The effectiveness of Rad-Pak ICs for space-radiation hardening

Rad-Pak IC packages with radiation shields as an integral part of their structure have been designed and manufactured. Two styles were designed and fabricated assuming a fission-enhanced orbit: a 68 lead chip carrier designed to shield to the bremsstrahlung limit, and a 22 lead chip carrier providing forty-fold dose reduction. The accuracy of the computer models developed to design these packages was experimentally verified by irradiating dosimeters and functional ICs with 2-MeV electrons. The durability of the packages was demonstrated by testing samples of both designs to the test methods of MIL-STD-883C. There were no failures. The electrical and thermal characteristics of the Rad-Pak design were compared to those of standard IC packages of similar design. The shields were found to have only a slight effect on the electrical characteristics and to significantly improve the thermal properties of the Rad-Pak demonstration packages. Rad-Pak counterparts of some VHSIC packages have been designed. Computer studies of the efficiency of Rad-Pak packages as shields against ionizing radiation in space environments indicate weight savings as high as 80% over box shielding schemes. >