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Thanks God, yesterday i’ve finished to presented my final project and i got ‘A’ for all my hard work in 3 months. This is a very great news and also a little bad news for me. The great news is, now i’m free until the graduation date. And a little bad news is, i must find a real job for my new life Thanks God, yesterday i’ve finished to presented my final project and i got ‘A’ for all my hard wis, i must find a real job for
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For many critical electronic applications, there is a need for dielectric systems that exhibit better electrical insulation performance than epoxies and other conventional materials. In the production of advanced telecommunications, high-speed electronic and microwave equipment as well as radomes and other products being developed today throughout the world, manufacturers rely on materials such as Teflon®, cyanate esters, and cyanate ester/epoxy blends to meet their performance requirements. However, these materials feature disadvantages that can make them costly and difficult to use as dielectrics in some of these demanding applications. We have an active research program to develop novel new thermosetting polymers with low Dk/Df properties. This paper focuses on the testing of one of these materials as a base resin for PWB multilayers. This new system may also have applications outside the scope of this study.
1.0 Introduction Organic polymers play a very important role in the manufacture of composite PWBs. Among the materials that have been used for building complex electronics are epoxies, phenolics, bismaleimides and cyanate esters. These polymers exhibit the required electrical insulation, thermal properties, chemical resistance and mechanical strength necessary for the applications. Two of the most important measures of a polymer’s ability to perform as a PWB resin system are the dielectric constant [Dk] and the dissipation factor [Df]. The dielectric constant determines the speed of the electronic signal in the PWB. The Df represents the dielectric loss of the signal in the circuit. Both values affect the size of the PWB and the signal quality. In addition, the size of the copper conductors and the insulation space on the PWB are affected by the Dk/Df values. Low Dk and Df characteristics will result in faster signal speeds with lower loss of power in the PWB. Therefore, resins with low Dk/Df properties support the production of small PWBs with close line/conductor spaces. One of the Huntsman materials currently under study for building PWBs is a new benzoxazine. Benzoxazines as a product family are good candidates for complex electronics because they:
Although this class of products also has good electrical properties with low Dk and Df values, the Dk/Df properties are not stable at all frequencies. When these materials are tested at ≥1 GHz, their Dk/Df values increase substantially. As a result these systems are difficult to use for electronics that operate at higher frequencies. Recently, we developed a new experimental material with electrical properties that remain stable at frequencies in the gigahertz range.
A dielectric is a nonconducting substance, i.e. an insulator. The term was coined by William Whewell in response to a request from Michael Faraday.[1] Although “dielectric” and “insulator” are generally considered synonymous, the term “dielectric” is more often used when considering the effect of alternating electric fields on the substance while “insulator” is more often used when the material is being used to withstand a high electric field.[citation needed] Von Hippel, in his seminal book, takes this definition further, stating: Dielectrics… are not a narrow class of so-called insulators, but the broad expanse of nonmetals considered from the standpoint of their interaction with electric, magnetic, of electromagnetic fields. Thus we are concerned with gases as well as with liquids and solids, and with the storage of electric and magnetic energy as well as its dissipation.[2] Dielectrics is the study of dielectric materials and involves physical models to describe how an electric field behaves inside a material. It is characterized by how an electric field interacts with an atom and is therefore possible to approach from either a classical interpretation or a quantum one. Many phenomena in electronics, solid state and optical physics can be described using the underlying assumptions of the dielectric model. This can mean that the same mathematical objects can go by many different names.
