The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Numerical Simulations for Reliability Assessment of Lead-Free Solder Interconnections in BGA Packages

Jue Li

Doctoral dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the School of Electrical Engineering for public examination and debate in Auditorium S4 at the Aalto University School of Electrical Engineering (Espoo, Finland) on the 21st of June 2011 at 12 noon.

Overview in PDF format (ISBN 978-952-60-4147-6)   [2189 KB]
Dissertation is also available in print (ISBN 978-952-60-4146-9)

Abstract

This work presents the results of computer-aided numerical simulations for the reliability assessment of lead-free solder interconnections in BGA packages. The finite element and Monte Carlo methods were employed for the macroscale structural and the mesoscale microstructural simulations, respectively. The major reliability tests for electronic component boards, i.e. thermal cycling, power cycling and drop impact tests, were simulated via the finite element method. The results provide a feasible tool for a better understanding of the observed failure modes in the reliability tests. The lifetime predictions based on the simulation results are helpful for the lifetime estimations of the BGA packages. The temperature effects on the drop impact reliability of the BGA packages were successfully elucidated by the finite element numerical experiments. In addition, a new algorithm was developed in order to predict dynamic recrystallization in solder interconnections during thermal cycling. The approach was realized by combining the Potts model based Monte Carlo method and the finite element method. The correlation between real time and Monte Carlo simulation time was established with the help of the in situ test results. Recrystallization with the presence of intermetallic particles in the solder matrix was simulated by introducing the energy amplification factors in the particle-affected deformation regions. The present algorithm predicted both the incubation period of the recrystallization as well as the growth tendency of the recrystallized regions in a way consistent with the experimental findings.

This thesis consists of an overview and of the following 6 publications:

  1. Jue Li, Juha Karppinen, Tomi Laurila, and Jorma Kalevi Kivilahti. 2009. Reliability of lead-free solder interconnections in thermal and power cycling tests. IEEE Transactions on Components and Packaging Technologies, volume 32, number 2, pages 302-308.
  2. Jue Li, Toni T. Mattila, and Jorma K. Kivilahti. 2009. Computational assessment of the effects of temperature on wafer-level component boards in drop tests. IEEE Transactions on Components and Packaging Technologies, volume 32, number 1, pages 38-43.
  3. J. Li, T. T. Mattila, H. Xu, and M. Paulasto. 2010. FEM simulations for reliability assessment of component boards drop tested at various temperatures. Simulation Modelling Practice and Theory, volume 18, number 9, pages 1355-1364.
  4. J. Li, T. T. Mattila, and J. K. Kivilahti. 2010. Multiscale simulation of microstructural changes in solder interconnections during thermal cycling. Journal of Electronic Materials, volume 39, number 1, pages 77-84.
  5. J. Li, H. Xu, T. T. Mattila, J. K. Kivilahti, T. Laurila, and M. Paulasto-Kröckel. 2010. Simulation of dynamic recrystallization in solder interconnections during thermal cycling. Computational Materials Science, volume 50, number 2, pages 690-697.
  6. Jue Li, Hongbo Xu, Jussi Hokka, Toni T. Mattila, Hongtao Chen, and Mervi Paulasto-Kröckel. 2011. Finite element analyses and lifetime predictions for SnAgCu solder interconnections in thermal shock tests. Soldering & Surface Mount Technology, volume 23, number 3, pages 161-167.

Keywords: ball grid array, drop impact, finite element method, Monte Carlo, recrystallization, thermal cycling

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Last update 2011-10-05