beryllia


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beryllia

[bə′ril·ē·ə]
(inorganic chemistry)
References in periodicals archive ?
The simulation model includes a novel rectangular copper-plated helix tape made of Molybdenum, three rectangular support rods made of Beryllia, and a copper-plated stainless steel shell.
Ceramic materials such as beryllia and alumina may be measured accurately from the microwave to the millimeter-wave band in a Courtney resonator.
Aluinum nitride was developed as a non-toxic alternative to beryllia. These custom thin film circuits can be produced as conductor networks, or as resistor networks.
American Beryllia Inc 973-248-8080 www.americanberyllia.com
Material CTE [10.sup.6]/ W/mK @25 [degrees]C @25 [degrees]C Metals Kovar (FeNiCo) 5.5 17 Copper 17 400 Molybdenum 5.2 139 Nickel 14 90 Semiconductors Silicon 2.8 145 Gallium Arsenide (GaAs) 5.7 33 Germanium 5.8 60 Ceramics (substrates) Alumina 6.7 24 Beryllia 8.0 298 Aluminum Nitride 4.5 160 Silica 0.8 2 Organic Material (substrates) FR-4 (epoxy-glass) 16 0.1 Polyimide 30-60 0.1-0.2 CTE, W/mK of common materials used for microelectronic packages.
From loss tangents to realizable line widths, lending materials manufactures will present the electrical parameters for substrate materials such as High Temperature Cofired Ceramics, Low Temperature Cofinsi Ceramic, Ceramic Filled Fluoropolymers, PTFE and thermoset composites, Beryllia Ceramic, SU-8, and Liquid Crystal Polymer.
TABLE I TYPICAL PROPERTIES OF 85W/15Cu COMPOSITE Characteristic Standard Enhanced Thermal conductivity 170 207 (W/mK) Electrical conductivity 31 43 (% IACS) Young's modulus (GPa) 274 298 Thermal capacity(J/cc K) 2.95 2.78 TABLE II COMPOSITIONS TYPICALLY USED FOR COMMON PACKAGING MATERIALS Device/Substrate Typical Material Grade(s) GaAs MMIC-mount/ 85W/15Cu, heat spreader 87W/13Cu, 90W/10Cu Alumina ceramic 85W/15Cu, carrier/flange 87W/13Cu Beryllia ceramic 82W/18Cu carrier/flange Also very common are carriers onto which circuits are built for inclusion into a larger system.
Thin-film microwave circuits requiring high thermal transfer capability can be manufactured on as-fired beryllia substrates.
However, processing of [BeF.sub.2] involves the use of highly toxic beryllia, and handling techniques for practical production techniques will have to be developed.