Papers by Keyword: Micro-Electroforming

Abstract: To provide appropriately high and uniform magnetic field for micro electroforming process, a permanent magnet generator was specially developed which based on the fundamental process requirements. On the basis of determining the number of permanent magnet combinations numerically. Mainly, the geometrical shape of the permanent magnet blocks and magnetic circuit structure were optimized, and then the working gap regulating mechanism for this generator was designed. Utilizations indicated that the developed generator met the requirements well.

Abstract: Micro gears with different dimension were fabricated by micro metal injection molding and sintering behavior of the micro gear was investigated. For this, ultraprecision micro molds were prepared by micro electroforming. The sintered micro gears had outer diameter of 470μm and 250 μm, respectively. From the sintering results at 1200°C and 1250°C, the grain growth and the degree of thermal etching depend dominantly on the size of micro part rather than micro feature size. The sintering temperature of micro parts should be lower than that of macro components.

Abstract: Micro-components were electroplated using composite electroforming technology under magnetic field. The surface morphology of the micro components was examined using scanning electron microscope (SEM) and X-ray spectrometer was used to detect texture. The results show that: the texture and surface morphology of the micro components are influenced by the current density and the magnetic field intensity. With the increase of current density, the size of crystal grains decrease firstly but increase later .And as the increase of the magnetic field intensity, the size of crystal grains become smaller and more uniform. Besides, the current density and the magnetic field intensity have a great impact on the texture of castings. As the increase of the current density, the texture orientation changes from (111) to (200). At the same time, along with the increase of the magnetic field intensity, the diffraction peak (200) is suppressed while the diffraction peak (111) is enhanced obviously.

Abstract: Precision metal sieve-sheets are one of the key components of several high-tech products. Fabrication of the precision sieve-sheets possessing high open area percentage, large thickness and good quality simultaneously has always been a tickler in micro-machining area. In this paper, aiming to manufacture micro-sieves with open areas of about 90% and good quality, micro-electroforming was taken as a major process means, and the technical points and technical difficulties of some key process steps in the preparation of micro-precision sieves were explored emphatically. Meanwhile, operational conditions were optimized and major technological parameters were selected optimally. Using the optimal conditions as well as the optimum parameters, two specifications of hexagon micromesh sieve-sheets whose side length, open-area percent and sheet-thickness was 210μm, 88%, (120±3)μm and 520μm, 92%, (100±2)μm, respectively, were successfully obtained. The electroformed sieves are characterized by flat and smooth surfaces of aperture walls, sharp edge definition, rigid and homogeneous structures and well-distributed mesh.

Abstract: The numerical simulation of flow field and pressure field in the micro-region with different power ultrasonic were performed by FLUENT6.3 simulation software. Ultrasonic power on mass transfer effect was analyzed through the simulation results combined with surface morphology of micro casting. The results illustrated that micro electroforming assisted with appropriate power ultrasonic can significantly enhance mass transfer process and improve surface morphology of micro casting. And it was confirmed that Fluent was reliable in simulating the effect of ultrasonic on mass transfer and helpful to optimize and design deposition experiments with ultrasonic.

Abstract: Pinhole defect in the deposit is one of the ticklers which have not yet been solved fundamentally when micro-electroforming nickel into high-aspect-ratio (HAR) micro-molds. To obtain void-free micro-components, a new micro-electroforming technique, which was carried out under the complex circumstance of vacuum-degassing and temperature-gradient, was developed in this paper. Mechanisms of this micro-electroforming process were introduced using graphic and simulation methods. To investigate the feasibility of the exploited technique, a series of experiments were performed using special equipment developed by authors, followed by the evaluating of surface morphology of nickel micro-electroforms using a scanning electron microscope (SEM). Experimental results showed that, comparing with the conventional electroforming practices, a significant reduction in pinhole defects of the samples electroformed by the novel process was achieved.

Abstract: High frequency acoustic agitation is known to improve mass transport in conventional electroplating and electroforming. To better understand the effect of ultrasonic agitation on microelectroforms with high height-to-width aspect recessed microstructure features, electroforming of Ni from a nickel sulfamate type electrolyte under the influence of high frequency ultrasound (33KHz) at different level of power intensity from 2W/cm2 to 16W/cm2 was investigated experimentally in this paper, and then optimum operating parameters were determined basing on surface topography. A number of microelectroforming experiments assisted with acoustic agitation were further carried out to demonstrate and revise the optimum process parameters and further some metal microdevices were produced. Experimental results showed that fewer drawbacks in the microelectroforms, such as nubbles, pits, blunt-edges, and collapses were observed in the microcomponents when sonication power 12W/cm2~14W/cm2 was drawn on. Microelectroforming with ultrasonic irradiation at appropriate power intensity was characterized by better surface morphology and better uniform filling behavior.

Abstract: Micro hot embossing mold of microfluidic chip used in flow cytometry is designed and microfabricated. After some kinds of microfabrication processes are tried, this paper presents a novel microfabrication technology of micro hot embossing metal mold. Micro metal mold is fabricated by low-cost UV-LIGA surface micro fabrication process using negative thick photoresist, SU-8. Different from other micro hot embossing molds, the micro mold with vertical sidewalls is fabricated by micro nickel electroforming directly on Nickel base. Based on the micro Nickel mold and automation fabrication system, high precision and mass-producing microfluidic chips have been fabricated and they have been used in flow cytometry