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A diffusion-viscous analysis and experimental verification of defect formation in sintered silver bond-line

Published online by Cambridge University Press:  18 March 2014

Kewei Xiao ,
Khai D.T. Ngo  and
Guo-Quan Lu
Kewei Xiao
Affiliation:
Center for Power Electronics Systems, Virginia Tech, Blacksburg, Virginia 24061; and Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061
Khai D.T. Ngo
Affiliation:
Center for Power Electronics Systems, Virginia Tech, Blacksburg, Virginia 24061; and The Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061
Guo-Quan Lu*
Affiliation:
Center for Power Electronics Systems, Virginia Tech, Blacksburg, Virginia 24061; Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061; and The Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061
*
a)Address all correspondence to this author. e-mail: gqlu@vt.edu
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Abstract

The low-temperature joining technique (LTJT) by silver sintering is being implemented by major manufacturers of power electronic devices and modules for bonding power semiconductor chips. A common die-attach material used with LTJT is a silver paste consisting of silver powder (micrometer- or nanometer-sized particles) mixed in organic solvent and binder formulation. It is believed that the drying of the paste during the bonding process plays a critical role in determining the quality of the sintered bond-line. In this study, a model based on the diffusion of solvent molecules and viscous mechanics of the paste was introduced to determine the stress and strain states of the silver bond-line. A numerical simulation algorithm of the model was developed and coded in the C++ programming language. The numerical simulation allows determination of the time-dependent physical properties of the silver bond-line as the paste is being dried with a heating profile. The properties studied were solvent concentration, weight loss, shrinkage, stress, and strain. The stress is the cause of cracks in the bond-line and bond-line delamination. The simulated results were verified by experiments in which the formation of bond-line cracks and interface delamination was observed during the pressure-free drying of a die-attach nanosilver paste. The simulated results were consistent with our earlier experimental findings that the use of uniaxial pressure of a few mega-Pascals during the drying stage of a nanosilver paste was sufficient to produce high-quality sintered joints. The insight offered by this modeling study can be used to develop new paste formulations that enable pressure-free, low-temperature sintering of the die-attach material to significantly lower the cost of implementing the LTJT in manufacturing.

Keywords

bondingkineticssintering
Type
Articles
Information
Journal of Materials Research , Volume 29 , Issue 8 , 28 April 2014 , pp. 1006 - 1017
Copyright
Copyright © Materials Research Society 2014 

