Papers by Keyword: LIGA

Abstract: This paper proposes a vision detection algorithm to acquire LIGA part’s edges based on an in-house multi-DOF manipulator for LIGA part assembly. Feature recognition based on maximum information entropy is proposed to solve the problem that high precision edge recognition under backlight source. In order to further improve vision recognition accuracy, edge feature recognition algorithm based on symmetrical edge is proposed to recognize the center line of the symmetrical parts when the quality of the image is poor.

Abstract: The basic principle and technological methods of electroforming are briefly described. With the progress in materials, processes and equipment, electroforming has got a considerable development. It is increasingly combined with other technologies, such as assembling electrotype, fabrication of MEMS, LIGA, etc. The shortcomings of electroforming technologies at present stage are also pointed out. As an inter-disciplinary subject area, electroforming will be widely developed and applied.

Abstract: Polymer materials, such as PMMA and PDMS, have been of great interest in the research and development of MEMS recently due to their relatively low cost and easy process. In this research, we are trying to fabricate Ni Micro needle array from PMMA master by through PDMS mold based on multi-mold transformation technology. The fabricated micro nickel needles array is 900 microneedles in 1 cm2 chip area and the height of each needle is about 150um.

Abstract: Micro electro mechanical system (MEMS) has been increasingly used in military application. For the reliability and specialty of military requirements, the material of the MEMS device is supposed to be metal and the device is moveable. Lithographic, Galvanoforming, Abformung (LIGA) technology capable of producing high aspect ratio structures in metals like nickel is one of the important fabrication technologies in military MEMS. There are many moveable MEMS device like micro-gear and micro-slider producing by LIGA technology. But the moveable devices cannot behave well because of the friction effect. In this paper, an improved elastic-plastic model including roughness effects and an experimental procedure that predict the static friction prosperity of LIGA-processed nickel is proposed. Firstly, we use the 3D optical profilometer to research the surface roughness of LIGA-processed nickel, the surface heights distribution was found to be nearly Gaussian distribution. Secondly, the static friction model, the Kogut-Etsion (KE) model is adopted to obtain the static friction coefficient. Finally, a special designed static friction coefficient measurement apparatus is used to conduct the friction experiments. The results indicate that the surface roughness affects the friction and the smoother surface leads to a higher friction coefficient. Also good agreement was found between simulations and experimental results.

Abstract: Micro-structure nickels were fabricated by LIGA, and their surface morphology, microstructure and texture were studied by Microscope, SEM and XRD. The results show that the specimens have uneven microstructure, and the grains are relatively small. The grains grow mainly by the form of columnar and cluster-like, and there are obviously preferred orientation in the (220) plane.

Abstract: One Micro-Electro-Mechanical System(MEMS) based actuator that fabricated by LIGA (Lithographie ,Galanoformung and Abformung) technology was designed to distinguish the change of the exterior condition. In order to prove whether the parts in the actuator intervene each other during motion, ADAMS software was utilized to simulate the motion. The rigid-flexible coupling dynamic modeling of the design was obtained by combining finite element method (FEM) with Lagrange equation, the mathematics modeling was solved with Gear method in ADAMS. The results showed that the MEMS-based actuator could move smoothly, and the simulated curve meets the intent.

Abstract: This paper presents a novel LIGA-like process to fabricate the nozzle plate for matching the requirements of the 600 dpi inkjet printhead. This novel fabrication technique reduces the production cost from 100% current process to 50%. This mass production technique comprises two main technologies: Ni-Co electroforming and plastic injection molding. The nozzle plate consists ink channels, ink cavities, and nozzles for enhancing the integrity and excusing the assembly process. The dimensions of nozzle plate are 4.16mm in width and 7.3mm in length, respectively. Total thickness of micro-nozzle plates are thickness≦100um(ink channels and ink cavities), and the diameter and pitch of the nozzle holes are 40±3um and 168±3 um, respectively. Straightly speaking, for being the main compositions of the 600 dpi inkjet printhead design, the above fabrication process is qualified enough and capable of yielding satisfactory results.

Abstract: Non-destructive and on-line Li diffusion experiments in Li ionic conductors are conducted using the short-lived !-emitting radiotracer of 8Li. The radiotracers produced as an energetic and pulsed ion beam from TRIAC (Tokai Radioactive Ion Accelerator Complex) are implanted into a structural defect mediated Li ionic conductor of NaTl-type intermetallic compounds ("-LiGa and "-LiIn). The experimental time spectra of the yields of !-particles are compared with simulated results and Li diffusion coefficients in the intermetallic compounds are extracted with an accuracy of ±10%. The diffusion coefficients obtained for "-LiGa with Li content of 43-54 at.% are discussed in terms of the interaction between Li-ion and the structural defects in the specimen, compared with the cases of "-LiAl and "-LiIn. The nonlinear Li-content dependency of Li diffusion coefficients for "-LiGa suggests that the Li diffusion with the Li-deficient region is obstructed by the defect complex composed of vacancies at the Li sites.

Abstract: The reliability and optimal design of Micro Electro Mechanical Systems (MEMS) can be achieved only with the determination of material properties at the micro-scale. The major challenges in performing fatigue tests at the micro-scale are related to the accurate measurement of tiny deformations, to the control of very low forces and to the preparation, handling and positioning of μm-sized samples. In order to investigate the fatigue behaviour of MEMS components a new experimental setup based on the Phase Lock Loop (PLL) technique and a continuum mechanical model were developed for the characterization of micro-sized test samples. The main advantage of PLL is the achievable resolution in the crack length measurement, which increases with the decreasing of specimen size. Therefore, micro-beams with notches and without notches were prepared by electroplating Nickel in a SU8 photoresist mold (UV-LIGA). Investigations on the initiation and near-threshold crack growth behavior were performed to improve the understanding of the micro-mechanisms involved in fatigue phenomena.

Abstract: One of the authors proposed a non-equilibrium powder metallurgy process, which enables the fabrication of a near net-shape product using TiC and TiN/Silicide ceramic composites. The PM process in combination with mechanical alloying (MA) and Spark Plasma Sintering (SPS) are applied to produce nano-grain composite, TiC/Ti5Si3. Powders of elements Ti and SiC whose composition is Ti-20 mass%SiC are blended for MA. After the alloying, the MA powder whose average particle size is 20~30 μm, has amorphous-like structures, and then the MA powder is compacted by SPS. Results of compression-tests indicate the occurrence of unusual hightemperature deformation behaviors such as low flow stress at the lower deformation temperature or at the high initial strain rates were observed in the SPS compacts. TEM observations of the deformed compacts after the compression-tests indicate the microstructure has no-strain equiaxial - grains and clear boundaries. This serves as proof of a superplasticity deformation. In addtion, the results of the XRD analysis of the compressed-compacts show that new phases are formed during the compression-test. Therefore, the above deformation is attributed to a "pseudo" superplasticity in which the phase transition of metastable microstructure occurs during the deformation.