A strain range based model for life assessment of Pb-free SAC solder interconnects

This paper presents a strain based fatigue model for Pb-free SAC (Sn3.9Ag0.7Cu) solder interconnects based on the results of a designed experiment. Testing consists of temperature cycling CLCC packages soldered to printed wiring board under a fixed 100degC temperature range with the mid-point temperature varying between 25 and 75degC. In addition, the dwell (hold) time at the maximum temperature is varied between 15 and 75 minutes. The mean cycles to failure (N50) is related to the strain range using a numerical regression program. This strain-range failure model captures the observed transition point where fatigue life of SnPb solder is greater than Pb-free SAC solder. Further, the model captures the effect of extended dwell and changes in cycle temperature. The model can be used to predict acceleration factors between test and field conditions

[1]  H. Reichl,et al.  Fatigue life models for SnAgCu and SnPb solder joints evaluated by experiments and simulation , 2003, 53rd Electronic Components and Technology Conference, 2003. Proceedings..

[2]  W. Engelmaier.  Fatigue Life of Leadless Chip Carrier Solder Joints During Power Cycling , 1983 .

[3]  A. Primavera,et al.  Reliability and Failure Analysis of Lead-Free Solder Joints , 2002 .

[4]  Y. Matsuda,et al.  Development of environmentally preferred plastic ball grid array, PBGA, components , 2001, Proceedings Second International Symposium on Environmentally Conscious Design and Inverse Manufacturing.

[5]  J. Clech.  Lead-Free and Mixed Assembly Solder Joint Reliability Trends , 2004 .

[6]  A. Syed.  Reliability and Au embrittlement of lead free solders for BGA applications , 2001, Proceedings International Symposium on Advanced Packaging Materials Processes, Properties and Interfaces (IEEE Cat. No.01TH8562).

[7]  J.‐P. CIech,et al.  Solder Reliability Solutions: A PC‐based Design‐for‐reliability Tool* , 1997 .

[8]  R. Darveaux,et al.  Shear deformation of lead free solder joints , 2005, Proceedings Electronic Components and Technology, 2005. ECTC '05..

[9]  Michael Pecht,et al.  Solder Creep-Fatigue Analysis by an Energy-Partitioning Approach , 1992 .

[10]  Ahmer Syed,et al.  Predicting solder joint reliability for thermal, power, and bend cycle within 25% accuracy , 2001, 2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220).

[11]  A. Syed.  Accumulated creep strain and energy density based thermal fatigue life prediction models for SnAgCu solder joints , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).