Hi Darrell,
By coincidence, I'm reading the book you recommended. I found your descriptions
consistent with the book. Please allow me to insert some supplements below.
Barry Ma
Anritsu Company
On Fri, 08 September 2000, Darrell Locke wrote:
>
> HALT. Highly Accelerated Stress Testing. This can go by other names. This
> is where you stress the product (prototype stage typically) using a number
> of criteria, the most common being temperature extremes and vibration.
... many HALT results have shown that all-axis vibration far surpass the
effectiveness of thermal cycling for the broad spectrum of faults found in many
types of equipment ...
-(quoted from p. 13 of the book)
> You test first to determine the operational limits of the EUT (fails to
> operate
> but recovers when the stresses are removed), then continue until you reach
> the destruct limits (unit is damaged). The test is of short duration
> (couple days) and is intended to simulate life expectancy. This can be
> shown using mathematical analysis with the Arrhenius equation among others.
In the process of finding upper and lower operational and destruct limits and
pushing them to ... ... a very robust product ... will be generated. ... The
product is made better, but how much better is not known, at least not by the
MALT methods. However, when results of the MTBF based on field failure rates
(the only meaningful MTBF) become known, it will probably be far higher than
ever...
- (quoted from p. 72 of the book)
> There has also been a high degree of correlation experimentally. The
> failures seen in HALT are usually what you see in the field. The idea is to
> find the weak points in your product, remedy them, such as using a higher
> rated part, then re-test to find the new limits. The goal is to add lots of
> margin concerning the reliability of your product. These tests must be done
> in specially designed chambers (called HALT chambers by most). They start
> around $130K. If you don't have the money to buy one there several labs
> that will gladly do the tests. One such lab is Qualmark. Others are
> popping up all the time.
>
> HASS. Highly accelerated Stress Screening. This is a production test
> designed to find manufacturing defects, engineering changes, etc., that may
> affect the reliability of the product. You need some kind of environmental
> or HALT chamber, or you can send all your units to a lab, but that gets
> expensive real fast. The test is similar to HALT but you don't go to the
> destruct limits, just high enough to stress the unit and find defects. The
> limits are usually established during HALT testing
>
> Many books are available on the above subject, most notably Accelerated
> Reliability Engineering. HALT & Hass by Greg K. Hobbs distributed by Wiley.
>
> Good Luck
> Darrell Locke
> Advanced Input Devices
> -----Original Message-----
> From: Dave Wilson [mailto:dwil...@alidian.com]
> Sent: Friday, September 08, 2000 10:34 AM
> To: 'emc-p...@ieee.org'; 'n...@world.std.com'
> Subject: HALT/HASS Testing
>
> We make a Metro DWDM product (all fiber) and one of our potential customers
> mentioned HALT/HASS environmental testing. Has anyone else had to go through
> this for similar products?
>
> Thanks,
>
> Dave Wilson
> Alidian Networks Inc.
>
Thanks.
Best Regards,
Barry Ma <b...@anritsu.com>
ANRITSU www.anritsu.com
Morgan Hill, CA 95037
Tel. 408-778-2000 x 4465
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