Study of Different Dispensing Patterns of No-Flow Underfill Using Numerical and Experimental Methods

2020 ◽  
Author(s):  
Muhammad Naqib Nashrudin ◽  
Mohamad Aizat Abas ◽  
Mohd Z. Abdullah ◽  
M. Yusuf Tura Ali ◽  
Zambri Samsudin
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Void Formation ◽  
Velocity Flow ◽  
Incomplete Filling ◽  
Underfill Flow ◽  
Dimensional Simulation ◽  
Volume Method ◽  
Capillary Underfill ◽  
Good Agreement

Abstract The conventional capillary underfill process has been a common practice in the industry, somehow the process is costly and time consuming. Thus, no-flow underfill process is developed to increase the effective lead time production since it integrates the simultaneous reflow and cure of the solder interconnect and underfill. This paper investigates the effect of different dispense patterns of no-flow underfill process by mean of numerical and experimental method. Finite volume method (FVM) was used for the three-dimensional simulation to simulate the compression flow of the no-flow underfill. Experiments were carried out to complement the simulation validity and the results from both studies have reached a good agreement. The findings show that of all three types of dispense patterns, the combined shape dispense pattern shows better chip filling capability. The dot pattern has the highest velocity and pressure distribution with values of 0.0172 m/s and 813 Pa, respectively. The high-pressure region is concentrated at the center of the chip and decreases out towards the edge. Low in pressure and velocity flow factor somehow lead to issue associated to possibility of incomplete filling or void formation. Dot dispense pattern shows less void formation since it produces high pressure underfill flow within the BGA. This paper provides reliable insight to the industry to choose the best dispense pattern of recently favorable no-flow underfill process.

Influence of Laser Soldering Temperatures On Thru-Hole Component

2021 ◽  
Author(s):  
Saiful Majdy ◽  
Mohamad Aizat Abas ◽  
Mohamad Fikri Mohd Sharif ◽  
Fakhrozi Che Ani
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Void Formation ◽  
Lead Free ◽  
Bottom Surface ◽  
Lead Free Solder ◽  
Soldering Process ◽  
Incomplete Filling ◽  
Laser Soldering ◽  
Free Solder

Abstract The conventional method of selective soldering has been practiced using wave soldering, convection reflow, and hand soldering. However, due to industry automation and high demand for quality, repeatability and flexibility, laser soldering process has been developed to meet these demands. This paper investigates the effect of different temperature of laser soldering process on lead free solder (SAC305) by means of numerical method that is validated by experiment. Finite Volume Method (FVM) was used for the three-dimensional (3D) simulation to simulate the filling flow of the lead-free solder. Experiments were carried out to complement simulation validity and the results of far both methods have reached a good agreement. The findings show that a better result can be achieved when angle of lead component (?le) approaches 90°. Using the optimized lead angle, five different temperature simulations were set in the range of 550K < T < 700K. The finding shows that, 600K has the best velocity and pressure distributions with average values of 63.3 mm/s and 101.1386kPa, respectively. The high-pressure region is concentrated at the top and bottom surface of solder pad. High difference in pressure and velocity spots somehow lead to issue associated with possibility of incomplete filling or void formation. 650K model shows less void formation since it produces high pressure filling flow within the solder region.

scholarly journals Experimental and Numerical Investigation about Small Clearance Journal Bearings under Static Load Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Carlo Alberto Niccolini Marmont Du Haut Champ ◽  
Fabrizio Stefani ◽  
Paolo Silvestri
Keyword(s):  
Three Dimensional ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Small Scale ◽  
Test Rig ◽  
Small Clearance ◽  
Dimensional Simulation ◽  
Dynamic Loading Conditions ◽  
Static And Dynamic Loading ◽  
Good Agreement

The aim of the present research is to characterize both experimentally and numerically journal bearings with low radial clearances for rotors in small-scale applications (e.g., microgas turbines); their diameter is in the order of ten millimetres, leading to very small dimensional clearances when the typical relative ones (order of 1/1000) are employed; investigating this particular class of journal bearings under static and dynamic loading conditions represents something unexplored. To this goal, a suitable test rig was designed and the performance of its bearings was investigated under steady load. For the sake of comparison, numerical simulations of the lubrication were also performed by means of a simplified model. The original test rig adopted is a commercial rotor kit (RK), but substantial modifications were carried out in order to allow significant measurements. Indeed, the relative radial clearance of RK4 RK bearings is about 2/100, while it is around 1/1000 in industrial bearings. Therefore, the same original RK bearings are employed in this new test rig, but a new shaft was designed to reduce their original clearance. The new custom shaft allows to study bearing behaviour for different clearances, since it is equipped with interchangeable journals. Experimental data obtained by this test rig are then compared with further results of more sophisticated simulations. They were carried out by means of an in-house developed finite element (FEM) code, suitable for thermoelasto-hydrodynamic (TEHD) analysis of journal bearings both in static and dynamic conditions. In this paper, bearing static performances are studied to assess the reliability of the experimental journal location predictions by comparing them with the ones coming from already validated numerical codes. Such comparisons are presented both for large and small clearance bearings of original and modified RKs, respectively. Good agreement is found only for the modified RK equipped with small clearance bearings (relative radial clearance 8/1000), as expected. In comparison with two-dimensional lubrication analysis, three-dimensional simulation improves prediction of journal location and correlation with experimental results.

