In recent years, LED and power semiconductor devises are spread rapidly towards the realization of the energy-saving society. Chemical mechanical polishing (CMP) is an important technology in the manufacturing process. In the CMP, the Preston's low is beneficial formula for estimating the removal rate, however, this formula only includes the mechanical parameters; the polishing pressure and the relative velocity. Here, it is well known that the slurry flow behavior has high correlation with the removal rate. This paper reveals the slurry flow in the contact interface between the polishing pad and the substrate. Furthermore, we discuss the novel mathematical evaluation of the removal rate owing to the multiple correlation analysis. As a result, we propose an innovative formula for predicting the removal rate by using the slurry and polishing pad characteristics.
Diamond cutting tools show severe wear in turning of nickel, while electroless nickel deposits remarkably reduces the wear. To understand the wear mechanism in turning of nickel and electroless nickel, thermodynamics analyses of chemical reaction, erosion tests of diamond contacting with work materials and first principle analyses simulating wear process were carried out. The results show that the essential wear mechanism is the dissociation of carbon atoms on diamond surface due to the interaction with nickel atoms on work surface. Phosphorous addition reduces the dissociation because the interaction is suppressed. The lower cutting temperature in turning of electroless nickel than that of nickel also suppresses the interaction between the diamond and work surface. The easy dissociation of carbon atoms is also occurs with small activation energy due to the reaction with oxygen atoms adsorbed on work surface. However, the process causes a tool wear with very small rate in practical cutting, because the oxygen atoms are difficult to enter into the interface between tool and work material. The results suggest that the machinability of difficult-to-cut materials in diamond turning can be improved by some additional elements.
Single-crystal diamond is increasingly used in the fields of cutting tools, semiconductors, micro electromechanical systems and optical devices. It is important to fabricate high-precision microstructures on diamond surfaces at a low cost. In this study, a novel cost-effective technique is proposed for fabricating microstructures on single-crystal diamond by thermochemical reaction-based press imprinting method. Pure iron was used as a mold material and its characteristics in the imprinting process were investigated under various pressure, temperature and processing time. The processed diamond surface was examined by scanning electron microscopy, laser probe surface metrology and energy dispersive X-ray spectroscopy. Results showed that at the same temperature a pure iron mold produced a processing depth four times higher than that of a nickel mold. The thermochemical imprinting mechanisms for pure iron molds were discussed based on the cross-sectional observation results of the mold/diamond interfaces.
Lead magnesium niobate-lead titanate (PMN-PT) single crystals having higher dielectric properties were ground with various diamond wheels and an ultra-precision surface grinder. The grinding force measured with a dynamometer depends upon the grinding time, depth of cut, feed per wheel revolution and grain size of diamond wheels. The dielectric constant of ground sample is a function of thickness of sample, grinding force and grain size, but not a function of depth of cut and grinding direction. The dielectric constant of ground sample is higher than that of polished one, and can be recovered by the heat treatment. The domain of ground surface re-orientates to the grinding direction.
Bullet identification requires special skills and takes a long time. So novel method is expected to be developed for assisting this skillful and time-consuming work. The discrimination of two bullets needs similarity quantification of striated toolmarks most. But conventional method based on image correlation is not applicable because of lower striated toolmark similarity. In this paper, a new method based on intersection which extracts common elements is proposed to measure similarity correctly between striated toolmarks of bullets and makes it possible to extract inherent striated toolmarks of used gun. The effectiveness of the proposed method is confirmed through experiments.
Lithography has been generally used for printing two-dimensional patterns on flat wafers. Recently, however, it is also applied to a three-dimensional patterning for fabricating various MEMS (Micro Electro Mechanical Systems) components. In this research, plastic micro-lens arrays are fabricated utilizing lithographically replicated quasi-spherical concave resist patterns. At first, resist (Tokyo Ohka Kogyo, PMER P-LA900 PM) patterns with densely arrayed hexagonal concaves were replicated by intentionally shifting the focal position of projection exposure. As an exposure system, a handmade 1/19 reduction projection system with a field size of 2-mm square was used. The initial resist thickness was approximately 10 µm. Next, liquid epoxy resin (Nissin resin, Crystal resin Neo) was injected on the concave resist-mold patterns and coagulated. To control the total thickness of hardened resin-lens arrays including the back-side flat part and secure the smoothness and transparency, the resin thickness was controlled by attaching an acrylic lid covering the surface of resist-mold patterns. Finally, focusing performances of the resin lens array were also demonstrated. Using a lens array with a pitch of 42.1µm, a curvature radius of 28.3 µm, and a height of 4.9 µm, focused light spots with a diameter of approximately 3 µm in diameter were obtained.
This paper experimentally and theoretically investigates the relationship between the nonlinear spring behavior (NSB) of linear ball guide and the quadrant glitch in microscopic circular motions. A high precision stage which has nanometer resolution consists of eight grooved linear ball guides and a linear motor is developed for the experiments. Microscopic circular motion tests are carried out to investigate the quadrant glitches in the region. The experimental results suggest that the shape of the quadrant glitches depend on the radius of the circle. It is also suggested that the height of quadrant glitches depend on the frequency of the motion. Relationship between the shape and height of quadrant glitches and NSB of the linear ball guides has theoretically analyzed based on the simplified NSB model. The theoretical model can adequately explain the actual behaviors. Influence of the ball retainer and preload conditions on the NSB are also investigated. It is confirmed that the ball retainers significantly influences the NSB.
In this paper, Haptic End-effector for Medicine and Manufacturing (HEM2) with five degree of freedom (DoF) motion is developed for safer and more intuitive robotic surgery. In resent years, multi DoF forceps robots have been studied and developed to support surgeons. However, conventional multi DoF forceps robots cannot transmit force sensation to surgeons adequately. Force sensation is important for safe and accurate teleoperation. In this paper, a master-slave five DoF HEM2 is developed as a haptic forceps robot. Five DoF motion corresponds with the motion of human hand which can realize complex tasks. By implementing acceleration based bilateral control, force sensation can be transmitted. Spherical joint driven by parallel link mechanism realizes the bending motion of the end-effector. The coaxial driving power transmission mechanism is used to decrease the weight of movable part and improve backdrivability. Besides, the mechanism is composed of rigid parts. The performance of the five DoF HEM2 is validated by experiments.