| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 90 === The growth of the integrated circuit (IC) and semiconductor industry causes a need of great amount of solder paste, which is mainly imported from foreign countries. There exists an urgent need to produce the solder paste domestically; however, the specification of the solder powder requires very narrow size distribution. It leads to a requirement of classification step in the process to be developed. Conventional classification technique does not work effectively for the powder sizes less than 38μm which are the main constituent of the solder paste.
To predict non-dense two-phase flows nowadays, the most popular approach is the combines Eulerian -Lagrangion models that treat the fluid as a continuum and the particles as discrete entities. In this study, the classification of powder is done by means of transverse blowing. The carrier-phase flow field is described by the Reynolds averaged Navier-Stokes equations with the low-Reynolds-number k-ε turbulence model. The particle trajectories are solved by using stochastic separated flow (SSF) method in Lagrangian framework. For SSF model, the turbulent dispersion effects are simulated by using Monte-Carlo method. A parametric study on geometric of the classifier dimension, particles size and gas phase velocity are performed. The results show that in the two-way coupling regime the momentum transfer from the particles is large enough to alter the turbulence structure. The influences of transverse blowing wind on large particle are less than small particle. The small particle responsed to the fluid motion easily. The classification by means of gas dynamics of particles (less than 100μm) is possible in the present modeling without considering particle collision process.
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