Papers by Keyword: UV-LIGA

Abstract: In this paper, a fabrication process of ultra-high metal micro electrode array by means of UV-LIGA technology and its application in micro Electrochemical Machining (ECM) was investigated, and a new aided method, which can completely remove the ultra-thick cross-linked SU-8 resist without leaving remnants of the resist or destroying the electroplated microstructures, was advanced. During the lithography process, 1mm thick SU-8 moulds of different patterns were fabricated on the substrate. Before the electroforming process, a through-mask electrochemical micromachining (through-mask EMM) procedure was carried out to process micro roots on the substrate, the processed micro roots could improve the adhesion of micro electrode array electroformed on the substrate. After the electroforming process, cross-linked SU-8 resist was removed by the hot remover PG (MicroChem). Under the optimal experiment conditions of this fabrication process, the electrode arrays up to 800μm high of different shapes were fabricated. Finally, the fabricated electrode arrays was used as cathode to machine micro hole arrays on stainless steel by micro ECM.

Abstract: Fuze Micro-Electro-Mechanical System (MEMS) has become a popular subject in recent years. Studies have been done for the application of MEMS-based fuze safety and arm devices. The existing researches mainly focused on reducing the cost and volume of the fuze safety device. The reduction in volume allows more payloads and, thus, makes small-caliber rounds more effective and the weapon system more affordable. At present, MEMS-based fuze safety devices are fabricated mainly by using deep reactive ion etching (DRIE) or LIGA technology, and the fabrication process research on the fuze MEMS safety device is in the exploring stage. In this paper, a new trans-scale fabrication method of metal-based fuze MEMS safety device is presented based on UV-LIGA technology and the micro Wire-cut Electrical Discharge Machining (WEDM). The method consists of fabrication of micro-spring by UV-LIGA technology, the fabrication of mesoscale structure by WEDM, the micro assembly of micro spring and mesoscale structure. Because UV-LIGA technology and WEDM technology were introduced, the production cycle was shortened and the cost was reduced. The overall dimension of the micro-fuse safety device is 9.5×12.3×0.6 mm and the smallest dimension is 10μm. Besides, four problems in the fabrication process have been solved effectively, which is helpful for the fabrication of similar kinds of micro devices. The fabrication method presented in this paper provides a new option for the development of MEMS fuze.

Abstract: To remove the shortcomings from the manufacturing process it is necessary to optimize all process parameters, for all stages of technological process: the exposure, the development, the electroforming and removal of the exposed SU8. This research implies that various types of MEMS devices can be developed at a high accuracy with design flexibility, only if all process parameters are optimized. This article is presenting a study regarding typical errors arisen during manufacturing of micro-parts using UV-LIGA technology.

Abstract: UV-LIGA technics which used in high aspect ratio micro-structure fabrication has been developed quickly currently, but there still exist many technical problems which may affect the reliability of production, especially in lithography and electroform process. According to analyzing the technical process of bi-layer micro-gear, the reliability problems have been studied from two aspects, including deep lithography and micro electroform. In the deep lithography technology, the adhesive property between SU-8 photoresist and substrate and the non-uniform thickness and bubble problems of SU-8 photoresist layer have been presented. In the micro electroform aspect, problems include non-uniformity, air holes, and adhesive property of electroformed layer. Aimed at these problems, the resolvents have been put forward and validated, which improve the reliability of technics and possess fine effect.

Abstract: In this paper, differential capacitors sandwiched structure of a high-G capacitive microaccelerometer with round metal proof mass supported by multi-beam and its characteristic are presented. The operation principle and built-in self-calibration and self-test functions are described. The fabrication process and the fabricated chip of the microaccelerometer based on UV-LIGA technology are reported. The detection and closed-loop control circuits of the microaccelerometer are designed and calibrated. The range of the detection channel is ±6pF, the sensitivity is 89.3mV/pF, and the linearity is 2.59%.

