CFD Prediction of Multiple Jet Impingement in a Reflow Soldering Process

Multiple jet impingement is a technology widely implemented in reflow soldering process. Forced convection through jet impingement allows high average heat transfer coefficients and increases the uniformity of the heat transfer over the target surface. These characteristics are required to enhance the process and to avoid local hot (or cold) spots. To reduce products defects, all the variables identified in reflow soldering need to be controlled. Generating such data from experimentation is quite demanding in terms of planning, facilities and cost of experimentation. In that sense, to improve industrial processes and to reduce time and costs, the implementation of the computational simulation plays an important role. Considering the relevance of this area for the industry, this paper presents the numerical modeling of multiple air jets system using the SST k-ω model, considered by several authors as the most appropriate turbulence model for jet impingement simulation. Through the CFD study, it is possible to analyze the flow behavior of air jets considering different nozzle shapes but also the variation of the surface temperature and heat transfer with time. Results revealed an accurate simulation of the jets flow field from the nozzle plate to the target surface. The jet-to-jet and jet-to-plate interactions were clearly identified, proving that the variables identified in a multiple jet system need to be cautiously analyzed since they interfere with the performance of the heat transfer over the target surface.