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Reliability physics behind the QFN state of stress

Journal of Materials Science: Materials in Electronics volume 28, pages 2160–2171 (2017)Cite this article

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Abstract

A physically meaningful analytical stress model is developed for the explanation of the reliability physics underlying the relief in the thermally induced interfacial shearing stresses in a typical Quad Flat No-lead (QFN) assembly. The stress relief in a QFN design is, in effect, an implementation of the general concept developed and quantified by the first author about a decade ago of using inhomogeneous bonds for lower thermal stresses in adhesively bonded or soldered assemblies. It is shown also that the maximum stress in the QFN design can be minimized, if the lengths of the peripheral zones are established based on the requirement that the stresses at the ends of the assembly are made equal to the stresses at the ends of its mid-portion. In the carried out numerical example the gain in the relief in the maximum interfacial shearing stress owing to the application of a bond with an elevated compliance is 9.94 %. When the optimized inhomogeneous bond is applied, the gain is 16.87 %. The gain in the stress relief owing to the optimized inhomogeneous bond (with respect to the homogeneous compliant bond) is 10.66 %. The computed interfacial stresses are below the yield stress of the solder material.

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References

  1. J. Lau (ed.), Solder Joint Reliability: Theory and Applications (Van Nostrand Reinhold, New York, 1990)

    Google Scholar 

  2. J.-P. Clech, F.M. Langerman, J.A. Augis, Local CTE mismatch in SM leaded packages: a potential reliability concern, in Proceedings of 40th Electronic Components and Technology Conference, Las Vegas, NE (1990), p. 377

  3. W. Engelmaier, Reliability for surface mount solder joints: physics and statistics of failure, in Proceeding of Surface Mount International, Vol. 1, San Jose, CA (1992), p. 433

  4. E. Suhir, Stresses in bi-metal thermostats. ASME J. Appl. Mech. 53(3), 657–660 (1986)

    Article  Google Scholar 

  5. E. Suhir, Interfacial stresses in bi-metal thermostats. ASME J. Appl. Mech. 56(3), 595–600 (1989)

    Article  Google Scholar 

  6. A.Y. Kuo, Thermal stress at the edge of a bi-metallic thermostat. ASME J. Appl. Mech. 57, 585–589 (1990)

    Google Scholar 

  7. JEDEC MO-247, Plastic quad no-lead staggered multi-row packages, Issue A (2003)

  8. D.V. Retuta, B.K. Lim, H.B. Tan, Design and process optimization for dual row QFN, in ECTC (2006)

  9. S. Abdullah, M.F. Abdullah, A.K. Ariffin, Z.A. Aziz, M.J.Ghazali, Thermal-mechanical analysis of a QFN stacked-die leadframe under reflow process, in World Congress on Engineering (WCE), London, UK (2008)

  10. C. Caswell, Manufacturing and reliability challenges with QFN, in IMAPS Conference, Atlantic City, NJ (2010)

  11. S. Krishnamoorthi, K.Y. Goh, D.Y.R. Chong, R. Kapoor, A.Y.S. Sun, Thermal characterization of thermally enhanced QFN package, in EPTC (2003)

  12. JEDEC MO-257, Plastic fine pitch quad no-lead staggered two-row thermally enhanced package family, Issue B (2005)

  13. JEDEC, Thermally enhanced plastic very thin and very-very thin fine pitch quad flat no lead package, MO-220, Rev. K (2011)

  14. JEDEC, Thermally enhanced plastic very thin and very-very thin fine pitch small outline no lead package, MO-229, Rev. E (2011)

  15. A. Syed, W.-J. Kang, Board level assembly and reliability considerations for QFN type packages, in SMTA International (2003)

  16. B.K. Lim, K.S.F. Poh, D.Y.R. Chong, S.W. Kow, Improving the reliability of quad flat no-lead packages through test and structural optimization, in ECTC (2004)

  17. S. Sytsma, M. Wrightson, Lead-free solder durability testing at accelerated thermal excursions for QFN and DFN package interconnections, in SMTA Pan Pacific Symposium (2007)

  18. G. Xia, F. Qin, W. Zhu, Comparative analysis of reliability between dual row and conventional QFN packages, in International Conference on Electronic Packaging (2012)

  19. L. Li, Reliability modeling and testing of advanced QFN packages, in ECTC (2013)

  20. P. Vianco, M.K. Neilsen, Thermal mechanical fatigue of a 56 I/O plastic quad-flat no-lead (PQFN) package, in SMTA International, Rosemont, IL (2015)

  21. C. Yin, S. Stoyanov, C. Bailey, P. Stewart, S. McCallum, Reliability assessment of QFN components for aerospace applications, in ECTC (2016)

  22. E. Suhir, Predicted thermal mismatch stresses in a cylindrical bi-material assembly adhesively bonded at the ends. ASME J. Appl. Mech. 64(1), 15–22 (1997)

    Article  Google Scholar 

  23. E. Suhir, Adhesively bonded assemblies with identical nondeformable adherends and inhomogeneous adhesive layer: predicted thermal stresses in the adhesive. J. Reinf. Plast. Compos. 17(14), 951–972 (1998)

