Showing papers on "Insulator (electricity) published in 1999"

Aging of nonceramic insulators due to corona from water drops

Abstract: The fundamental principles of water drop corona as an aging mechanism for nonceramic insulators are presented. It is demonstrated that water drops in the sheath regions enhance the electric field and may cause corona which can play an important role in long-term performance. Electric field enhancement caused by water drops in different locations on the shed and sheath are demonstrated by means of electric field calculations and small scale experiments. The threshold magnitude of the surface electric field for corona from water drops is presented for two silicone rubber surfaces having different hydrophobic properties. The effect of water drop corona activity on the properties of the surface material is shown using small scale aging experiments.

Insulator layers for magnetoresistive transducers

Abstract: A magnetoresistive (MR) transducer has at least one insulative layer made of tetrahedral amorphous carbon (ta-C). The ta-C layer is formed by filtered cathodic arc deposition, has an essentially zero concentration of hydrogen and can serve as a read gap for the transducer. The hydrogen-free t-aC read gap has high thermal conductivity, keeping an adjoining MR sensor from overheating during operation. This extends sensor lifetimes and/or improves sensor performance. The read gap also has low defects and porosity, preventing unwanted electrical conduction or shorting between a sensor and a shield. The high hardness of the read gap resists plasma and chemical etching processes such as ion milling that are used to form the sensor. The increased hardness and reduced defects and porosity allow the read gaps to be made thinner without risking electrical shorting. Other hydrogen-free t-aC layers are employed for other sensor elements where electrical insulation and reduced thickness are important.

Current-induced insulator-metal transition and pattern formation in an organic charge-transfer complex

Abstract: Organic molecular Mott insulators, in which carriers are localized as a result of the electron correlation, showed nonlinear electric conduction upon application of a high electric field along the molecular stacking axis. The current-driven low-resistive state of potassium 7,7,8,8-tetracyanoquinodimethanane was stabilized down to 2 kelvin, where a metallic path was visible with a microscope. The current flow caused a stripe-like periodic phase-segregation into the carrier-rich and carrier-poor regions along the current path.

Water drop corona effects on full-scale 500 kV non-ceramic insulators

Abstract: It is shown that certain regions of commercially available 500 kV non-ceramic insulators have surface electric fields that are above the threshold for water drop corona. Observations made in a full scale accelerated aging chamber, and in service, demonstrate that water drop corona occurs on such insulators. A correlation between the magnitude of the surface electric fields and the condition of the silicone rubber non-ceramic insulator surfaces due to water drop corona is illustrated for two different insulator types in an accelerated aging chamber. Other examples of degradation of nonceramic insulators due to water drop corona are illustrated.

Buried patterned conductor planes for semiconductor-on-insulator integrated circuit

Abstract: A semiconductor-on-insulator integrated circuit with buried patterned layers as electrical conductors for discrete device functions, thermal conductors, and/or decoupling capacitors.

Flashover mechanism of non-ceramic insulators

Abstract: The contamination performance of non-ceramic (NO insulators is better than porcelain insulators. The paper describes the pollution collection mechanism and concludes that silicone rubher insulators collect more pollution than porcelain insulators. Long term exposure of silicone rubber insulators produces a thin layer of pollution, which is a mixture of dust, salt and silicone oil. Fog or morning dew produces droplets on the flat surfaces and forms conductive regions. Spot discharge starts between the regions, which reduces hydrophobicity. Simultaneously, dry-band arcing starts on the shank of the insulator. The two arcs join together, which leads to flashover. The flashover voltage of polluted NC insulators is significantly higher than porcelain ones. Insulator performance is measured with laboratory tests. However, salt-fog and clean-fog tests can give different flashover values.

Method of manufacturing interconnection structural body

Abstract: Disclosed is a method for producing a circuit structure having an insulator layer comprising a porous silicon oxide thin film, which comprises (1) forming a preliminary insulator layer comprising a silicon oxide-organic polymer composite thin film formed on a substrate, which silicon oxide-organic polymer composite thin film comprises a silicon oxide having an organic polymer dispersed therein, (2) forming, in the preliminary insulator layer, a groove which defines a pattern for a circuit, (3) forming, in the groove, a metal layer which functions as a circuit, and (4) removing the organic polymer from the preliminary insulator layer to render the preliminary insulator layer porous, thereby converting the preliminary insulator layer to an insulator layer comprising a porous silicon oxide thin film. By the method of the present invention, the capacitance between mutually adjacent circuit lines (line-to-line capacitance) in the circuit structure can be lowered.

