Microstructure of Solder Joint Interconnect in Used Mobile Phone


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A tin-lead solder is generally used to mount an electronic package on to a printed circuit board (PCB) of an electronic devices. In this study, we investigated the microstructure of the solder joint from a four years old used mobile phone. Microstructure and morphology of the joint was obtained using optical and scanning electron microscopy (OM and SEM) respectively. Cracks and voids can clearly be seen in the solder area for the most of the sample observed. Crack up to 10 μm wide appeared to be propagating along the solder line between Cu lead and Cu substrate. Energy dispersive X-ray (EDX) analysis revealed that cracks occurred at the richer tin content. It was not clear the exact mechanism that leads to the existence of the crack. However we believe that thermomechanical cause such as thermal fatigue, void formation and the thicker layer of intermetallic compound contributed to the failure of the solder joint.



Edited by:

A.K. Arof and S.A. Hashim Ali






S. N. Shahdan et al., "Microstructure of Solder Joint Interconnect in Used Mobile Phone", Materials Science Forum, Vol. 517, pp. 123-128, 2006

Online since:

June 2006




[1] N.M. Poon, C.M. Lawrence Wu, Joseph K.L. Lai and Y.C. Chan: Residual Shear Strength of Sn-Ag and Sn-Bi Lead-Free SMT Joints after Thermal Shock. IEEE Trans. Adv. Package Vol. 23. (2000).

DOI: 10.1109/6040.883762

[2] J.W. Yoon, S.W. Kim, S.B. Jung: IMC Morphology, Interfacial Reaction and Joint Reliability of Pb-free Sn-Ag-Cu Solder in Electrolytic Ni BGA Substrate. Journal of Alloy and Compounds. (2004), p.389.

DOI: 10.1016/j.jallcom.2004.09.045

[3] P.L. Wu, M.K. Hang, C. Lee, S.R. Tzan: Failure Behavior of Small Outline J Lead/Sn-X (X = AgCu or Pb) Solder Joints Under Thermomechanical Fatigue Test. Material Chemistry and Physics (2004), p.87.

DOI: 10.1016/j.matchemphys.2004.05.044

[4] Hongfang Wang, Mei Zhao, Qiang Guo: Vibration Fatigue Experiments of SMT Solder Joint. Microelectronics Reliability. (2004), p.44.

DOI: 10.1016/j.microrel.2004.01.008

[5] Y.H. Lin, Y.C. Hu, C.M. Tsai, C.R. Kao, K.N. Tu: In Situ Observation of the Void Formation-and-Propagation Mechanism in solder Joints Under Current-Stressing. Acta Materialia. (2005), p.53. IMC layer void.

DOI: 10.1016/j.actamat.2005.01.014

[6] B.Y. Wu, Y.C. Chan: Electric Current Effect on Microstructure of Ball Grid Array Solder Joint. Journal of Alloy and Compounds. (2004), p.425.

[7] J.W. Yoon, Y.H. lee, et al. Intermetallic Compound Layer Growth at the Interface Between Sn-Cu-Ni Solder and Cu Substrate. Journal of Alloy and Compounds. (2004), p.381.

[8] M. Yunus, K. Srihari, J. M. Pitarresi, A. Primavera: Effect of Voids on the reliability of BGA/CSP solder Joints: Microelectronics Reliability 43 (2003), p.2077-(2086).

DOI: 10.1016/s0026-2714(03)00124-0

[9] C. Basaran, M. Lin, H. Ye: A thermodynamic model for electrical current induced damage. International journal of solids and structures. 40 (2003), pp.7315-7327.

DOI: 10.1016/j.ijsolstr.2003.08.018

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