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
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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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The major trend in electronic industry is , to make the products smarter, lighter, functional and highly compact
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