Advertisement

Heat and Mass Transfer

, Volume 46, Issue 11–12, pp 1315–1325 | Cite as

Effect of vertical stacking dies on flow behavior of epoxy molding compound during encapsulation of stacked-chip scale packages

  • C. Y. KhorEmail author
  • M. K. Abdullah
  • M. Z. Abdullah
  • M. Abdul Mujeebu
  • D. Ramdan
  • M. F. M. A. Majid
  • Z. M. Ariff
Original

Abstract

This paper presents three dimensional (3D) simulation of flow visualization in the encapsulation of stacked-chip scales packages (S-CSP), using finite volume method. The S-CSP model is constructed using GAMBIT and simulated using FLUENT CFD software. The epoxy molding compound is Hitachi CEL-9200 XU (LF) and its flow is assumed laminar and incompressible. Cross viscosity model and volume of fluid technique are applied for flow front tracking of the encapsulant. The meshing is performed using tetrahedral elements and the discretization is done by first order upwind scheme. SIMPLE algorithm is selected for solving the governing equations. The top view and 3D view of simulation flow front profiles in the encapsulation process are presented. The percentage of filled volume versus filling time, viscosity versus shear rate and number of voids versus rows of stacked die are plotted. The temperature and pressure distributions within the mold cavity during the encapsulation process are also observed. Further, the possibility and cause of void formation during the encapsulation process are analyzed and discussed in detail. The number of vertical stacking dies and horizontal rows of packages are found to be crucial in the void formation. The numerical results are compared with previous experimental results and found in good conformity.

Keywords

Finite Volume Method Void Formation Mold Filling Static Random Access Memory Encapsulation Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

A1, A2

Pre-exponential factors (1/s)

B

Exponential-fitted constant (Pa s)

C1, C2

Fitting constant

Cp

Specific heat (J/kg K)

E1, E2

Activation energies (K)

F

Front advancement parameter

k

Thermal conductivity (W/m K)

K1, K2

Rate parameters described by an Arrhenius temperature dependency (1/s)

L

Linear viscous operators

m1, m2

Constants for the reaction order

N

Non-linear viscous operators

n

Power law index

p

Pressure (Pa)

T

Temperature (K)

t

Time (s)

Tb

Temperature-fitted constant (K)

u

Fluid velocity component in x-direction (mm/s)

v

Fluid velocity component in y-direction (mm/s)

w

Fluid velocity component in z-direction (mm/s)

x, y, z

Cartesian coordinates

Greek symbols

α

Conversion of reaction

αgel

Degree of cure at gel

ΔH

Exothermic heat of polymerization (J/kg)

η

Viscosity (Pa s)

η0

Zero shear rate viscosity (Pa s)

ρ

Density (kg/m3)

τ

Shear stress (Pa)

\( \dot{\gamma } \)

Shear rate (1/s)

τ*

Parameter that describes the transition region between zero shear rates and the power law region of the viscosity curve (Pa)

Notes

Acknowledgments

The authors would like to thank the Ministry of Technology and Innovation, Malaysia and Universiti Sains Malaysia for the financial support for this research work.

