Rubyca Jaai1, Michael Pecht1, and Jason Cook2
1CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
2U.S. Army, ARDEC, USA
Abstract:
A failure precursor is a measurable parameter which
provides an indication of impending failure. By detecting
changes in these precursors, deviation of the system from its
healthy state can be detected early and unanticipated failures
can be avoided. The case study illustrates the use of
Multivariate State Estimation Technique (MSET) and
Sequential Probability Ratio Test (SPRT) to detect the onset of
failure in Ball Grid Arrays (BGA) subjected to Accelerated
Temperature Cycling (ATC) tests. The residuals from MSET
show a shift in their distribution as they degrade; SPRT
detects the anomalous behavior (degradation) in the
interconnects. The time to detection of anomalies was found to
be earlier than the time to failure of the BGA interconnects,
providing a prognostic distance. Hence the change in
resistance of the BGA can be used as a precursor to failure.