Fine Circuit Research Articles

マイクロ波を利用した微細電子回路上の金属加熱技術の開発

マイクロ波を利用した微細電子回路上の金属加熱技術の開発

Fine Coal Measurement Needs for Improved Control

The monitoring and management of fine coal circuits in coal preparation plants is limited in current practice. As part of the Australian Coal Association Research Program (ACARP) “Intelligent Plant Project” (C11069), the relationships between the main operational and control factors for the unit operations and the circuit and the performance indicators have been identified. The unit operations examined included desliming (hydrocyclones and sieve bends), small coal cleaning (spirals and hydraulic separators), flotation, and dewatering (vacuum filters, centrifuges, and thickeners). These relationships were then used to assist in the identification of the important parameters to be measured and the preferred level of accuracy required to be useful. An important issue was the interconnection between the various unit operations and the potential impact of an upstream problem on the subsequent performance of downstream units. Analysis with the relationships showed that the flow rate of respective feed slurries and the solids content were found to be significant variables. This article will discuss this analysis and provide some case studies.

Formation of Fine Circuit Patterns on Cyclo Olefin Polymer Film

In recent years, with the miniaturization of electric devices, the demand for flexible printed circuits (FPCs) using polyimide has increased, because of its excellent heat resistance and size stability. Polyimide also has good flexibility and surface smoothness. However, polyimide absorbs moisture readily and is highly permeable to gas. In contrast, Cyclo Olefin Polymer (COP) has low moisture absorption, excellent size stability and excellent high frequency electrical properties. Therefore, COP is attractive as a substrate for FPCs. However, it is difficult to form a metal film using electroless plating on the COP with conventional processes. We could form a copper film with high adhesion strength while maintaining a smooth resin surface by modifying the surface using UV irradiation. Surface modification by UV irradiation was effective to achieve good adhesion (about 1.0 kN/m) between the COP resin and the deposited metal without roughening the COP surface. The interface electric conductivity of the printed circuit on COP produced by this method indicated a value of approximately 80% up to around 30 GHz.

내플라즈마성 알루미나 세라믹스 제조 공정

Need for plasma resistant ceramic materials has been continuously increased in semiconductor and display industry requiring plasma processing to realize ultra fine circuit process. Among promising candidates, alumina ceramics have still some advantages with respect to its economic aspect. In this study, fabrication of plasma resistant alumina ceramics was tried, and its processing optimization was also aimed. Careful processing control and thereby uniform microstructure of Al₂O₃ gave rise to enhanced plasma resistance, even comparable to market-governing commercial Al₂O₃. A further study is needed concerning β-Al₂O₃ materials system, presumably playing a decisive role in decreasing plasma resistance of Al₂O₃ ceramics.

Surface Metallization on High Temperature Liquid-Crystal-Polymer Film by UV-Irradiation Process

A highly adherent Cu–Ni–P film was successfully grown on a UV-irradiated liquid-crystal-polymer (LCP) film. Irradiation from a UV light under an atmospheric condition created hydrophilic nanometer-scale roughness on the LCP film surface by introducing hydrophilic groups on the surface. The high adhesion strength of more than 0.8 kN/m was obtained because of the anchoring effect of the nanometer-scale roughness developed at the interface between the deposited metal and the LCP film. Copper circuit patterns formed on the LCP film showed satisfactory performance for various reliability tests. Fine circuit formation and selective plating facilitated by UV irradiation could lead to a manufacturing approach for the next generation of flexible-printed-circuit technology.

無電解めっきによるガラス上へのニッケルマスクの形成

This paper addresses the formation of the nickel mask on glass using electroless nickel plating without a pinhole. The resultant fine-patterned mask formed on the glass using electroless Ni plating with precision filtration is almost pore-free. The optical density of the glass was greater than 4.0 because of the nickel deposits, with thickness greater than 0.15 μm. The adhesion strength between the deposited Ni and glass is slightly lower than that of the sputtered Cr. The adhesion strength is, however, increased and reaches an almost identical value after heat treatment at 350°C for 1 hr. Fine circuit patterns without a pinhole were formed by the etchant, a HNO3 and H3PO4 mixture. Furthermore, the conventional repair method for the chromium mask pattern is applicable for the repair of nickel patterns on glass.

