Investigation of atmospheric-pressure plasma deposited SiOx films on polymeric substrates

The novel technique of plasma chemical vapor deposition without using vacuum chamber was investigated to deposit SiOx films on polymeric substrates through tetraethoxysilane (TEOS)/Air atmospheric-pressure plasma (APP) glow discharge. Depending on the proper deposition parameters, thin and smooth SiOx films on polycarbonate substrates were prepared. The atmospheric-pressure plasma deposited SiOx films obtained the desirable transparency in the visible and increased absorption in UV region. The surface characteristics of APP deposited SiOx films were examined by various surface analysis methods including FTIR, XPS, and SEM. It is shown that SiOx films exhibited low porosity and admirable hardness for optical applications.     

A vision-aided automation system for destructive web thickness measurement of microdrills

Microdrills are fundamental cutting tools used in mechanical microdrilling. The web thickness of a microdrill is an important design parameter in balancing drill rigidity and chip removal ability. Conventional destructive method for measuring the web thickness is currently adopted by some microdrill manufactures. The conventional method must be carried out manually by experienced inspectors and thus lacks sufficient efficiency and accuracy. To improve the drawbacks of the conventional method, a vision-aided automation system for performing the destructive web thickness measurement is introduced in this paper. Based on the integration of motion and logic control, machine vision, and image processing techniques, an automated measuring process is then established. Experiments to measure the web thickness of microdrill samples were conducted to test the feasibility and effectiveness of the presented automation system and automated measuring process. The experimental results showed that the presented vision-aided automation system, in combination with the automated measuring process, could be an efficient and precise manner for replacing the conventional manual procedure in performing the destructive web thickness measurement of certain microdrills.     

Mechanical error analysis of disk cam mechanisms with a flat-faced follower

By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.     

Effects of brominated flame retardants and crosslinking agents on the flame retardancy of rubbers

Tetrabromo-p-cresol (TBPC), pentabromophenol (PBP), and their allyl ether derivatives—tetrabromo-p-cresol allyl ether (TBPC–AE) and pentabromophenol allyl ether (PBP–AE)—were used in the study of flame retardancy of ethylene–vinyl acetate (EVA) copolymer and styrene–butadiene rubber (SBR), which were cured by dicumyl peroxide (DCP) and sulfur, respectively. The dependence of the flammability of crosslinking polymers on the polymer matrix, its additives, and the degree of crosslinking was investigated. The empirical equations of flame retardancy were established for these rubbers and compared with the measured values. It was found that the oxygen index of SBR–S system was in accordance with the empirical equations, while the EVA–DCP system, affected by the decomposed residue of DCP, showed a slight deviation. The brominated phenolic compounds of allyl ether (BPs–AE) showed a greater deviation than their precursors. This may be due to the fact that allyl group could react with DCP and lose its excellent flame resistance characteristic, which may be caused by the modified Claisen rearrangement produced in the thermal processing or burning. The phenolic brominated compounds containing the allyl group and a higher bromine content showed better flammability.     

A novel laser-processed self-aligned gate-overlapped LDD poly-SiTFT

A novel process for fabricating self-aligned gate-overlapped LDD (SAGOLDD) poly-Si thin film transistors (TFTs) was demonstrated. Laser irradiation for dopant activation was performed from the backside of the quartz wafer. The graded LDD structure was naturally formed under the gate edges due to the lateral diffusion of the dopants during the laser activation. In comparison with the conventional laser-processed self-aligned poly-Si TFTs, the SAGOLDD poly-Si TFTs exhibited lower leakage current, suppressed kink effect, and higher reliability. Moreover, the proposed process was simple and very suitable for low-temperature processing     

Manipulation of silver nanostructures using supercritical fluids in the presence of polyvinylpyrrolidone and ethylene glycol

This study reports on a new method for manipulating the size and shape of silver nanostructures using supercritical carbon dioxide (CO₂) in the presence of polyvinyl pyrrolidone (PVP) and ethylene glycol (EG). The temperature and pressure of CO₂ as well as the ratio of the capping agent PVP to the precursor of silver nitrate are used to control the growth of the silver nuclei and grains during the synthesis of silver nanostructures in ethylene glycol. The as-synthesized nanostructures were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X-ray powder diffraction (XRD). The results indicate that the aspect ratio of silver nanostructures, in particular, increases with an increase in the temperature and pressure of supercritical CO₂ from 3.5 to 50.     

Misalignment inspection of multilayer PCBs with an automated X-ray machine vision system

In recent times, multilayer printed circuit boards (PCBs) have been extensively applied in the electronics industry owing to their high capacities for complex and densely packed circuit layouts arranged in a limited space. The inspection of fabricated multilayer PCBs is thus important in order to ensure quality control and improve the fabrication process. In this paper, an automated X-ray machine vision system was developed exclusively for the inspection of the layer-to-layer misalignment of laminated multilayer PCBs. Based on a mechatronics system and X-ray image processing techniques, an automated misalignment inspection process was established. Experiments meant to inspect three critical layer-to-layer misalignment modes, expansion, contraction, and offset, found within ten-layer PCB samples, were conducted to test the feasibility of the developed machine inspection system. The experimental results show that the developed X-ray machine vision system, combined with the automated misalignment inspection process, was able to undertake misalignment inspection of certain multilayer PCBs.     

The force transmissivity index of planar linkage mechanisms

In this paper, a new force transmissivity index (FTI) of planar linkage mechanisms is proposed. The index is used to quantitatively measure the force transmission quality from the input link to an output link. Traditionally, the transmission angle is used to measure the ability to transmit motion for planar four-bar linkages. However, the transmission angle is usually limited to be used at four-bar linkages due to the structural simplicity. For complex multi-loop mechanisms, it is often difficult to define the force transmissivity. Here we have established a procedure of force transmissivity analysis for planar linkage mechanisms. The method is based on the static force analysis and the concept of power flow path. It is found that the force transmissivity of a mechanism depends not only on the configurations of the mechanism, but also on the selection of the output link and the forms of the loading. We have compared the results based on the FTI with the results from the Jacobian matrix method and the joint force index (JFI) method for four-bar mechanisms. It shows that the proposed FTI can describe the force transmission performance more accurately than other methods do. It is concluded that the index can be used as a better measure of force transmissivity analysis for planar linkage mechanisms.     

Creative mechanism design for a prosthetic hand

In this paper, an auxiliary methodology called the creative mechanism design is introduced into the innovation of gripping devices for prosthetic hands. This methodology is a systematic approach based on modification of existing devices for the generation of all possible topological structures of mechanisms and mechanical devices. An existing gripping device (Teh Lin ATG-5F prosthetic hand) constructed by a planar six-bar linkage with one degree of freedom is dealt with by using this methodology. Through the processes of generalization, number synthesis, specialization and particularization for the existing design, five new mechanisms are created in this study to apply to anthropomorphic prosthetic hands. The results show that the methodology for creative mechanism design is a powerful tool for creating new categories of mechanisms to avoid existing designs that have patent protection and can help designers in the conceptual phase. Also, this methodology is validated as a useful way to improve prosthetic hands for amputees.