Highly accelerated life test

A highly accelerated life test (HALT), is a stress testing methodology for enhancing product reliability. HALT testing is currently in use by most major manufacturing and research & development organizations to improve product reliability in a variety of industries, including electronics, computer, medical and military.

HALT can be effectively used multiple times over a product's life time. During product development, it can find design weakness when changes are much less costly to make. By finding weaknesses and making changes early, HALT can lower product development costs and compress time to market. When HALT is used at the time a product is being introduced into the market, it can expose problems caused by new manufacturing processes. When used after a product has been introduced into the market, HALT can be used to audit product reliability caused by changes in components, manufacturing processes or suppliers etc.

Highly accelerated life testing (HALT) techniques are important in uncovering many of the weak links of a new product. These discovery tests rapidly find weaknesses using accelerated stress conditions. The goal of HALT is to proactively find weaknesses and fix them thereby increasing product reliability. Because of its accelerated nature, HALT is typically faster and less expensive than traditional testing techniques.

HALT is the Test Technique called as Test-to-Fail where product is tested till failure. HALT does not help to determine or demonstrate the Reliability Value or failure probability in field. Many of the Accelerated life test are Test-to-Pass, means they are used to demonstrate the Product life or Reliability.

HALT is done in separate chamber and its highly recommended to performed in the initial phases of product development to uncover weak links in product, so that there is much chance and time to modify and improve the product.

HALT uses several stress factors (decided by Reliability Test Engineer) and/or the combination of various factors. Commonly used stress factors are Temperature, Vibration, Humidity etc for Electronics and Mechanical Products. Other factors can include Voltage, current, power Cycling and combination of them.

Environmental stresses are applied in a HALT procedure, eventually reaching a level significantly beyond that expected during use. The stresses used in HALT are typically hot and cold temperatures, temperature cycles, random vibration, power margining and power cycling. The product under test is in operation during HALT and is continuously monitored for failures. As stress-induced failures occur, the cause should be determined, and if possible, the problem should be repaired so that the test can continue to find other weaknesses.

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