Influence of Gap Height in Flip Chip Underfill Process With Non-Newtonian Flow Between Two Parallel Plates

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
C. Y. Khor ◽  
M. Z. Abdullah ◽  
M. Abdul Mujeebu
Keyword(s):  
Pressure Drop ◽  
Flip Chip ◽  
3D Model ◽  
Fluid Dynamic ◽  
Power Law Model ◽  
Parallel Plates ◽  
Newtonian Flow ◽  
Filling Time ◽  
Gap Height ◽  
Volume Method

In this paper, the finite volume method (FVM) is used for the simulation of flip chip underfill process by considering non-Newtonian flow between two parallel plates that emulate the silicon die and the substrate. 3D model of two parallel plates of size 12.75 mm × 9.5 mm with gap heights of 5 μm, 15 μm, 25 μm, 35 μm, 45 μm, and 85 μm are developed and simulated by computational fluid dynamic (CFD) code, fluent 6.3.26. The flow is modeled by using power law model and volume of fluid (VOF) technique is applied for flow front tracking. The effect of change in height of the gap between the plates on the underfill process is mainly studied in the present work. It is observed that the gap height has significant influence on the melt filling time and pressure drop, as the gap height decreases filling time and pressure drop increase. The simulation results are compared with previous experimental results and found in good conformity.

A Model for Underfill Viscous Flow Considering the Resistance Induced by Solder Bumps

2004 ◽  
Vol 126 (2) ◽  
pp. 186-194 ◽  
Author(s):  
Chyi-Lang Lai ◽  
Wen-Bin Young
Keyword(s):  
Flip Chip ◽  
External Pressure ◽  
Good Prediction ◽  
Parallel Plates ◽  
Rectangular Array ◽  
Chip Technology ◽  
Solder Bumps ◽  
Proposed Model ◽  
Filling Time ◽  
Underfill Flow

During the underfill process, polymers driven by either capillary force or external pressure are filled at a low speed between the chip and substrate. Current methods treated the flow in the chip cavity as a laminar flow between parallel plates, which ignored the resistance induced by the solder bumps or other obstructions. In this study, the filling flow between solder bumps was simulated by a flow through a porous media. By using the superposition of flows through parallel plates and series of rectangular ducts, permeability of the underfill flow was fully characterized by the geometric arrangement of solder bumps and flat chips. The flow resistances caused by adjacent bumps were represented in its permeability. The model proposed in this study could provide a numerical approach to approximate and simulate the undefill process for flip-chip technology. Although the proposed model is applicable for any geometric arrangement of solder bumps, rectangular-array of solder bumps layout was used first for comparison with experimental results of other article. Comparisons of the flow-front shapes and filling time with the experimental data indicated that the flow simulation obtained from the proposed model gave a good prediction for the underfill flow.

A Theoretical Analysis of the Concept of Critical Clearance Toward a Design Methodology for the Flip-Chip Package

2007 ◽  
Vol 129 (4) ◽  
pp. 473-478 ◽  
Author(s):  
J. W. Wan ◽  
W. J. Zhang ◽  
D. J. Bergstrom
Keyword(s):  
Flip Chip ◽  
Solder Bump ◽  
Flow Characteristics ◽  
Quantitative Relation ◽  
Package Design ◽  
Solder Bumps ◽  
Filling Time ◽  
Encapsulation Process ◽  
Advanced Packaging ◽  
Gap Height

In this article, we present a theoretical study on the concept known as critical clearance for flip-chip packages. The critical clearance phenomenon was first observed in an experiment reported by Gordon et al. (1999, “A Capillary-Driven Underfill Encapsulation Process,” Advanced Packaging, 8(4), pp. 34–37). When the clearance is below a critical value, filling time begins to increase dramatically, and when the clearance is above this value, the influence of clearance on filling time is insignificant. Therefore, the optimal solder bump density in a flip-chip package should be one with a clearance larger than the critical clearance. The contribution of our study is the development of a quantitative relation among package design features, flow characteristics, and critical clearance based on an analytical model we developed and reported elsewhere. This relation is further used to determine critical clearance given a type of underfill material (specifically the index n of the power-law constitutive equation), the solder bump pitch, and the gap height; further the flip-chip package design can be optimized to make the actual clearance between solder bumps greater than its corresponding critical clearance.