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References

REFERENCES

Lu, G.Q., Calata, J.N., Zhang, Z.Y., and Bai, J.G.: Lead-free, low-temperature sintering die-attach technique for high-performance and high-temperature packaging. In Proceedings of the Sixth IEEE CPMT Conference on High Density Microsystem Design and Packaging and Component Failure Analysis (Hdp'04), (IEEE, New York, NY, 2004); pp. 42–46.Google Scholar
Schulze, E., Mertens, C., and Lindemann, A.: Pure low temperature joining technique power module for automotive production needs. Presented at the 6th International Conference on Integrated Power Electronics Systems (CIPS), Nuremberg, Germany, 2010.Google Scholar
Glazer, J.: Microstructure and mechanical-properties of Pb-free solder alloys for low-cost electronic assembly: A review. J. Electron. Mater. 23, 693–700 (1994).Google Scholar
Zhang, Z. and Lu, G.Q.: Pressure-assisted low-temperature sintering of silver paste as an alternative die-attach solution to solder reflow. IEEE Trans. Electron. Packag. Manuf. 25, 279–283 (2002).Google Scholar
Bai, J.G., Zhang, Z.Z., Calata, J.N., and Lu, G.Q.: Low-temperature sintered nanoscale silver as a novel semiconductor device-metallized substrate interconnect material. IEEE Trans. Compon. Packag. Technol. 29, 589–593 (2006).Google Scholar
Knoerr, M. and Schletz, A.: Power semiconductor joining through sintering of silver nanoparticles: Evaluation of influence of parameters time, temperature and pressure on density, strength and reliability. Presented at the 6th International Conference on Integrated Power Electronics Systems (CIPS), Nuremberg, Germany, 2010.Google Scholar
Bai, J.G.F. and Lu, G.Q.: Thermomechanical reliability of low-temperature sintered silver die attached SiC power device assembly. IEEE Trans. Device Mater. Reliab. 6, 436–441 (2006).Google Scholar
Scheuermann, U.: Reliability challenges of automotive power electronics. Microelectron. Reliab. 49, 1319–1325 (2009).Google Scholar
Knoerr, M., Kraft, S., and Schletz, A.: Reliability assessment of sintered nano-silver die attachment for power semiconductors. In Electronics Packaging Technology Conference (EPTC), 2010 12th, (IEEE, New York, NY, 2010); pp. 56–61.CrossRefGoogle Scholar
Mayor, L. and Sereno, A.: Modelling shrinkage during convective drying of food materials: A review. J. Food Eng. 61, 373–386 (2004).CrossRefGoogle Scholar
Wang, N. and Brennan, J.G.: Changes in structure, density and porosity of potato during dehydration. J. Food Eng. 24, 61–76 (1995).Google Scholar
Perez, M. and Calvelo, A.: Modeling the thermal conductivity of cooked meat. J. Food Sci. 49, 152–156 (1984).Google Scholar
Bordia, R.K. and Scherer, G.W.: On constrained sintering—I. Constitutive model for a sintering body. Acta Metall. 36, 2393–2397 (1988).Google Scholar
Bordia, R.K. and Scherer, G.W.: On constrained sintering—II. Comparison of constitutive models. Acta Metall. 36, 2399–2409 (1988).CrossRefGoogle Scholar
Scherer, G.W.: Viscous sintering under a uniaxial load. J. Am. Ceram. Soc. 69, C–206–C–207 (1986).Google Scholar
Lu, G-Q., Sutterlin, R.C., and Gupta, T.K.: Effect of mismatched sintering kinetics on camber in a low-temperature cofired ceramic package. J. Am. Ceram. Soc. 76, 1907–1914 (1993).Google Scholar
Scherer, G.W.: Theory of drying. J. Am. Ceram. Soc. 73, 3–14 (1990).CrossRefGoogle Scholar
Bramhall, G.: The validity of Darcy's law in the axial penetration of wood. Wood Sci. Technol. 5, 121–134 (1971).Google Scholar
Van Brakel, J.: Pore space models for transport phenomena in porous media review and evaluation with special emphasis on capillary liquid transport. Powder Technol. 11, 205–236 (1975).Google Scholar
Bažant, Z. and Najjar, L.: Drying of concrete as a nonlinear diffusion problem. Cem. Concr. Res. 1, 461–473 (1971).Google Scholar
Bažant, Z. and Najjar, L.: Nonlinear water diffusion in nonsaturated concrete. Matér. Constr. 5, 3–20 (1972).Google Scholar
Bazǎnt, Z.P. and Raftshol, W.J.: Effect of cracking in drying and shrinkage specimens. Cem. Concr. Res. 12, 209–226 (1982).Google Scholar
Sakata, K.: A study on moisture diffusion in drying and drying shrinkage of concrete. Cem. Concr. Res. 13, 216–224 (1983).Google Scholar
Li, S.F. and Ong, H.M.: Infinite dilution diffusion coefficients of several alcohols in water. J. Chem. Eng. Data 35, 136–137 (1990).Google Scholar
Wang, T., Zhao, M.H., Chen, X., Lu, G.Q., Ngo, K., and Luo, S.F.: Shrinkage and sintering behavior of a low-temperature sinterable nanosilver die-attach paste. J. Electron. Mater. 41, 2543–2552 (2012).CrossRefGoogle Scholar
Xiao, K., Calata, J., Ngo, K., Ibitayo, D., and Lu, G-Q.: Large-area chip attachment by sintering nanosilver paste: Process improvement by nondestructive characterization. Trans. Jpn. Inst. Electron. Packag. 4, 101–109 (2011).Google Scholar