Modeling the Thermal Behavior of Solder Paste Inside Reflow Ovens

2003 ◽  
Vol 125 (3) ◽  
pp. 335-346 ◽  
Author(s):  
A. Tava´rez ◽  
J. E. Gonza´lez
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Solder Paste ◽  
Soldering Process ◽  
Coupled Heat Transfer ◽  
Numerical Predictions ◽  
Loss Of Weight ◽  
Manufacturing Applications ◽  
Free Solder ◽  
Paste Properties

The development of a mathematical model of the soldering process of actual pastes as used in surface mount technology (SMT) lines is described in this paper. The coupled heat transfer processes between the solder paste and the flux including changes in solder paste properties are considered in the model. Specifically, the loss of solvents in the vehicle system, melting, solidification and further single phase cooling of the solder paste are contemplated in the model. Experiments were conducted with the objective of validating the predictions of the solder paste temperature profile and of the loss of weight due to flux extraction. Results are shown in this paper for typical eutectic paste 63%Sn-37%Pb and experimental data is in good agreement with the numerical predictions. Simulations using the lead-free solder paste systems 96.5%Sn-3.5%Ag and 42%Sn-58%Bi are also reported in this paper. The proposed model is suitable for incorporation into existing three dimensional heat transfer models of PCBs for simulations in ovens with similar characteristics as those used in actual manufacturing applications.

Numerical Study on 3D Coupled Heat Transfer of Thrust Chamber with Regenerative Cooling

2011 ◽  
Vol 52-54 ◽  
pp. 1057-1061
Author(s):  
Tao Nie ◽  
Wei Qiang Liu
Keyword(s):  
Heat Transfer ◽  
Optimization Design ◽  
Numerical Study ◽  
Computing Time ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Performance Estimation ◽  
Transfer Model ◽  
Empirical Formulas ◽  
Coupled Heat Transfer

To obtain temperature distribution in regenerative-cooled liquid propellant rocket nozzle quickly and accurately, three-dimensional numerical simulation employed using empirical formulas. A reduced one-dimensional model is employed for the coolant flow and heat transfer, while three dimensional heat transfer model is used to calculate the coupling heat transfer through the wall. The geometrical model is subscale hot-firing chamber. The numerical results agree well with experimental data, while temperature field in nozzle obtained. In terms of computing time and accuracy of results, this method can provide a reference for optimization design and performance estimation.

Laminar Natural Convection in a Discretely Heated Cavity: II—Comparisons of Experimental and Theoretical Results

1995 ◽  
Vol 117 (4) ◽  
pp. 910-917 ◽  
Author(s):  
T. J. Heindel ◽  
F. P. Incropera ◽  
S. Ramadhyani
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Companion Paper ◽  
Nusselt Numbers ◽  
Numerical Predictions ◽  
Number Flow ◽  
Experimental Geometry

Three-dimensional numerical predictions and experimental data have been obtained for natural convection from a 3 × 3 array of discrete heat sources flush-mounted on one vertical wall of a rectangular cavity and cooled by the opposing wall. Predictions performed in a companion paper (Heindel et al., 1995a) revealed that three-dimensional edge effects are significant and that, with increasing Rayleigh number, flow and heat transfer become more uniform across each heater face. The three-dimensional predictions are in excellent agreement with the data of this study, whereas a two-dimensional model of the experimental geometry underpredicts average heat transfer by as much as 20 percent. Experimental row-averaged Nusselt numbers are well correlated with a Rayleigh number exponent of 0.25 for RaLz ≲ 1.2 × 108.

HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Imran Qureshi ◽  
Andy D. Smith ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Three Dimensional ◽  
Leading Edge ◽  
Good Deal ◽  
Vortex Center ◽  
Research Facility ◽  
Lean Burn ◽  
Numerical Predictions ◽  
The Impact

Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over ±40 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NOx combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.

