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Comparisons of Solder Joints Fatigue Life Predictions and Several Long-Term Testing Results

: Dudek, R.; Kreyssig, K.; Rzepka, S.; Novak, M.; Grübl, W.; Frühauf, P.; Weigert, A.


Institute of Electrical and Electronics Engineers -IEEE-; International Electronics Packaging Society -IEPS-:
18th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2019. Proceedings : May 28 - 31, 2019, Las Vegas, Nevada, USA
Piscataway, NJ: IEEE, 2019
ISBN: 978-1-72812-461-2
ISBN: 978-1-72812-460-5
ISBN: 978-1-72812-462-9
Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm) <18, 2019, Las Vegas/Nev.>
Bundesministerium für Bildung und Forschung BMBF (Deutschland)
16ES0558; radar4FAD
Fraunhofer ENAS ()

Solder fatigue phenomena on lead-free solder joints have been subject of numerous studies. In most cases, reference was made to test cycling conditions. To address the reliability of solder joints subjected to service conditions, long-term studies have been made using two test setups. The first used a standard industrial board with either SAC 305 or Innolot joints and cycling conditions 22 degrees C/95 degrees C, 6 hours, and the other one a test board with SAC 357 joints and cycling conditions 18 degrees C/80 degrees C, 7.1 hours. Both cyclic conditions have been applied for approximately ten years. The tests have reached solder fatigue failure for the most critical components, which are reported in the paper. Acceleration factors are additionally reported for these components related to test cycling results performed in parallel. Two predictive methodologies were applied to evaluate the acceleration prediction by the testing results: analytical models of Norris/Landzberg type and numerical modeling (FEA). It is shown that the estimates of acceleration factors from published Norris/Landzberg formulas result in a wide span of predictive results. The solder damage prediction based on FEA is finally shown to be on the safe side, but its usefulness also for service conditions is obvious.