Electric-field-induced insulator–metal transitions in thin films of charge-ordered rare-earth manganates

Abstract: Thin films of charge-ordered Nd0.5Ca0.5MnO3, Y0.5Ca0.5MnO3, and Nd0.5Sr0.5MnO3 have been prepared on Si(100) and LaAlO3(100) substrates by the nebulized spray pyrolysis of organometallic precursors. Small electric fields induce insulator–metal transitions in the films with the resistivity decreasing with increasing current. The current–voltage characteristics are non-ohmic and show some hysteresis. The current-induced negative differential resistance found in these manganate films could have potential technological applications.

Process for depositing a metal coating on a metallic component of an electrical structure

Abstract: A process is provided for depositing a silver coating on a metallic component of a feedthrough assembly to displace surface oxide and to deposit a conductive finish suitable for making an electrical connection. The feedthrough assembly includes a ferrule, an insulator mounted within the ferrule, and at least one tantalum terminal pin extending through the insulator. An inert gas dispensing hood is positioned over the terminal pin to create an argon gas environment around the terminal pin to prevent oxidation. A ground electrode of an electric circuit is connected to the feedthrough assembly. The electric circuit includes a direct current power source electrically connected to a resistor and a high energy storage capacitor. An active electrode of the electrical circuit is attached to a silver anode. The silver anode is brought into contact with a selected area of the terminal pin or ferrule to cause a portion of the silver anode to be deposited onto the contacted area while removing surface oxides from the contacted area. Areas which are not to be coated are shielded from contact with the silver anode using a paper mask.

Method and apparatus for reducing electrical resonances in power and noise propagation in power distribution circuits employing plane conductors

Abstract: Electrical resonances are reduced and noise propagation is attenuated in a multi-layer construction using planar power and ground planar conductors separated by insulating material by loading the power and ground planar conductors with a sufficient amount of capacitance, or series capacitance and resistance, at specific locations so that the planar conductors are electrically broken up into smaller sections which resonate at frequencies above the signal bandwidth. The propagation of injected noise is suppressed by the low-pass filter effect of the capacitive loading at the discrete locations. In accordance with one embodiment of the invention, islands of material with a dielectric constant higher than the dielectric constant of the overall insulator are placed at regular intervals where the capacitance of each high dielectric constant island is comparable to, or higher than, the capacitance of the “low” dielectric material which comprises the remainder of the insulating material. In accordance with a second embodiment, high dielectric constant islands are placed around power and ground vias where most of the transient charge capability is needed.

Flashover of discontinuous pollution layer on HV insulators

Abstract: This paper deals with discontinuous pollution layers deposited on the insulator surface. Two zones are known to form: a clean (dry) zone and a polluted (wetted) zone. The influence of the length and position of the dry zone on the leakage current and the arc length are investigated. These were made on a plane experimental model under ac voltage. Two configurations were studied: pollution deposited near the HV electrode, and pollution deposited near the ground electrode. This study was made using pollution layers with different conductivities. Based on the experimental results, a theoretical model allowing us to calculate the gap impedance, the transferred (gap) voltage and the leakage current was established. This model enables to predict the pollution severity based on the sample's equivalent impedance.

Surface acoustic wave device and its production

Abstract: PROBLEM TO BE SOLVED: To obtain a surface acoustic wave device such as a surface acoustic wave filter or an oscillator, which has the size of the occupation area of the outside shape approximately equal to that of an incorporated surface acoustic wave element and is extremely miniaturized and is capable of surface mounting, and a production method which can perform the production up to packaging in the wafer state and is superior in mass productivity. SOLUTION: In a surface acoustic wave device S, an excitation electrode 2 covered with a protection cover 4 and input/output pads 3a and 3b connected to this excitation electrode 2 are formed on a piezoelectric substrate 1, and columnar electrodes 5 are stood on input/output pads, and at least outer peripheral parts of columnar electrodes 5 are surrounded with an insulator 6, and upper end parts of columnar electrodes 5 are used as input/output terminals of an electric signal.

Electron emission device with specific island-like regions

Abstract: An electron emission device includes an electron-supply layer formed of metal or semiconductor; an insulator layer formed on the electron-supply layer; and a thin-film metal electrode formed on the insulator layer, whereby electrons are emitted when an electric field is applied between the electron-supply layer and the thin-film metal electrode. The insulator layer and the thin-film metal electrode have at least one island-like region where the thicknesses of the insulator layer and the thin-film metal electrode gradually decrease.

