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'; 'nebs@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
