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The conflict of longevity of satellite's service and limited life of Sterling cooler decides that coolers should work on the
intermittent mode in space. As a result, The HgCdTe (MCT) infrared (IR) detectors in satellite are commonly subjected
to thousands of repeated thermal cycles from below -173°C to room temperature (20°C), which brings some new
reliability problems. Especially the mismatch of coefficient of thermal expansion (CTE) of different materials may lead
to some unfamiliar failure modes with such low temperature and nearly 200°C span of thermal cycles. In order to study
the characteristics of MCT detectors under the stress of thermal cycles, this paper introduced a special automatic system.
The system is mainly composed of a sub-container of liquid nitrogen, a heater controlled by the PID hardware, and an
object stage on which the MCT detectors to be tested are mounted. Furthermore, the sub-container, the heater and the
stage are positioned in a large vacuum tank. In the course of thermal cycles, the object stage moved up and down with
MCT detectors is driven by a step motor. When it rises to the bottom of liquid nitrogen sub-container, the stage is to be
cooled with detectors, and when declines to the heater, the stage to be heated with detectors, too. At last, two long
wavelength MCT detector samples are tested with this equipment, and the resistance, the signal and the noise are
measured. It shows that all the pixels' resistance didn't change beyond 5% after 5000 cycles. However, the tested signal
of the last pixel of both detectors increased sharply after 1000 cycles, and fell to normal level after 5000 cycles, with its
noise altering a little from beginning to end. A deduction is given in this paper for this phenomenon. In accordance, the
thermal cycle equipment and the experimental data, would supply some references to the design and fabrication of MCT
IR detectors.
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