Acoustic Emission Analysis for Fatigue Prediction of Lap Solder Joints in Mode Two Shear

Proceedings of IPACK'01 The Pacific Rim/ASME International Electronic Packaging Technical Conference and Exhibition July 8–13, 2001, Kauai, Hawaii, USA

DRAFT

IPACK2001-15680

ACOUSTIC EMISSION ANALYSIS FOR FATIGUE PREDICTION OF LAP SOLDER JOINTS IN MODE TWO SHEAR

1LT Bryan J. Van De Wal Benet Weapons Laboratory U.S. Army Research, Development, Engineering Command Dr. Bahgat Sammakia Department of Mechanical Engineering State University of New York at Binghamton Dr. Gay Kendall Benet Weapons Laboratory U.S. Army Research, Development, Engineering Command Dr. James Constable Department of Electrical Engineering State University of New York at Binghamton

Dr. C. Sahay, P.E. Chair, Department of Mechanical Engineering University of Connecticut at Hartford

ABSTRACT This current research method combined the disciplines of Fractography, ConFocal© analysis, and Acoustic Emission to discover and identify failure modes of eutectic (62%Sn36%Pb2%Ag) solders (with and without rosin core flux) and lead free (99CSn-Cu) solder under cyclic displacement controlled Mode II shear fatigue. Results show a strong pattern of acoustic emission correlating to stages of failure. Three distinct stages were found “ Stage I” (crack initiation), “ Stage II” (nucleation), and “ Stage III” (failure and/or propagation). Time domain analysis shows distinct waveforms for each stage of fatigue. The frequency domain analysis shows a distinct pattern in the PSD. The combination of these two trends allows for a basis to predict solder joint fatigue in an acoustical manner utilizing acoustic emissions. Fractographic results support the trends seen in the acoustic emission analysis for each stage of fatigue. Dominant failure modes of specimens appeared to be intermetallic crack growth, grain coarsening, and dislocation energy effects. These failure modes can be explained in both the time and frequency responses of these specimens. Conclusion is that utilizing acoustic emissions with the...