Abstract: In recent years an increasing interest has grown in using Micro Electro Mechanical System (MEMS) fabrication technology in mechanical timepieces. The UV-LIGA process which combines ultraviolet lithography and electroforming is among micro-production technologies providing exciting possibilities. It has been established as industrial viable for the fabrication of various micromechanical components. Current limitations are that the technology is restricted to the use of nickel. It is too soft (~ 300HV) and has magnetic properties. It is not perfect for the movement of timepieces. However, by adding other materials, e.g. phosphor-Nickel (Ni-P), these alloys have their attractions, being stainless, non-magnetic and very high hardness. As a new technique, details are still being perfected. In this work, the process of Ni-P micro electroforming has been developed to extend UV-LIGA technology. And attempt has been made to investigate the magnetic properties and the hardness of the manufactured Ni-P alloy components. The results showed that the phosphor content can be controlled by different concentration of phosphorous acid (H3PO3) in the electrolyte solution. Corresponding properties have been analyzed which shows good hardness and lower magnetic properties. When the phosphorous content reaches over 12 wt%, the Ni-P alloy is with non-magnetic properties while pure nickel is ferromagnetic material. And the hardness of electroformed Ni-P alloy is about 600 HV and can be above 1000 HV after special heat treatment.

Abstract: This paper presents the design, simulation and fabrication of an mm-scale air-driven microturbomachine. The circumferential-flow turbomachine has a plain-shaped structure with an overall size of 8×8×3mm³. The predicted formulas for driving torque and driving power are deduced by analyzing the working condition of the model. Finite element simulation is carried out to determine the driving torque and driving power. Turbine and stator are fabricated using UV-LIGA technique, while other components using pension micromachining. Test results of assembled prototype show that under the air-flow speed of 80m/s, no-load and load rotation speed are 10kr/min and 9.5kr/min respectively, and the output power is 326.57µW. The results indicate micro turbomachine is potential power source for the micro system.

Abstract: An analytical model of an eddy current sensor designed for noncontact distance measurement is presented. The device consists of two planar coil (driver coil and pickup coil) stacked on the magnetic core. The planar coil fabricated by UV-LIGA technology with SU-8 photoresist is illustrated, and the permalloy magnetic core electroforming process is presented also. Tested with 10-50 KHz sine signal, the output voltage of the sensing coil reached 30mv with a Ni target placed at a distance of 20μm. And the experimental showed a linear relation between the distance and output voltage within 60μm distance. The amplitude trend increases with the increasing of the frequency and amplitude of excited signal, which is according with the theory analytics. The whole size of the device is: Φ5mm×1.5mm. The results demonstrated that the device could nondestructive evaluate the distance and be easily integrated on chip, and the UV-LIGA Process could be used as a new method to fabricate the micro eddy current sensor massly.

Abstract: The research work reported in this paper design a novel biodegradable multichamber microstructure for implantable drug controlled release by introducing the approach of topology optimization. It is therefore highly desirable to overcome these restrictions that pre-defined topology of the device result in difficulty to obtain a linear or pulsed drug release profile. The designed biodegradable multichamber microstructure is fabricated using UV-LIGA microfabrication and Micro-molding technique. The simulation results show that the multichamber microstructure exhibits a preferable linear drug release profile.

Abstract: This paper investigated the impact of area effect in the batch mode micro-EDM on shape accuracy and surface morphology of the machined microstructures, as well as electrode wear, using both the positive-type and the negative-type electrode arrays fabricated by the UV-LIGA process. Experimental results showed that ,with the increase of electrode-pair scale from Φ1mm, Φ2mm, Φ4mm to Φ8mm, the shape accuracy of the machined stainless steel microstructures increased, but the eroded microcavities of the machined area reduced in both the positive-type and the negative-type micro-EDM using the same electrical pulse parameters. It was also found that, with the same pulse energy and electrode-pair area, the electrode wear reduced as the electrode-couple area increased, and the wear ratio in the positive-type micro-EDM was larger than that in the negative-type micro-EDM.