Flip-Chip Underfill Packaging Considering Capillary Force, Pressure Difference, and Inertia Effects

2006 ◽  
Vol 129 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Chao-Ming Lin ◽  
Win-Jin Chang ◽  
Te-Hua Fang
Keyword(s):  
Capillary Force ◽  
Pressure Difference ◽  
Driving Force ◽  
Flip Chip ◽  
Inertia Force ◽  
Inertia Effects ◽  
Filling Time ◽  
Circular Rotation ◽  
Gap Height ◽  
Force Pressure

This study aims to enhance the flow rate and reduce the filling time in flip-chip underfill packaging by combining capillary force, pressure difference, and inertia effects. In the designed underfill apparatus, the capillary force effect is developed by surface tension, the pressure difference between the inlet and the outlet is established using a pump or a vacuum, and the inertia force is achieved via circular rotation. The governing equations containing the three analyzed effects are derived and solved using a dimensionless technique. The analytical results indicate that for the general gap height of approximately 10-1000μm, the pressure difference and inertia effects dominate the driving force and provide a significant reduction in the filling time. However, for a gap height of less than 1μm, the driving force is dominated by the capillary effect. The present results confirm that the productivity of the flip-chip underfill packaging process can be enhanced through the appropriate control of the capillary force, pressure difference, and inertia effects.

scholarly journals Clogging sensitivity of flow distributors designed for radially elongated hexagonal pillar array columns: a computational modelling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farideh Haghighi ◽  
Zahra Talebpour ◽  
Amir Sanati-Nezhad
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Contact Zone ◽  
Separation Efficiency ◽  
Fluid Dynamic ◽  
Computational Modelling ◽  
Channel Width ◽  
Fluid Distribution ◽  
Design Parameters ◽  
Pillar Array

AbstractFlow distributor located at the beginning of the micromachined pillar array column (PAC) has significant roles in uniform distribution of flow through separation channels and thus separation efficiency. Chip manufacturing artifacts, contaminated solvents, and complex matrix of samples may contribute to clogging of the microfabricated channels, affect the distribution of the sample, and alter the performance of both natural and engineered systems. An even fluid distribution must be achieved cross-sectionally through careful design of flow distributors and minimizing the sensitivity to clogging in order to reach satisfactory separation efficiency. Given the difficulty to investigate experimentally a high number of clogging conditions and geometries, this work exploits a computational fluid dynamic model to investigate the effect of various design parameters on the performance of flow distributors in equally spreading the flow along the separation channels in the presence of different degrees of clogging. An array of radially elongated hexagonal pillars was selected for the separation channel (column). The design parameters include channel width, distributor width, aspect ratio of the pillars, and number of contact zone rows. The performance of known flow distributors, including bifurcating (BF), radially interconnected (RI), and recently introduced mixed-mode (MMI) in addition to two new distributors designed in this work (MMII and MMIII) were investigated in terms of mean elution time, volumetric variance, asymmetry factors, and pressure drop between the inlet and the monitor line for each design. The results show that except for pressure drop, the channel width and aspect ratio of the pillars has no significant influence on flow distribution pattern in non-clogged distributors. However, the behavior of flow distributors in response to clogging was found to be dependent on width of the channels. Also increasing the distributor width and number of contact zone rows after the first splitting stage showed no improvement in the ability to alleviate the clogging. MMI distributor with the channel width of 3 µm, aspect ratio of the pillars equal to 20, number of exits of 8, and number of contact zones of 3 exhibited the highest stability and minimum sensitivity to different degrees of clogging.

scholarly journals The Influence of Different Types of Nanofluid on Thermal and Fluid Flow Performance of Liquid Cold Plate

2018 ◽  
Vol 7 (4.35) ◽  
pp. 148 ◽  
Author(s):  
Nur Irmawati Om ◽  
Rozli Zulkifli ◽  
P. Gunnasegaran
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Cold Plate ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Types ◽  
Volume Method

The influence of utilizing different nanofluids types on the liquid cold plate (LCP) is numerically investigated. The thermal and fluid flow performance of LCP is examined by using pure ethylene glycol (EG), Al2O3-EG and CuO-EG. The volume fraction of the nanoparticle for both nanofluid is 2%. The finite volume method (FVM) has been used to solved 3-D steady state, laminar flow and heat transfer governing equations. The presented results indicate that Al2O3-EG able to provide the lowest surface temperature of the heater block followed by CuO-EG and EG, respectively. It is also found that the pressure drop and friction factor are higher for Al2O3-EG and CuO-EG compared to the pure EG.

