A study on μBGA solder joints reliability using lead-free solder materials
- 144 Downloads
In this study, the numerical prediction of the thermal fatigue life of a μBGA (Micro Ball Grid Array) solder joint was focused. Numerical method was performed using the three-dimensional finite element analysis for various solder alloys such as Sn-37%Pb, Sn-3.5%Ag, Sn-3.5%Ag0.7%Cu and Sn-3.5%Ag-3%In-0.5%Bi during a given thermal cycling. Strain values obtained by the result of mechanical fatigue tests for solder alloys, were used to predict the solder joint fatigue life using the Coffin-Manson equation. The numerical results showed that Sn-3.5%Ag with the 50-degree ball shape geometry had the longest thermal fatigue life in low cycle fatigue. A practical correlation for the prediction of the thermal fatigue life was also suggested by using the dimensionless variable γ. Additionally Sn-3.5Ag-O.75Cu and Sn-2.0Ag-0.5Cu-2.0Bi were applied to 6X8μBGA obtained from the 63Sn-37Pb Solder. This 6X8μBGA were tested at different aging conditions at 130°C, 150°C, 170°C for 300, 600 and 900 hours. Thickness of the intermetallic compound layer was measured for each condition and the activation energy for their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS (Energy Dispersive Spectroscopy).
Key WordsThermal Fatigue Life Finite Element Method Lead-Free Solder Intermetallic Compound Solder Joint Micro Ball Grid Array
Unable to display preview. Download preview PDF.
- Coffin, L. F., Jr. and Schenectady. N. Y., 1954, “A Study of the Effect of Cyclic Thermal Stress on a Ductile Metal,”Transactions of the ASME. Vol. 76, pp. 932–950.Google Scholar
- Habu, K., 1999, “Development of New Pb-free Solder Alloy of Sn-Ag-Bi System,”Proceeding of the 1999 IEEE International Symposium on Electronics and the Environment, pp. 21–24.Google Scholar
- Kariya, Y., Kagawa, H. and Otsuka, M., 1998, “Effect of Strain Rate, Hold Time and Third Element on the Fatigue Damage of Sn-3.5mass Ag Alloy,”Microjoining and Assembly Technology in Electronics 98, pp. 259–264.Google Scholar
- Lau, John H. and Pao, Yi-Hsin, 1998,Solder Joint Reliability of BGA, CSP, Flip Chip and Fine Pithch S MT Assemblies, McGraw-Hill, p. 118.Google Scholar
- Lau, John H., Suresh Golwalkar and Steve Erasmus, 1993, “Advantages and Disadvantages of TSOP with Copper Gull-Wing Leads,”Advanced in Electronic Packaging ASME, EEP-Vol. 4- 2. pp. 1119–1126.Google Scholar
- Maeda, K., 1999, “Creep Effects on Solder Fatigue and Life time Prediction,”Microjoining and Assembly Technology in Electronics ’99, pp. 57–62.Google Scholar
- Oguchi, Y., Kariya, Y. and Otsuka, M., 1998, “Shear Fatigue Characteristics of Sn-Ag-Bi, Sn-Ag-Cu and Sn-Ag-In Solder Joint,”Microjoining and Assembly Technology in Electronics 98, pp. 253–258.Google Scholar
- Partridge, J. and Boysan, P., 1998, “Influence of Process Variables on the Reliability of Micro BGA package Assemblies,”IEEE, pp. 451–457.Google Scholar
- Robert Darveaux, 1995, “Optimizing the Reliability of Thin Small Outline Package (TSOP) Solder Joints,”Advanced in Electronic Packaging ASME, EEP-Vol. 10-2, pp. 675–685.Google Scholar
- Yao, Q. and Qu, J., 1999, “Three-Dimensional Versus Two Dimensional Finite Element Modeling of Flip-Chip Packages.”Transactions of the ASME, Vol. 121, pp. 196–201.Google Scholar
- Yao, Q., Qu, J. and Wu, S. X., 1999, “Estimate the Thermomechanical Fatigue Life of Two Chip Scale Packages,”IEEE Proceedings of the 49th Electronic Components & Technology Conference, pp. 797–802.Google Scholar