Investigation of Novel Heat Removal Techniques for Power Transistors.

摘要

The feasibility of new cooling methods for VHF power transistors capable of providing a reduction in junction temperature of 33%,compared to conventionally packaged devices was investigated. Design objective for the transistors are 25watts CW power from a 28-volt supply with a minimum power gain of 6dB. The electrical characteristics of the devices are to be within 10% of conventional devices,the volume no more than 4times,and the weight no more than 5times that of equivalent hermetically sealed devices. Achievement of these objectives was based on the application of heat pipe cooling techniques to the chip surface,within a standard TO-package. The conclusions to be drawn from the program are that the cooling method provides significant improvement in the thermal characteristics of the VHF power transistors without loss of RF performance. No significant deterioration of performance was noted in the extended duration high temperature testing. These goals were achieved without significant change in the transistor case size or weight. The cooling techniques demonstrated on this program are recommended for production development. (Author)