Polymeric encapsulant is widely used to protect the integrated circuit chips and thus to enhance the reliability of electronic packages. Residual stresses are introduced in the plastic package when the polymer is cooled from the curing temperature to ambient, from which many reliability issues arise, including warpage of the package, premature interfacial failure, and degraded interconnections. Bimaterial strip bending experiment has been employed successfully to monitor the evolution of the residual stresses in underfrill resins for flip chip applications. A numerical analysis is developed to predict the residual stresses, which agree well with the experimental measurements. The changes of material properties, such as flexural modulus and coefficient of thermal expansion, of the resins with temperature are taken into account in the finite element analysis.
Keywords:
resins,
polymers,
strips,
integrated circuit packaging,
integrated circuit reliability,
plastic packaging,
flip-chip devices,
internal stresses,
stress analysis,
thermal expansion,
failure analysis,
elastic moduli,
encapsulation,
bending,
shrinkage,
finite element analysis,
Residual Stress,
Underfill Resins,
Bi-Material Strip Bending (BMSB),
Finite Element Method
1.
Okura, J. H., Reinikainen, T., Dasgupta, A., and Caers, J. F. J. M., 2000, “Guidelines to Select Underfills for Flip Chip on Board Assemblies,” Proceeding 4th International Conference On Adhesive Joining & Coating Technology in Electronics Manufacturing, IEEE, pp. 86–92.
2.
Quinones, H., 1994, “Underfill Reliability, Why Underfilling Flip-Chip Improves Reliability,” Flip Chip and Ball Grid Array Conference in Sinagpore, Center for Management Technology, IEEE.
3.
Lee, C. Y., and Kim, J. K., 1998, “Measurements of Residual Stresses in Plastic Encapsulant,” Proc. 2nd Electronic Packaging Technology Conference (EPTC ’98), Singapore, A. O. Tay and T. B. Lim, eds., IEEE, pp. 286–290.
4.
Wu
, Z.
, Lu
, J.
, and Guo
, Y.
, 2000
, “A Study of Process-Indeced Residual Stress in PBGA Packages
,” ASME J. Electron. Packag.
, 122
, pp. 262
–266
.5.
Suhir
, E.
, and Manzione
, L. T.
, 1992
, “Predicted Bow of Plastic Packages Due to the Nonuniform Through Thickness Distribution of Temperature
,” ASME J. Electron. Packag.
, 114
, pp. 329
–335
.6.
Kong
, J. W. Y.
, Kim
, J. K.
, and Yuen
, M. M. F.
, 2003
, “Warpage in Plastic Packages: Effects of Materials, Geometry and Process Conditions
,” IEEE Trans. Compon., Packag. Manuf. Technol., Part C. Electr. Packag. Manuf.
, 26
, pp. 245
–252
.7.
Yeung
, D. T. S.
, and Yuen
, M. M. F.
, 2001
, “Warpage of Plastic IC Packages as a Function of Processing Conditions
,” ASME J. Electon. Packag.
, 123
, pp. 268
–272
.8.
Liu
, S.
, Zhu
, J.
, Zou
, D.
, and Benson
, J.
, 1997
, “Study of Delaminated Plastic Packages by High Temperature Moire´ and Finite Element Method
,” IEEE Trans. Compon., Packag. Manuf. Technol., Part A
, 20
(4
), pp. 505
–511
.9.
Zhang
, W.
, Wu
, D.
, Su
, B.
, Hareb
, S. A.
, Lee
, Y. C.
, and Masterson
, B. P.
, 1998
, “The Effect of Underfill Epoxy on Warpage in Flip-Chip Assemblies
,” IEEE Trans. Compon., Packag. Manuf. Technol., Part A
, 21
(2
), pp. 323
–329
.10.
Wang
, J.
, Ren
, W.
, Zou
, D.
, Qian
, Z.
, and Liu
, S.
, 1999
, “Processing Mechanics for Flip-Chip Assemblies
,” Comput. Struct.
, 71
, pp. 457
–468
.11.
Zou
, Y.
, Suhling
, J. C.
, Johnson
, R. W.
, Jaeger
, R. C.
, and Mian
, A. K. M.
, 1999
, “In-Situ Stress State Measurements During Chip-on-Board Assembly
,” IEEE Trans. Electron. Packag. Manufact.
, 22
, pp. 38
–52
.12.
Palaniappan
, P.
, Baldwin
, D. F.
