Radiation is an important factor in the space environment. It degrades materials and also integrated circuits. The knowledge about the behaviour of electronic components in the space environment allow to design reliable electronics which can comply with the mission requirements.
a) TOTAL IONIZING DOSE (TID)
The TID test uses a Gamma source to irradiate the components. This radiation ages the electronics. The Gamma source consists in a Cobalt-60 pill protected in a lead box. From a small window on the front size the gamma ray will be irradiated. The DUT will be fixed in front of the window in the adequate distance. By changing the distance between the DUT and the source the radiation dose will be adjusted. The irradiation area is normally big. Depends of the source strength it can be typical 1 m2. The ESA published for the TID test the standard ESCC 22900 “Total Dose Steady-State Irradiation Test Method” where the TID test is specified.
In this test the main activity is related with the characterization of the components (DUT). Taking a diode as example the characteristic curve will be measured during test and with the increment of the radiation dose the characteristic curve will change or move. It is common to observe that the power consumption increases. The accumulated doses uses the old unit “krad” (kilo-rad). 1 rad = 0.01 Gy (Gray) = 0.01J/kg. Following ECSS standard for TID the accumulated dose should be 100 krad at the end of the test. For Hi-Rel components typical will be tested until 300 krad. It is possible that the DUT is not robust enough and in the middle of the test will be destroyed. In such a case the test will end earlier.
The MIL-STD-883 Method 1019.8 can also be applied for this test.
ELDRS (ENHACED LOW DOSE RADIATION)
In the last years the Enhanced Low Dose Rate Sensitivity (ELDRS) is considered a serious concern for MEO, GEO and deep space missions. In the ELDRS test the device degradation increases when the TID dose rate decreases. ELDRS affects mainly bipolar technologies.
The ESCC-22900 and the MIL-STD-883 Method 1019.8 will be applied for this test.
b) SINGLE EVENT EFFECTS (SEE)
This test has the purpose to reproduce effects of charged particle in semiconductors. These effects distort digital information or even worse can destroy the component. The device will process data during the irradiation and soft error will be detected and counted.
For this test the standard ESCC-25100 (Single Event Effects Test Method and Guidelines) will be applied.
The irradiation of semiconductor components with Protons is needed to investigate the Displacement Damage in the semiconductor lattice. A particle accelerator will generated the Proton beam. For this test no vacuum environment is needed.
Heavy Ions will speed up with a particle accelerator and focussed in the “naked” (Decapping) IC. The irradiation of the component with a Heavy Ions Cocktail request a vacuum environment.