Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

Abstract:

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

• Periodical: Materials Science Forum (Volumes 830-831)
• Pages: 265-269
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.830-831.265
• Online since: September 2015
• Authors: Satyanarayan Satyanarayan*, K.N. Prabhu
• Keywords: Lead-Free Solder, Roughness, Shear Energy Density, Shear Force, Wettability

References

[1] H. H. Manko, Solder and Soldering, 3rd ed., McGraw-Hill, Inc., New York, (1979).

[2] J.S. Hwang, Implementing lead-free electronics, McGraw-Hill, (2005).

[3] G. Kumar, K.N. Prabhu, J ASTM Int. 7(5) (2010) JAI103055.

[4] N.C. Lee, Adv Microelectron. (1999) pp.29-36.

[5] F.A. Mario, M. He, V.L. Acoff, J Electron Mater. 35(7) (2006) pp.1530-36.

[6] Satyanarayan, K.N. Prabhu, Adv. Colloid Interface Science. 166 (2011).

[7] G. Kumar, K.N. Prabhu, Adv. Colloid Interface Sci. 133 (2007) p.61–89.

[8] Satyanarayan, K.N. Prabhu, JASTM Int. 7(9)(2010)JAI103052.

[9] R. Mayappan, A.B. Ismail, Z.A. Ahmad, T. Ariga, L.B. Hussain, J. Teknologi. 46C (2007) p.1–14.

[10] K.N. Prabhu, G. Kumar, J Electron Packag. 132 (2010) 041001-7.

[11] D.R. Nalagatla, Master of Science thesis, The Graduate School, University of Kentucky (2007) (http: /archive. uky. edu/bitstream/10225/736/Thesis_Nalagatla. pdf, ) accessed on 10-12-(2010).

[12] Chen, Y.Y. and Duh, J.G., J. Mater. Sci. - Mater. Electron 11 (2000), 279-283.