Kovar

Note: A nickel-iron-cobalt controlled-expansion alloy containing 29% nickel. Its coefficient of expansion, which decreases with rising temperature to the inflection point, matches the expansion rate of borosilicate glasses and alumina ceramics. Used for glass-to-metal seals in applications requiring high reliability or resistance to thermal shock. Examples are high-power transmitting valves, transistor leads and headers, integrated-circuit lead frames, and photography flash bulbs. Chemistry By % Weight C: 0.02% Max Co: 17% Fe: Balance Mn: 0.3% Ni: 29% Si: 0.2% Coefficient of Thermal Expansion (Nominal): 30°C - 200°C 5.5 (x 10-6 m/m · K) 30°C - 600°C 7.9 30°C - 300°C 5.1 30°C - 700°C 9.3 30°C - 400°C 4.9 30°C - 800°C 10.4 30°C - 450°C 5.3 30°C - 900°C 11.5 30°C - 500°C 6.2 Applications Power tubes, microwave tubes, transistors, diodes, hybrid packages, and other kinds of scientific instruments. Available Product Forms: Tube, strip and sheet, wire and round bar, etc.