11,505 research outputs found
Research and development study on improvement of advanced radiation resistant modularization techniques Final report, 15 May - 30 Nov. 1964
Radiation-resistant modularization techniques for development of wrap-around solar cell - fabrication of modules on thin dielectric material containing printed circuit connection
Co-fired AlN–TiN assembly as a new substrate technology for high-temperature power electronics packaging
New wide-band gap semiconductors (SC) for power electronics such as SiC, GaN and diamond will allow higher power densities, leading to
higher operating temperatures. However, the surrounding materials will also undergo an increase in temperature, meaning that a parallel effort is needed in SC packaging technologies research. One of the essential components, the substrate, is used to insulate electrically the SC from the rest of the system, drain the generated heat and provide a path to connect the SC to the rest of the system. Direct bonded copper (DBC) and active metal-brazed (AMB) substrates have limited temperature and cycling operation, owing to the large differences in the thermal expansion coefficients between the ceramics and the metals. In this work we propose a new and original substrate technology based on two co-sintered ceramics: an insulating ceramic (AlN) and a conductive one (TIN). The microstructure, the chemical compatibility and the electrical properties indicate that the proposed substrate could operate at a temperature above 200 1C the current substrate technologies, which makes it particularly attractive for high-temperature power electronics applications
High-Temperature, Wirebondless, Injection-Molded, Ultra-Compact Hybrid Power Module
Silicon carbide (SiC)and other wide band-gap semiconductors offer great promise of high power rating, high operating temperature, simple thermal managment, and ultra-high power density for both military and commercial power electronic systems. However, this great potential is seriously limited by the lack of reliabe high temperature device packaging technology. This invention is to provide a cost-effective, ultra-compact, hybrid power module packaging technology that allows device operation at over 300 degrees Celcius to leverage recent advances in SiCi and other wide band-gap semiconductor material. The inention is based on the use of double metal leadframes directly bonded o the front and backside of semiconductor chips, and injection molded high temperature polymer materials to form the module encapsulation. The invention eliminates the use of the unreliable metal wirebonds and solder joints, and expensive aluminum nitride ceramic substrate commonly used in prior-art conventional a
Radical Fluoroalkylation Reactions
Recent protocols and reactions for catalytic radical perfluoroalkylations will be described. The production of perfluoroalkyl radicals (RF = CnF2n+1, n ≥ 2), which effect both addition and substitution reactions on organic substrates, can be realized through a range of diverse methods such as the well-established visible-light transition-metal-mediated photocatalysis, organic-dye-photocatalyzed reactions, electron donor-acceptor complexes, and more recently frustrated Lewis pairs. Thus, perfluoroalkylation reactions of carbon-carbon multiple bonds, isocyanides, nitrones, hydrazones, β-keto esters, α-cyano arylacetates, sulfides, and (hetero)arenes will be described. Special emphasis will be placed on examples published after 2015, where higher fluorinated series of fluoroalkylating reagents are studied.Fil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cooke, María Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Postigo, A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentin
Near-Field UHF RFID Transponder with a Screen-Printed Graphene Antenna
As a method of producing RFID tags, printed graphene provides a low-cost and
eco-friendly alternative to the etching of aluminum or copper. The high
resistivity of graphene, however, sets a challenge for the antenna design. In
practice, it has led to using very large antennas in the UHF RFID far field
tags demonstrated before. Using inductive near field as the coupling method
between the reader and the tag is an alternative to the radiating far field
also at UHF. The read range of such a near field tag is very short, but, on the
other hand, the tag is extremely simple and small. In this paper, near field
UHF RFID transponders with screen-printed graphene antennas are presented and
the effect of the dimensions of the tag and the attachment method of the
microchip studied. The attachment of the microchip is an important step of the
fabrication process of a tag that has its impact on the final cost of a tag. Of
the tags demonstrated, even the smallest one with the outer dimensions of 21 mm
* 18 mm and the chip attached with isotropic conductive adhesive (ICA) was
readable from a distance of 10 mm with an RF power marginal of 19 dB, which
demonstrates that an operational and small graphene-based UHF RFID tag can be
fabricated with low-cost industrial processes.Comment: 8 pages, 9 figures. IEEE Transactions on Components, Packaging and
Manufacturing Technology, 201
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