Three-Dimensional Fluid Flow and Coupled Heat Transfer in Simplified Bipolar Plates

2007 ◽  
Author(s):  
Jianfei Wu ◽  
Jianhu Nie ◽  
Yitung Chen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Solid Wall ◽  
Three Dimensional ◽  
Cathode Side ◽  
Uniform Heat Flux ◽  
Bipolar Plates ◽  
Coupled Heat Transfer ◽  
Temperature Distributions

Numerical simulations were performed for three-dimensional fluid flow and coupled heat transfer in simplified bipolar plates. The Reynolds number of inlet flow is varied from 100 to 900 on the anode side while the Reynolds number is maintained as a constant of 100 on the cathode side. The solid wall surfaces of the bipolar plates are assumed to be adiabatically insulated, except that the active areas of the channels are supplied with uniform heat flux. Results of velocity and temperature distributions for different Reynolds numbers are presented and discussed. It is shown that effects of flow pattern on temperature distributions in channels becomes negligible when the Reynolds number is as high as 900.

An Investigation of the Lead-Free Surface Mount Soldering Process: Solder Joint Evaluation and Process Optimisation

2004 ◽  
Author(s):  
Claire Ryan ◽  
Jeff M. Punch ◽  
Bryan Rodgers ◽  
Greg Heaslip ◽  
Shane O’Neill ◽  
...  
Keyword(s):  
Screen Printing ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Surface Mount ◽  
Snagcu Solder ◽  
Soldering Process ◽  
Free Process ◽  
Free Solder

A European Union ban on lead in most electrical and electronic equipment will be imposed as of July 1st 2006. The ban, along with market pressures, means that manufacturers must transfer from a tin-lead soldering process to a lead-free process. In this paper the implications on the surface mount (SMT) soldering process are presented. A set of experiments was conducted to investigate the screen-printing and reflow steps of the SMT process using a tin-silver-copper (95.5Sn3.8Ag0.7Cu) solder and a baseline of standard tin-lead (63Sn37Pb). 10×10 arrays of micro Ball Grid Array (micro-BGA) components mounted on 8-layer FR4 printed wiring boards (PWBs) were used. The screen-printing experiment addressed the deposition of the solder paste on the board. The parameters used in the investigation were print speed, squeegee pressure, snap-off distance, separation speed and cleaning interval, with the responses being measurements of paste height and volume. Optimum screen-printer settings were determined which give adequate paste volume and height and a good print definition. The reflow experiment investigated the following parameters of the temperature profile: preheat, soak, peak and cool down temperatures, and conveyor speed. The resulting solder joints were evaluated using cross-section analysis and x-ray techniques in order to determine the presence of defects. A mechanical fatigue test was also carried out in order to compare the strength of the solder joints. The overall quality of the lead-free solder joints was determined from these tests and compared to that of tin-lead. The outcome is a set of manufacturing guidelines for transferring to lead-free solder including optimum screen-printer and reflow oven settings for use with an SnAgCu solder.

Measurement and Computation of Heat Transfer in High-Pressure Compressor Drum Geometries With Axial Throughflow

1997 ◽  
Vol 119 (1) ◽  
pp. 51-60 ◽  
Author(s):  
C. A. Long ◽  
A. P. Morse ◽  
P. G. Tucker
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Multigrid Algorithm ◽  
Numerical Predictions ◽  
High Pressure Compressor ◽  
Dependent Form ◽  
Pressure Compressor

This paper makes comparisons between CFD computations and experimental measurements of heat transfer for the axial throughflow of cooling air in a high-pressure compressor spool rig and a plane cavity rig. The heat transfer measurements are produced using fluxmeters and by the conduction solution method from surface temperature measurements. Numerical predictions are made by solving the Navier–Stokes equations in a full three-dimensional, time-dependent form using the finite-volume method. Convergence is accelerated using a multigrid algorithm and turbulence modeled using a simple mixing length formulation. Notwithstanding systematic differences between the measurements and the computations, the level of agreement can be regarded as promising in view of the acknowledged uncertainties in the experimental data, the limitations of the turbulence model and, perhaps more importantly, the modest grid densities used for the computations.

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