Long term reliability tests take extended periods of time Of

Long term reliability tests take extended periods of time. Often, high frequency tests are proposed to provide a number of stress reversals in a short period of time. When is this valid for predicting long term behavior from a short test duration? What would invalidate this as a reliability test method?

Solution

The increase in number of stress reversals in a short period of time is also known as Highly Accelerated Life Test. This test is valid to find the design weakness when changes are much less costly to make. The method lowers product development cost & the compress time to market.

The test finds weaknesses using accelerated stress conditions. Environmental stresses are applied in the test procedure , eventually reaching a level significantly beyond that expected during use. The stresses used in test are typically hot and cold temperatures, temperature cycles, random vibration, power margining and power cycling. The product under test is in operation during random cycle test 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.