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

2011 ◽  
Vol 312-315 ◽  
pp. 971-976 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
W.C.P. Barbosa de Lima ◽  
Gelmires Araújo Neves ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Three Dimensional ◽  
Average Moisture Content ◽  
Stress Distributions ◽  
Drying Process ◽  
Convective Boundary ◽  
Volume Method ◽  
Hygrothermal Stress ◽  
Thermo Physical Properties ◽  
Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

Three-Dimensional Paddle Shift Modeling for IC Packaging

2004 ◽  
Vol 127 (3) ◽  
pp. 324-334 ◽  
Author(s):  
Chien-Chang Pei ◽  
Sheng-Jye Hwang
Keyword(s):  
Structural Analysis ◽  
Integrated Circuits ◽  
Three Dimensional ◽  
Void Formation ◽  
Model Performance ◽  
Computational Time ◽  
Pressure Loading ◽  
Filling Process ◽  
Molding Process ◽  
Incomplete Filling

The plastic packaging process for integrated circuits is subject to several fabrication defects. For packages containing leadframes, three major defects may occur in the molding process alone, namely, incomplete filling and void formation, wire sweep, and paddle shift. Paddle shift is the deflection of the leadframe pad and die. Excessive paddle shift reduces the encapsulation protection for the components and may result in failures due to excessive wire sweep. Computer-aided analysis is one of the tools that could be used to simulate and predict the occurrence of such molding-process-induced defects, even prior to the commencement of mass production of a component. This paper presents a methodology for computational modeling and prediction of paddle shift during the molding process. The methodology is based on modeling the flow of the polymer melt around the leadframe and paddle during the filling process, and extracting the pressure loading induced by the flow on the paddle. The pressure loading at different times during the filling process is then supplied to a three-dimensional, static, structural analysis module to determine the corresponding paddle deflections at those times. The paper outlines the procedures used to define the relevant geometries and to generate the meshes in the “fluid” and “structural” subdomains, and to ensure the compatibility of these meshes for the transfer of pressure loadings. Results are shown for a full paddle shift simulation. The effect on the overall model performance of different element types for the mold-filling analysis and the structural analysis is also investigated and discussed. In order to obtain more accurate results and in a shorter computational time for the combined (fluid and structural) paddle shift analysis, it was found that higher-order elements, such as hexahedra or prisms, are more suitable than tetrahedra.

scholarly journals Three Dimensional Simulation Technology Research of Split Type Cooling Transformer Based on Finite Volume Method

2017 ◽  
Vol 141 ◽  
pp. 405-410 ◽  
Author(s):  
Wei Bengang ◽  
Huang Hua ◽  
Lou Junshang ◽  
Wu Nannan ◽  
Dai Mingqiu ◽  
...  
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Three Dimensional ◽  
Technology Research ◽  
Simulation Technology ◽  
Dimensional Simulation ◽  
Volume Method

Preliminary Results of Numerical Simulations of a Bio-Mimetic Wells Turbine

2016 ◽  
Author(s):  
Qiuhao Hu ◽  
Ye Li ◽  
Fangyi Wei
Keyword(s):  
Energy Conversion ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Maximum Efficiency ◽  
Wells Turbine ◽  
Turbulence Effects ◽  
Dimensional Simulation ◽  
Lower Torque ◽  
Good Agreement

Wells turbine is a kind of self-rectified air turbines used in an oscillatory water column (OWC) device for wave energy conversion. In this study, a steady three-dimensional simulation of a fan-shaped Wells turbine is performed on Star CCM+ commercial software by solving the Reynolds-averaged Navier-Stokes (RANS) equations. The turbulence effects are taken into account by using the Spalart-Allmaras turbulence model. Good agreement between the numerical results and the experimental results within the operation region (5< α <11 degrees) is observed. The geometry of the turbine rotor has a significant effect on the performance of energy conversion. Inspired by the aerodynamics of low Reynolds flyer, the normal fan-shaped Wells turbine is optimized by a bio-mimetic method in which the profile of a hawk moth wing of Manduca Sexta is applied on the blades. The modified turbine has a lower torque and pressure drop coefficient with higher efficiency. The maximum efficiency for the modified turbine is 0.61, compared to 0.48 for the normal fan-shaped one. By analysis of the detailed flow-field, it has also been found that only the middle parts of the blade can effectively generate the momentum. In order to acquire a higher efficiency, further optimization is carried out by refining some blade parts in the tip and the hub which cannot effectively produce power.

