Development of a High Voltage and High Current Transcalent Transistor.
Final technical rept.,
RCA CORP LANCASTER PA SSD-ELECTRO-OPTICS AND DEVICES
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All of the objectives of the contract were obtained or exceeded. An NPN Transcalent transistor was developed which was capable of blocking 800 to 1000 volts and of switching up to 150 amperes. A 500 watts dissipation capability was demonstrated as well as very fast switching times. To achieve these goals, a novel emitter ballast resistor was made a portion of the assembly. This ballast resistor forces current sharing to all areas of the emitter on the transistor chip. The Transcalent transistor uses two heat-pipes as an integral part of the package to cool the silicon transistor chip and its integral ballast resistor. With heat-pipe cooling of the device, it has been demonstrated that 523 watts of heat can be dissipated from the package. A thermal resistance as low as 0.20 Cwatt has been observed between the junction and the base of the fins attached to the heat-pipes. The thermal resistance between the junction and 25 C ambient air flowing at 1650 feet per minute was found to be only 0.35 Cwatt. The switching speeds of the Transcalent transistor are very fast, less than 1.0 microsecond turn-on time and 2.0 microseconds turn-off time. A large area Safe Operating Curve was determined from the second breakdown, current gain, saturation and sustaining voltage characteristics measured during the contract. Besides the exceptional electrical and thermal characteristics, the Transcalent transistor provides reductions in size, weight and ease of installation when compared to other large power transistors and their externally attached heat sinks.
- Electrical and Electronic Equipment
- Solid State Physics