Andrew, David,
A method that I read about in the 1980's, in the Hewlett-Packard
Journal, was a method called STRIFE Testing. In this method you tested
prototypes to the design limits, then you progressively increased the
stresses until your prototype(s) broke. You analyzed the failures,
hardened your prototypes against this failure mode, and resumed testing.
At some point you would see several different failure modes within a
fairly narrow band of (hopefully outside the design window) stresses.
This told you that you had pushed your basic design scheme about as far
as it would go. You now knew:
1. How to squeeze the most out of your design.
2. How much margin you had.
If you wanted more design margin in this area, you would have to look at
other design schemes.
A. D. Moore's book "Electrostatics" talks about this kind of progressive
hardening of a design on pages 78 to 83.
I still haven't managed to find that original HP Journal article, but
Meeker, William Q., and Hamada, Michael. "Statistical Tools for the
Rapid Development & Evaluation of High-Reliability Products," Sept.
20, 1999 (download from
http://www.stat.iastate.edu/preprint/articles/1995-07.pdf )
talks about STRIFE testing on page 21.
John Barnes
dBi Corporation
http://www.dbicorporation.com/
Andrew Carson wrote:
>
> 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:david.spr...@alexanderlynn.co.uk]
> 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: owner-emc-p...@majordomo.ieee.org
> [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Brian O'Connell
> Sent: 31 July 2002 14:12
> To: emc-p...@ieee.org
> 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:pmerguer...@itl.co.il]
> 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?
>
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