    Google Scholar 

  24. E. Suhir, Thermal stress in a polymer coated optical glass fiber with a low modulus coating at the ends. J. Mater. Res. 16(10), 2996–3004 (2001)

    Article  Google Scholar 

  25. E. Suhir, Thermal stress in a bi-material assembly adhesively bonded at the ends. J. Appl. Phys. 89(1), 120–129 (2001)

    Article  Google Scholar 

  26. E. Suhir, Thermal stress in an adhesively bonded joint with a low modulus adhesive layer at the ends. J. Appl. Phys. 93, 3657–3661 (2003)

    Article  Google Scholar 

  27. E. Suhir, Interfacial thermal stresses in a bi-material assembly with a low-yield-stress bonding layer. Model. Simul. Mater. Sci. Eng. 14, 1421 (2006)

    Article  Google Scholar 

  28. E. Suhir, On a paradoxical situation related to bonded joints: could stiffer mid-portions of a compliant attachment result in lower thermal stress? JSME J. Solid Mech. Mater. Eng. (JSMME) 3(7), 990–997 (2009)

    Article  Google Scholar 

  29. E. Suhir, Thermal stress in a bi-material assembly with a ‘piecewise-continuous’ bonding layer: theorem of three axial forces. J. Phys. D Appl. Phys. 42, 508–517 (2009)

    Google Scholar 

  30. E. Suhir, A. Shakouri, Assembly bonded at the ends: could thinner and longer legs result in a lower thermal stress in a thermoelectric module (TEM) design? ASME J. Appl. Mech. 79(6), 061010-1–061010-8 (2012)

    Article  Google Scholar 

  31. E. Suhir, L. Bechou, B. Levrier, Predicted size of an inelastic zone in a ball-grid-array assembly. ASME J. Appl. Mech. 80, 021007-1–021007-5 (2013)

    Google Scholar 

  32. E. Suhir, Predicted stresses in a ball-grid-array (BGA)/column-grid-array (CGA) assembly with a low modulus solder at its ends. J. Mater. Sci. Mater. Electron. 26(12), 9680–9688 (2015)

    Article  Google Scholar 

  33. E. Suhir, Expected stress relief in a bi-material inhomogeneously bonded assembly with a low-modulus-and/or-low-fabrication-temperature bonding material at the ends. J. Mater. Sci. Mater. Electron. 27(6), 5563–5574 (2016)

    Article  Google Scholar 

  34. E. Suhir, R. Ghaffarian, Predicted stresses in a ball-grid-array (BGA)/column-grid-array (CGA) assembly with epoxy adhesive at its ends. J. Mater. Sci. Mater. Electron. 27(5), 4399–4409 (2016)

    Article  Google Scholar 

  35. E. Suhir, Bi-material assembly with a low-modulus-and/or-low-fabrication-temperature bonding material at its ends: optimized stress relief. J. Mater. Sci. Mater. Electron. 27(5), 4816–4825 (2016)

    Article  Google Scholar 

  36. E. Suhir, R. Ghaffarian, J. Nicolics, Could thermal stresses in an inhomogeneous BGA/CGA system be predicted using a model for a homogeneously bonded assembly? J. Mater. Sci. Mater. Electron. 27(1), 570–579 (2016)

    Article  Google Scholar 

  37. E. Suhir, Avoiding low-cycle fatigue in solder material using inhomogeneous column-grid-array (CGA) design. ChipScale Rev. (2016)

  38. S.P. Timoshenko, S. Woinowsky-Krieger, Theory of Plates and Shells (Van-Nostrand Reinhold, New York, 1940)

    Google Scholar 

  39. E. Suhir, Structural Analysis in Microelectronics and Fiber Optics (Van-Nostrand Reinhold, New-York, 1991)

    Book  Google Scholar 

  40. V. Mishkevich, E. Suhir, Simplified approach to the evaluation of thermally induced stresses in bi-material structures, in Structural Analysis in Microelectronics and Fiber Optics, ed. by E. Suhir (ASME Press, New York, 1993), pp. 563–572

    Google Scholar 

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Authors and Affiliations

  1. Portland State University, Portland, OR, USA

    E. Suhir & S. Yi

  2. ERS Co., 727 Alvina Ct., Los Altos, CA, 94024, USA

    E. Suhir

  3. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

    R. Ghaffarian

Authors
  1. E. Suhir
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  2. R. Ghaffarian
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  3. S. Yi
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Correspondence to E. Suhir.

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Suhir, E., Ghaffarian, R. & Yi, S. Reliability physics behind the QFN state of stress. J Mater Sci: Mater Electron 28, 2160–2171 (2017). https://doi.org/10.1007/s10854-016-5781-x

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  • DOI: https://doi.org/10.1007/s10854-016-5781-x

Keywords

  • Print Circuit Board
  • Interfacial Stress
  • Flexural Rigidity
  • Interfacial Shearing Stress
  • Bonding Layer