References

  1. 1.
    Chang R-Y, Yang W-S, Chen, E, Lin C, Hsu C-H (1998) On the dynamics of air trap in the encapsulation process of microelectronics package. In: Proc. ANTEC’ 98 Conf., 1998, pp 1178–1180Google Scholar
  2. 2.
    Liang CW, Kulakarni VM, Narayana PAA, Seetharamu KN (2005) Parametric studies in transfer molding for Newtonian fluids. J Phys Sci 16(2):103–114Google Scholar
  3. 3.
    Kulkarni VM, Seetharamu KN, Azid IA, Narayana PAA, Quadir GA (2006) Numerical simulation of underfill encapsulation process based on characteristic split method. Int J Numer Meth Eng 66:1658–1671zbMATHCrossRefGoogle Scholar
  4. 4.
    Pei CC, Hwang SJ (2005) Three-dimensional paddle shift modelling for IC packaging. Trans ASME J Electron Packag 127:324–334CrossRefGoogle Scholar
  5. 5.
    Zhou T, Dreiza M (2004) Stacked die package design guidelines. In: Proc IMAPS conference, 17 November 2004Google Scholar
  6. 6.
    Fukui Y, Yano Y, Juso H, Matsune Y, Miyata K, Narai A, Sota Y, Takeda Y, Fujita K, Kada M (2000) Triple-chip stacked CSP. In: IEEE international electronic components and technology conference. 0-7803-5908-9/00Google Scholar
  7. 7.
    Kada M, Lee S (2000) Advancements in stacked chip scale packaging (S-CSP) provides system-in-a-package functionality for wireless and handheld applications. Future Fab Int 9Google Scholar
  8. 8.
    Sze MWH, Papageorge M (1998) Encapsulation selection, characterization and reliability for fine pitch BGA (fpBGA). In: 4th annual flip chip, BGA, chip scale packaging ‘98, 28–29 April 1998, pp 1–7Google Scholar
  9. 9.
    Lee MW, Kim JY, Yoo M, Chung JY, Lee CH (2006) Rheological characterization and full 3d mold flow simulation in multi-die stack CSP of chip array packaging. In: Electronic components and technology conference. 1-4244-0152-6/06Google Scholar
  10. 10.
    Nguyen L, Quentin C, Lee W, Bayyuk S, Bidstrup-Allen SA, Wang ST (2000) Computational modeling and validation of the encapsulation of plastic packages by transfer molding. Trans ASME J Electron Packag 122:138–146CrossRefGoogle Scholar
  11. 11.
    Turng LS, Wang VW (1993) On the simulation of microelectronic encapsulation with epoxy molding compound. J Reinf Plast Compos 12:506–519CrossRefGoogle Scholar
  12. 12.
    Han S, Wang KK (1995) Flow analysis in a cavity with lead frame during semiconductor chip encapsulation. Adv Electron Packag ASME EEP 10(1):73–78MathSciNetGoogle Scholar
  13. 13.
    Nguyen L (1993) Reactive flow simulation in transfer molding of IC packages. In: IEEE. Proceedings – Electronic Components and Technology Conference, pp 375–390. 0569-5503/93/0000-0375Google Scholar
  14. 14.
    Nguyen L, Jackson J, Teo CH, Chillara S, Asanasavest C, Burke T, Walberg R, Lo R, Weiler P, Ho D, Rauhut H (1997) Wire sweep control with mold compound formulation. 47th Electron. Comp. & Tech. Conf., pp 60–71Google Scholar
  15. 15.
    Kim SW, Turng LS (2004) Developments of three-dimensional computer-aided engineering simulation for injection molding. Inst Phys Publ Model Simul Mater Sci Eng 12:S151–S173CrossRefGoogle Scholar
  16. 16.
    Wan JW, Zhang WJ, Bergstrom D (2006) Recent advances in modeling the underfill process in flip-chip packaging. Microelectron J 38:67–75CrossRefGoogle Scholar
  17. 17.
    Wan JW, Zhang WJ, Bergstrom D (2009) Numerical modeling for the underfill flow in flip-chip packaging with a general-purpose finite element program. IEEE Trans Adv Electron Packag 32(2):227–234CrossRefGoogle Scholar
  18. 18.
    Abdullah MK, Abdullah MZ, Kamarudin S, Ariff ZM (2007) Study of flow visualization in stacked-chip scale packages (S-CSP). Int Commun Heat Mass Transf 34:820–828CrossRefGoogle Scholar
  19. 19.
    Abdullah MK, Abdullah MZ, Mujeebu MA, Kamaruddin S, Ariff ZM (2010) Three-dimensional modelling on effect of multi die-stacking shape in mould filling during encapsulation of microelectronic chips. IEEE Trans Adv Packag 33(2):438–446CrossRefGoogle Scholar
  20. 20.
    Abdullah MK, Abdullah MZ, Mujeebu MA, Kamaruddin S (2008) A study of effect of epoxy molding compound (EMC) rheology during encapsulation on stacked-CHIP scale packages (S-CSP). J Reinf Plast Compos 28(20):2527–2538CrossRefGoogle Scholar
  21. 21.
    Chang R-Y, Yang W-H, Hwang S-J, Su F (2004) Three-dimensional modelling of mold filling in microelectronics encapsulation process. IEEE Trans Compon Packag Technol 27(1):200–209CrossRefGoogle Scholar
  22. 22.
    Khor CY, Mujeebu MA, Abdullah MZ, Che Ani F (2010) Finite volume based CFD simulation of pressurized flip chip underfill encapsulation process. Microelectron Reliab 50:98–105CrossRefGoogle Scholar
  23. 23.
    Khor CY, Ariff ZM, Che Ani F, Mujeebu MA, Abdullah MK, Abdullah MZ, Joseph MA (2010) Three-dimensional numerical and experimental investigations on polymer rheology in meso-scale injection molding. Int Commun Heat Mass Transf 37:131–139CrossRefGoogle Scholar
  24. 24.
    Chen SC, Chen YC, Cheng NT (1998) Simulation of injection-compression mold-filling process. Int Commun Heat Mass Transf 25(7):907–917CrossRefGoogle Scholar
  25. 25.
    Geng T, Li DQ, Zhou HM (2006) Three-dimensional finite element method for the filling simulation of injection molding. Eng Comput 21:289–295CrossRefGoogle Scholar
  26. 26.
    Bidstrup-Allen SA, Wang ST, Nguyen LT, Arbalaez F (1997) Rheokinetics models for epoxy molding compounds used in IC encapsulation. In: IEEE PEP’97. 0-7803-3865-0/97Google Scholar
  27. 27.
    Modeling multiphase flow, FLUENT documentation, Chap. 23Google Scholar
  28. 28.
    Halley PJ, George GA (2009) Chemorheology of polymers: from fundamental principles to reactive processing. Cambridge University Press, New YorkCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • C. Y. Khor
    • 1
    Email author
  • M. K. Abdullah
    • 1
  • M. Z. Abdullah
    • 1
  • M. Abdul Mujeebu
    • 1
  • D. Ramdan
    • 1
  • M. F. M. A. Majid
    • 1
  • Z. M. Ariff
    • 2
  1. 1.School of Mechanical and Aerospace EngineeringUniversiti Sains MalaysiaNibong TebalMalaysia
  2. 2.School of Material and Mineral ResourcesUniversiti Sains MalaysiaNibong TebalMalaysia

Personalised recommendations