CFD Simulation Of Underfill Encapsulation Process In Flip Chip Packaging With Various Dispensing Methods
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Date
2010-05
Authors
Khor, Chu Yee
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The major trend in electronic industry is to make the products smarter, lighter,
functional and highly compact, at the same time cheaper. This trend has necessitated
stringent packaging requirements and the flip-chip technology has emerged as a
promising option to tackle this issue. However, a serious issue in flip-chip packaging
is the difference in the coefficient of thermal expansion between the silicon chip and
the organic substrate, which generates thermo-mechanical stresses and causes fatigue
in solder joints. This problem is effectively solved by the underfill process in which
the space between the silicon die and the PCB is filled with the underfill encapsulant
that redistributes the induced stresses thereby enhancing the solder joints reliability.
In this research, the studies on the 3-D flip chip underfill process is presented. A
finite volume method based on Navier-Stokes equation has been applied for the flow
analysis in the underfill process. The fluid flow models without curing effect (Cross
model ) is take into consideration the polymer rheology model. The effects of
different dispensing and injection situation have been studied on conventional and
pressurized underfill process. In addition, the effect of the solder bump array has
been studied. Verification of FLUENT software on handling polymer filling process
has been performed. The numerical results showed good agreement with the
experimetal results. The results showed that the L-dispensing and injection situation
give better filling on underfill filling process. Moreover, the solder bump array gives
the effect to the underfill flow during the conventional underfill process. The solder
bump array significantly influence the filling time, thus it may effecting the
manufacturing costs. However, pressurized underfill method is found suitable for
multichip underfill process. The novelty of this work is the used of FLUENT for
prediction of flip chip underfill process in microelectronics industry.
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Keywords
The major trend in electronic industry is , to make the products smarter, lighter, functional and highly compact