Spectrum Control, Inc. introduces an EMI filter plate with special epoxy potting and a rubber pin protector for applications where rough handling or challenging environmental conditions are typical. Spectrum’s value added filter plates utilize ceramic capacitors as the filter element and the special potting protects their electrical and mechanical integrity during shipping and typical use. The epoxy potting reduces the likelihood of any physical stresses, which might crack the capacitors and cause them to fail. Additionally, Spectrum has added a rubber pin protector to prevent the leads from being bent during transit and handling. Bent leads could also cause the capacitors to crack as well as prevent a proper union with a connector. Spectrum’s filter plates are available in Easy Mate® , Easy Mate® Jr., bolt-in and shrouded latch styles. These plates provide an EMI filtered signal line between electronic modules, excellent isolation from 5 MHz to 18 GHz, and are available in a variety of plate sizes and up to 74 lines per plate in hi-density (2mm) and 60 pins per plate in standard density (.100″) configurations. Spectrum offers a variety of value added features to meet customer manufacturing needs, as well as designing plates that meet the most stringent high reliability specifications. In addition to epoxy potting and pin protectors, Spectrum provides custom assemblies with varying cable lengths and terminations, ribbon connectors, filtered headers, flat conductor cables and lead stabilizers. Spectrum Control’s epoxy potted filter plates with pin protector have pricing ranging from $20 to $100 depending on configurations and quantities required. These value added filter plates are ideal for medical, telecom, aerospace and industrial applications where rough handling would adversely affect its stability. About Spectrum Control The Spectrum Control Signal & Power Integrity Group produces discrete surface mount EMI filters, resin sealed and hermetically sealed EMI filters, EMI filtered arrays, EMI filtered connectors, ESD/EFT protected connectors, filtered data-com connectors, gaskets and shielding, patch antenna elements, single line filters, filtered terminal blocks, power entry modules, power line filters, military/aerospace multi-section filters, and commercial custom assemblies. Spectrum Power Management Systems produces AC and DC power distribution and remote management systems. Products include off-the-shelf SMART start products as well as customized products or systems designed to suit specific user requirements. DC power circuit breaker and fuse interface panels, power outlet strips and data acquisition modules are also offered. Spectrum Microwave is a wholly owned subsidiary of Spectrum Control, Inc. and produces a wide range of microwave components and systems. Integrated Microwave Systems include switchable filter banks, low noise amplifiers, local oscillator multipliers, microwave synthesizers, digitally tuned oscillators and integrated assemblies. Microwave Filters include bandpass filters and duplexers, lumped element filters, cavity filters, waveguide filters, tubular filters, base station products and resonators. Frequency Control Components include a wide range of amplifiers, mixers, voltage-controlled oscillators (VCOs) and dielectric resonator oscillators (DROs). Spectrum Sensors & Controls Precision Positioning Sensors Operation manufactures a variety of precision co-molded conductive plastic potentiometers and position sensors, as well as element segments and cable assemblies. Designs for these potentiometers and position sensors include rotary, motorized, hollow shaft, linear and fader types, as well as custom assemblies. The company’s Advanced Thermal Products Operation produces temperature sensing probes and assemblies, PTC and NTC thermistors and resistive temperature detectors (RTDs).
Phase Locked Dielectric Resonator Oscillators (PDROs) are widely used in both commercial and military applications. PDROs offer low cost, small size, low noise, efficient power consumption and high reliability required for local oscillator generation in commercial applications such as modern radar, communication, and test instrumentation systems. PDROs offers lower phase noise, lower spurious, smaller size, millimeter wave frequencies of operation, and higher output power options. The standard PDRO consists of a BJT or GaAs MESFET fundamental Voltage Tuned Dielectric Resonator Oscillator (VTDRO) which is phase locked via a sampling loop to a low noise crystal oscillator reference. The phase locked loop (PLL) acts as a low pass filter to the multiplied up reference phase noise and as a high pass filter to the VTDRO’s phase noise. Through the use of proprietary sampling phase locked loop circuitry, single loop PDRO models provide exceptionally low phase noise, typically -120 dBc at 10 kHz offset from a 13 GHz carrier when phase locked to an external 100 MHz crystal reference. This proprietary low loop phase noise floor, along with the inherent low phase noise of the VTDRO, allows the use of wide loop bandwidths of approximately 200kHz to 300kHz. Wide loop bandwidths enable low microphonics and phase hit free operation, two critical parameters in both commercial and military systems. Electronic Engineering Services
TT electronics IRC has raised the dielectric withstanding voltage of its high density power resistors to 4000Vac. Designated the MHP150 through MHP600 Series, the resistors are offered in power ratings ranging from 150W to 600W. The robust high voltage, high power resistors are designed for high voltage motor drives and military and medical x-ray equipment, along with pulse generators, high frequency amplifiers and power supply snubbers. “The wide range of power ratings not only allows design engineers to specify the appropriate resistor to meet their specific application, but customers are now able to employ these resistors in high voltage circuits as well,” said Gary Bleasdell, thick film business unit director for IRC. “Along with the high dielectric withstanding voltage rating, the SOT-227 style resistors also feature extremely low thermal resistance, high impulse power capability, superior vibration handling, and an extremely low series inductance of less than 15nH.” The UL94V0-approved MHP150 to MHP600 series resistors feature power ratings of 150-, 200-, 250-, 300-, 550- and 600W, with a dielectric withstanding voltage rating to 4,000Vac. Resistance range is from 0.1Ω to 1KΩ, with tolerances available from ±1 percent to ±5 percent, and TCRs of ±100ppm/°C when R>=1Ω, and ±250ppm/°C when R<=1Ω. Operating temperature range is -55°C to +120°C. IRC will also produce devices outside these specifications to meet customer requirements.
