Numerical Simulation Of Magnetic Convection Effect During The Micro-electroforming Process

Fine metallic structures (Meso/Micro) and parts (such as micro gears, micro shaft, micro gate electrode, etc.) are important component of micro-mechanical (MEMS), electronic products, precision instruments and other important component of high-tech products. Micro-electroforming is one of the main implementation technologies to manufacture these products, but serious mass transfer limited phenomenon often exists in the micro-electroforming process, and thereby leads to the generation of variety deposition defects. Crack the mass transfer limited problem in micro-electroforming process is one of the tricky problems urgently to be solved. Magnetic drive n convection effect has some advantages, such as efficiency, non-contact, easy to control and not limited spatial scale. The use of magneto-hydrodynamics (MHD) effects to resolve the mass transfer limited problem especially in the micro-electroforming of high aspect ratio microstructures (HARMS) is a groundbreaking idea.This paper relying on the National Natural Science Foundation of "magnetic force-driven convection effect on the micro electroforming technology" (NO.50805077) and Henan University of Technology Innovation Fund for graduate student thesis project "micro electroforming process characterization and magnetic analysis of convection effect." For blind holes with high aspect ratio micro electroforming process of mass transfer effects in the numerical analysis, special conditions of the external magnetic field within the porous flow field, and the micro-space magnetic convection effect in production, development and incentive mechanism. And the development of an experimental device, and amended by numerical simulation experiment results. Specific content and the results:(1) Theory discussed the micro-electroforming process of the mechanism of liquid phase mass transfer limited.(2) Establishment the mathematical model of a highly porous diameter than the deposition of derived liquid transfer process described in mathematical expression, based on computational fluid dynamics software FLUENT numerical analysis under the micro actuator of conventional liquid transfer by the electroforming limited mechanism. Analysis shows that the depth to diameter ratio greater than 3 pore diameter less than 2 mm, the role of conventional mixing is difficult to go deep into porous bottom; with the smaller aperture, depth to diameter ratio, stirring more and more weak.(3) Calculate under construction field pore solution convection in the mathematical equations, numerical analysis of the characteristics of different pore structure (pore size, depth to diameter ratio) of the porous, magnetic field strength, current density, electrical conductivity within a factor of porous the impact of the flow field. Simulation results show that the magnetic field conditions, the solution to produce a more porous vortex; pore velocity of each point proportional to the size and current density; with the magnetic field strength increases exponentially; when the conductivity is greater than 6S/m, the pore velocity of the solution was increased with the rapid increase of conductivity.(4) Develop the display and measurement technique based on a microscopy-based platform, monodisperse polystyrene tracer and M2D-IMG software; develop a micro-macro integration, under the conditions used to observe the magnetic field during deposition flow field in the porous state of the experimental apparatus. Experimental results and revised the conclusions of numerical simulations: electroforming solution in the current and magnetic field inside and outside the pores produce multiple vortex; porous flow field by the magnetic field strength, current density, aperture, depth to diameter ratio and other factors impact. The experimental apparatus by the MHD effect of the latest international research, inspired experimental device (Introduction of 1.3.2 and Chapter 5).