Intermittent failure in electrical interconnection of avionics system

The intermittent failure is one of the causes of No-Fault-Found (NFF). Intermittent failure in electrical interconnections of avionics is intensively investigated. An avionics system vulnerable to the intermittent failure is identified and its mockup is constructed. Vibration and thermal cycling tests are conducted to generate intermittent failures in the interconnections of the mockup. Intermittent failures occur after the accelerated thermal cycling test in vibration environment. Failure analysis reveals a line of crack at the interconnection. The mechanism for the crack generation is explained by a numerical simulation. A hypothesis is suggested for the explanation of the occurrence of intermittent failure from the crack. A combined vibration and temperature test is conducted to verify the hypothesis. The test results follow the expectation of the hypothesis.