Dielectric Communications has provided antennas, transmission line, and a complete RF system for a new tower site that has brought high-power DTV broadcasts to the Denver metropolitan area. The new installation serves Lake Cedar Group, an organization that represents Gannett Broadcasting-owned KTVD (a MyNetworkTV affiliate) and KUSA (an NBC affiliate), McGraw Hill-owned ABC affiliate KMGH, and CBS owned-and-operated KCNC. The system is currently on air and broadcasting signals for all four stations. “There were a number of technical and logistical challenges that we faced in the design of this system and in obtaining support from the surrounding community, so we’re very pleased to have this transmission site completed and on the air,” said Lake Cedar Group General Manager Don Perez. “We selected Dielectric to provide the antenna and transmission line for this project based on its previous engineering successes, technical abilities, and competitive pricing. We felt confident Dielectric would be a great partner in getting these stations on air with high-power digital transmissions.” This custom-designed RF system with three VHF antennas and three UHF antennas allows six channels to operate in both main and alternate configurations for VHF channels 7 and 9 and UHF channels 16, 17, 19, and 33. Previously, the channels were limited to transmitting low-power digital signals from the tallest building in downtown Denver. By airing signals from the new 730-foot tower located on Lookout Mountain west of Denver, KCNC, KMGH, KTVD, and KUSA benefit from greater transmission performance and streamlined, merged operations that reduce the number of towers visible on the mountain. Unique in its consolidation of several major network broadcasters on a single tower, the installation is further distinguished by the construction of a 250-foot underground tunnel that houses the 10 phased transmission line runs. The tunnel was designed to reduce impact on the appearance of the mountain, maintaining as much of an uninterrupted ridgeline as possible. “Lake Cedar Group had significant technical hurdles to clear in getting this project off the ground, so we’re very pleased to see the project completed with all four stations successfully on the air,” said Dielectric President Garrett VanAtta. “Our engineering staff worked closely with the group to fine-tune the signal patterns and ensure that, even as a consolidated tower site, this installation would meet the individual needs of each member station.”
Key Specifications/Special Features:
Industrial-scale filter dryers, equipped with one or more microwave input ports, have been modelled with the aim of detecting existing criticalities, proposing possible solutions and optimizing the overall system efficiency and treatment homogeneity. Three different loading conditions have been simulated, namely the empty applicator, the applicator partially loaded by both a high-loss and low loss load whose dielectric properties correspond to the one measured on real products. Modeling results allowed for the implementation of improvements to the original design such as the insertion of a wave guide transition and a properly designed pressure window, modification of the microwave inlet\’s position and orientation, alteration of the nozzles\’ geometry and distribution, and changing of the cleaning metallic torus dimensions and position. Experimental testing on representative loads, as well as in production sites, allowed for the confirmation of the validity of the implemented improvements, thus showing how numerical simulation can assist the designer in removing critical features and improving equipment performances when moving from conventional heating to hybrid microwave-assisted processing.
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