, Selman
, P. J.
, Wu
, J.
, and Wong
, C. P.
, 1999
, “Correlation of Flip Chip Underfill Process Parameters and Material Properties With In-Process Stress Generation
,” IEEE Trans. Electron. Packag. Manufact.
, 22
, pp. 53
–62
.13.
Palaniappan
, P.
, and Baldwin
, D. F.
, 2000
, “In Process Stress Analysis of Flip-Chip Assemblies During Underfill Cure
,” Microelectron. Reliab.
, 40
, pp. 1181
–1190
.14.
Du
, Y.
, Zhao
, J.
, and Ho
, P.
, 2001
, “An Optical Method for Measuring the Two-Dimensional Surface Curvatures of Electronic Packages During Thermal Cycling
,” ASME J. Electon. Packag.
, 123
, pp. 196
–199
.15.
Lu, G., Kromann, G. B., Mogilevsky, B., and Gupta, T. K., 1992, “Evaluation of Die-Attach Adhesives by Curvature Measurements,” 1992 InterSociety Conference Thermal Phenomena, IEEE, 1992 I-Therm IV Intersociety Conference on Thermal Phenomena in Electronic Systems, Austin, Texas, pp. 155–158.
16.
Bogert, van den W. F., Molter, M. J., Gee, S. A., Belton, D. J., and Akylas, V. R., 1989, “Thermal Stress in Epoxy Molding Compounds and Packaged Devices,” ACS 407, Polymeric Materials for Electronics Packaging and Interconnection, J. H. Lupiuski and R. S. Moore, eds., American Chemistry Society, Washington, DC, Chap. 28.
17.
Biernath, R. W., and Soane, D. S., 1989, “Characterization of Stresses in Polymer Films for Microelectronics Applications,” “Thermal Stress in Epoxy Molding Compounds and Packaged Devices,” ACS 407, Polymeric Materials for Electronics Packaging and Interconnection, Lupiuski, J. H. and Moore, R. S., eds., American Chemistry Society, Washington, DC, Chap. 29.
18.
Djokic
, D.
, Johnston
, A.
, Rogers
, A.
, Lee-Sullivan
, P.
, and Mrad
, N.
, 2002
, “Residual Stress Development During the Composite Patch Bonding Process: Measurement and Modelling
,” Composites, Part A
, 33
, pp. 277
–288
.19.
Wang
, H. B.
, Yang
, Y. G.
, Yu
, H. H.
, Zhang
, Y. H.
, and Zhou
, H. W.
, 1995
, “Assessment of Residual Stresses During Cure and Cooling of Epoxy Resins
,” Polym. Eng. Sci.
, 35
(23
), pp. 1895
–1898
.20.
Sham, M. L., and Kim, J. K., 2001, “Measurement of Residual Stresses in Flip Chip Underfill Resins,” First International IEEE Conference on Polymers and Adhesives in Microelectronics and Photonics 2001, Helsinki, Finland, IEEE, pp. 160–167.
21.
Sham
, M. L.
, and Kim
, J. K.
, 2004
, “Evolution of Residual Stresses in Modified Epoxy Resins for Electronic Packaging Applications
,” Composites, Part A
, 35
, pp. 537
–546
.22.
Pang
, J. H. L.
, Tan
, T. I.
, Chong
, Y. R.
, Lim
, G. Y.
, and Wong
, C. L.
, 1998
, “Analysis of Underfill Encapsulation Curing Deformations on Flip Chip on Board (FCOB) Package Reliability
,” J. Electron. Manufact.
, 8
, pp. 181
–191
.23.
Sham, M. L., Xu, Z., and Kim, J. K., 2002, “Numerical Analysis of Delamination Failure and Interfacial Adhesion Measurements in Flip Chip Package,” 2002 International Conference Electron. Packaging, Tokyo, Japan, IEEE, pp. 278–283.
24.
Timoshenki
, S.
, 1925
, “Analysis of Bi-Metal Thermostats
,” J. Opt. Soc. Am.
, 11
, pp. 233
–255
.25.
Nakamura
, Y.
, Tabata
, H.
, Suzuki
, H.
, Iko
, K.
, Okube
, M.
, and Matsumoto
, T.
, 1986
, “Internal Stress of Epoxy Resin Modified With Acrylic Core-Shell Particles Prepared by Seeded Emulsion Polymerization
,” J. Appl. Polym. Sci.
, 32
, pp. 4865
–4871
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