A small Pb-free solder joint exhibits an extremely strong anisotropy due to the bodycentered tetragonal (BCT) lattice structure of β-Sn.Grain orientations can significantly influence the failure mode of Pb-free solder joints under thermomechanical fatigue (TMF) due to the coefficient of thermal expansion (CTE) mismatch of β-Sn grains.The research work in this paper focused on the microstructure and damage evolution of Sn3.0Ag0.5Cu BGA packages as well as individual Sn3.5Ag solder joints without constraints introduced by the package structure under TMF tests.The microstructure and damage evolution in cross-sections of solder joints under thermomechanical shock tests were characterized using optical microscopy with cross-polarized light and scanning electron microscopy (SEM),and orientations of Sn grains were determined by orientation imaging microscopy (OIM).During TMF,obvious recrystallization regions were observed with different thermomechanical responses depending on Sn grain orientations.It indicates that substantial stresses can build up at grain boundaries,leading to significant grain boundary sliding.The results show that recrystallized grains prefer to nucleate along pre-existing high-angle grain boundaries and fatigue cracks tend to propagate intergranularly in recrystallized regions,leading to an accelerated damage after recrystallization.
参考文献
| [1] | T.T.MATTILA;J.K.KIVILAHTI .Failure Mechanisms of Lead-Free Chip Scale Package Interconnections under Fast Mechanical Loading[J].Journal of Electronic Materials,2005(7):969-976. |
| [2] | T. Laurila;T. Mattila;V. Vuorinen;J. Karppinen;J. Li;M. Sippola;J.K. Kivilahti .Evolution of microstructure and failure mechanism of lead-free solder interconnections in power cycling and thermal shock tests[J].Microelectronics and reliability,2007(7):1135-1144. |
| [3] | A.U. Telang;T.R. Bieler;A. Zamiri .Incremental recrystallization/grain growth driven by elastic strain energy release in a thermomechanically fatigued lead-free solder joint[J].Acta materialia,2007(7):2265-2277. |
| [4] | M.A. MATIN;E.W.C. COENEN;W.P. VELLINGA .Correlation Between Thermal Fatigue and Thermal Anisotropy in a Pb-Free Solder Alloy[J].Scripta materialia,2005(8):927-932. |
| [5] | H.T. CHEN;L. WANG;J. HAN;M.Y. LI;Q.B. WU;J.M. KIM .Grain Orientation Evolution and Deformation Behaviors in Pb-Free Solder Interconnects Under Mechanical Stresses[J].Journal of Electronic Materials,2011(12):2445-2457. |
| [6] | M. Erinc;P.J.G. Schreurs;M.G.D. Geers .Intergranular thermal fatigue damage evolution in SnAgCu lead-free solder[J].Mechanics of materials,2008(10):780-791. |
| [7] | J.G. Lee;K.N. Subramanian .Effects of TMF heating rates on damage accumulation and resultant mechanical behavior of Sn-Ag based solder joints[J].Microelectronics and reliability,2007(1):118-131. |
| [8] | S.Choi;J.G.Lee;K.N.Subramanian;J.P.Lucas;T.R.Bieler .Microstructural characterization of damage in thermomechanically fatigued Sn-Ag based solder joints[J].Journal of Electronic Materials,2002(4):292-297. |
| [9] | X.W. LIU;W.J. PLUMBRIDGE .Damage Produced in Solder Alloys during Thermal Cycling[J].Journal of Electronic Materials,2007(9):1111-1120. |
| [10] | S. TERASHIMA;T. KOHNO;A. MIZUSAWA;K. ARAI;O. OKADA;T. WAKABAYASHI;M. TANAKA;K. TATSUMI .Improvement of Thermal Fatigue Properties of Sn-Ag-Cu Lead-Free Solder Interconnects on Casio's Wafer-Level Packages Based on Morphology and Grain Boundary Character[J].Journal of Electronic Materials,2009(1):33-38. |
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