Size Classification in Scroll Centrifuges

The incorporation of a fine coal circuits (1.4 to 0.1 mm size fraction) into plants has raised the issue of the efficiency of size classification at separation sizes in the region of 0.1 mm. Recent work with centrifuges with laser cut screens has indicated they have shown not only good dewatering capabilities but also provide potential for rapid size classification in the size range of interest. An Australian Coal Association Research Program funded project resulted in a detailed investigation of this potential. The experimental results suggest that this type of unit provides a different classification capability that could assist in particular plant situations. The results have been able to be analyzed and described with a general model for size classification that has incorporated the possibility of particle capture in the bed of oversize particles.

Coal-Fine Beneficiation Studies of a Bench-Scale Water-Only Cyclone Using Artificial Neural Network

Coal fines generated in Indian coal preparation plants account for 25%–30% of run-of-mine (ROM) coal. Coal cleaning is receiving increasingly greater attention of process engineers in view of the increase in amounts to be handled as well as the difficult washability characteristics of high-ash-content Indian coals. Froth flotation is usually practiced in Indian coal washeries for washing the coals to bring down their ash content to acceptable limits. Because of the supply of feed coal from multiple sources, their different characteristics and composition, viz., varying mineralogy and ash content, presence of microfines, and their varying oxidation levels, the fine coal circuits, more often than not, fail to deliver consistent product quality and desired yields. Water-only cyclones have been used in most of the western countries for treating coal and mineral fines below 3 mm. However, the industrial use of these cyclones in India has not yet been put to practice in the coal-washing industry; the primary reason for this being that their design is unsuitable for high-ash content coals and therefore needs to be suitably modified according to the feed material characteristics. Highlighted in the present paper are the results of a case study of beneficiation of high-ash fine coal, using a water-only cyclone. The influence of two of the critical design variables, viz., cyclone length and solid concentration, on which the cyclone performance and the process yield (%) depend to a great extent, is described. Further, based on the experimental data of a water-only cyclone of varying lengths used for below a 3 mm coal beneficiation study, an attempt has also been made to develop a three-layer feed-forward artificial neural network (ANN) model, which is inherently trained using an error-back propagation algorithm. The results evince that the predictions from the ANN model are in good qualitative and quantitative agreement with the experimental observations, thereby validating the applicability and accuracy of the developed ANN model.

Fine electronic circuit pattern formation on plastic substrates by metal nanoparticle pastes

Fine electronic circuit pattern formation on plastic substrates by metal nanoparticle pastes

Ultrafine coal classification using 150 mm gMax cyclone circuits

A two-stage classification circuit using 150 mm diameter gMax cyclones was installed and evaluated in a coal preparation plant in an effort to achieve a clean coal product without the use of froth flotation. Particle size separations of around 37 μm were achieved while limiting ultrafine bypass to less than 10% in the circuit underflow stream. As a result, approximately 81% of the ash-bearing material in the circuit feed was rejected to the circuit overflow stream. The feed ash content was reduced from around 50% to values in the range of 22–30% in the circuit underflow stream with a mass recovery of about 30%. Further reductions in the coarse product ash content were limited due to the particle density effect and the remaining presence of a significant quantity of high-ash slime material in the coarse product. The typical D 50 for the coal particles was 40 μm while the estimated value for mineral matter was 17 μm. Based on the findings of the study, the use of classification to recover a low-ash, coarse fraction in the feed of a fine coal circuit is limited by the density effect regardless of the ability to eliminate ultrafine bypass.

Fine coal circuitry considerations in treatment of soft coal with difficult washabilities

A typical process used in Chinese metallurgical coal preparation plants employs heavy-media separation to treat the coal coarser than 0.5 mm. The − 0.5 mm fine coal is treated with froth flotation. A major disadvantage of this process is that a large quantity of fine coal is recycled in the heavy-media cyclone circuit, which results in high magnetite losses. The − 0.5 mm fine coal in the media is a result of poor raw coal deslime screen efficiency and the continuous breakage associated with the processing of soft coal. Another disadvantage of this typical process is that some coarse clean coal particles are lost to the froth flotation tailings. This investigation focuses on the simulation of processing fine soft coal with water-only cyclone (WOC) and spirals. WOCs and spirals have become popular devices for treating fine coal. WOCs can operate at low specific gravity cut points to produce low ash clean coal while spirals tends to operate at high specific gravity cut points and act as a scavenger to rewash the underflow (refuse) from WOCs. The combination of WOCs and spirals can compete with a heavy-media cyclone with respect to both efficiency and clean coal yield when treating 1 mm × 100 Mesh fine coal. This fine coal processing circuit can subsequently increase the bottom size of the heavy-media cyclone feed from 0.5 mm to 1 mm which will reduce the loading of the heavy-media cyclone circuit. This change in circuitry thus reduces magnetite consumption without scarifying separation efficiency of the 1 mm × 0 size fraction. Furthermore, the reduction of the nominal top size of the froth flotation feed from 0.5 mm to 0.15 mm will greatly decrease or eliminate the loss of clean coal to flotation tailings.

