The quality of benzocyclobutene (BCB) and Parylene-N (PA-N) films after chemical-mechanical polishing (CMP) is influenced by 3 factors: slurry composition, quality of the as-deposited film or post-deposition treated f...
The quality of benzocyclobutene (BCB) and Parylene-N (PA-N) films after chemical-mechanical polishing (CMP) is influenced by 3 factors: slurry composition, quality of the as-deposited film or post-deposition treated film, and polishing time. The quality of the films has been investigated by using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is shown that the higher the quality of the as-deposited film (or post-deposition treated film), the higher the quality of the polished film. The polishing time has little effect on the surface characteristics of high quality PA-N films, however it has an effect on BCB film. This is attributed to the structure and thermal-stability and higher chemical resistance of PA-N. The RMS surface roughness measured by AFM, for as-deposited PA-N is 90Å. The roughness after CMP processes is greater than 200Å. The roughness for as-spin-coated and polished BCB film is 5Å, and 20Å, respectively. The morphology of the PA-N film, either as-deposited or polished, is not as good as the BCB film. A slurry which is good for BCB polishing is not good for PA-N polishing, and vice versa. These results indicate that the nature of the polymer film, including its chemical structure as well as the quality of the as-deposited/post-deposition treated film, plays an important role in polymer CMP.
Multi-junction silicon light emitting devices (Si LED's) were designed and realised by using standard 1.2 micron and 2 micron CMOS processes with a bipolar capability and with no modifications to the processes. Th...
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Multi-junction silicon light emitting devices (Si LED's) were designed and realised by using standard 1.2 micron and 2 micron CMOS processes with a bipolar capability and with no modifications to the processes. The designs were optimised to increase the power conversion efficiency, quantum conversion efficiency, intensity of emission and also the uniformity of emission. The devices emit light of several nW per 5 to 10 mA at 4-30 V in the 450 to 850 nm wavelength range. All the devices operated with at least one pn junction in the field emission or avalanche breakdown mode. Quantum conversion efficiencies of up to 1/spl times/10/sup -5/ have been measured which is two and a half orders to three orders of magnitude higher than previously published values for light emission from Si p-n avalanching junctions. Some directional light emission characteristics were also observed. The developed devices are viable for on-chip electro-optical applications and also for high speed chip-to-environment electro-optical applications.
The flexibility required of an agile manufacturing system must be achieved largely through computer software. The system's control software must be adaptable to new products and to new system components without be...
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The flexibility required of an agile manufacturing system must be achieved largely through computer software. The system's control software must be adaptable to new products and to new system components without becoming unreliable or difficult to maintain. This requires designing the software specifically to facilitate future changes. As part of the Agile Manufacturing Project at Case Western Reserve University, we have developed a software architecture for control of an agile manufacturing workcell, and we have demonstrated its flexibility with rapid changeover and introduction of new products. In this paper, we describe the requirements for agile manufacturing software and how our software architecture addresses them.
The generation of rule-bases in conventional fuzzy logic controllers can be a difficult and time consuming problem for implementation by process operators thus affecting their wider applicability. A Self-Learning Fuzz...
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The generation of rule-bases in conventional fuzzy logic controllers can be a difficult and time consuming problem for implementation by process operators thus affecting their wider applicability. A Self-Learning Fuzzy Logic Control (SLFLC) offers a possible solution. A performance study is therefore presented to evaluate the performance of a proposed SLFLC by analysing its transient performance for a variety of on-line tests and examining its ability to generate a consistent set of rules, based on a predetermined criteria. The results presented show that even with a limited knowledge of the process, the self-learning procedure is able to develop a suitable set of rules and produce a satisfactory process performance with some degree of robustness and repeatability when applied to a non-linear single-input single-output (SISO) or multi-input multi-output (MIMO) laboratory liquid-level processes.
Enhanced ZT has been predicted theoretically for low dimensional electronic systems under appropriate experimental conditions. Enhanced ZT has been observed experimentally within 2D quantum wells of PbTe, and good agr...
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Enhanced ZT has been predicted theoretically for low dimensional electronic systems under appropriate experimental conditions. Enhanced ZT has been observed experimentally within 2D quantum wells of PbTe, and good agreement between theory and experiment has been obtained. The advantages of low dimensional systems for thermoelectric applications are described, and prospects for further enhancement of ZT are discussed.
An agile workcell has been developed for light mechanical assembly in collaboration with industrial sponsors. The workcell includes multiple Adept robots, a Bosch conveyor system, multiple flexible parts feeders at ea...
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An agile workcell has been developed for light mechanical assembly in collaboration with industrial sponsors. The workcell includes multiple Adept robots, a Bosch conveyor system, multiple flexible parts feeders at each robot's workstation, CCD cameras for parts feeding and hardware registration, and a dual VMEbus control system. Our flexible pairs feeder design uses multiple conveyors to singulate the parts and machine vision to locate them. Specialized hardware is encapsulated on modular grippers and modular worktables which can be quickly interchanged for assembly of different products. Object-oriented software (C++) running under VxWorks, a real-time operating system, is used for workcell control. An agile software architecture was developed for rapid introduction of new assemblies through code re-use. A simulation of the workcell was developed so that controller software could be written and tested off-line, enabling the rapid introduction of new products.
A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structure...
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A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.
In an era of fiscal austerity, downsizing and unforgiving pressure upon human and economic capital, it is an Augean task to identify resources for fresh and creative work. The realities of the day and the practical de...
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In an era of fiscal austerity, downsizing and unforgiving pressure upon human and economic capital, it is an Augean task to identify resources for fresh and creative work. The realities of the day and the practical demands of more immediate fleet needs can often dictate higher priorities. Yet, the Navy must avoid eating its seed corn. Exercising both technical insight and management foresight, the fleet, the R&D community, the Office of the Chief of Naval Operations (OpNav) and the product engineering expertise of the Naval Surface Warfare Center (NSWC) are joined and underway with integrated efforts to marry new, fully demonstrated technologies and operational urgencies. Defense funding today cannot sponsor all work that can be mission-justified over the long term because budgets are insufficient to support product maturation within the classical development cycle. However, by rigorous technical filtering and astute engineering of both marketplace capabilities and currently available components, it is possible in a few select cases to compress and, in effect, integrate advanced development (6.3), engineering development (6.4), weapon procurement (WPN), ship construction (SCN), operation and maintenance (O&M,N) budgetary categories when fleet criticalities and technology opportunities can happily meet. In short, 6.3 funds can be applied directly to ''ripe gateways'' so modern technology is inserted into existing troubled or aging systems, sidestepping the lengthy, traditional development cycle and accelerating practical payoffs to recurrent fleet problems. To produce such constructive results has required a remarkable convergence of sponsor prescience and engineering workforce excellence. The paper describes, extensively, the philosophy of approach, transition strategy, polling of fleet needs, technology assessment, and management team requirements. The process for culling and selecting specific candidate tasks for SHARP sponsorship (matching operational need with t
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