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Irradiated Electronic Reliability Study
AIR FORCE WEAPONS LAB KIRTLAND AFB NM
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In 1969 the U.S. Air Force withdrew approximately 790 modules of electronics circuitry, in the form of 10 operational guidance and control systems, from the field and irradiated them. A module consists of an average of about 25 small scale integrated circuits, 45 discrete semiconductor devices, and miscellaneous R, L, and C components. The average total dose used was approximately 1800 radsSi of 4.2 MeV mean bremsstrahlung. This dose was distributed over 8 to 10 pulses per system, with average half power width approximately 72 nanoseconds per pulse. The average over all modules maximum half-power-point-rate was about 8.4E9 radsSisec. The irradiated modules were then returned to field service. A primary objective of the radiation tests was to determine the photocurrent induced latchup susceptibility of the guidance and control system to known short duration pulses of radiation. The purpose of this report, in contrast, is to indicate how that radiation testing affected the longer term reliability of the electronics circuitry via certain other mechanisms, assuming that any immediately obvious radiation damage was corrected. Six years later, in 1975, failure and repair records were analyzed statistically to determine whether the radiation had functionally affected the electronics. There remained 650 irradiated modules available for this statistical analysis after culling. These modules had been carefully associated by individual serial number with approximately 1050 modules in field use which were not irradiated and which served as controls.
APPROVED FOR PUBLIC RELEASE