Vacuum field transistor

Abstract: Disclosed are flat/vertical type vacuum field transistor (VFT) structures, which adopt a MOSFET-like flat or vertical structure so as to increase the degree of integration and can be operated at low operation voltages at high speeds. The flat type comprises a source and a drain, made of conductors, which stand at a predetermined distance apart on a thin channel insulator with a vacuum channel therebetween; a gate, made of a conductor, which is formed with a width below the source and the drain, the channel insulator functioning to insulate the gate from the source and the drain; and an insulating body, which serves as a base for propping up the channel insulator and the gate. The vertical type comprises a conductive, continuous circumferential source with a void center, formed on a channel insulator; a conductive gate formed below the channel insulator, extending across the source; an insulating body for serving as a base to support the gate and the channel insulator; an insulating walls which stand over the source, forming a closed vacuum channel; and a drain formed over the vacuum channel. In both types, proper bias voltages are applied among the gate, the source and the drain to enable electrons to be field emitted from the source through the vacuum channel to the drain.

Theory of Spin polarized Tunneling in Superconducting Sr2RuO4

Abstract: A theory of tunneling conductance in ferromagnetic metal/insulator/triplet - supercondcutor junctions is presented for unitary and non-unitary spin triplet pairing states which are promising candidates for the superconducting paring symmetry of Sr2RuO4. As the magnitude of the exchange interaction in the ferromagnetic metal is increased, the conductance for the unitary pairing state below the energy gap is reduced in contrast to the case for the non-unitary pairing state.

Electron emission device and display apparatus using the same

Abstract: An electron emission device comprises an electron-supply layer made of metal or semiconductor and disposed on an ohmic electrode; an insulator layer formed on the electron-supply layer; and a thin-film metal electrode formed on the insulator layer. The electron-supply layer has a rectifier function layer, whereby the electron emission device emits electrons when an electric field is applied between the electron-supply layer and the thin-film metal.

Semiconducting polymer field effect transistor

Abstract: A field effect transistor is made of five parts. The first part is an insulator layer, the insulator layer being an electrical insulator such as silica, the insulator layer having a first side and a second side. The second part is a gate, the gate being an electrical conductor such as silver, the gate being positioned on the first side of the insulator layer. The third part is a semiconductor layer, the semiconductor layer including a polymer, at least ten weight percent of the monomer units of the polymer being a 9-substituted fluorene unit and/or a 9,9-substituted fluorene unit, the semiconductor layer having a first side, a second side, a first end and a second end, the second side of the semiconductor layer being on the second side of the insulator layer. The fourth part is a source, the source being an electrical conductor such as silver, the source being in electrical contact with the first end of the semiconductor layer. The fifth part is a drain, the drain being an electrical conductor such as silver, the drain being in electrical contact with the second end of the semiconductor layer. A negative voltage bias applied to the gate causes the formation of a conduction channel in the semiconductor layer from the source to the drain. On the other hand, a positive bias applied to the gate causes the formation of an electron conducting channel in the semiconductor layer.

Structure evolution of implanted polymers: Buried conductive layer formation

Abstract: The polarization, temperature and frequency dependence of the conductivity of polyethylene and poliamide-6 films implanted with B+ ions at 60–100 keV to various fluences were investigated. The phenomenon of hysteresis was observed in the d.c. current–voltage dependence for the polymers implanted with moderate fluences. This effect was attributed to the aligning of electric dipoles (attributed to the carbon-rich clusters) in the implanted layer by the applied electric field. The possibility of fabrication of a sandwich structure insulator/conductive layer/insulator combining the ion implantation with the electrochemical deposition of dielectric polymer poly-ortho-phenylenediamine from solution was demonstrated. The spatial characteristics of this structure enable the control of the conductance of the concealed carbonaceous layer by applying an external electric field that opens the way for fabrication of a transistor-like electronic switch.

Criteria for the diagnostic of polluted ceramic insulators based on the leakage current monitoring technique

Abstract: Ceramic insulators installed in a 400 kV line located in a semidesertic area in Monterrey, Mexico have registered flashover caused during critical pollution (high amount of low solubility material) and wetting conditions (dense fog). In previous studies, the contaminant deposited on these insulators was chemically and electrically reproduced in the laboratory and the wetting conditions needed to cause the flashover at nominal voltage were also determined. To get more information, five different profiles of glass and porcelain insulators and several on-line leakage current monitors were installed in this line to determine the pollution accumulation process. Pollution tests were carried out in laboratory using the same insulator profiles in order to determine the leakage current patterns during critical conditions. The obtained values are being used to compare the performance of the insulators installed in the field with the purpose of providing preventive maintenance indicators. The maximum leakage current levels have been defined for the different profiles and a tighten relation between ESDD and leakage current has been obtained. The current levels have been used as a sign of alarm for the maintenance of this line during several years.