Feasibility of the 248 nm Excimer laser in the laser structuring of fine circuit lines on printed circuit board

Excimer laser (KrF) is used as a new laser source to determine its feasibility in the laser structuring process. Compared with frequency-tripled Nd:YAG lasers, the Excimer laser can conveniently change the spot size of a laser beam to get a smaller sized circuit line/space by inserting a mask. Some frequently used laser parameters of the Excimer laser are discussed in this paper, such as laser energy, number of repetition, repetition rate, bite size and laser beam size. The differences between the Nd:YAG laser and the Excimer laser in laser structuring are also explored in this paper.

Novel Method for Simultaneous Formation of Wires and Vias of a Printed Circuit Board Using Nanoporous Body

A new type of a flexible printed circuit board with landless vias is developed using a novel method called interconnection via nanoporous structure (INPS). This method can make wires and vias of the printed circuit board simultaneously by a single photo-exposure process. A new photo-induced selective plating method was used to impregnate a nanoporous substrate with copper, and a new photomask was designed, which constitutes of a completely vacant large hole for via and aggregation patterns of very fine holes for wire. Because of the simple process, the INPS board is characterized by landless vias and very fine circuit. Owing to the structure, it is also characterized by flexibility and detachable wires.

SEMICONDUCTORS FROM LIQUIDS

A NOVEL SEMICONDUCTOR-processing technique based on a liquid precursor to solid silicon may one day replace traditional vapor-deposition methods for fabricating microelectronic devices. The procedure, developed by researchers in Japan, may enable the use of low-cost ink-jet printing methods to manufacture large-area displays and other advanced electronic devices. At the core of most modern microelectronic devices lies a siliconbased brain that's been painstakingly constructed via a variety of exacting and energy-intensive processes. Manufacturers often depend on procedures in which highly purified silicon is heated and vaporized in vacuum and then deposited on a support material to build up structures in a layer-by-layer fashion. The overall process generally involves multiple refining, deposition, and etching steps to convert the solid film into a functioning circuit component. Simpler approaches using liquids could capitalize on today's high-resolution printing technology to draw fine circuit featur...

光触媒としてＴｉＯ２を用いたビルドアップ法による絶縁材料への無電解銅めっき

Printed circuit boards (PCBs) have required higher density and more integration, since many electronic devices have become downsized and multi-functionalized. For higher density, PCBs should have enough adhesion between the substrate and the conductive layer, maintaining a smooth surface for finer patterning. Newly developed surface modifications using TiO2 powder as a photocatalyst and UV irradiation has achieved excellent adhesion strength of 1.15kN/m without increasing the roughness of the substrate. This paper reported a mechanism of excellent adhesion and fabrication of fine patterns on PCBs with lines and spaces of 10μm/10μm. A modified surface of PCBs in a depth of 30-50nm was created by the irradiation of UV light under the presence of TiO2 as a photocatalyst. Moreover, it is confirmed that palladium (Pd) and tin (Sn) as the catalysts penetrated into the surface modified layer, and electroless copper (Cu) plating was initiated at the bottom of this layer. Therefore, it is suggested that the excellent adhesion was originated from the nano-level anchor effect by the formation of a co-existed layer between the PCBs and the deposited copper. Accordingly, fine patterns with line and space of 10μm/10μm were actually fabricated by using the new surface modification in place of etching and followed by conventional pre-treatment. By introducing the new surface modification, fine line circuits were formed without roughening the surface of the PCB, and no extraneous deposition was observed between the lines in contrast to the conventional method. It is concluded that this new method has an intrinsic advantage for the formation of finer patterned PCBs.

