the name HALT is misleading. There is no way to relate HALT data to a failure rate or MTBF figure within a field population.
Saying that though, HALT testing does very quickly reveal mechanical weakness within a design and is incredibly useful. I always take the approach that HALT testing pushes your product to the limit and finds the weak points. Then from this data you set up a HASS regime to screen all your outgoing goods. Non military parts do carry MTBF figures, and I have been finding in recent months, more and more customers requiring calculated and proven reliability data before they place an order for goods. Andrew Carson - Senior Compliance Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 -----Original Message----- From: David Sproul [mailto:[email protected]] Sent: 01 August 2002 11:22 To: Brian O'Connell Cc: EMC-PSTC Subject: RE: HALT and HAAS Hello group, I would actually disagree that HALT is misnamed, as Brian suggests. I have seen clients find mechanical and electronic weakness in their designs within days of testing that may otherwise have taken many weeks of conventional temperature and vibration testing, or even years in the field, before they were discovered. By fixing these problems these companies were able to strengthen their product still further and greatly reduce, and in some cases eradicate, repairs or returns from customers. I may be wrong, but is it not the case that components destined for non military use do not come with MTBF figures, thus making it impossible to calculate accurate MTBF figures for products they are used in? I must stress that I this is more supposition that known fact. If it is so, then perhaps HALT could be seen as a commercial alternative to MTBF. I think HAAS may actually be HASS, which stands for highly accelerated stress screening. This I'm afraid I've had very little experience of, but It seems to take the product lessons learned from your HALT testing and apply them, in a less destructive manner, to the manufacturing process. HALT and HASS are very expensive and must be weighed against perceived potential savings from reduced field repairs or replacements. I know it is not for all companies. I used to work for a large British manufacturer of military electronics who made as much money (if not more) from spares and repairs, as they did from the original product sales. I hope this has helped. Best regards, David Sproul. -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Brian O'Connell Sent: 31 July 2002 14:12 To: [email protected] Subject: RE: HALT and HAAS Geez, just jump to Google. HALT-> misnamed: Highly Accelerated Life Testing. Actually has noting to do with Life-time or MTBF-type longevity analysis. Look at the Calmer web site; they were one of the pioneers of HALT. Also, GM has published an engineering standard, GMW8287, that provides a decent overview of HALT and HASS/HASA processes. There may be minimal ROI for simple digital stuff, but mixed-signal and/or more complex mechanical constructions should be subject to HALT, and perhaps HASS follow-up. If your manufacturing and design engineers take the time to actually READ your HALT report and take corrective action, you will probably find that RMA problems are greatly reduced. In any case, playing with liquid nitrogen is great fun... Brian -----Original Message----- From: Peter Merguerian [mailto:[email protected]] Sent: Wednesday, July 31, 2002 3:38 AM To: "EMC-PSTC (E-mail)" < Subject: HALT and HAAS Dear All, 1. Has anyone heard of HALT and HAAS? 2. What are some overseas labs (in Europe, North America and Asia) testing for HALT and HAAS? 3. What does a manufacturer testing to HALT and HAAS gain? ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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