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FEA Improves Reliability of Flip-Chip Packaging

On Aug 10, 2009, Semiconductor International (SI) Newsbreak published a report on my work in AMD about 3D fracture study of underfill delamination as the top story in that issue.  I have never imagined that. Except the pleasure I received from this good news, I wonder if this work is also interesting to iMechanica community.  For that reason, I attach here the SI news report and the original paper published on ITherm2008 Proceedings. Welcome any comments and thoughts.


Links: 1. Semiconductor Internatinal Newsbreak top story. 

          2. Z. Zhang, C Zhai, and RN Master, “3D fracture mechanics analysis of underfill delamination for flip chip packages.” in the Proceedings of ITherm

2008. Orlando, Florida, USA. May 28-31, 2008, Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, pp.751-755,

2008.  Preprint . and DOI: 10.1109/ITHERM.2008.4544343 .




PDF icon Zhang, Zhai, Master @ ITherm2008.pdf561.81 KB


Interesting study!

After reading your paper, I have some questions:

1. If my understanding is correct, this is a thermal coupled problem. In such case, the strain field from displacement is not consistent with the strain field from temperature, which can sometimes cause large error. Do you use the same order of interpolation function to solve both the thermal and the elastic problems?

2. Did you use several models based on nested refinement mesh to compute? What I mean is that how you are sure that you got the converged results. The mesh you showed in the paper seems a little coarse.

3. Do you have any singularities in your model? Singularities can cause pollution error which can pollute the solution everywhere even the solution at the far field. How did you deal with singularities?

4. I think there are multi-material singularities in your thermal analysis. How did you handle them?




Hi Tony,

 Thank you for your interest and questions.

1. The temperature field is uniform. The temperature change is the applied load.  This is actually not a coupled problem. 

2. Yes. I did. Actually, except the study of mesh sensitivity on global model I presented in the paper, I also use global-local submodeling technique to verify the mesh sensitivity, which is not presented in the paper.  About the convergence, you can request 5 or more contour integral results for each segment along crack front in Abaqus. You can see if the results from contours 2 to 5 are close enough. 

3. Yes, inverse square root singularities are implemented since I am only interested in linear elastic fracture mechanics in this study. Of course, since this is an interfacial cracking issue, the singularities are complex. But this issue has been solved very well since Rice (1988 JAM).  I don't get at what you mean by pollution error here. Coul d you please explain more? 

4. I did not solve any heat transfer problem in this study actually. 



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