RE: HALT/HASS Testing
Sorry, I was pointed out a typo in the email I sent 2 hrs ago this afternoon. MALT should be corrected to HALT in the second insertion with "The product is made better, but how much better is not known, at least not by the MALT methods." -BM Thanks. Best Regards, Barry Ma ANRITSUwww.anritsu.com Morgan Hill, CA 95037 Tel. 408-778-2000 x 4465 ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: HALT/HASS Testing
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 ANRITSUwww.anritsu.com Morgan Hill, CA 95037 Tel. 408-778-2000 x 4465 ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: HALT/HASS Testing
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. 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. 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. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: HALT/HASS Testing
Don't forget that proper HALT testing is to test to failure, i.e., if the product doesn't fail the HALT test was not performed properly. You do not "pass" a HALT test. You learn from the failures. Hans
RE: HALT/HASS Testing
Dwight, Our engineering group regularly sends products out for HALT testing. We design ITE, although not computers. Some of the system problems that they uncover are broken solder joints (mass of component), poor connections (circuit boards), and other mechanical problem (fasteners). The main idea is to increase the thermal stress on the product, with vibration, until failure occurs. The test temperature starts at your maximum operating temperature. The products generally undergo about 3 days of testing. The cost is related to how long it takes to verify functionality. We need about 15 minutes. It will cost you about $8k for 3 days of test. You will need to either send an engineer, or include a lot of replacement parts. Figure about two months to schedule. James Goedderz Sensormatic Electronics goedd...@sensormatic.com Views expressed by the author do not necessarily represent those of Sensormatic. > -- > From: Dwight Hunnicutt[SMTP:dwight.hunnic...@vina-tech.com] > Reply To: Dwight Hunnicutt > Sent: Monday, July 20, 1998 12:01 PM > To: EMC PSTC; TREG Newsgroup; NEBS Newsgroup > Subject: HALT/HASS Testing > > In a related area of compliance world, have any of you had experience > subjecting your prototypes to HALT testing, then your production units > to HASS testing (such as by QualMark)?? I'm wondering if this sort of > "accelerated life" testing is something out there for the satellite and > space shuttle designers, rather than for ITE and Telecom equipment > manufacturers. > > For those that did do some of this, did you break the bank and use 6 > months of your life for this testing, or was it relatively quick and > painless (yeah, right)? > > We're considering shaking and baking our telecom unit using these types > of tests as a design verification tool, but one doesn't hear much about > it on the newswire... > > Dwight > > p.s. HALT - Highly Accelerated Life Testing > HASS - Highly Accelerated Stress Screening > > -- > > DWIGHT HUNNICUTT > Sr. Compliance Engineer > > > ** > * (510) 413-1349 direct * > * (510) 492-0808 fax * > * VINA Technologies,Inc. * > * 42709 Lawrence Place* > * Fremont, CA 94538 * > >
Re: HALT/HASS Testing
Dwight: As you may be aware, there is a major push to use COTS (commercial off-the- shelf) hardware in military and space systems for non-critical (i.e., not life threatening or the equivalent for non-repairable spaceborne systems). The clear implication is that cool-running, functionally-efficient, state-of-the- art (i.e., designed and built with current, leading-edge technology) commercial designs are respectable in performance AND of high quality, while costing less than full mil-spec systems. With the exception of the actual test schedule/time, IF your designers have PROPERLY done their job AND your prototype construction is representative of your production quality for device heatsinking (or other cooling method) and solder connections, your company should benefit from HALT/HASS testing. It will serve to alert managers to incompetent designers and also (very importantly) avoid the reputation- and cost-damaging effects of multiple field failures. Field failures always directly affect a company's bottom-line profits. I recommend a full speed ahead attitude with the expectation that some weaknesses that NEED CORRECTING will be identified. Such testing gives designers a better perspective on the end use of the hardware, rather than just thinking in ones and zeros and only being "terminal literate" (one of my favorite phrases). Respectable hardware quality in the marketplace generally brings both professional AND monetary rewards to a company (Hewlett-Packard test and measurement equipment comes to mind). Good Engineering to you, Mike Conn Owner/Principal Consultant Mikon Consulting
