Investigations on Microstructure and Mechanical Properties of the Cu/Pb-free Solder Joint Interfaces

This thesispresents a series of mechanical test methods and comprehensively investigatesthe deformation and damage behavior of Cu/Pb-free solder joints under differentloading conditions. The fracture behavior of Pb-free joint interfaces inducedby stress, deformation of solder and substrate are shown, the shear fracturestrength of the Cu6Sn5 IMC is measured experimentally for the first time, andthe dynamic damage process and microstructure evolution behavior of Pb-freesolder joints are revealed intuitively. The thesis puts forward the argumentthat the local cumulative damage is the major cause of failure in solderjoints. The research results provide the experimental and theoretical basis forimproving the reliability of solder joints.

Qingke Zhang Degree: Doctor of Engineering, Materials Science and EngineeringRewards: The Chinese Academy of Sciences Dean Reward, the Excellent Doctoral Dissertation of Chinese Academy of SciencesPublications:1. Zhang QK, and Zhang ZF, In-situ observations on creep-fatigue fracture behaviors of Sn-4Ag/Cu solder joints, Acta Mater., 59 (2011) 6017-6028.2. Zhang QK, and Zhang ZF, In-situ tensile creep behaviors of Sn-4Ag/Cu solder joints revealed by electron back-scatter diffraction, Scripta Mater., 67 (2012) 289-292.3. Zhang QK, Tan J, and Zhang ZF, Fracture behaviors and strength of Cu6Sn5 intermetallic compounds by indentation testing, J. Appl. Phys., 110 (2011) 014502.4. Zhang QK, and Zhang ZF, Influences of reflow time and strain rate on interfacial fracture behaviors of Sn-4Ag/Cu solder joints, J. Appl. Phys., 112 (2012) 064508.5. Zhang QK, Zhu QS, Zou HF, Zhang ZF, Fatigue fracture mechanisms of Cu/lead-free solders interfaces, Mater. Sci. Eng. A527 (2010) 1367-1376.6. Zhang QK, and Zhang ZF, In situ observations on shear and creep-fatigue fracture behaviors of SnBi/Cu solder joints, Mater. Sci. Eng. A528 (2011) 2686-2693.7. Zhang QK, and Zhang ZF, In-situ observations on fracture behaviors of Cu-Sn IMC layers induced by deformation of Cu substrates, Mater Sci Eng A530 (2011) 452-461.8. Zhang QK, and Zhang ZF, Thermal fatigue behaviors of Sn-4Ag/Cu solder joints at low strain amplitude, Mater Sci Eng A 580 (2013) 374-384.9. Zhang QK, Zou HF, and Zhang ZF, Improving tensile and fatigue properties of Sn-58Bi/Cu solder joints through alloying substrate, J. Mater. Res. 25 (2010) 303-314.10. Zhang QK, Zou HF, and Zhang ZF, Tensile and fatigue behaviors of aged Cu/Sn-4Ag solder joints, J. Electron. Mater., 38 (2009) 852-859. 11. Zhang QK, Zou HF, and Zhang ZF, Influences of substrate alloying and reflow temperature on Bi segregation behaviors at SnBi/Cu interface, J. Electron. Mater., 40 (2011) 2320-2328.12. Zhang QK, and Zhang ZF, Fracture mechanism and strength-influencing factors of Cu/Sn-4Ag solder joints aged for different times, J. Alloys Compds., 485 (2009) 853-861.13. Zhang QK, Zou HF, Zhang ZF. Bi segregation mechanisms and aging embrittlement prevention of SnBi/Cu interface (Review). Sci China-Tech Sci, 42 (2012) 13-21.14. Zou HF, Zhang QK, and Zhang ZF, Eliminating interfacial segregation and embrittlement of bismuth in SnBi/Cu couple by alloying Cu substrate, Scripta Mater., 61 (2009) 308-311.15. Zou HF, Zhang QK, and Zhang ZF, Transition of Bi embrittlement of SnBi/Cu joint couples with the reflow temperature, J. Mater. Res. 26 (2011) 449-454.16. Zou HF, Zhang QK, and Zhang ZF, Interfacial Microstructure and Growth Kinetics of Intermetallic Compound Layers in Sn-4wt%Ag/Cu-X (X=Zn, Ag, Sn) Couples, J. Electron. Mater., 40 (2011) 1542-1548.17. Zou HF, Zhang QK, and Zhang ZF, Interfacial microstructure and mechanical properties of SnBi/Cu joints by alloying Cu substrate, Mater. Sci. Eng. A532 (2012) 167-177.18. Yang, LM, Zhang QK, and Z