Electric rotating machine with reduced thickness and volume of insulation

Abstract: An the electric rotating machine which is compact and of reduced cost by improving the thermal conductivity of the main insulation in the thickness direction while maintaining the insulation breakdown voltage of the main insulation high. The initial breakdown voltage V in the thickness direction of the main insulator 30 of the stator winding 3 is higher than 20 kV/mm, and the thermal conductivity λ in the thickness direction is within a range of 0.35 to 1 W/m·K, and the product Vλ of the initial breakdown voltage V and the thermal conductivity λ satisfies a relationship of 7≦Vλ≦20 (MWA/m2·K). The amount of resin is within a range of 20 to 50 weight % of the main insulation material.

High-frequency switch

Abstract: PROBLEM TO BE SOLVED: To simultaneously improve passing-loss characteristics under the on-state of a silicon high-frequency switch and isolation characteristics under an off state, by holding the insulator layer of a silicon oxide film having a dielectric constant lower than silicon between a high-resistance silicon substrate and an FET and forming the FET and a signal transmission path. SOLUTION: The insulator layer 10 of a silicon oxide film having a permittivity lower than silicon is held between a silicon substrate 9 and an FET 1, and the FET 1 and a signal transmission path 7 are formed. A high- resistance silicon substrate having a resistivity of 500 Ωcm or more is used as the silicon substrate 9. Accordingly, field distribution to the high-resistance silicon substrate 9 side is interrupted by the silicon oxide film 10 having thickness of several μm inserted between the p-type silicon channel layer 1 and the high-resistance silicon substrate 9, an induced current induced in the high- resistance silicon substrate 9 is lowered, and passing loss in the case of passing through the FET can be reduced. Isolation characteristics at an off time can be improved by SOI structure. COPYRIGHT: (C)2000,JPO

Performance of Non-ceramic Insulators in Tropical Environments

Abstract: Non-ceramic insulators have been tested in the field and under laboratory conditions in many countries for more than three decades. Nevertheless, information about their performance in tropical environments is rather limited. Thus, this project was conducted in order to fill the gap. Six different types of 33 kV insulators (silicone rubber, EPDM, RTV coated porcelain and porcelain) were installed at three different sites exposed to marine, industrial and clean environments in Sri Lanka. The insulator performance was periodically tested by visual scrutiny, hydrophobicity classification and pollution severity measurements for more than three and half years. The silicone rubber insulators and RTV coatings, in general, preserved hydrophobicity, whereas the EPDM insulators showed distinct surface changes. Porcelain insulators flashed over on several occasions. Algae growths were found on silicone rubber surfaces but, their effects on insulator performance were not strong. In parallel, laboratory tests were carried out on insulators in order to develop a method of evaluating insulator performance. A leakage current data acquisition system was developed first. Leakage current waveforms were measured on naturally and artificially contaminated insulators and the measurements were extended to artificially contaminated material samples. A non-linear behavior of leakage current was observed. It was found that this non-linearity was caused by the formation of dry band on hydrophilic surfaces in the presence of contamination. It's relation to surface hydrophobicity and electric stress has been described. Non-linear leakage currents were modeled by RC components characterizing a polluted surface. Neural networks were trained to recognize different leakage current waveforms. It has been suggested that the trained neural networks could be used, in practice, for estimating the risk for flashover development.

High resistance surface coating of solid insulating components for HVDC metal enclosed equipment

Abstract: The field distribution of DC insulation systems is controlled by the conductivity κ of the insulation material. It can be improved by using a high resistance surface coating. Furthermore this coating can prevent charge accumulation on the surface of the insulation. This paper reports about the investigations regarding such a coating that is applied to HVDC stress. The influence of voltage, electrical stress and temperature on the resistance of the coating are investigated.