Fluid Flow and Heat Transfer in a Novel Microchannel Heat Sink Partially Filled With Metal Foam Medium

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
E. Farsad ◽  
S. P. Abbasi ◽  
M. S. Zabihi
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Metal Foam ◽  
Three Dimensional ◽  
Numerical Data ◽  
Flow And Heat Transfer ◽  
Cooling Devices ◽  
Volume Method ◽  
Steady Laminar ◽  
Good Agreement

Performance of microchannel heatsink (MCHS) partially filled with foam is investigated numerically. The open cell copper foams have the porosity and pore density in the ranges of 60–90% and 60–100 PPI (pore per inch), respectively. The three-dimensional steady, laminar flow, and heat transfer governing equations are solved using finite volume method. The performance of microchannel heatsink is evaluated in terms of overall thermal resistance, pressure drop, and heat transfer coefficient and temperature distribution. It is found that the results of the surface temperature profile are in good agreement with numerical data. The results show the microchannel heatsink with insert foam appears to be good candidates as the next generation of cooling devices for high power electronic devices. The thermal resistance for all cases decreases with the decrease in porosity. The uniformity of temperature in this heatsink is enhanced compared the heatsink with no foam. The thermal resistance versus the pumping power is depicted, it is found that 80% is the optimal porosity for the foam at 60 PPI with a minimum thermal resistance 0.346 K/W. The results demonstrate the microchannel heatsink partially filled with foam is capable for removing heat generation 100 watt over an area of 9 × 10−6 m2 with the temperature of heat flux surface up to 59 °C.

Three-Dimensional Simulation for Diffusion of Matter in Compound Round Jet by Particle Method

2003 ◽  
Author(s):  
Tomomi Uchiyama ◽  
Akihito Ichikawa
Keyword(s):  
Three Dimensional ◽  
Concentration Field ◽  
Particle Method ◽  
Vortex Method ◽  
Vortical Flow ◽  
Round Jet ◽  
The Mean ◽  
Dimensional Simulation ◽  
Mean Concentration ◽  
Good Agreement

The diffusion of matter in compound round jet is simulated by three-dimensional particle method. The flow field is calculated with a vortex method, whereas the concentration field is simulated through a particle method analogous to the vortex method. It is shown that the concentration distribution yielded by the three-dimensional vortical flow is in good agreement with the experimental one obtained by the flow visualization. The mean concentration is confirmed to be in the self-preservation state.

Calculation of Three-Dimensional, Inviscid, Rotational Flow in Axial Turbine Blade Rows

1984 ◽  
Vol 106 (2) ◽  
pp. 430-436 ◽  
Author(s):  
W. Van Hove
Keyword(s):  
Complex Geometry ◽  
Three Dimensional ◽  
Rotational Flow ◽  
Flow Angle ◽  
Cylindrical Coordinate ◽  
Time Marching ◽  
Flow Through ◽  
Outflow Boundary ◽  
Volume Method ◽  
Good Agreement

This paper describes a fully explicit, time marching, corrected viscosity, finite volume method to solve the Euler equations in a cylindrical coordinate system. The rotational character of the incoming flow can be taken into account. On the outflow boundary, a generalized radial equilibrium condition is imposed. Blade rows of complex geometry can be handled. At present, the method has been used to calculate the flow through the nozzle vanes of the VKI low-speed turbine facility. The calculated results show good agreement with the experimental data for the spatial distribution of both the static pressure and the flow angle.

Modelling Three Dimensional Unsteady Turbulent HVAC Induced Flow

2021 ◽  
Vol 87 (1) ◽  
pp. 76-90
Author(s):  
Ahmed Hussein Hafez ◽  
Tamer Heshmat Mohamed Aly Kasem ◽  
Basman Elhadidi ◽  
Mohamed Madbouly Abdelrahman
Keyword(s):  
Three Dimensional ◽  
Computational Effort ◽  
Temperature Profiles ◽  
Flow Equations ◽  
Time Stepping ◽  
Adaptive Time ◽  
Induced Flow ◽  
Dimensional Simulation ◽  
Complex Boundaries ◽  
Good Agreement

A three-dimensional numerical model for HVAC induced flow is presented. The nonlinear set of buoyancy driven incompressible flow equations, augmented with those of energy and turbulence model is solved. Various relevant are discussed. These challenges include avoiding expensive commercial packages, modeling complex boundaries, and capturing near wall gradients. Adaptive time stepping is employed to optimize computational effort. Three-dimensional simulation requirements are addressed using parallel computations. Two-dimensional and three-dimensional results are presented to clarify the model significance. Validation is done using full scale measurements. Good agreement with velocity and temperature profiles are illustrated.

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