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


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.


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)


Exponential-fitted constant (Pa s)

C1, C2

Fitting constant


Specific heat (J/kg K)

E1, E2

Activation energies (K)


Front advancement parameter


Thermal conductivity (W/m K)

K1, K2

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


Linear viscous operators

m1, m2

Constants for the reaction order


Non-linear viscous operators


Power law index


Pressure (Pa)


Temperature (K)


Time (s)


Temperature-fitted constant (K)


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


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


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

x, y, z

Cartesian coordinates

Greek symbols


Conversion of reaction


Degree of cure at gel


Exothermic heat of polymerization (J/kg)


Viscosity (Pa s)


Zero shear rate viscosity (Pa s)


Density (kg/m3)


Shear stress (Pa)

\( \dot{\gamma } \)

Shear rate (1/s)


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



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.


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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

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