Flotation process diagnostics and modelling by coal grain analysis

In coal flotation, particles of different components of the coal such as maceral groups and mineral matter and their associations have different hydrophobicities and therefore different flotation responses. By using a new coal grain analysis method for characterising individual grains, more detailed flotation performance analysis and modelling approaches have been developed. The method involves the use of microscopic imaging techniques to obtain estimates of size, compositional and density information on individual grains of fine coal. The density and composition partitioning of coal processed through different flotation systems provides an avenue to pinpoint the actual cause of poor process performance so that corrective action may be initiated. The information on grain size, density and composition is being used as input data to develop more detailed flotation process models to provide better predictions of process performance for both mechanical and column flotation devices. A number of approaches may be taken to flotation modelling such as the probability approach and the kinetic model approach or a combination of the two. In the work reported here, a simple probability approach has been taken, which will be further refined in due course. The use of grain data to map the responses of different types of coal grains through various fine coal cleaning processes provided a more advanced diagnostic capability for fine coal cleaning circuits. This enabled flotation performance curves analogous to partition curves for density separators to be produced for flotation devices.

Reagents in igneous phosphate ores flotation

The role of reagents utilised in igneous phosphate ores flotation is reviewed. Fatty acids soaps derived from different vegetable species are utilised as collectors. Less expensive species, such as rice and soybean bran oils replaced successfully the more expensive tall oil as the source for the apatite collector. Synthetic collectors such as sarcosinate and sulphosuccinate are also employed. The collector species plays also the frother role. Corn starch is the gangue depressant. Less pure starches, with oil contents equal to or higher than 3%, may be utilised without the risk of suppressing the froth. Actually they may act as a froth controller due to the fact that the fatty acid soap that plays the frother role is an ionic species, generating thus a voluminous froth. Non ionic ethoxylated surfactants may also be used to control the surface tension of the system. Barite, when present, may be either pre-floated with cetyl-stearyl sodium sulphate or depressed, in the fine apatite flotation circuit, at pH 12.

Thin-film particles of graphite oxide. 2: Preliminary studies for internal micro fabrication of single particle and carbonaceous electronic circuits

Some preliminary studies to realize a carbonaceous electronic circuit were carried out using the liquid-dispersible thin-film particles of graphite oxide and their conductive reduction product. (1) The affinity of insulator substrates (diamond, silicon carbide, silicon, sapphire and three kinds of glass) for the particles was improved by heating and immersion in water. (2) The electric conductivity was measured for a wide wiring pattern formed by a large number of the reduced thin-film particles mounted on the substrate, and the value was 1600 S/m after heating at 500 °C. (3) To make the prototype of a narrow wiring or a micro device, the internal micro fabrication (position-selective removal) of a single particle was attempted using focused ion beam. Many kinds of patterns which contain narrow wiring having a width of 200 nm etc. were formed in the reduced thin-film particle having about 10 nm thickness. (4) The simple model calculation of anisotropic conductivity was executed for thin graphite which has a small number of layers and finite size. In the case of the fine graphitic carbonaceous devices and circuits, much attention must be paid to their sizes in all directions.

Wideband Magnetooptic Probe with 10 µm-Class Spatial Resolution

In this paper we give the results of the trial fabrication and basic performance evaluation of the fiber-edge magnetooptic (FEMO) probe with an approximately 10-µm-thick magnetooptic (MO) crystal. It utilizes the Faraday effect during rotational magnetization in a MO crystal for magnetic field sensing. One should note that as compared to a previously reported FEMO probe, the spatial resolution was improved keeping the similar measurable bandwidth. The developed probe had a 10-µm-class spatial resolution as well as a measurable bandwidth of approximately 2.5 GHz. Furthermore, the realization of this probe made it possible to perform GHz-range magnetic near-field mappings over a fine meander circuit, which means that one can visualize fine current distributions in this frequency range. We compared the measured magnetic field maps with the simulated ones obtained using an electromagnetic field simulator for analyses of GHz-range electromagnetic field distributions. As a result, it was found that sufficiently precise near-field distributions could be measured due to the low invasiveness and superior spatial resolution of the probe.

Study of the Crystal Size Effect on Spatial Resolution in Three-Dimensional Measurement of Fine Electromagnetic Field Distribution by Optical Probing

The effect of crystal size on the spatial resolution of electro/magneto-optic probing measurement has been studied. This is especially important when one deals with three-dimensional field visualization over fine and complicated circuit patterns. Through experimental three-dimensional field analyses, the concept of the sensitive volume is introduced and has been proved to be an appropriate measure to define the three-dimensional spatial resolution. Based upon the reduction of the sensitive volume of a magneto-optic crystal, a magnetic field distribution over a 10-µm-class miniature circuit was precisely visualized in the x–z plane by the fiber edge magneto-optic probe using a 20-µm-thick crystal.