Micro-scale BGA has attracted more and more interest due to their high performance/area ratio. This technology is especially important for mobile personal equipment, such as cellular phones and laptop computers. With the decrease of solder ball sizes, the reliability problem becomes the major concern for the package design, which requires more powerful tools to address this issue. Finite element method is a useful tool for packaging design and analysis. For some BGAs, the critical solder balls are sometimes not located at a symmetric plane and the deformations in three directions will affect the distribution of stress/strain in these solder balls. Therefore, a full three-dimensional analysis is necessary to address these effects. However, it is almost impossible to run a three-dimensional single finite element model to consider all design details even with simplified material properties, not to mention creep constitutive law. Therefore, the global/local modeling technique provides an alternate way, which can simplify the modeling work’ Significantly, reduce the computational time, and enhance the crucial information at critical locations. In this study, the global/local technique was used to study a micro-scale BGA assembly and to investigate the three-dimensional effects of stress/strain distribution inside the solder joints. It was found that the maximum creep strain is not located at the plane passing through the package center and solder joint axis. It was also found that the position of maximum creep strain will shift during first several cycles, but will stabilize after the fourth cycle. This result is also helpful in evaluating the reliability of the critical solder joints in micro-scale BGA assemblies.

Issue Section:
Technical Papers
Topics:
Ball-Grid-Array packaging, Manufacturing, Microscale devices, Solder joints, Creep, Design, Solders, Cycles, Modeling, Reliability, Stress, Constitutive equations, Deformation, Finite element methods, Finite element model, Laptop computers, Materials properties, Packaging
1.
Buratynski, E. K., 1992, “Thermomechanical Modeling of Direct Chip Interconnect Assembly,” paper presented at ASME 92-WA/EEP-9, November 8–13, Anaheim, CA.
2.
Darveaux, R., 1997, “Solder Joint Fatigue Life Model,” presented at the 1997 Metallurgical Society Annual Meeting, Orlando, FL, February 9–13, 1997.
3.
Darveaux
R.
, and
Banerji
K.
,
1992
, “
Constitutive Relations for Tin-Based Solder Joints
,”
IEEE Transactions on Components, Hybrids, and Manufacturing Technology
, Vol.
15
, No.
6
, December, pp.
1013
–
1024
.
4.
Lau, J. H., and Pao, Y. H., 1997, Solder Joint Reliability of BGA, CSP, Flip Chip, and Fine Pitch SMT Assemblies, McGraw-Hill, New York.
5.
Liu, D. R., and Jairazbhoy, V. A., 1998, “Metal Screen Sandwiched solder joints for Long Thermal Cycling Life,” paper presented at the 1998 International Mechanical Engineering Congress & Exposition, Anaheim, CA, (98-WA/EEP-3), Nov. 15–20.
6.
Liu, S., 1992, “Damage Mechanics of Cross-Ply Laminates Resulting from Transverse Concentrated Loads,” Ph.D. thesis, Mechanical Engineering Dept., Stanford University, CA.
7.
Mukai, M., Kawakami, T., Takahashi, K., Iwasaki, K., and Kishimoto, K., 1997, “Thermal Fatigue Life of Solder Bumps in BGA,” Presented at the Pacific Rim/ASME International Intersociety Electronic & Photonic Packaging Conference (InterPACK’97), Kohala Coast, Hawaii, June 15–19.
8.
Simon, B. R., Yuan, Y., Umaretiya, J. R., Prince, J. L., and Staszak, Z. J., 1989, “Parametric Study of a VLSI Plastic Package Using Locally Refined Finite Element Models,” Proceedings, Fifth IEEE SEMI-THERM Symposium, pp. 52–58.
9.
Simon, B. R., Yuan, Y., Umaretiya, J. R., Bavirisetty, R., and Prince, J. L., 1990, “Thermal and Mechanical Finite Element Analysis of a VLSI Package Including Spatially Varying Thermal Contact Resistance,” Proceedings, Sixth IEEE SEMI-THERM Symposium, pp. 74–81.
10.
Stennett, M., Bonnell, R., and Villarreal, J., 1992, “Reliability Enhancement for Large Brazed Pin Ceramic Modules (Modeling and Assembly Process Modifications),” Proceedings, 1992 International Symposium on Microelectronics, San Francisco, CA, Oct. 19–21, pp. 643–647.
11.
Zhu, J., 1996, “Modeling and Validation of Thermally-Induced Failure Mechanisms in Microelectronic Packaging,” Ph.D. dissertation, Mechanical Engineering Department, Wayne State University, Detroit, MI.
12.
Zhu, J., Ojala, K., and Tuominen, A., 1997, “The Application of Global/Local Technique Infinite Element Simulation of BGA Assemblies,” presented at the ASME International Mechanical Engineering Congress & Exposition (97-WA/EEP-5), Dallas, Texas, Nov. 16–21.
13.
Zhu, J., 1999, “3-D Parametric FEA Models Of Electronic Packages,” presented at the 1999 International Mechanical Engineering Congress and Exhibition, Nashville, TN.
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