Experimental and Numerical Validation of Conical Strainer Fluid/Structural Performance Model

2012 ◽  
Author(s):  
M. Carlomagno ◽  
S. Rossin ◽  
M. Delvecchio ◽  
A. Anichini
Keyword(s):  
Pressure Drop ◽  
Fluid Dynamic ◽  
Performance Model ◽  
Structural Performance ◽  
Mechanical Resistance ◽  
Gas Industry ◽  
Process Gas ◽  
Compressor Inlet ◽  
Geometric Variables ◽  
Definition Of

Temporary conical strainers are widely employed in the Oil & Gas industry as filtering devices in the Centrifugal Compressors suction line. They protect compressor stages from the ingestion of foreign objects whether coming from dirty process gas or left in the pipeline after its construction. Very few literature and research papers are available on the fluid dynamic and structural performance of conical strainers. The purpose of this work is to plug this gap by the definition of a theoretical-experimental model for the characterization of the pressure drop and mechanical resistance of these devices. Starting from the definition of the main fluid dynamics and geometric variables which influence the performances, an experimental campaign has been performed in order to derive the relationship governing the pressure drop behavior. The model efficacy has been confirmed by a CFD analysis, which also allowed a qualitative insight review into the dynamics of velocity and turbulence intensity fields. Further tests have been performed in order to validate the model at off-design points. As far as the structural analysis is concerned, several FEM models and DOE techniques have been implemented in order to define relationships for bust pressure computation and feasible design improvements with respect to the current state of the art. Besides fluid dynamic and structural correlations, the notable achievements of this work are the definition of best pressure static probes positioning and the maximum clogging level that a strainer can withstand before collapse. Furthermore, some guidelines are given in order to prevent pipeline resonance and acoustic fatigue caused by the interaction between strainer turbulence and compressor inlet flow.

CFD Simulation of a Co-rotating Twin-screw Extruder: Validation of a Rheological Model for a Starch-Based Dough for Snack Food

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Giorgia Tagliavini ◽  
Federico Solari ◽  
Roberto Montanari
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Second Phase ◽  
Snack Food ◽  
Suitable Model ◽  
Twin Screw Extruder ◽  
Parallel Plates ◽  
Screw Extruder ◽  
Twin Screw

AbstractThe extrusion of starch-based products has been a matter of interest, especially for the pasta and the snack food production. In recent years, twin-screw extruders for snack food have been studied from both structural and fluid dynamics viewpoints. This project started from the rheological characterization of a starch-based dough (corn 34 wt%, tapioca 32 wt%), comparing viscosity values acquired in laboratory with different theoretical models found in literature. A computational fluid dynamic (CFD) simulation recreating the simple case of a fluid flow between two parallel plates was carried out to validate the former comparison. After the rheological validation was completed, the second phase of this work covered a 3D CFD simulation of the first part of the twin-screw extruder (feeding zone). The objective was to find a suitable model for describing the dough rheological behavior and the operating conditions of a co-rotating intermeshing twin-screw extruder. Once the model would be defined, it would allow to investigate several working conditions and different screws geometries of the machine, predicting the evolution of the product rheological properties.

scholarly journals Non-newtonian flow and pressure drop of pineapple juice in a plate heat exchanger

2010 ◽  
Vol 27 (4) ◽  
pp. 563-571 ◽  
Author(s):  
R. A. F. Cabral ◽  
J. A. W. Gut ◽  
V. R. N. Telis ◽  
J. Telis-Romero
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Plate Heat Exchanger ◽  
Newtonian Flow ◽  
Plate Heat ◽  
Pineapple Juice
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