Electrical machine including toothless flux collector made from ferromagnetic wire

Abstract: A flux collector (30, 50) for an electrical machine includes a continuous strand (36, 52) of ferromagnetic material; and an electrical insulator (38) covering the strand. The strand forms a tight cylindrical coil including a plurality of turns that are stacked axially. The insulator (38) provides turn-to-turn insulation. The insulated wire is covered with a binder (40) and cured. The strand can be a high permeability wire (36) made of soft iron, silicon steel or cobalt steel. In the alternative, the strand can be a strip of METGLAS® amorphous alloy (52).

Vacuum heat insulator, heat insulating box body, heat insulating panel, and manufacture of vacuum heat insulator

Abstract: PROBLEM TO BE SOLVED: To improve the recycle property of a vacuum heat insulator, and reduce the weight thereof by filling the powder carrying at least the oxidation inhibitor in a part of the powder formed by crashing the organic resin composition as a core material of a vacuum heat insulator in an inner bag material having a ventilating property. SOLUTION: The powder 4 of the crashed organic resin composition powder and the oxidation inhibitor 5 are mixed and agitated so as to manufacturing the powder 4 carrying the oxidation inhibitor 5. The predetermined a quantity of this powder 4 is filled in an inner bag material 3 having a ventilating property so as to manufacture a core material 2 for vacuum heat insulator 1. After performing the heating to the core material 2, the core material 2 is inserted with the gas adsorbent 6 into an outer material 7 made of the gas barrier type laminated film. Thereafter, evacuation is performed in a vacuum chamber provided with a thermal fusion device, and an end of the outer material 7 is sealed by thermal fusion so as to form a vacuum heat insulator 1. As an organic resin composition, the hard urethane foam as a foaming body of the urethane resin composition is especially desirable.

Insulating material, electric winding, and method of manufacture thereof

Abstract: An insulating tape (1) of high heat conductivity comprises a mica layer (3) containing 10-25% resin by weight, a reinforcement layer (5), and a filler layer (7) of high temperature conduction containing 10-25% resin by weight. A winding conductor (10) is covered with an insulator (11) of high heat conductivity composed of the insulating tape (1) of high heat conductivity to form an insulated electric winding with superior electric characteristics.

A metal/insulator tunnel transistor with 16 nm channel length

Abstract: A nanometer transistor, metal/insulator tunnel transistor (MITT), which consists of only metal and insulator is experimentally studied. In the MITT, the Fowler–Nordheim tunneling currents through an insulator in lateral metal/insulator/metal structure are controlled by changing a voltage at a gate electrode upon the middle insulator, due to variation of tunnel-barrier thickness at the insulator. It is demonstrated that the MITT with 16 nm channel length fabricated by conventional photolithography can operate similarly to the conventional metal/oxide/semiconductor field-effect transistor with on/off ratio of current larger than 105. The result indicates that the MITT is a promising candidate for future switching transistors in ultralarge scale integrated circuits.

Spark plug, alumina insulator for spark plug, and method of manufacturing the same

Abstract: An insulating material mainly containing alumina and having a Na content of a range from 0.07 to 0.5 weight % in terms of Na2O. Such a Na content is fairly high and has conventionally been thought absurd. The insulation resistance at high temperatures and the mechanical strength are unexpectedly not low. The material has a good performance compared to those of conventional insulating materials having Na contents lower than that of the material of the invention. As a result, in place of conventional low-soda alumina, intermediate-soda alumina or plain-soda alumina which are much more inexpensive. The manufacturing cost of an insulator (2) for spark plugs and further the manufacturing cost of a spark plug (100) made thereof can be drastically lowered.

Method of forming thick-film hybrid circuit on a metal circuit board

Abstract: A hybrid circuit structure that includes a metal substrate, an inorganic electrical insulator layer and at least one inorganic thick-film passive circuit element, such as a thick-film resistor, capacitor or conductor. An interface layer is provided between the insulator layer and the circuit element to prevent the detrimental effects of interlayer diffusion. The composition of the interface layer is selected to prevent the diffusion of constituents from the inorganic insulator layer, and to have a CTE near that of the circuit element to reduce thermal fatigue. As a result, the passive circuit element can be formed of essentially any one of a number of conventional inorganic thick-film materials that are widely used on alumina substrates.

High-Q inductive elements

Abstract: A first insulator is formed on a base layer. A first conductor is formed on the first insulator. The first conductor is patterned. A second insulator is formed over the first insulator. A via hole is formed in the second insulator and is electrically coupled to the first conductor through the via hole. A second conductor is formed on the second insulator, and is electrically coupled to the first conductor by the via hole. The second conductor is patterned. A cavity is formed under the second conductor, and in the first and second insulators.