Simulation-enhanced qualification of printed wiring board-level reliability in microelectronics

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Doctoral thesis (article-based)
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Electronics Production Technology Unit / Helsinki University of Technology, 19
In this thesis a new method was developed for relating PWB-level reliability test results to service environment performance, with the emphasis on solder joint reliability. The method consists of both experimental testing and virtual computer simulations. Realistic computer simulations demand the use of appropriate material models and correctly determined material parameters. For this purpose, a new materials testing method, the grooved-lap test, was developed for accurate assessment of solder deformation properties, especially in the case of small solder volumes. The benefits of the new testing method, in comparison to the conventional ones, was demonstrated with the help of finite-element simulations as well as analytically. It was shown by using the new grooved-lap test and uniaxial tests that under thermal stress conditions Sn-based solders exhibit various rate-controlling deformation mechanisms, such as dislocation climb controlled and dislocation viscous glide controlled creep. The rate-controlling deformation mechanisms were assessed for Sn2Ag0.5Cu, Sn3.4Ag0.8Cu, and Sn4Ag0.5Cu solders with the grooved-lap test. Furthermore, the measured data were implemented into a constitutive model, which can be used in finite-element simulation programs. This procedure enables the utilization of the life-prediction method for evaluating and developing new hardware components, being assembled with Pb-free alloys.
materials testing methods, reliability, solder joints, microelectronic components, material properties, modelling
Other note
  • [Publication 1]: Virpi Pennanen, Markku Tammenmaa, Tommi Reinikainen, Jiansen Zhu, and Wei Lin. 2000. TBGA reliability in telecom environment. Soldering & Surface Mount Technology, volume 12, number 2, pages 42-46.
  • [Publication 2]: T. Reinikainen, F. W. Wulff, W. Kolbe, and T. Ahrens. 1995. A new method to determine crack shape and size in solder joints. Journal of Electronic Packaging, volume 117, number 4, pages 266-269.
  • [Publication 3]: T. Reinikainen, M. Poech, M. Krumm, and J. Kivilahti. 1998. A finite-element and experimental analysis of stress distribution in various shear tests for solder joints. Journal of Electronic Packaging, volume 120, number 1, pages 106-113.
  • [Publication 4]: E. Suhir and T. Reinikainen. 2008. On a paradoxical situation related to lap shear joints: could transverse grooves in the adherends reduce the interfacial stresses? Journal of Physics D: Applied Physics, volume 41, number 11, 115505.
  • [Publication 5]: T. Reinikainen and J. Kivilahti. 1999. Deformation behavior of dilute SnBi(0.5 to 6 at. pct) solid solutions. Metallurgical and Materials Transactions A, volume 30, number 1, pages 123-132.
  • [Publication 6]: T. O. Reinikainen, P. Marjamäki, and J. K. Kivilahti. 2005. Deformation characteristics and microstructural evolution of SnAgCu solder joints. In: L. J. Ernst, C. Q. Zhang, P. Rodgers, S. Marco, M. Meuwissen, and O. de Saint Leger (editors). Proceedings of the 6th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Micro-Electronics and Micro-Systems (EuroSimE 2005). Berlin, Germany. 18-20 April 2005. IEEE/CPMT, pages 91-98.