Circuit Boards Example

Circuit Boards Example

Twenty-seven circuit boards were tested with temperature as the accelerated stress (or stimuli). The goal was to estimate the reliability after 10 years at 100ºC. The circuit boards were tested and the following data obtained:

Test Chamber Temperature 463K
# of units	Time, hr	Observation
1	2,403	Failure
1	2,668	Unrelated Failure
1	3,669	Test Fixture Failure
1	3,863	Failure
2	4,400	Test Fixture Failure
2	4,767	Failure
1	5,219	Failure
4	5,276	Power Surge Failure
2	7,517	Failure
1	7,840	Failure
2	8,025	Failure
1	8,571	Removed - Test Terminated

Test Chamber Temperature 488K
# of units	Time, hr	Observation
2	346	Power Regulator Failure
1	1,416	Failure
1	2,197	Unrelated Failure
1	2,533	Failure
1	2,630	Failure
1	2,701	Test Fixture Failure
1	3,000	Failure
1	3,489	Failure
1	6,720	Removed - Test Terminated

The data were entered in ALTA and analyzed utilizing an Arrhenius-Weibull model. Note that all units that did not fail in the test but failed for unrelated reasons were entered as suspensions. The reliability after 10 years at 100ºC is 45.67% as shown in the next figure.

Reliability plot at use stress level