Omnirel readies ceramic power- switching modules for electric aircraft

Engineers at the AlliedSignal Aerospace/ Aerospace Equipment Systems division in Torrance, Calif., are looking for a rugged, yet inexpensive high-power switch module for aircraft power conditioning systems and for the new breed of electric control actuators for military and commercial aircraft.

May 1st, 1998
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Editor's note: Omnirel was purchased in 2000 by International Rectifier in El Segundo, Calif., and now is part of the International Rectifier HiRel Products segment in Leominster, Mass.

Engineers at the AlliedSignal Aerospace/ Aerospace Equipment Systems division in Torrance, Calif., are looking for a rugged, yet inexpensive high-power switch module for aircraft power conditioning systems and for the new breed of electric control actuators for military and commercial aircraft.

Among the requirements that Allied-Signal engineers must meet in their aerospace designs are hermetically sealed parts that are immune to the environmental effects of humidity and salt spray, resist shock and vibration, and have the ability to handle high amounts of electric current.

The AlliedSignal designers believe they have found their solution in the new CERMOD hermetic high-power insulated gate bipolar transistor (IGBT) from Omnirel Corp. in Leominster, Mass.

CERMOD, which Omnirel officials are introducing this month, represents a substantial departure from existing high-power switch modules, which tend to be either in plastic packaging, or in classic hybrid packaging of baseplate, ring frame with glass-to-metal sealed leads, and a welded cover.

CERMOD uses a ceramic cover as the hermetic enclosure. Using ceramic packaging, rather than metal, reduces cost, lightens weight, and offers even better performance than classic hybrid devices, in part, because the ceramic cover has the same thermal coefficient of expansion as the ceramic components inside the package.

"This device really looks attractive, especially for our business," says Evgeni Ganev, systems engineer in the Allied- Signal Aerospace/Aerospace Equipment Systems power management and generation systems section.

Ganev and his colleagues design aircraft propulsion engine controls, air data systems, hydraulic and pneumatic valves, quartz pressure sensors, jet engine controls, monitoring and diagnostic systems, environmental control systems, cabin pressurization systems, starters, generators, power management systems, aerospace fire and smoke detection equipment, and ground test equipment.

"We use high-power switch modules based on classic hybrid technology, but we are looking for something cheaper," Ganev explains. "Our applications are mostly military, so plastics do not comply with our environmental requirements. We need hermetic sealing."

Three aspects of Omnirel`s CERMOD technology are attracting the attention of Ganev and other electronic systems designers in the aerospace and defense industry - cost, reliability, and power handling.

Omnirel officials claim their CERMOD devices will be slightly more expensive than plastic-packaged power switches, but will be about three times less expensive than metal-packaged hybrids.

For CERMOD, in addition, "the reliability is better, and they can handle higher current, Ganev says. "Hybrids use wire bonding between terminals and power connectors. There are up to 10 wires, and it is not a reliable way to design a part. But CERMOD does direct copper bonding between power devices and terminals."

CERMOD uses non-punch-through IGBT and soft-recovery diode technology, which minimize the effects of the tailing current, Omnirel officials say. These devices will operate over the military temperature range of -55 degrees Celsius to 125 C.

Prime applications for CERMOD devices include power controllers for aircraft power-distribution systems, and fly-by-wire power actuators, says Tim Hickey, Omnirel`s director of international sales and marketing.

Although Omnirel officials are only offering CERMOD in IGBT modules today, they will offer these devices as custom power MOSFETs within the next three to four months, and will offer CERMOD three-phase bridges for motor control within one year, Hickey says. - J.K.

For more information, contact Omnirel by phone at 978-534-5776, by fax at 978-537-4246, by post at 205 Crawford St., Leominster, Mass., 01453, or on the World Wide Web at http://www.omnirel.com/.

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The CERMOD hermetic high-power insulated gate bipolar transistor from Omnirel, depicted above, will give systems designers a new option - ceramic-packaged power devices that are more rugged than plastic packages, and less expensive than metal packages.

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