Alexander Teverovsky, QSS Group, Inc./NASA Goddard Operations
Alexander.A.Teverovsky.1@gsfc.nasa.gov
301.286.6216
NASA GSFC, Code 562, Greenbelt, MD 20771

Abstract

Temperature excursions can change mechanical stresses in plastic encapsulated microcircuits (PEMs) and cause parametric shifts (temperature hysteresis) in characteristics of linear devices. Exposure of linear PEMs to extreme temperatures during deep space missions might cause significant errors and failures in sensitive circuits. However, this phenomenon, its temperature dependence, and the rate of relaxation have not been adequately investigated, in particular, as applicable to voltage reference microcircuits.

In this work, characteristics of precision voltage reference PEMs (Linear Technology LT1461 and Analog Devices AD780 AR and BR parts) have been evaluated in the temperature range from -120 oC to +160 oC. Parametric shifts as a result of extreme temperature excursions were measured at room temperature and monitored during long-term relaxation at temperatures from room to +85 oC.

Results showed that without load, the output voltage of the parts remain within +3,000 ppm tolerance at temperatures up to +160 oC and -3,000 ppm at temperatures down to

-120 oC. However, under the load (Iout = 10 mA) failures occurred at temperatures below -100 oC and above +140 oC. It has been shown that even a short-term (15 minutes) low temperature

(-65 oC to -120 oC) exposure of the parts causes output voltage shift of 100 to 200 ppm, which is large enough to cause failures in sensitive systems with resolutions of 12 bits and higher. Excessive moisture content in the molding compound of the package increases parametric shifts after the low temperature exposure to 500 – 700 ppm. Measurements within 1,000 hours did not reveal any significant relaxation in the voltage output at temperatures below ~75 oC. A physical mechanism of the parametric shift is discussed.

This work was performed as a part of NEPP PEMs’ evaluation activities, and the full report will be posted on the NEPP Web site when it has been completed.