Circuit Boards Example

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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