Effect of current stressing on the reliability of 63Sn37Pb solder joints
- 111 Downloads
The effect of current stressing on the reliability of 63Sn37Pb solder joints with Cu pads was investigated at temperatures of −5 °C and 125 °C up to 600 h. The samples were stressed with 3 A current (6.0 × 102 A/cm2 in the solder joint with diameter of 800 μm and 1.7 × 104 A/cm2 in the Cu trace with cross section area of 35 × 500 μm). The temperatures of the samples and interfacial reaction within the solder joints were examined. The microstructural change of the solder joints aged at 125 °C without current flow was also evaluated for comparison. It was confirmed that the current flow could cause the temperature of solder joints to rise rapidly and remarkably due to accumulation of massive Joule heat generated by the Cu trace. The solder joints stressed at 125 °C with 3 A current had an extensive growth of Cu6Sn5 and Cu3Sn intermetallic compounds (IMC) at both top and bottom solder-to-pad interfaces. It was a direct result of accelerated aging rather than an electromigration or thermomigration effect in this experiment. The kinetic is believed to be bulk diffusion controlled solid-state reaction, irrespective of the electron flow direction. When stressed at −5 °C with 3 A current, no significant change in microstructure and composition of the solder joints had occurred due to a very low diffusivity of the atoms as most Joule heat was eliminated at low temperature. The IMC evolution of the solder joints aged at 125 °C exhibited a subparabolic growth behavior, which is presumed to be a combined mechanism of grain boundary diffusion and bulk diffusion. This is mainly ascribed to the retardant effect against the diffusion course by the sufficiently thick IMC layer that was initially formed during the reflow soldering.
KeywordsSolder Joint Solder Ball Bulk Diffusion Joule Heat Organic Solderability Preservative
This work described herein was supported by a grant from the National Natural Science Foundation of China and Research Grants Council of Hong Kong Joint Research Scheme (Project No. N_CityU103/03). The authors wish to thank Prof. and Mrs. B. Ralph at Brunel, UK and Mr. C. W. Tan at Photonics Manufacturing Services (Shenzhen) in P.R. China.
- 1.Brandenburg S, Yeh S, in Proceedings of the Surface Mount International Conference and Exhibition, SMI98, San Jose, CA, August (SMTA, Edina, MN, 1998), p 337Google Scholar
- 11.Lai YS, Kao CL (2006) Electrothermal coupling analysis of current crowding and Joule heating in flip-chip packages. Microelectron Reliab, In Press, Available online 10 January 2006Google Scholar
- 13.Chiew HT (2004) Effect of Ni and Cu additive on electromigration in Sn solder joints and lines. Master Thesis, Department of Chemical and Materials Engineering, National Central University Chung-Li, Taiwan, June, 2004Google Scholar
- 15.Chen SW, Chen CM (2003) JOM-J Mineral Metal Mater Soc 55:62Google Scholar
- 16.Hu YC, Lin YH, Kao CR (2003) J Mater Res 18:2544Google Scholar
- 19.Roush W, Jaspal J (1982) In: Proceedings of the 32nd Electronic Components Conference, San Diego, CA, vol. 32, pp. 342–345Google Scholar
- 21.Huang AT, Gusak AM, Tu KN (2006) Appl Phys Lett 88, 141911:1–3Google Scholar
- 24.Mei Z, Sunwoo A, Morris JW (1992) Metallur Trans A 23A:857Google Scholar
- 25.Jung K, Conrad H (2001) J Electron Mater 30:1038Google Scholar
- 26.Roming AD, Chang JRYA, Stephens JJ, Frear DR, Marcotte V, Lea C (1991) In: Frear DR, Jones WJ, Kinsman KR (eds) Solder mechanics-A state of the art assessment. The Minerals, Metals and Materials Society, Warrendale, PA, USA, p 54Google Scholar